CVIndependent

Mon02172020

Last updateTue, 18 Sep 2018 1pm

Robert Victor

Few people will choose to arise early to catch the start of the lunar eclipse on Saturday morning, April 4, when the spring’s first full moon begins to enter the umbra, or dark central core, of Earth’s shadow at 3:16 a.m. local time.

For the next 1.7 hours, more and more of the moon will be immersed in the Earth’s circular dark shadow, until the start of the total eclipse at 4:58 a.m. Even before then, the rusty color typical of the moon in deep eclipse should be noticed—at least in the lower part of the moon’s disk, closer to the center of Earth’s shadow. Totality lasts less than five minutes, as the northern (upper) edge of the moon barely passes within the outer edge of Earth’s umbra. There should be a pronounced difference in color and brightness between the top and bottom edges of the moon.

Totality ends by 5:03 a.m., after which the moon will gradually emerge from the shadow, with the eclipse concluding at 6:45 a.m. From the Coachella Valley, the moon sets several minutes before then, cutting off our view.

If you prefer to watch this early-morning eclipse for just an hour, I recommend from 4:30 until 5:30 a.m., centering on the deepest eclipse at 5 a.m. At mid-totality, the moon will be quite dim compared to a normal full moon, and observers in dark locations will get a spectacular view of the Milky Way.

Other bright objects of April mornings: Spica will be just 10 degrees to the upper left of the moon at mid-eclipse on April 4, with golden Arcturus high to their upper right. The next morning, on Easter Sunday, April 5, Spica will appear within 4 degrees below the moon, and on April 8, the moon will appear within 2 degrees to the upper right of Saturn, and 10 degrees to the upper right of twinkling Antares, the red supergiant star marking the scorpion’s heart. The waning gibbous moon moves through the predawn Milky Way April 9-11, and by April 12, it has passed last quarter phase and appears slightly less than half full. The last easy view of the waning crescent will be low in the east an hour before sunup on April 16, with another chance for binocular users a half-hour before sunrise on April 17, only 30 hours before the new moon.

The brightest “stars” in evening mid-twilight: In order of brilliance, they are: Venus, in the west to west-northwest; Jupiter, passing just south of overhead around midmonth; Sirius, in the southwest sky, bluish and twinkling, heading lower as the month progresses; Mercury, emerging from superior conjunction beyond the sun on April 9 to appear very low in the west-northwest to lower right of Venus starting around April 18; Arcturus,in the east-northeast to east, higher as month progresses; and Capella, high in the northwest.

This is a good month to follow the motion of Venus against background stars. During April 9-11, Venus passes within three degrees south of the Pleiades, or Seven Sisters star cluster,an especially beautiful sight for binoculars! On April 16-22, Venus passes Aldebaran and the Hyades cluster, those stars together making up the “V”-shaped head of Taurus, the Bull. Meanwhile Jupiter lingers within 5-6 degrees east of the Beehive all month. Use binoculars to find that star cluster.

On April 19, 40 minutes after sunset, the thin young crescent, 32 hours past new, will be low in the west to west-northwest. Binoculars may show Mercurywithin 8 degrees to the moon’s lower right; and dim Mars within 4 degrees to the upper left of Mercury, and within 5 degrees to the lower right of the moon. This is the same night Venuspasses closest north (7 degrees to the upper right) of Aldebaran. On April 20, the lovely crescent moon will be almost directly below Venus, within 9 degrees to the lower right of Aldebaran, and 9 degrees to the lower left of the Pleiades. On April 21, the moon climbs to 5 degrees to the upper left of Aldebaran, while Venus shines within 8 degrees to their upper right. Far to their lower right, dim Mars glows only 1.5 degrees to upper left of bright Mercury.

On Apr. 22, Betelgeuse, shoulder of Orion, is 10 degrees south (to the lower left) of the crescent moon, while Mercury and Mars appear closest to each other, 1.3 degrees apart, with fainter Mars to the lower left. This is the first evening emerging Mercury is higher than sinking Mars. They’ll be 2 degrees apart on April 23, while the moon is midway between Betelgeuseand Pollux, brighter of Gemini twins. On April 24, the fat crescent moon exits the winter hexagon nearly halfway from Procyon to Pollux. On April 25, the first-quarter moon, half full, is 9 degrees to the lower right of Jupiter.

On April 26, the moon is in waxing gibbous phase, 8 degrees to Jupiter’s lower left, and on the next night, April 27, it appears 4 degrees south of Regulus, heart of Leo, the Lion.

