CVIndependent

Thu04272017

Last updateFri, 16 Sep 2016 12pm

Robert Victor

In April 2017, bright and steady Jupiter is likely the first “star” to be spotted after sunset, south of east. Twinkling, blue-white Sirius, in the southwest quadrant, is next. Jupiter is at opposition to the sun, and above the horizon all night, on April 7-8; you can estimate the hour by noting the planet’s location—low in the eastern sky at dusk, high in the south in the middle of night, and low in the western sky at dawn.

As morning twilight brightens, we find an even more spectacular planet, Venus, rising in the east, as Jupiter slinks off toward the western horizon. Before dawn brightens too much, locate Saturn in the south.

Our evening sky chart plots daily positions of the brightest objects in the current month’s sky at mid-twilight. As April begins, the most-prominent objects, in order of brightness, are steady yellow-white Jupiter, climbing in the east to southeast as the month progresses; twinkling blue-white Sirius in the south-southwest to southwest; golden Arcturus ascending in the east-northeast to east, to the far left of Jupiter; and Capella, high in the northwest.

Sirius and Capella mark extreme south and north points of the huge Winter Hexagon, encircling Betelgeuse and Orion’s three-star belt inside. The belt points the way to Sirius, the Dog Star, and in the opposite direction, to Aldebaran, eye of Taurus, the Bull. In clockwise order around the hexagon from Sirius, locate Procyon, Pollux (with his fainter twin brother Castor nearby, not plotted), Capella, Aldebaran, Rigel and then back to Sirius.

Preceding the Hex across the sky in April 2017 is faint Mars, itself preceded by Mercury, as bright as zero-magnitude Arcturus on April 1, but fading to first magnitude by April 6, and very sharply thereafter. The trailing Pollux-Procyon side of the Hex crosses due south into the western half of the sky in twilight at the start of April. Following is Regulus, heart of Leo, reaching south at month’s end. Still farther east in April 2017, we find Jupiter, with Spica close by, and Arcturus.

The moon in evening sky: On the evening of April 1, the crescent moon, about one-third full, appears several degrees to the upper left of Aldebaran. The waxing moon, moving eastward, remains within the Winter Hexagon for two more evenings, but by April 4, the now-gibbous moon has exited (in a maneuver known as Hexit), appearing to the left of the Pollux-Procyon line. On April 6, the moon passes closely south of Regulus. On the evening of Sunday, April 9, the moon appears about 9 degrees above Jupiter, and on Monday, April 10, the full moon appears 3-4 degrees to the lower left of Jupiter. That evening, the moon rises about 17 minutes before sunset. Using binoculars, can you spot Jupiter in daylight to the moon’s upper right? As the sky darkens, notice Spica 7 degrees to the lower right of the moon-Jupiter pair.

After the full moon of early spring, the moon rises later and farther south nightly. On Tuesday, April 11, moonrise occurs at 7:52 p.m.; on April 12, at 8:47 p.m.; on April 13, at 9:41 p.m.; on April 14, at 10:34 p.m.; and on April 15, at 11:25 p.m.

The moon in morning sky: From the full moon onward, it may be more convenient for most folks to follow the moon at dawn. On Sunday, April 10, one hour before sunrise, find bright Jupiter low in the west-southwest to west, with Spica 7 degrees to its left. The nearly full moon will be 7 degrees to Jupiter’s lower right. On the next morning, April 11, the moon, just past full, will appear 7 degrees to Jupiter’s upper left. By Saturday, April 15, the waning gibbous moon will appear in the south-southwest, about 10 degrees above Antares. On Easter Sunday, April 16, the moon will appear closely to the upper right of Saturn in the south, and on April 17, farther to Saturn’s upper left. While you’re up early enjoying the moon and Saturn those two mornings, add to your total of solar system objects by spotting brilliant Venus low in the east before Jupiter sets in the west-southwest to west. Our morning twilight sky chart shows all these stars and planets, plus Arcturus in the west, to the upper right of Jupiter, and Vega, passing just north of overhead. High in the eastern sky, Altair and Deneb complete the Summer Triangle with Vega.

By the morning of April 19, the moon will reach last quarter phase, half full and 90 degrees or one-quarter of a circle west of the sun. After April 19, the moon is a waning crescent, closer to the sun each day.

On Saturday, April 22 there won’t be much moonlight to interfere with the peak of the Lyrid meteor shower, best in the hour or two before first light of dawn. To see the greatest number of meteors, observe from a dark place, and get most of your viewing in before 4:30 a.m.

On Sunday, April 23, moonrise occurs at 4:27 a.m., with sunrise at 6:05 a.m. Look an hour before sunrise, and you’ll see a 12-percent crescent moon very low in the east to east-northeast, 7-8 degrees to the lower right of Venus. Slight optical aid will reveal Venus itself is a crescent, 20 percent illuminated that morning.

The Venus-moon pairing on April 23 isn’t particularly close—the next one, on May 22, will be much tighter and more impressive—but this is the first of eight monthly predawn Venus-moon pairings through November.

On Monday, April 24, moonrise occurs at 5:06 a.m., with sunrise at 6:04 a.m., so look about 40 minutes before sunrise, at 5:24 a.m., to catch the last old moon, a 5 percent crescent, 3 degrees up just south of due east, and 11 degrees to the lower left of Venus.

Some special sights for binoculars:

1. Venus in April 2017 appears in crescent phase, less than 3 percent full on April 1, while nearly one arcminute across. One arcminute is 1/60 of a degree, and the moon is about a half-degree in apparent diameter, so a magnification of just over 30-power used to observe Venus at the start of April makes it appear as large as the moon is with the unaided eye! Even 7-power binoculars reveal a crescent if Venus is observed in bright twilight or in daylight. As weeks pass, Venus recedes from Earth and shrinks in apparent size, as the crescent begins to fill.

2. Star clusters, including the Hyades with Aldebaran in the foreground. Aim binoculars at Aldebaran, placing that bright star in the upper left part of the field, and other stars within the field will complete the V-shaped head of Taurus, the Bull. Those fainter stars belong to the Hyades, about 150 light years away, compared to Aldebaran at 67 light years. Also, find Pleiades, or Seven Sisters: This compact star cluster, located about 400 light years away, can be found in April’s evening sky about 14 degrees to the lower right of Aldebaran.

3. Jupiter’s Galilean moons: As many as all four of Jupiter’s satellites discovered by Galileo in 1610 can be spotted in binoculars very close to the planet. The brightest and easiest to see is Ganymede, the biggest moon in our solar system, larger than Mercury! In its seven-day orbit, this month find it farthest west of Jupiter on weekends, April 1, 8 and 9, 15 and 16, 22 and 23, and 30. Fainter, wider-ranging Callisto, in its 17-day orbit, appears farthest east of Jupiter on April 2 and 19, and farthest west on April 10 and 27. Slower-moving, it remains easy to see for about two days before and after these dates.

4. The thin crescent moon with earthshine. The moon returns to evening sky on Thursday, April 27. Your first chance to see the waxing crescent moon of the next lunar month will be at dusk on April 27, when the moon of age 39 hours will be very low, between the west and west-northwest. About an hour after sunset, look for the 4-percent lunar crescent to the lower right of Aldebaran, and lower left of Mars and the Pleiades. On Friday, April 28, the thicker 10-percent lunar crescent will appear a few degrees to the upper left of Aldebaran. On both evenings, and perhaps for a few more, note the faint, bluish illumination on the dark, non-sunlit portion of the moon. This is earthshine, from sunlight reflected from Earth.

Star parties provide wonderful opportunities to join with other folks who love to share their interest in observing the sky, and to get great views of astronomical objects through a variety of binoculars and telescopes. The Astronomical Society of the Desert will host the last of the season’s monthly public star parties at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Saturday, April 1, from 7 to 10 p.m., and on Saturday, May 17, from 8 to 10 p.m. The Visitor Center is on Highway 74, within four miles south of Highway 111 in Palm Desert. Check www.astrorx.org for listings of our regular star parties and our high altitude star parties at Sawmill Trailhead starting at dusk. The next high-altitude star party (at 4,000 feet; wear warm clothes!) will be held on Saturday, April 22. Follow links to maps and directions to both star party sites.

Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

This month’s selection of happenings includes the last evening and first morning appearances of Venus; the year’s most favorable apparition of Mercury; early evening moonrises; simultaneous views of planets low above opposite horizons (Mars-Jupiter and Mercury-Jupiter in the evening, with Venus-Jupiter in the morning); and a bright, far southern star, Canopus, reaching its high point very low over our southern mountains.

Venus is still very prominent in the evening sky as this month opens, setting in a dark sky 2 1/2 hours after sunset on March 1. By March 17, Venus sets just one hour after sunset, and by March 21, Venus drops below the horizon barely half an hour after sunset. By that date, Venus is already rising ahead of the sun, and it’s possible to observe it at both dusk and dawn for a few days. Through a telescope or even 7-power binoculars, the planet displays a crescent—best observed in daytime, or in bright twilight.

Our evening sky chart plots daily positions of the brightest objects in the sky at mid-twilight, when the sun is 9 degrees below the horizon, about 40 minutes after sunset. As March begins, the most prominent objects, in order of brightness, are Venus in the west; Sirius in the south-southeast; Canopus very low, just east of due south; Capella just north of overhead; and Rigel in the south. As March runs its course, Venus descends the near side of her orbit and drops below the western horizon, but not before Mercury climbs into view on the far side of his orbit. For a few evenings, both planets are visible. They appear closest to each other on March 18, with emerging Mercury passing 8.5 degrees south (to the lower left) of departing Venus. In the eastern sky just before month’s end, bright Jupiter rises a few degrees south of due east, while golden Arcturus rises in the east-northeast.

Sirius and Capella mark extreme south and north vertices of the huge “Winter Hexagon,” with Betelgeuse and Orion’s belt inside. The belt points the way to Sirius, and in the opposite direction, to Aldebaran. Preceding the Hex across the sky in March is faint Mars, itself preceded by Venus or Mercury, or both planets for a few days starting in midmonth. The trailing Pollux-Procyon side of the Hex reaches due south at mid-twilight at the end of March. Following them is Regulus, heart of Leo, Still farther east, we find Jupiter and Arcturus rising into view later in the evening, or by mid-twilight at month’s end.

In morning twilight: Jupiter, in the southwest to west-southwest as dawn brightens, ranks first in brightness, until Venus emerges north of east late in the month. Before the sky brightens too much, note Spica 4-6 degrees to the lower left of Jupiter. The most prominent stars are golden Arcturus high in the west-southwest to west, far to the upper right of the Jupiter-Spica duo, and blue-white Vega, very high in the northeast. Next in brightness is steady yellow Saturn, in the south-southeast to south. Look also for Altair and Deneb, completing the Summer Triangle with Vega. Find twinkling reddish Antares to the west and south of Saturn.

On March 1, the 15 percent crescent moon appears well to the upper left of Venus and a few degrees left of Mars. The moon climbs much higher each evening, and on Saturday, March 4, the nearly half-lit moon will occult, or cover, the bright star Aldebaran, with a sudden disappearance behind the moon’s leading dark edge slated for 7:12 p.m., and reappearance for 8:30 p.m. Binoculars and maybe even the unaided eye will suffice for the first event, but a telescope will be required to catch the star’s reappearance at the moon’s bright edge.

The moon continues to march eastward, passing between Procyon and the Gemini twins, Pollux and Castor, by March 7, and getting past Regulus, heart of Leo, by the evening of March 10. On Saturday evening, March 11, the almost-full moon rises at 5:14 p.m., still before sunset, which occurs at 5:51 p.m. Remember to set your clocks one hour ahead, and you won’t be surprised by Sunday’s later sunset at 6:52 p.m., and moonrise (just past full) at 7:13 p.m. After moonrise on Wednesday, March 15, look for bright Jupiter nearby, with Spica just a few degrees to the lower right.

With daylight saving time shifting our sunrises an hour later, predawn sky-watching becomes more attractive. Look an hour before sunrise on March 14 and 15 for the waning gibbous moon with Jupiter nearby, in the southwest to west-southwest. Spica is to Jupiter’s lower left. On the weekend of March 18-19, find reddish twinkling Antares near the moon in the southern sky, with brighter, steady Saturn to their left. On Monday morning, March 20, the moon, nearly at last quarter phase and just over half full, will appear closely to the upper left of Saturn. A telescope reveals the planet’s amazing rings, tipped nearly 27 degrees from edge-on this year, the greatest angle possible.

See Venus at both dawn and dusk for a few days! Around March 20, start trying to observe Venus rising before the sun, even though it’s still also visible in the evening, setting after sunset. Binoculars will reveal Venus as a large, thin crescent, as little as 1 percent illuminated on March 23-26.

On March 25, at 6:22 a.m., about 20 minutes before sunrise, find the thin (8 percent) old crescent moon 12 degrees up in the east-southeast. Locate Venus 32 degrees farther left and 10 degrees lower, or 10 degrees north of east and only 2 degrees up. This is the day Venus appears at inferior conjunction, an unusually wide 8.3 degrees north of the sun and 1 percent illuminated. On Friday, March 26, at 6:21 a.m., find the 3 percent crescent moon 12 degrees south of east and 4 degrees up.

The young lunar crescent first appears in the evening on Tuesday, March 28, around 7:29 p.m., nearly due west, just 5 degrees up and a few degrees to the lower left of bright Mercury. The next evening, March 29, look for the 5 percent crescent moon 40 minutes after sunset, 15 degrees up and to the upper left of Mercury. As twilight deepens, look for dim Mars about 10 degrees above the moon and a little right. By Thursday evening, March 30, the moon will climb to the upper left of Mars. Watch for Jupiter rising 7 degrees south of east just more than half an hour after sunset. Can you observe the three evening planets, Mercury, Mars and Jupiter, simultaneously?

The Astronomical Society of the Desert will host the next in our series of monthly star parties on Saturday, March 4, from 6 to 9 p.m., and on Saturday, April 1, from 7 to 10 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Check www.astrorx.org. The next high-altitude star party at Sawmill Trailhead (at 4,000 feet—wear warm clothes!) will be held Saturday, March 25. Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

Venus reaches peak brilliance, near magnitude -4.9, in February’s evening sky—giving rise to lots of UFO reports!

Through a telescope or even 7-power binoculars, the planet displays an ever-larger and thinner crescent, especially if viewed in daytime or at sunset. Venus appears 39 percent full and a half-arcminute across on Feb. 1, and only 17 percent full and 0.8 arcminute across by Feb. 28. (One arcminute equals 1/60th of a degree.) Try locating Venus in daylight when it’s highest and due south: On Sunday, Feb. 5, Venus is 59 degrees up at 2:44 p.m.; Feb. 12, 62 degrees up at 2:32 p.m.; Feb. 19, 65 degrees up at 2:16 p.m.; Feb. 26, and 67 degrees up at 1:55 p.m.

Find Venus easily with the unaided eye by sunset or shortly thereafter, 45 degrees to the sun’s upper left, on Feb. 1, to 33 degrees directly above the setting sun on Feb. 28. At dusk, Venus is in the west-southwest to west, getting lower as month progresses. Much fainter Mars (about magnitude +1.2) is 5 to 12 degrees to its upper left. Next in brilliance after Venus is the blue-white twinkling “Dog Star” Sirius (the brightest star, at magnitude -1.5) in the southeast to south, and next is yellowish Capella, the Mother Goat star, just northeast to north of overhead. Sirius and Capella mark extreme south and north vertices of the huge “Winter Hexagon,” with Betelgeuse and Orion’s belt inside. At the start of February, Regulus, heart of Leo the Lion, rises north of east over an hour after sunset. By Feb. 17, it rises at sunset and can be seen all night long.