On April 30, Mercury passes within two degrees south of the Pleiades. (Use binoculars to see the cluster low in twilight so late in April.)

Mid-April is a good time to start keeping a checklist of bright stars seen each evening. Many bright stars are gathered in the western sky, including the huge winter hexagon. Striking changes in the visibility of stars will occur in the next several weeks, as a result of the Earth’s revolution around the sun. An observer’s log can be downloaded here.

The Astronomical Society of the Desert will host a public star party on Saturday, April 25, from 8 to 10 p.m. at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74. For more information and directions, visit www.astrorx.org.

Robert 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.

March 2015 at dusk: Early in the month, the four brightest “stars,” in order of brilliance, are: Venus, in the west; Jupiter, in the eastern sky; Sirius, the “Dog Star,” 40 degrees up in the south as seen from the Coachella Valley; and Canopus, less than 4 degrees up when it passes due south about 21 minutes before Sirius does.

From the Coachella Valley, you must choose your site carefully to see Canopus, or mountains might block your view. From my abode in Palm Springs, I see Canopus blink out when it goes behind a mountainside several minutes before it reaches its high point.

From Palm Springs and Desert Hot Springs, Canopus passes due south only 4 degrees up in a dark sky at 7:32 p.m. on March 1, and then four minutes earlier each day, to 7:08 p.m. on March 7, and suddenly 8:04 p.m. on Sunday, March 8—an hour later than you might expect, until you recall that you’ve just reset your clock to daylight saving time. By March 11 or 12, the star reaches its high point only about an hour after sunset. Within a few more days, as the star’s “transit time” backs closer to the time of sunset, the sky will become too bright to catch Canopus at its high point.

Sounds of nature enrich the stargazing experience. In Palm Springs, we’ve been hearing frogs in nearby Tahquitz Creek on warmer nights since December.

Other features of the early evening: A telescope reveals Venus now in gibbous phase,and up to four of Jupiter’s moons discovered by Galileo in 1610. Mars, now on the far side of its orbit, doesn’t reveal much telescopically, but it’s visible to the naked eye and binoculars, sinking lower in twilight, 4 degrees to 17 degrees below Venus.

Orion’s three-star belt (not bright enough to be shown on our twilight chart) lies midway between red Betelgeuse and blue Rigel. The belt points the way leftward toward Sirius, and the opposite way toward Aldebaran, eye of Taurus, the Bull, and beyond to the Pleiades or “Seven Sisters” star cluster (also not plotted, but beautiful in binoculars). The huge “Winter Hexagon”—in counterclockwise order, Sirius, Rigel, Aldebaran, Capella, Pollux, Castor (not shown), Procyon and back to Sirius, with Betelgeuse inside—contains seven of the 21 stellar objects of first magnitude or brighter (16 stars and five planets) ever visible from Southern California. Their constellations include a bull backing away from a charging hunter and his two canine followers, a pair of twins and a chariot driver with mother goat and three kids on his shoulder.

Following this menagerie is bright Jupiter, itself followed by Leo, the Lion, with the star Regulus marking his heart.

By March’s end, Arcturus, the “Bear Guardian” star, pops up above the east-northeast horizon before mid-twilight. Use this memory aid: “Follow the arc (curve of the bear’s tail or handle of the Big Dipper) to Arcturus.”

The moon can be easily spotted daily at evening mid-twilight (about 40 minutes after sunset) March 1-5 and March 21-April 4. At dusk on Monday, March 2, the fat gibbous moon is well up in the eastern sky, 5 to 6 degrees to the north (upper left) of Jupiter. Now through July, the moon will pass Jupiter in the evening sky every 27 or 28 days. The interval is shorter than the moon’s cycle of phases, 29.5 days, so each time it overtakes Jupiter, the moon will appear progressively less full.

On March 4, the nearly full moon will rise 35 to 40 minutes before sunset, and on March 5, the moon, just past full, rises shortly after sunset. In the following days, moonrise occurs nearly an hour later each night, making it more convenient to switch your moon-watching time to predawn.

March 2015 at dawn: The brightest objects in morning twilight, in order of brilliance, are: Arcturus, high in the west-southwest to west; and Vega, high in the northeast. Early in the month, Mercury, low in the east-southeast, closely matches or slightly outshines Arcturus, but it sinks into bright twilight after midmonth. Saturn, steady in the south to southwest, is next in brightness in the morning sky.

In morning twilight on Thursday, March 5, the full moon is low in the west, with Regulus setting 4 to 5 degrees to its lower right. On March 8 and 9, the waning gibbous moon appears in the southwest near Spica. On Thursday, March 12, Saturn appears within 3 degrees to the lower right of the moon in the south, while the reddish twinkling star Antares appears 8 to 9 degrees to their lower left. On Friday, March 13, the moon is close to half full and essentially at last quarter phase, 90 degrees west of the sun and 14 to 16 degrees left (east) of Antares and Saturn. The last easy morning view of the waning moon will come on Wednesday, March 18.

The moon returns to the evening on Saturday, March 21, at dusk, when the 1.7-day-old waxing crescent will be very easy to spot. Mars will be 2 degrees to its lower right. For a few more evenings, look for beautiful earthshine, from sunlight reflected by Earth onto the moon’s dark (non-sunlit) side. Watch the crescent thicken daily as it moves farther from the sun on each successive evening.

Mark your calendars: On Friday evening, April 3, the nearly full moon will rise 4 to 5 degrees south of due east about 26 minutes before sunset. About 13 minutes before sunset, the sun and moon can be viewed simultaneously, in opposite directions, each about 2 degrees above unobstructed horizons. About an hour after sunset, look for Spica 13 degrees below the moon—and then atotal lunar eclipsewill happen early Saturday morning, April 4. More on this next month and at CVIndependent.com.

Using a rectified Earth globe outdoors in sunlight: If it is set up properly outdoors in sunlight, an Earth globe can reveal the location of the sunlit area on the actual Earth at the moment you are viewing the globe.

Here are directions for setting it up. It would be most helpful if you could use a globe with a dull finish:

1. Find your location. Use longitude and latitude if necessary.

2. Place the globe so that your location is at the top of the globe, i.e., at the highest point on the sphere, at the point of tangency of a horizontal plane tangent to the top of the globe.

3. Rotate the globe about a vertical axis until the directions north, east, south and west at your chosen location on the surface of the globe match the directions of your actual surroundings. During this step, make sure your location remains on the top of the globe.

4. You have now “rectified the globe,” and its orientation in space matches that of the actual Earth. The rotation axis of the globe points very nearly toward the North Star, Polaris, as does the axis of rotation of the actual Earth. Any time you view the globe, its sunlit area matches the sunlight area on the actual Earth.

Examine the globe to discover in what parts of the world the sun is rising, and where it is setting at the time you view the globe. To help solve this problem, watch the globe for several minutes or check it after an hour to detect changes in the location of the lighted area.

On March 20, the date of the spring equinox, the North and South poles should both be on the terminator, or dividing line between the day and night sides of Earth. The sun is directly overhead on the equator. As the Earth rotates on its axis on that date, each location will have days and nights each 12 hours long.

Before March 20, the sunlit area extends beyond the South Pole, and falls short of the North Pole. It is daytime at the South Pole and nighttime (perhaps twilight, depending on the date) at the North Pole. After March 20, the sunlit area falls short of the South Pole, and extends beyond the North Pole, so it is nighttime (perhaps twilight) at the South Pole and daytime at the North Pole.

The “half moon” as a reviewer or predictor of the seasons: The following statement is true throughout the year: the last quarter moon, or half moon at sunrise, reviews the sun’s location of three months ago, and the first quarter moon, or half moon at sunset, predicts the sun’s location three months in the future.

These facts are especially well demonstrated in March: The morning half moon at sunrise on March 13 is low in the southern sky, in Ophiuchus, not far from the southernmost part of the zodiac in Sagittarius where the sun appeared in December, near the start of winter.

The evening half moon at sunset nearly two weeks later on March 26 is high in the southern sky, in the club of Orion, not far from the northernmost part of the zodiac near the Taurus-Gemini boundary where the Sun will appear in June, near the start of summer.

You can construct models of the solar system to explain the above facts. Essentials to include in the model are an Earth rotating about its tilted axis while revolving about the sun, and the moon revolving about the Earth in approximately the same plane. All three motions are counterclockwise as seen from “above” or north of the solar system. Placards with names of the 13 zodiac constellations can also be properly arranged around the model, as on the planet orbit charts available online at www.abramsplanetarium.org/msta.

Observing challenge: Opposing crescents on consecutive days, March 19 and 20: Given perfect skies and no mountains blocking the view, use binoculars or a telescope to try to see a very thin waning crescent moon on Thursday, March 19, 25 minutes before sunrise, 1-2 degrees up and 5 degrees south of due east. From Palm Springs, the moon is then only 20.2 hours before new.