In morning twilight: Jupiter, well up in the southwest as dawn brightens, ranks first in brightness in this month’s morning sky. Before the sky brightens too much, note Spica,about 4 degrees away. Catch bright Mercury very low in the east-southeast in the first week. The most prominent stars at dawn are golden Arcturus, high above the Jupiter-Spica duo, and blue-white Vega, high in east-northeast. Look also for Altair and Deneb, completing the Summer Triangle with Vega. Find steady yellow Saturn in the southeast with twinkling reddish Antares to its right.

Changes in predawn sky: In mid-February each year, the Earth’s orbiting motion carries us in a direction between the stars Spica and Antares, toward a spot in the sky 90 degrees west of the sun. As we face between those stars before dawn in mid-February, we are looking out the “front window” of Spaceship Earth. Go out an hour before sunrise and visualize how the motions of the Earth and other planets, orbiting at different speeds, will change the positions of planets and stars in our predawn sky. Speedy Mercury is now pulling away from Earth, and in early February sinks into the solar glare and disappears on the far side of the sun. On the night of February 17-18, our planet will pass between the sun and Regulus, and that star will appear at opposition, visible all night, low in the east at dusk, high in the south in the middle of night, and low in the west at dawn. Regulus appears lower in the west each morning.

As for the moon: On Tuesday, Jan. 31, the four-day-old waxing crescent forms a beautiful compact gathering with Venus and Mars. For the next few evenings, Venus and Mars remain 5.4 degrees apart. Meanwhile the moon moves on, passing widely south of the Pleiades (Seven Sisters) star cluster on Feb. 4; skipping past Aldebaran, eye of Taurus, by Feb. 5; getting by the Gemini twins, Pollux and Castor, by Feb. 8; and reaching full and rising at sunset on Friday, Feb. 10. That evening, sunset and moonrise occur simultaneously at 5:26 p.m. (assuming no mountains block the view), but that’s almost 45 minutes too late to catch the moon in deepest penumbral eclipse. Tell your friends east of the Rocky Mountains to look for a slight dusky shading covering the left or upper left part of the moon at 5:44 p.m. MST, 6:44 p.m. CST, or 7:44 p.m. EST. A much more impressive total lunar eclipse will be visible on Jan. 31, 2018—when Californians will have a great view!

A bit later in the evening of Feb. 10, watch for the rising of Regulus below the moon. The moon closes in on that star for the rest of the night, until dawn. On subsequent evenings, watch the waning moon rise later each night, farther south each time: on Feb. 11 at 6:28 p.m.; on Feb. 12 at 7:28 p.m.; on Feb. 13 at 8:26 p.m.; on Feb. 14 at 9:23 p.m. Or you can shift your viewing times to mornings, about an hour before sunrise. On the morning of Feb. 15, look for the beautiful gathering of the waning gibbous moon, Jupiter and Spica in the southwest an hour before sunrise. By Feb. 19, a fat crescent moon will appear above Antares, heart of the Scorpion. On Feb. 20, the one-third-illuminated lunar crescent will appear above Saturn, in the south-southeast. In morning twilight on Feb. 24, the 5 percent crescent is still easy to see, but very low in the east-southeast. Spotting the thin old 1 percent crescent, 25 hours before new, some 25-30 minutes before sunrise on Feb. 25, will be very difficult, requiring binoculars and very clear skies.

After new moon on Feb. 26 at 6:58 a.m., our first chance to see the waxing crescent will be at dusk on Monday, Feb. 27, when the 1.5-day old 3 percent moon will be very low, just south of due west, and far below and a little left of Venus. At dusk on Feb. 28, the 8 percent crescent moon appears about 10 degrees to the lower left of Venus.

The Whitewater Preserve will be hosting a star party on Saturday, Jan. 28, weather permitting, beginning at 6:30 p.m. Reservations are requested at 760-325-7222.

The Astronomical Society of the Desert will host the next of our series of monthly star parties on Saturday, Feb. 4 and March 4, from 6 to 9 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Also, check www.astrorx.org for listings of our high altitude star parties at Sawmill Trailhead starting at dusk. The next high-altitude star party (at 4,000 feet—wear warm clothes!) will be Saturday, Feb. 18. Follow links to maps and directions to both star party sites, and for dates and locations of lecture meetings. The meeting at 7 p.m., Friday, Feb. 10, at the Portola Community Center in Palm Desert will feature astronomy author Dennis Mammana on “The Great American Total Eclipse: August 21, 2017.”

Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

In January, Venus dominates the evenings! Find it in the southwest to west-southwest, with Mars to its upper left. In the west to west-northwest, find the Summer Triangle of Vega, Altair and Deneb. Vega is its brightest member, and Altair is the first to depart, around mid-month, if mountains don’t block your view. Fomalhaut, to the lower left of the two planets, may be easily overlooked.

The eastern sky is filling up with winter’s jewels! The “Dog Star” blue-white Sirius (the brightest star) and the Little Dog Star Procyon, preceding it, rise into view below Orion’s bright shoulder, red Betelgeuse, and bright foot, blue Rigel. (Sirius, Procyon and Betelgeuse form the nearly equilateral Winter Triangle.) Follow Orion’s belt downward to Sirius, and upward to orange Aldebaran, eye of Taurus, the Bull. To the left of Orion, look for Pollux (with Castor, 4.5 degrees away). Midway between Orion’s belt and the North Star, look for bright, yellowish Capella, the Mother Goat star.

Meanwhile, Jupiter ranks first in brilliance in the dawn sky. Find it well up in the south to southwest, with Spica only 4 degrees away. High above them is golden Arcturus, brightest star of January mornings. Regulus sinks lower in the west-southwest to west as the month progresses. Still lower in the west to west-northwest, the last stars of the “Winter Hexagon”—Procyon, Pollux and Capella—make their exits. Low in the southeast morning twilight to the lower left of Saturn, Mercury brightens to magnitude 1 on Jan. 5, and to 0 on Jan. 11. These planets approach to within 7 degrees on Jan. 9, widening to 26 degrees by Jan. 31. Find red twinkling Antares to Saturn’s upper right. Blue-white Vega, ascending in the northeast to east-northeast, ranks next after Arcturus in brilliance. Altair emerges low in the east at midmonth, completing the Summer Triangle.

The first evening of the New Year, Sunday, Jan. 1, features a beautiful crescent moon a few degrees to the lower right of brilliant Venus. Notice dim reddish Mars starting this month within 12 degrees to the upper left of Venus. On the next evening, find a slightly thicker crescent moon between Venus and Mars, closer to Mars. In early January in the Coachella Valley, sunset still occurs before 5 p.m., so 6 p.m. is a great time to enjoy these moon-planet gatherings.

By Thursday evening, Jan. 5, the waxing moon has reached first quarter phase, 90 degrees (a quarter-circle) from the sun, and appears half-full. On Sunday night, Jan. 8-9, from dusk until moonset (after 3 a.m. on Monday), watch the gibbous moon gradually creep closer to Aldebaran. On Wednesday, Jan. 11, the moon rises about 20 minutes before sunset. Full late that night, the moon passes several degrees south of the stars Castor and Pollux in Gemini. Each year late in January’s second week, our planet Earth passes between the sun and the Twins, causing those stars to remain above the horizon all night.

By Thursday evening, Jan. 12, the moon has passed full and rises about 40 minutes after sunset. Taking time out to watch moonrises with those you love can be relaxing and fun! Here are times for Palm Springs: Thursday, Jan. 12, at 5:38 p.m.; Jan. 13 at 6:42 p.m.; and Jan. 14 at 7:45 p.m. From the Coachella Valley, with our mountain surroundings, it might take several extra minutes until the moon’s disk becomes visible.

To continue following the moon, shift your viewing time to mornings. Within three hours after sunset on Saturday evening, Jan. 14, the waning gibbous moon rises closely south (to the lower right) of Regulus. The moon remains near that star for the rest of the night, with the pair moving into the western sky at dawn.