On the next day, Friday, March 20, in the evening 25 minutes after sunset, use binoculars to try for an even thinner, waxing crescent, 2-3 degrees up and 2 degrees north of due west. From Palm Springs, the moon is then 16.8 hours after new.

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.

Two planets and a star far outshine all competitors at dusk in February.

They are: Venus, of magnitude -4, low in the west-southwest, shifting toward the west and slowly gaining altitude as this month progresses; Jupiter, of magnitude -2.6, starting very low in the east-northeast, moving into the east and climbing about 1 degree higher each day (if viewed at the same stage of twilight daily); and blue-white Sirius, the “Dog Star” and brightest of nighttime stars, twinkling at magnitude -1.4 and ascending through southeast toward south-southeast at dusk as February runs its course.

Follow these three bright objects at dusk in coming months. Sirius will disappear into the west-southwest twilight glow during May, while Venus and Jupiter remain in view until at least late in July.

February’s other naked-eye evening planet is Mars, appearing as a red “star” of magnitude +1.2 to +1.3, not far from Venus all this month. Look about 9 degrees to the upper left of the brighter planet on Feb. 1, to 3 degrees to the lower right on Feb. 28. Both planets move rapidly against background stars, and remain within 10 degrees of each other for six weeks, starting on Jan. 31.

Stars at dusk: Look for the huge Winter Hexagon of Sirius-Procyon-Pollux-Capella-Aldebaran-Rigel. The noticeably red star Betelgeuse is within the Hexagon. Find the three-star belt of Orion, the hunter, midway between his shoulder, Betelgeuse, and his foot, bluish Rigel. The belt extended southeastward locates Sirius. Extend the belt in the opposite direction, bending north a bit, and you’ll find Aldebaran, eye of Taurus, the bull. Go farther to find the Pleiades, or Seven Sisters, a wonderful sight for binoculars!

Moon at dusk in early February: On Feb. 1 at dusk, less than two days before full, the moon appears between Pollux, the brighter of the Gemini twins, and Procyon, the Lesser Dog star. (The moon will return to the same place among the stars in just a little more than 27 days, but at a lesser phase, on the final evening of this month.) On Feb. 3, the moon, just past full and rising a few minutes after sunset, appears 5-6 degrees south (to the right) of bright Jupiter. The moon rises about an hour after sunset on Feb. 4, and nearly an hour later nightly for the next several evenings. Rather than staying up late to watch moonrise, shift your viewing time to morning, and follow our satellite in the morning twilight, less than an hour before sunrise:

Moon in morning twilight:

Feb. 3: Nearly full moon, setting in the west to west-northwest, 10 degrees to the lower right of Jupiter.

Feb. 4: Moon just past full, low, just north of west, 7 degrees to the lower left of Jupiter.

Feb. 5: Moon low in the west, 5-6 degrees to the lower left of Regulus.

Feb. 9: Waning gibbous moon in the southwest, less than 4 degrees to the upper right of Spica.

Feb. 12: Moon just past last quarter phase in south, a little less than half full, 5 degrees to the upper right of Saturn.

Feb. 13: Waning crescent moon in the south-southeast, about 8 degrees left of Saturn and 8-9 degrees to the upper left of Antares.

Feb. 16: Thin crescent moon low in the southeast to east-southeast, 9 degrees to the upper right of Mercury.

Feb. 17: Last old very thin crescent moon very low in the east-southeast, 6 degrees to the lower left of Mercury.

The new moon, invisible near the sun, occurs on Feb. 18 at 3:47 p.m. The moon returns to evening sky on Feb. 19. About 40 minutes after sunset, look for the young, thin crescent about 9 degrees south of due west and 6 degrees up, 13-14 degrees to the lower right of Venus.

Be sure to catch the spectacular gathering of the crescent moon and two planets at dusk on Feb. 20, all within a 2 degree field. The 2-day-old moonwill be within 1.7 degrees to the upper right of Venus, with Mars in between them, 0.7 degrees to the upper right of Venus. Venus-Mars appear closest to each other the next evening, Feb. 21, as Venus passes 0.4 degrees south of Mars. That same evening, the crescent moon will appear 14-15 degrees above the pair; as darkness falls, binoculars will show another planet, sixth-magnitude Uranus, just 2 degrees below and slightly right of the moon.