Jupiter, of magnitude -2 and well up in the south to south-southwest an hour before sunrise, rules the dawn. Note first-magnitude Spica move from 4.4 degrees from Jupiter on Jan. 1, to 3.6 degrees on Jan. 31. The moon, approaching last quarter phase, is in a beautiful grouping with Jupiter and Spica from about midnight until dawn on the morning of Jan. 19. (The pair remains separated by about 4 degrees from January into March.) That same morning, about an hour before sunrise, around 5:50 a.m., we find Mercury reaching greatest elongation, 24 degrees from the sun. Look for bright Mercury low in the southeastern sky, 12 degrees to the lower left of Saturn.

A waning crescent moon appears widely north of Antares on the morning of Jan. 23, and more closely north of Saturn on the morning of Jan. 24. A thin old crescent moon appears near Mercury on moon’s last two mornings, Jan. 25 and 26.

Back to the evening sky: The new moon occurs on Friday, Jan. 27, at 4:07 p.m. Spot the first young moonabout 25 1/2 hours later, soon after sunset on the next evening. From the Coachella Valley, begin looking around 5:35 p.m., when the hairline 1 percent crescent will be six degrees up in the west-southwest, only 12 degrees from the sun, and 34 degrees to the lower right of Venus. Three nights later, on Jan. 31, the four-day-old waxing crescent forms a beautiful compact gathering with Venus and Mars. Can you fit all three within a single field of view of your binoculars?

This month, Venus attains spectacular brilliance, magnitude -4.4 to -4.7, in the southwest to west-southwestern evening sky, and on Jan. 11-12, reaches greatest elongation, 47 degrees east or to the upper left of the setting sun. Can you spot Venus with an unaided eye before sunset? On Jan. 1, telescopes reveal Venus 56 percent illuminated, nearly 0.4 arcminutes in diameter. Before mid-January, Venus wanes to only half-lit (50 percent), and on Jan. 31, Venus is a crescent, 40 percent lit, but grows to 0.5 arcminutes across. Then Venus will nearly double in apparent size by late March!

The Astronomical Society of the Desert will host the next in our series of monthly star parties on Saturday, Jan. 7, from 5-8 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Check www.astrorx.org for listings of our high-altitude star parties at Sawmill Trailhead starting at dusk. The next (at 4,000 feet—wear warm clothes!) will be held on Saturday, Jan. 21.

Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time. Coming events might include old and young crescent-moon watches at dawn and dusk; daytime and evening sessions to observe the crescent Venus; and sessions to observe flyovers of the International Space Station.

Whitewater Preserve will be hosting a star party on Saturday, Jan. 28, weather permitting, beginning at 6:30 p.m. Reservations are requested at 760-325-7222.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

Evening twilight: Venus rules! You won’t fail to notice this brilliant light in the southwest at dusk. Look for Mars to its upper left, and, for the first two or three weeks of December, Mercury to Venus’ lower right, provided you have an unobstructed view. The moon passes through this section of sky Nov. 30-Dec. 5.

The Summer Triangle of Vega, Altair, and Deneb is not far west of overhead in twilight in early December, and drifts westward as this month progresses. Blue-white Vega is next in brightness after Venus among objects visible in December’s evening twilight. Yellow Capella in the northeast is almost as bright. To Capella’s lower right, red-orange in color, is Aldebaran, eye of Taurus, the Bull, ascending in the east-northeast to east. Later in the month, Orion’s brightest stars, reddish Betelgeuse and bluish Rigel, rise almost together not far from due east. In December at dusk, look for Fomalhaut, mouth of the Southern Fish, crossing the southern sky about 25 degrees above the horizon.

Later in the evening, Orion is higher, and now the “Dog stars,” Sirius and Procyon, following the Hunter across the sky, have risen into view. Notice that Orion’s belt points downward to Sirius, the brightest star, and upward toward Aldebaran and the Hyades star cluster, and beyond to the Pleiades, or Seven Sisters, star cluster. Both star clusters are spectacular fields for binoculars!

Morning twilight: Now Orion and company are descending in the western sky, with some stars already out of view. Jupiter is the dominant “morning star” in the southeast to south, with first-magnitude Spica in Virgo not far below. After Sirius departs in the southwest, the brightest actual star remaining is golden-orange Arcturus in the east. Vega, reincarnated in the northeast, and Capella, sinking in the northwest, are almost as bright. Regulus, heart of Leo, the Lion, is high in the southern sky, going west as weeks pass. Before month’s end, watch for Antares and Saturn emerging out of the sun’s glare in the southeast.

Moon and planets: Watch the waxing crescent moon pass three planets Nov. 30-Dec. 5. The moon will appear to the upper right of Mercury on Nov. 30; above Mercury and to the lower right of Venus on Dec. 1; near Venus on Dec. 2 and 3; and near Mars on Dec. 4 and 5. Mercury stays 24 degrees to the lower right of Venus Dec. 2-12, then falls away and fades. Venus-Mars are 23 degrees apart on Dec. 2, narrowing to 12 degrees on Dec. 31.

See Venus in daytime: On Tuesday, Dec. 6, Venus follows the sun’s path. Place the sun just above an object such as a treetop or building around midday or in the afternoon. Return to the same observing location three hours and 12 minutes later, and Venus will appear in the same spot! On that date, telescopes show Venus two-thirds full. Watch for big changes in coming months, as Venus draws closer to Earth and becomes backlighted by the sun.

Aldebaran, eye of Taurus, is occulted by the moon on evening of Monday, Dec. 12. Since the moon is almost full, a telescope is needed to observe the star’s disappearance and reappearance. From the Coachella Valley, the leading dark edge of the moon covers the star shortly after 7:02 p.m., and the star reappears at the moon’s bright edge at 8:09 p.m.

The full moon on Tuesday, Dec. 13, rises within a quarter-hour after sunset. The peak of the Geminid meteor shower later that night will be greatly spoiled by moonlight; only the brighter meteors will be seen. Meteors might appear anywhere in the sky. To check if a meteor is a member of the Geminid shower, extend its track backward beyond the point where you saw the meteor light up. The track should extend back toward the radiant of the shower, near the star Castor in Gemini. Castor is very low in the northeast two hours after sunset, and nearly overhead shortly before 2 a.m.

After passing full, the waning gibbous moon, in the morning sky, passes the Twin stars Pollux and Castor in Gemini on Dec. 16; and Regulus, heart of Leo, on Dec. 18.

Winter begins on Dec. 21 at 2:44 a.m. On the next morning, Dec. 22, the moon appears as a thick crescent near Jupiter and Spica, and then several days later on Dec. 26 and 27 as a much thinner crescent near Antares and Saturn.

On Tuesday, Dec. 27, as morning twilight brightens, bright Jupiter is in the south-southeast, approaching its high point in the south. Look low in the southeast to east-southeast for the last easy old crescent moon, with Saturn 4 degrees below. In late December, Jupiter and Saturn are 60 degrees apart.

On Wednesday, Dec. 28, the old moon is hard to see, but it’s worth trying for rare opposing crescent moons on consecutive days: Dec. 28 at dawn, and Dec. 29 at dusk. On Dec. 28, using binoculars 20 to 30 minutes before sunrise, try for the crescent moon rising 9-10 degrees to the lower left of Saturn. The new moon occurs later that day, at 10:53 p.m. At early dusk on Thursday, Dec. 29, about 20 minutes after sunset, note Venus well up in the southwest. Using binoculars, try for the young crescent moon within 39 degrees to the lower right of Venus. To see the old moon on Dec. 28 and the young moon on Dec. 29, you’ll need very clear skies, unobstructed views, and binoculars or a telescope. Good luck!

On New Year’s Eve, you can conveniently find the most distant planet of our solar system. Get your telescope out at nightfall (about 90 minutes after sunset), and point it at Mars. Neptune, very faint at eighth magnitude, will appear very closely east of Mars, following the red planet through the telescopic field. As the evening progresses, Mars will appear to close in on the dim, more-distant planet.

Star parties: They provide wonderful opportunities to join with other folks to get great views of astronomical objects through a variety of binoculars and telescopes. The Whitewater Preserve will be hosting a star party on Saturday, Dec. 10, weather permitting, from dusk until 9 p.m. Reservations are requested; please call 760-325-7222.

The Astronomical Society of the Desert will host the next of our series of monthly star parties on Saturday, Dec. 17, from 5 to 8 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Check www.astrorx.org for listings of our high altitude star parties at Sawmill Trailhead starting at dusk. The next one (at 4,000 feet—wear warm clothes!) will be held on Saturday, Dec. 3. Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

Brilliant Venus (magnitude -4.0) and fainter Saturn ( +0.5) are 4.5 degrees apart in the southwest at dusk on Nov. 1, but Venus speeds away while Saturn sinks into the solar glare, widening the gap between them to nearly 15 degrees by Nov. 11, and to 22 degrees by Nov. 18. Use binoculars to watch Venus pass background stars in Ophiuchus and Sagittarius on Nov. 4, 16, 17, and 22. Venus sets farthest south Nov. 14. By month’s end, Venus brightens to magnitude -4.2 and is noticeably higher than it was at the start of November. A telescope shows Venus in gibbous phase, 70 percent full at month’s end. Wonderful changes will happen in coming months, before Venus departs from the evening sky in late March.

Mercury (magnitude -0.5) passes 3.5 degrees south (to the lower left) of Saturn on Nov. 23, but they’ll both be very low in the twilight glow, with Mercury brighter. Using binoculars, look 27 degrees to the lower right of Venus. Replacing Saturn, Mercury is 25 degrees to the lower right of Venus on Nov. 30, and will hold 24 degrees to the lower right of Venus Dec. 2-12.

Look for dim Mars (magnitude +0. 4 to +0.6) in the south to south-southwest, to the upper left of Venus, by 37 degrees on Nov. 1; 30 degrees on Nov. 16; and 24 degrees on Nov. 30. Watch Mars pass third- and fourth-magnitude stars in Capricornus, the sea-goat, on Nov. 14 and 27, and on Dec. 10.

In the morning sky in the east-southeast to southeast, find bright Jupiter, magnitude -1.7 to -1.8. As the sun withdraws east of Jupiter this month because of Earth’s faster revolution around the sun, the giant planet ascends higher in predawn. Note the first-magnitude star Spica in Virgo, 13 degrees to 8 degrees below bright Jupiter.

The moon, as a waxing crescent in evening sky, can be seen in a pretty gathering with Venus and Saturn on Nov. 2; near Mars on Nov. 5 and 6; near Mercury on Nov. 30; near Venus on Dec. 2 and 3; and near Mars on Dec. 4 and 5. In the mornings, follow the waning moon, near Aldebaran, eye of Taurus, on Nov. 15; near Pollux, brighter of the Gemini twins, on Nov. 18; near Regulus, heart of Leo, on Nov. 21; near Jupiter on Nov. 24; and near Spica and Jupiter on Nov. 25.

The full moon, on Monday, Nov. 14, at 5:52 a.m., follows the moon’s perigee (closest approach to Earth) by only 2.5 hours. The resulting “Supermoon” is the closest until Nov. 25, 2034. (Get ready for the inevitable hype in the news media!) The next “Supermoon” closer than that one will occur on Dec. 6, 2052—the best of the 21st century. The moon this month will be closest for observers in the Coachella Valley on the night of Sunday, Nov. 13, just a few minutes after the moon reaches its highest point in the south, at 11:20 p.m., and, contrary to appearances, not when the moon is rising on Sunday around 4:33 p.m. or setting Monday morning around 6:11 a.m. (The moon just seems larger at rising or setting than when it is high in the sky. It’s called the “moon illusion.”) Also, this is not the brightest full moon of this year. That’s because this month’s full moon passes widely south of Earth’s shadow, and does not reflect as much light toward us as it would if the moon narrowly missed the shadow. The sharp brightening of the moon or an asteroid when it appears almost exactly 180 degrees from the sun is sometimes called “the opposition effect,” or “opposition surge.”

Star parties provide wonderful opportunities to join with other folks who love to share their interest in observing the sky, and to get great views of astronomical objects through a variety of binoculars and telescopes. The first two events, happening this weekend, are annual gatherings not far from the Coachella Valley: The 2016 Nightfall Star Party takes in Borrego Springs Oct. 27-30, while the 2016 Joshua Tree National Park Night Sky Festival is Oct. 28-30.

Local star parties (in and near the Coachella Valley): The Astronomical Society of the Desert will host the next of our series of monthly star parties on Saturday, Nov. 5, from 6 to 9 p.m., and on Saturday, Dec. 17, from 5 to 8 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within four miles south of Highway 111 in Palm Desert. Check the society’s website at www.astrorx.org for listings of our regular star parties at the Visitor Center, and our high altitude star parties at Sawmill Trailhead starting at dusk. The next high-altitude star parties (at 4,000 feet—wear warm clothes!) will be held on Saturday, Nov. 19, and on Saturday, Dec. 3. Follow links to maps and directions to both star party sites, and for dates and locations of lecture meetings. Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

On Thursday morning, Sept. 29, a beautiful sight will reward early risers who go out to enjoy the brightening dawn 45 minutes to an hour before sunrise: About 5:45 a.m. in the Coachella Valley that morning, very low, almost directly east, a slender, crescent old moon will be suspended just 2 degrees below Mercury.

Other sights in the morning sky through October include Sirius, the brightest star, well up in the south-southeast, and the rest of the Winter Hexagon’s stars—in clockwise order, Procyon, Pollux (and Castor, not shown), Capella, Aldebaran and Rigel, with Betelgeuse inside. Other bright stars include Canopus, very low in the south, the second brightest star (easier to see later in the month, when it reaches its high point, due south, earlier in a darker sky), and Regulus, heart of Leo, the Lion, in the east.

The old moon of Sept. 29 is followed by the new moon on Fri. Sept. 30 at 5:11 p.m., invisible as it passes close to the sun. The next chance to see the moon is on the evening of Saturday, Oct. 1, only about 20 to 30 minutes after sunset. With all the mountains around us, you must choose your vantage point carefully, because about 20 minutes after sunset in the Coachella Valley, or about 6:50 p.m., the very slender crescent will be only 3 to 4 degrees up. Binoculars will help. Look for the hairline crescent 9 degrees south of due west and 20 degrees to the lower right of Venus. This crescent moon is special, because its sighting marks the beginning of the first month of the new year of the Islamic calendar.

The moon will be much easier to spot as it thickens, appears higher, and sets more than half an hour later nightly. On Sunday, Oct. 2, the moon will be 10 degrees to the lower right of Venus. On Monday, Oct. 3, the moon will pass within 5 degrees to the upper right of Venus, and on Tuesday, the moon will appear 13 degrees to the upper left of Venus. On Oct. 5, the moon passes within 5 degrees to the upper right of Saturn, and on Friday the 7th, the moon will be 7 degrees to the upper right of Mars.

Besides these three planets, other prominent objects at dusk include golden Arcturus sinking in the west, and blue-white Vega northwest of overhead, with Deneb and Altair, completing the Summer Triangle.

The full moon of Saturday, Oct. 15, rises just north of due east a few minutes after sunset that evening. The waning moon rises later each night, shifting farther north along the horizon nightly through Oct. 20.

In the Coachella Valley at 9 p.m. on the evening of Tuesday, Oct 18, binoculars will show a bright star within one degree to the lower left of the moon, just risen in the east-northeast. By 10:19 p.m., the sunlit edge of the moon will cover first-magnitude Aldebaran, eye of Taurus, the Bull. Aldebaran remains hidden by the moon until 10:35 p.m., when the star reappears along the northern part of the moon’s dark edge. Even though this is the brightest star the moon can occult (cover), a telescope will be needed to observe the star disappear and reappear, since the moon is very bright—only three days past full.