On Feb. 24, the fat crescent moon passes 8 degrees to the south of the Pleiades, or Seven Sisters star cluster. By the next evening, the moon will have passed first quarter phase and will appear just over half full, within 2 degrees to the east of Aldebaran, eye of Taurus the bull. As we look out the rear window of Spaceship Earth on Feb. 24-28, we are speeding away from the Hyades star cluster with Aldebaran in the foreground. On the night of Feb. 28, the waxing gibbous moon will lie about midway between Pollux and Procyon.

February 2015 at dawn: For most of February, in the morning twilight, you can observe as many as three planets: Jupiter, before it drops below horizon in the west-northwest near end of third week; Saturn, in the south all month; and Mercury, after it brightens to first magnitude early in second week. Look for these bright stars, also within the zodiacal belt, within a few degrees of the plane of Earth’s orbit: Antares, heart of Scorpius, to the lower left of Saturn; Spica to right of Saturn; and Regulus, heart of Leo, in the west, far to lower right Spica and upper left of Jupiter.

Other bright stars at dawn are Arcturus, high above Spica in the southwest sky; and the Summer Triangle of Vega-Altair-Deneb, climbing in the eastern sky. Brightest objects at morning mid-twilight for most of February, in order of brilliance, are: Jupiter (until it drops below the west-northwest horizon), Arcturus, and Vega. In the last week of February, Jupiter sets before middle of morning twilight, but Mercury becomes a close match in brightness to these two stars.

A View out the Front Window of Spaceship Earth!

Step outside on February mornings about an hour before sunrise, and visualize the motion of our planet in orbit around the sun.

In what direction are we heading? The sun is below the eastern horizon, below the brightest twilight glow. If you could go to a place high “above” the solar system, high in the northern sky toward the constellation Draco, and look “down,” you would observe that the revolutions of the eight planets around the sun, as well as the revolution of the moon around the Earth would all be counterclockwise.

On Feb. 6, Earth passes between sun and Jupiter, and that planet appears at opposition, 180 degrees from the sun. Note the star Regulus, 12 degrees to the upper left of Jupiter that morning. Twelve days later, on Feb. 18, Earth passes between Sun and Regulus, and that star takes its turn at opposition. If you look each morning at the same stage of twilight, Jupiter and Regulus appear lower daily, as we overtake and then look back at them.

On Feb. 23, the revolution of Spaceship Earth around the sun is carrying us toward Saturn. By Feb. 28, Earth is heading toward a point 5 degrees north of Antares in the predawn sky (and away from a point 5 degrees north of Aldebaran in the evening sky). As we travel around our curving orbit and overtake Saturn on May 22, that planet will appear at opposition and be above the horizon all night, and on May 31, Antares will be at opposition.

Mercury, an inner planet moving faster than Earth, passed nearly between Earth and Sun, inferior conjunction, on Jan. 30, and then moved ahead of us to emerge into the morning sky in February (faint at first, while displaying a backlighted crescent). Mercury reaches greatest elongation on Feb. 24. Next heading toward the far side of the sun, Mercury will drop below the horizon at morning mid-twilight by mid-March, and finally pass beyond the Sun at superior conjunction on April 9.

Wishing you clear skies to enjoy the ride on Spaceship Earth!

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 and the planet orbit charts, 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.

The year begins with the three other terrestrial (rocky) planets of our solar system—Mercury, Venus and Mars—low in the west-southwest to southwest during evening twilight. Their span shrinks from 27 degrees on Jan. 1, to less than 20 degrees Jan. 11-20.

Bright Venus, of magnitude -3.9, draws attention to the gathering. Find Mercury just to its lower right, within 3 degrees Jan. 1-17, 2 degrees Jan. 4-15, and 1 degree Jan. 8-12. On Jan. 10 at dusk, Mercury appears within two-thirds of a degree to the lower right of Venus! As seen from Earth, Mercury will not overtake Venus, and will instead fall just short. This is a quasi-conjunction, an approach within 5 degrees without an actual conjunction, when two planets share the same “x-coordinate.” Mercury shines at magnitude -0.8 Jan. 1-11, fades through magnitude 0 on Jan. 19, magnitude +1 on Jan. 22, and magnitude +2 on Jan. 24, en route to inferior conjunction Jan. 30. Mars glows at magnitude +1.1 to +1.2, 24 degrees to 10 degrees to the upper left of Venus.