Watch the planets move! In the evening sky in October, Venus goes east 1.2 degrees per day against background stars, while Mars goes east about 0.7 degrees daily. Follow their progress easily from one night to next for several evenings around dates when planet passes a star. Track Venus for a few evenings around following dates when it passes close to a background star: Oct. 5, when Venus passes 0.8 degrees to the lower left of third-magnitude Alpha in Libra, also known as Zubenelgenubi, the southern claw of an early, larger version of the Scorpion; Oct. 20, when Venus passes within 1 degrees above second-magnitude Delta Scorpii, the middle of the three stars in the head of the Scorpion; Oct. 26, when Venus passes 3.1 degrees north (to the upper right) of first-magnitude Antares; and Oct. 29, when Venus passes 3.0 degrees south (to the lower left) of Saturn.

Watch Mars on Oct. 6, as it passes 0.2 degrees below third-magnitude Lambda Sagittarii, marking the top of the Teapot. This star is also known as Kaus Borealis, northern star of the Archer’s bow. On Oct. 15, Mars passes within 1.3 degrees north (to the upper right) of second-magnitude Nunki, or Sigma in Sagittarius, brightest star in handle of the Teapot.

Saturn, the only other bright evening planet, moves only 2.7 degrees east during Oct. 1-31, averaging less than 0.1 degrees per day.

In the mornings: Just before the start of twilight Sept. 29-Oct. 12 and Oct. 29-Nov. 11, from a very dark place, try to see the zodiacal light—from sunlight reflected off comet and asteroid dust in the plane of the solar system. Look for a huge pyramid of faint light extending upward from the eastern horizon toward the star Regulus in Leo.

Low in the east during morning twilight in October, bright, emerging Jupiter replaces Mercury. Using binoculars about 40 minutes before sunrise, see both planets for a few days around Oct. 11. The best mornings are Oct. 10-12: The planets are 1.5 degrees apart on Oct. 10, with Jupiter to the lower right of Mercury. They appear closest, 0.8 degrees apart, on Oct. 11, with Jupiter to the south (right) of Mercury. They’re 1.9 degrees apart on Wednesday, Oct. 12, with Jupiter to the upper right.

On Friday, Oct. 21, in the predawn darkness hours, watch for the peak of the Orionid meteor shower, consisting of particles from Halley’s Comet.

On Friday, Oct. 28, a waning crescent moon, two days before new, will appear 2-3 degrees to the lower left of Jupiter in morning twilight. On Saturday morning, Oct. 29, the last old crescent will appear 14 degrees to the lower left of Jupiter. Binoculars will help you pick out emerging Spica, just five degrees to the lower right of the delicate crescent. The new moon occurs on Sunday, Oct. 30, at 10:38 a.m.

On Monday evening, Oct. 31, 40 minutes after sunset, the young crescent moon will be 3 degrees up in the west-southwest, 24 degrees to the lower right of Venus.

The Astronomical Society of the Desert will host the next of our popular series of monthly star parties on Saturday, Oct. 8, from 7 to 10 p.m. They are held at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Check www.astrorx.org for listings of our high altitude star parties at Sawmill Trailhead starting at dusk. The next one will be held on Saturday, Oct. 22. Visit the website for maps and directions to both star party sites, and for dates and locations of lecture meetings. Also, follow the link to our “Impromptu Star Parties, which could be announced on short notice at any time.

Also, don’t miss the 2016 Joshua Tree National Park Night Sky Festival on Oct. 28-30 and the 2016 Nightfall Star Party in Borrego Springs Oct. 27-30.

The Wildlands Conservancy’s Whitewater Preserve at 760-325-7222 and the Pioneertown Mountains Preserve at 760-369-7105 occasionally host star parties. The next one at Pioneertown Preserve is set for Oct. 8. Reservations required; call the appropriate preserve.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

Our evening twilight chart for September, depicting the sky about 40 minutes after sunset, shows brilliant Venus remaining low, creeping from west to west-southwest and gaining a little altitude as the month progresses. Its close encounter within 2.5 degrees north of Spica on Sept. 18 is best seen with binoculars to catch the star low in bright twilight.

The brightest stars in the evening sky are golden Arcturus, descending in the west, and blue-white Vega, passing just north of overhead. Look for Altair and Deneb, completing the Summer Triangle with Vega. The triangle of Mars-Saturn-Antares expands as Mars seems to hold nearly stationary in the south-southwest as the month progresses, while Saturn and Antares slink off to the southwest.

The morning twilight sky is rich with stars as the Winter Hexagon, made up of stars from Orion, his Dogs, the Twins, the Charioteer with Mother Goat, and Taurus, the Bull. Tracing out the Hex starting with Sirius, the brightest star, going clockwise, we encounter Procyon, Pollux (and nearby Castor, not quite first magnitude, and therefore not bright enough to be plotted), Capella, Aldebaran, Rigel and back to Sirius. Inside the Hexagon lies Betelgeuse, Orion’s shoulder. The Summer Triangle’s Deneb sinks into the northwest. Regulus, Leo’s heart, emerges into the east-northeast early in the month and is well up in the east by month’s end. By Sept. 22, emerging Mercury approaches within 15 degrees below Regulus. Brightening rapidly, in its best-of-year morning appearance, Mercury reaches peak altitude just before month’s end. Can you spot the second-brightest star, Canopus, before month’s end? It’ll be easier in October, when the star reaches its high point in the south (only 3 degrees up!), four minutes earlier each day, in ever-darker morning skies. Choose your vantage point carefully, with no high mountains nearby to your south.

There are two new moons in September: on Sept. 1 at 2:03 a.m., and on the 30th at 5:11 p.m. That means that this month, we can observe a complete cycle of the moon from start to finish, starting as a thin crescent moon very low in the west at dusk on Sept. 2, and waxing through the first half of the month, until it becomes full on the 16th. Next, we can follow the waning moon in the morning sky through Sept. 29. There are many striking events, starting with a close pairing of Jupiter and a young crescent moon on Friday, Sept. 2. Early that evening, get to a place with an unobstructed view toward west by 25 minutes after sunset, and look for Jupiter and the crescent moon, about 5-6 degrees to the lower right of Venus. Binoculars will help! From the Coachella Valley, the moon occults, or covers, Jupiter that afternoon, from 2:50-3:44 p.m., but the event will be impossible to see in the daylight, as it occurs only 18 degrees from the sun.

Watch the moon pass planets, as shown on the Abrams Planetarium Sky Calendar. By Saturday. Sept. 3, the moon is easy to spot, about 6 degrees to the upper left of Venus. On Sunday, Sept. 4, look for Spica 5 degrees to the moon’s south (lower left). Binoculars will help. Wait for the sky to darken some, but don’t wait too long, or Spica and the moon will set! Don’t miss the moon sliding past the beautiful triangle of Saturn, Antares and Mars on the evenings of Sept. 8 and 9. (See above right.)

The full moon on Friday, Sept. 16, comes up within 15 minutes after sunset. It’s fun to watch moonrises, and on the next five nights, the moon rises about 40-50 minutes later each night.

Beginning Sept. 17, you can shift your viewing times to mornings, about an hour before sunrise, and catch the moon passing by bright zodiacal stars: Aldebaran in Taurus on Sept. 21 and 22; Pollux and Castor in Gemini on Sept. 24 and 25; and Regulus in Leo on Sept. 27 and 28. On the moon’s final morning, Sept. 29, the old crescent moon will appear low in the east, just 2 degrees below Mercury.

A tip for telescopic observation of the moon in daytime: When the moon is within two days before or after half full—this month, late in the afternoons of Sept 7-10, near first quarter phase, and on mornings of Sept 21-24, near last quarter phase—insert a single polarizing filter into a low-power eyepiece of your telescope. Next, while viewing the moon, rotate the eyepiece until the surrounding blue sky appears darkest, increasing contrast of the moon against the sky for wonderful views of lunar craters! (Threaded polarizing filters and threaded eyepieces can be obtained from Orion at telescope.com.) I often enjoy setting up my telescope at schools before the school day begins on mornings in autumn, on days when the moon is near last quarter phase and high in the sky.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

August 2016 has a rare gift for skywatchers: For most of the month, all five naked-eye planets can be seen during evening twilight, and they participate in beautiful pairings and groupings!

From a site with an unobstructed view of the western horizon, begin within a half-hour after sunset to catch Venus before it sinks too low. Use our evening twilight chart link to guide you. Venus, at magnitude -3.8, is visible with the unaided eye, even low in bright twilight, if you know where to look. (It will get higher in coming months, setting in a dark sky starting in October.)

Jupiter, next in brightness at magnitude -1.7, is easy to find not long after you spot Venus. For most of August, Jupiter appears to the upper left of Venus, getting one degree closer each day until their spectacular close pairing on Saturday, Aug. 27. Thereafter, Jupiter will appear to the lower right of Venus, getting increasingly difficult to see.

Use binoculars all month, if necessary, to catch Mercury, starting August at mag -0.1 while 8 degrees to the upper left of Venus, and fading to magnitude +0.5 by Aug. 24 while 6 degrees to the lower left of Venus.

As the sky darkens, Mars (magnitude -0.8 to -0.3), Saturn (+0.3 to +0.5), and first-magnitude Antares—6 degrees from Saturn all month—become easy for the unaided eye to see. The two planets and the red supergiant star will have a striking arrangement Aug. 23 and 24.

In morning twilight Aug. 4-14, look daily within an hour before sunrise and watch for the first appearance of Procyon, about 6-7 degrees north of east, and Sirius, in the east-southeast. The “Dog Star” Sirius is nearly in line with Orion’s belt, and completes the almost equilateral Winter Trianglewith Betelgeuse (Orion’s shoulder) and Procyon. The name Procyon means “before the dog,” because the star rises several minutes before Sirius does, and so gives notice of the imminent rising of the Dog Star. The heliacal rising (first morning appearance) of Sirius was a very important event in ancient Egypt, as it gave notice of the imminent flooding of the Nile River, which occurred around the summer solstice. Now, because of precession, the 26,000-year wobble of the Earth’s axis, the first appearance of Sirius occurs several weeks after the start of summer and the rise of the Nile.

Aug. 4, beginning 30 minutes after sunset: Find the 2.3-day-old crescent moon low in the west, and Venus 11 degrees to its lower right. Mercury appears 2 degrees to the left of the moon, nearly 9 degrees to the upper left of Venus, and 15 degrees to the lower right of Jupiter. Mars and Saturn are 10 degrees apart in the southern sky. Six solar system bodies—Venus-Mercury-moon-Jupiter-Mars-Saturn—span 100 degrees.

Aug. 5: Jupiter is about 1 degree above the moon.

Aug. 6: Three planets, Jupiter-Mercury-Venus, appear 12 degrees, 24 degrees and 33 degrees to the lower right of the moon. Mars and Saturn appear 57 degrees and 65 degrees to the moon’s upper left. Venus and Mars appear 90 degrees apart—in quadrature—this evening. Verify that by observation!

Aug. 7 and 8: The moon is near Spica, brightest star in Virgo.

Aug. 8 and 9: Mars is 0.9 degrees from Delta Scorpii, the middle and brightest of three stars in the head of the Scorpion.

Aug. 10: The moon passes first quarter phase at 11:21 a.m. Tip for telescopic observation of the moon in daytime:When the moon is within two days before or after half full—this month, on the afternoons of Aug. 8-11, near first quarter phase, and on mornings of Aug. 23-26, near last quarter phase—thread a singlepolarizing filter into a low-power eyepiece of your telescope. Next, while viewing the moon, rotate the eyepiece until the blue sky surrounding the moon appears darkest, increasing contrast of the moon against the sky for wonderful daytime views of lunar craters and other features!

Aug. 11-12: As darkness falls, note the beautiful diamond-shaped arrangement of moon-Mars-Antares-Saturn, about 6-7 degrees on each side. The peak of the Perseid meteor shower occurs after moonset, in Friday, Aug. 12’s predawn darkness hours! The dark, moonless sky should be wonderful for observing meteors.

Aug. 12: The moon is 8 degrees to the upper left of Saturn. The famous ringed planet marks the top vertex of an attractive triangle of three “stars.” Compare the color and brightness of its two other members, Mars and Antares. Venus is 15 degrees to the lower right of Jupiter, getting a degree closer each day!

Aug. 16: Mercury is at its greatest elongation, 27 degrees east of the sun. Since Mercury is more to the left of the setting sun, rather than high above it, the planet sets well before darkness falls; this is an unfavorable apparition for observers at mid-northern latitudes, despite Mercury’s unusually large angular distance from the sun. Here in Southern California, we will have an easier time spotting it than folks in northern part of the state.

Aug. 17-18: Venus is 10 degrees to the lower right of Jupiter at dusk. Five planets span 84 degrees. Also, the full moon occurs overnight, at 2:26 a.m. on the 18th. The moon shines with enhanced brightness in that hour as it narrowly misses the penumbra of Earth’s shadow and reflects sunlight toward us.

Aug. 19: Mercury is 3.8 degrees to the lower left of Jupiter, their minimum distance apart in a quasi-conjunction.

Aug. 22: Venus is 4.9 degrees to the lower right of Jupiter.

Aug. 23: Venus and Jupiter are within 3.9 degrees; Mercury and Jupiter 4.3 degrees; and Mercury and Venus 6.4 degrees, in a nearly isosceles triangle.

Aug. 23 and 24: In order from top to bottom, Saturn, Mars and Antares nearly line up, as Mars goes 4.4 degrees south of Saturn and 1.8 degrees north of Antares!

Aug. 25, predawn (using a telescope): The moon occults 3.7-magnitude Gamma Tauri, point of “V” of Hyades star cluster, from 1:17-2:10 a.m. in the Coachella Valley. The daytime occultation of Aldebaran is visible through a telescope: Disappearance on the moon’s bright side occurs in here at 10:24 a.m., with reappearance at the moon’s dark side at 11:27 a.m. Last quarter phase occurred on Aug. 24, at 8:41 p.m., so the moon on Aug. 25 is a fat crescent. Follow waning moon mornings through Aug. 31.

Aug. 25: Venus and Jupiter are within 1.8 degrees.

Aug. 26: Venus and Jupiter are within 0.8 degrees.

Aug. 27:This is the first evening Jupiter appears to the lower right of Venus. The planets are just 0.2 degrees apart, as seen from California—and about 0.1 degrees apart from the Eastern U.S. Alert your friends in that part of the country! Mercury, faded to magnitude +0.8, appears 5.1 degrees south (to the lower left) of the bright pair, and may be missed.

Aug. 28: Venus and Jupiter are 1.2 degrees apart. Their separation increases by about 1 degree daily. Venus and Mercury are 5 degrees apart, the minimum distance for this passage.

Aug. 31: Venus and Jupiter are 4.3 degrees apart, with Jupiter getting lower each evening. On what date will you last spot Jupiter?

Sept. 1: The new moon occurs at 2:03 a.m.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

All three bright outer planets remain prominent in the evening sky this July.

At dusk, find bright Jupiter in the west-southwest to west, apricot-colored Mars in the southern sky, and Saturn not far to the left of Mars. Venus passed behind the sun in early June, but by mid-July, it emerges into our early evening sky very low in the west-northwest bright twilight glow, 20 minutes after sunset. Look from a place with a view unobstructed by mountains, and use binoculars to help you spot Venus in bright twilight in its first weeks. Binoculars will reveal Mercury near Venus from mid-July until late August. That’ll bring the total to all five bright planets visible simultaneously!

Attend a star party hosted by one of the local astronomy clubs for telescopic views of Jupiter’s cloud belts and four largest moons; Saturn’s spectacular rings and largest moon Titan; the south polar cap and other markings on Mars; and many deep-sky wonders beyond the solar system, in our Milky Way galaxy, and beyond!