Bright Jupiter,of magnitude -2.5 to -2.6, rises in the east-northeast within 3.2 hours after sunset on Jan. 1, closing to within four-tenths of an hour after on Jan. 31. One hour before sunrise, Jupitergleams in the west-southwest, 8 to 12 degrees west of Regulus, while Saturn glows at magnitude +0.6 to +0.5 in the southeast to south-southeast, 11 to 9 degrees northwest of Antares.

As for the moon: In the evening sky, our satellite “leapfrogs” past Aldebaran from Jan. 1 to Jan. 2. Full moon occurs on evening of Jan. 4, and at dusk, it appears low, north of east, to the right of the Gemini Twins, Pollux and Castor. At next day’s dawn, on Jan. 5, the moon is low, north of west, to the lower left of the Twins. On the night of Jan. 7-8, from late evening to dawn, the waning gibbous moon keeps company with bright Jupiter. Regulus, heart of Leo, is nearby, 9 degrees east of the planet.

For two weeks after full, the waning moon can be followed in the mornings, about an hour before sunrise. The last quarter moon—half-full and 90 degrees, or one-quarter circle, west of the sun—appears very close to Spica on the morning of Jan. 13.

In mid-January each year, our Spaceship Earth heads toward Spica. In the coming months, as Earth curves around the sun, we will overtake the slower-moving outer planets: Jupiter in early February 2015, and Saturn after the middle of May. As a result, these planets, along with their background stars, will progress toward the western horizon of our morning sky, and will appear above our eastern horizon in the early evening sky as Earth passes each one in turn.

On the morning of Jan. 16, a waning crescent moon appears quite close to Saturn. Note the star Antares, heart of the Scorpion, 10 degrees below. On the next morning, Saturday, Jan. 17, the moon will appear in the southeast, widely left of Antares and to the lower left of Saturn. On Sunday, Jan. 18, the moon is still in easy view, 24 degrees to the lower left of Antares. On Monday, Jan. 19, the last old crescent moon is just 3 degrees up in mid-twilight, 23 hours before the invisible new moon of Jan. 20 at 5:14 a.m.

After new, the moon returns to the evening sky. At dusk on Wednesday, Jan. 21, you’ll have your first chance to observe the thin young moon, 37-38 hours after new, in close company with Venus and Mercury. Mars appears to their upper left as twilight fades. On the next night, Thursday, Jan. 22, the crescent will appear near Mars.

First quarter (evening half-moon) is reached on Monday, Jan. 26. As we look into the evening sky in the direction of the first quarter moon (below the bright stars of Aries, the Ram, and two days’ moon travel west of the Pleiades star cluster), we are facing back toward our “wake,” in the opposite direction of the motion of Spaceship Earth around the sun. Between the evenings of Jan. 28 and 29, for the second time this month, the waxing gibbous moon again “leapfrogs” over Aldebaran, eye of the Bull and follower of the Pleiades. It takes about 27.3 days for the moon to return to the same star field, but, because of the Earth’s revolution around the sun, it takes about 29.5 days until the moon repeats the same phase.

The next full moon will occur on Feb. 3, with Jupiter nearby all night.

The two brightest planets, Venus and Jupiter, will be visible simultaneously in the early evening from late January through July. On Jan. 18, Jupiter rises in the east-northeast as Venus sets in the west-northwest. On Jan. 20, near the end of twilight, they both appear about 1 degree up. Look just more than a minute earlier each day to catch these brightest planets equally above opposite horizons: 3 degrees up on Jan. 23; 6 degrees on Jan. 28; and 8 degrees on Jan. 31.

Looking ahead, Venus and Jupiter will gradually come together, attracting the attention of even casual observers, culminating with a spectacular close pairing of Venus and Jupiter on the evening of June 30, when they’ll appear just one-third of a degree apart in the western sky. (Do not miss the telescopic view!) The five-month run-up from late January to June 30 provides a fine chance to follow these planets and watch for changes. Not until 2035-2036 will there be such a long an interval to follow Venus and Jupiter in the sky together on their way to a brilliant pairing.

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.

Near the start of December every year, the first-magnitude star Aldebaran, eye of Taurus the Bull, and “follower” of the Pleiades, or Seven Sisters, is visible all night as Earth makes its annual passage between Aldebaran and the sun. Look for Aldebaran low in the east-northeast at dusk, high in the south in the middle of the night, and low in the west-northwest at dawn.

On New Year’s Eve, the brightest star, Sirius the Dog Star, reaches its high point in the south in the middle of the night. You can observe Sirius for much of that night, but not at dusk or dawn, because the star’s path from rising to setting is too far south and too short to keep it above the horizon through the long winter night.

Some 21 to 22 minutes earlier, and 36 degrees lower than Sirius at its highest, observers in Southern California can look for Canopus, the second-brightest star visible in the nighttime skies. However, from the Coachella Valley, the star appears 3 to 4 degrees up at its highest. (I’ve spotted Canopus from Palm Springs—as it passed through a gap in the Santa Rosa Mountains.)

The four brightest “stars” at dusk: Venus (after it emerges around midmonth) is at magnitude 3.9; Mercury (near month’s end) -0.8; Vega 0.0; and Capella +0.1.

Watch for the slow emergence of Venus from beyond the sun, followed by Mercury, closing to 3 degrees to the lower right of Venus at month’s end, in the southwest to west-southwest. Binoculars can help you spot Mercury very low in the bright twilight by closing days of December. On Jan. 10, Mercury will approach to just 0.6 degrees to the lower right of Venus! Mars (+1.0 to 1.1) is in the south-southwest to southwest throughout December, to the upper left of Venus.

As for stars: Thee Summer Triangle of Vega, Altair and Deneb is high in the west, still well up at dusk as winter arrives. Fomalhaut, mouth of the Southern Fish, crosses south. Capella is in the northeast, with Aldebaran in the east-northeast, both moving to the upper right as the month progresses. Appearing above the eastern horizon late in the month are Orion’s Betelgeuse and Rigel, and Gemini’s Pollux (with fainter Castor above it, not shown on the map).

The full moon appears closely to the upper right of Aldebaran at dusk on Dec. 5 (passing it overnight), and widely to the lower left of that star on the next evening. On Dec. 22, about 30 minutes after sunset, Venus appears about 6 degrees to the south (lower left) of the young crescent moon. On the next evening, look for Venus about 11 degrees to the moon’s lower right. On Dec. 24, look for Mars 6 to 7 degrees south (lower left) of the moon. On Dec. 5, Mars appears about 11 degrees to the moon’s lower right.

The five brightest “stars” at dawn: Jupiter (magnitude -2.3 to -2.4); Sirius (-1.4); Arcturus (mag. -0.1); Vega (0.0); and Capella (+0.1).

Jupiter is high in the southwestern sky; Saturn (+0.5) is ascending in the east-southeast to southeast.

All of the stars of the huge Winter Hexagon, except Rigel, are visible in the western morning sky at the start of December. As the month progresses, two more of its stars, Aldebaran and Sirius, drop out, as well as Betelgeuse within the Hexagon. The trailing side of the Hexagon, forming the arch of Procyon, Pollux (and Castor, not shown) and Capella, remains in view throughout December. Jupiter and Regulus are close in tow, following the descending arch into the western sky. In the eastern sky, Arcturus dominates, with Vega and Deneb far to its lower left, and Spica to its lower right. Find Saturn to Spica’s lower left and, late in month, Antares below and a little left of Saturn.

The full moon appears closely to the upper left of Aldebaran low in the west-northwest at dawn on Dec. 6. A waning gibbous moon appears between Procyon and Pollux on Dec. 9; near Jupiter on Dec. 11 and 12; and near Regulus on Dec. 12. A waning crescent moon appears near Spica on Dec. 16 and 17; closely to the upper right of Saturn on Dec. 19; and to the lower left of Saturn and upper left of Antares on Dec. 20.

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 and remains active in research and public outreach in astronomy.

In late November, catch the Pleiades, or Seven Sisters, star cluster visible all night, low in the east-northeast at dusk; high in the south in middle of night; and low in the west-northwest at dawn. The view of this beautiful star cluster through a pair of binoculars is a sight not to be missed!

The brightest stars in November at dusk: Arcturus, the “bear-chaser” star, can still be spotted very low in the west-northwest at dusk at start of November, but disappears below the horizon by second week. Mountains to the west will hasten its departure. Vega is very high in the west-northwest, three-quarters of the way from horizon to overhead on Nov. 1, and still halfway up to overhead at month’s end. Capella, the “mother-goat” star, is very low in the north-northeast to northeast at dusk in November, and slowly gaining in altitude.

Note how stars near the horizon, such as Arcturus and Capella, twinkle much more than stars nearly overhead, such as Vega. The twinkling, as well as the considerable dimming of stars near the horizon, is caused by the passage of their light through Earth’s atmosphere.