Our chart depicting the sky at evening mid-twilight in July follows positions of naked-eye planets and stars of first magnitude or brighter in the sky when the sun is 9 degrees below the horizon, roughly 45 minutes after sunset. Planets are plotted as dots, one for each day, with labels for dates at weekly intervals.

On this map, you’ll find bright Jupiter starting well up, a little south of due west, at dusk in early July 2016, with faint Regulus, heart of Leo, preceding it as they sink toward the western horizon over the course of the month.

Mars starts a little east of due south at dusk in early July. Note the shape of the triangle it forms with Saturn to its left, and the red twinkling star Antares, heart of the Scorpion, below Saturn. The triangle will shrink in coming weeks.

The Summer Triangle of Vega, Deneb and Altair ascends the eastern sky at dusk in July. Its brightest star, blue-white Vega, marks the top of the triangle. Two other bright stars, golden Arcturus and blue-white Spica, are high in the southwest quarter of the sky.

Mercury and Venus first appear on our evening mid-twilight chart in late July, but if you observe earlier in twilight, some 20 to 30 minutes after sunset, and use binoculars, you can catch their closest pairing very low in the west-northwest on July 16, as Mercury (magnitude -1.0) passes just 0.5 degrees north (to the upper right) of Venus (-3.9). (You’ll need a viewing site where mountains don’t block your view!) On the previous evening, July 15, you can spot Mercury 0.8 degrees to the right of Venus, with the two setting at about the same time. On following evenings, Mercury shifts to the upper right of Venus, and next above it, and then toward Venus’ upper left, with their separation widening. During July 16-Aug. 19, Mercury appears higher than Venus, and sets as much as 18 minutes after Venus during from July 30 to Aug. 4.

Follow the moon: Its day-to-day change in position against the stars, averaging 13 degrees per day, is much more noticeable than that of the planets. Watch the moon change from a thin crescent to just past full July 5-20, while passing the planets and the bright stars plotted on our evening twilight charts. Watch for these events:

Tuesday, July 5: See the first crescent moon, age 40.5 hours after new, half an hour after sunset. Binoculars give fine views of this thin moon very low in the west-northwest, provided mountains don’t obstruct your view. Sighting of this crescent marks the start of a new month, ending the fasting month of Ramadan.

Thursday, July 7: Regulus, heart of Leo, appears closely north of the crescent moon.

July 8 and 9: Jupiter is closely to the upper left of the moon on Friday, then not-so-closely to the lower right of the moon on Saturday.

Monday, July 11: The moon is near first quarter phase. Look for the star Spica, the spike of wheat in hand of Virgo, a few degrees north of the moon.

July 13 and 14: Mars is widely to the lower left of the gibbous moon on Wednesday, and not-so-widely to the lower right of the moon on Thursday.

Friday, July 15: Saturn is closely below the moon. Note Antares, heart of Scorpius, the Scorpion, below Saturn.

Saturday, July 16: A close pairing of Mercury-Venus in bright twilight is described above.

Tuesday, July 19: The moon passes full phase shortly before 4 p.m., and rises in the east-southeast at 7:45 p.m., or 10 minutes before sunset in Palm Springs. Because of our surrounding mountains, you must wait several minutes until the moon’s disk begins to appear.

Watch for the moonrise on subsequent evenings: Wednesday, July 20, at 8:30 p.m.; Thursday, July 21, at 9:12 p.m.; Friday, July 22, at 9:52 p.m.; Saturday, July 23, at 10:31 p.m.; Sunday, July 24, at 11:10 p.m., nearly due east; and Monday, July 25, at 11:49 p.m. You’ll notice the moon rising farther north each night until night of July 30-31, when it will rise in the east-northeast at 3:31 a.m. on Sunday morning, July 31.

Early in July, before the moon gets bright, and again beginning around July 22 or 23—when the waning moon after full starts rising late in the evening—go to a dark location after nightfall and enjoy spectacular views of the summer Milky Way. Follow its path from the “W” of Cassiopeia low in the north-northeast, through the Summer Triangle along the Northern Cross, or neck of Cygnus, the Swan, then down toward the Teapot of Sagittarius to the left of Scorpius in the southern sky. Part of the Milky Way resembles a puff of steam rising out of the spout of the Teapot. From within the Summer Triangle and southward, look for the long Great Rift, where the river of the Milky Way is divided into two streams by clouds of obscuring interstellar dust in the foreground blocking the light of the stars beyond. A pair of binoculars will easily resolve the bright Cygnus Star Cloud (where we look into our own spiral arm, along the neck of the Swan) into multitudes of stars!

Telescopic views of planets: Jupiter’s dark equatorial cloud belts and up to four of the bright satellites discovered by Galileo offer a pleasing view for small telescopes.

Mars, still showing a fair-sized disk after its closest approach in late May, displays surface detail! This month, Mars’ southern hemisphere spring equinox will occur on July 4. Although the south pole of Mars is then on the Martian terminator (day-night boundary), that pole is now tipped 15 degrees out of Earth’s view—the surrounding south polar cap of frozen carbon dioxiode (or its overlying cloud cover) is near its maximum extent, reaching halfway from pole to equator, far enough to spill over the southern limb. So whenever you look at Mars early this summer, you’ll see a bright southern edge to Mars’ disk.

Enjoy Saturn’s rings this summer! They’re now tipped from edge-on by almost the greatest angle possible. Using as high of a magnification as your telescope and atmospheric conditions allow (I often use 200x with my 6-inch reflector), try for the Cassini Division dividing the outer A ring from the broader, brighter B ring. This narrow gap is nearly two-thirds of the way from the inner edge of B toward the outer edge of A. Look also for Titan, Saturn’s largest moon, taking 16 days to complete one circuit about the planet. Its nearly circular orbit is almost nine times as large as the outer edge of Saturn’s A ring, in nearly the same plane as the rings now tipped 26 degrees from edge-on, and so it appears as an ellipse.

Titan will appear farthest west of Saturn on July 3 and 19, and farthest east on July 11 and 27. We are seeing the north face of the rings and of Titan’s orbit, so we’ll see Titan at superior conjunction (the far side of Saturn) four days after it appears farthest to the west, and at inferior conjunction (near side of Saturn) passing south of the planet four days after greatest elongation east.

Venus, just emerged from the far side of the sun, appears tiny and full, and low in twilight. It will become much more interesting for telescopic viewing as it nears the end of its evening apparition.

Predawn sky: There are no morning planets visible to the unaided eye in July. (Uranus and Neptune require at least binoculars and detailed finder charts.) But cooler mornings make for more comfortable sky viewing. As dawn begins to brighten, we find the Summer Triangle well up in the western sky, getting lower as the month progresses. Fomalhaut, mouth of the Southern Fish, is in south to south-southwest, and Capella, the Mother Goat star, is ascending in the northeast. To Capella’s lower right, we find ruddy Aldebaran, eye of Taurus the Bull. Before the sky brightens, look above Aldebaran for the beautiful Pleiades star cluster (the Seven Sisters), a wonderful target for binoculars!

Late in July, the two brightest stars of Orion the Hunter rise into view: reddish Betelgeuse with blue-white Rigel to its right. Between them lies the Hunter’s belt of three stars in a nearly vertical line. Orion will rise two hours earlier as each month passes.

The Astronomical Society of the Desert hosts monthly star parties at Sawmill Trailhead (elevation 4,000 feet). For dates, with map and directions to the site, visit the Society’s website at www.astrorx.org.

Sky’s the Limit Observatory in Twentynine Palms offers star parties most Saturday evenings, except when the moon is close to full. For details, visit www.skysthelimit29.org.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller, who provided the twilight charts, did graduate work in planetarium science and later astronomy and computer science at Michigan State University. He remains active in research and public outreach in astronomy. Dr. Jeffrey L. Hunt, a retired planetarium director now living in the Chicago area, did the Venus map below. He has taught astronomy and sky watching to all ages. He studied astronomy education at Abrams Planetarium at Michigan State University. Jeff writes an astronomy blog at jeffreylhunt.wordpress.com and can be followed on Twitter at @jeff_hunt.

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