Other bright stars at dusk include Altair, high in the south-southwest to west-southwest; it marks the southern point of the Summer Triangle it completes with Vega and Deneb. Fomalhaut, “mouth of the southern fish,” is low in the south-southeast, climbing toward its highest point in the south. Late in the month, Aldebaran, eye of Taurus the bull, begins rising before mid-twilight. Look in the east-northeast, about 14 degrees below Pleiades. Aldebaran’s name is Arabic; it means “the follower,” because that star follows the Pleiades cluster across the sky. (The cluster does not appear on our star maps, because its brightest star is of third magnitude; the maps plot only the stars of first magnitude or brighter, as well as the naked-eye planets.)

Every year around Dec. 1, the Earth passes between Aldebaran and the sun, and the first-magnitude star appears at opposition, nearly 180 degrees from the sun and above the horizon, nearly all night. About 10 days earlier, around Nov. 20-21, the Pleiades star cluster comes to opposition, rising in the east-northeast in deepening twilight. The scene is well described in Alfred Lord Tennyson’s Locksley Hall:

Many a night I saw the Pleiades,

rising thro’ the mellow shade

glittering like a swarm of fireflies

tangled in a silver braid.

As for evening planets: At dusk, Mars is the only planet visible to unaided eye. It glows at first magnitude in the south-southwest to southwest all month. Look 75 minutes after sunset to follow the eastward motion of Mars past the background stars of Sagittarius. On Nov. 4, Mars passes only 0.6 degrees north of the third-magnitude star, marking the top of the teapot. On Nov. 10, Mars passes 2 degrees north of a second-magnitude star in the teapot’s handle.

Venus passed superior conjunction on the far side of the sun on Oct. 25. Wait until just after the sun disappears below your horizon in late November, and start searching for Venus. By Nov. 30, Venus is 9 degrees to the upper left of the sun, and sets 33 minutes after sundown. In December, Venus will become easier to see with the unaided eye—and during spring and early summer of 2015, it will be very impressive indeed.

The moon, full on Nov. 6, draws closer to Aldebaran overnight on the next night, Nov. 7-8, and pulls away from that star on the night of Nov. 8-9, from two hours after sunset until dawn. A waxing crescent moon appears near Mars at dusk on Nov. 25 and 26.

The brightest stars in November at dawn: Jupiter of magnitude -2.1 to -2.2, is very high in the southeast to southwest; Sirius, the “dog star,” is in the south-southwest to southwest; Mercury, -0.6 to -0.9, is low in the east-southeast until it drops below mid-twilight horizon near end of third week; Arcturus is climbing in the east-northeast to northeast; Vega emerges in the northeast at month’s end; and Capella is well up in the northwest.

The huge Winter Hexagon now appears entirely west of the meridian (the north-south overhead line). In clockwise order, its stars are Sirius, Procyon, Pollux (with fainter Castor nearby, not shown), Capella, Aldebaran and Rigel. Betelgeuse, Orion’s shoulder, is inside the Hexagon. Rigel will be the first star of the Hexagon to reach the western horizon, near month’s end. Jupiter and Regulus cross the meridian in pursuit of the Hexagon. Arcturus and Spica ascend the eastern sky all month. Brighter descending Mercury passes 4 degrees north of Spica on Nov. 4, as Spica climbs higher daily.

The moon appears near Aldebaran at dawn on Nov. 8 and 9; widely north of Betelgeuse at dawn on Nov. 10; and between Procyon and Pollux at dawn on Nov. 12. At dawn on Nov. 14, find the last quarter (morning half moon) 5 degrees from Jupiter, with Regulus about 8 degrees east of the bright planet. At dawn on Nov. 15, the moon will appear within 6 degrees of Regulus. On Nov. 19, the waning crescent moon will appear within 3 degrees of Spica. Using binoculars, watch for Mercury rising 13 degrees to the lower left of the moon on Nov. 20, and just 2 degrees to the lower right of the last old crescent moon 40 minutes before sunrise on Nov. 21.

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.

This month’s highlights include a total lunar eclipse in the predawn hours of Wednesday, Oct. 8, and a partial solar eclipse on Thursday afternoon, Oct. 23. Read more about these eclipses here.

The two eclipses make October a good month to follow the moon through an entire cycle of phases and observe its changing visibility in day and night skies.

1. Observe the moon in early evening, about one hour after sunset.

During the two-week periods Sept. 26-Oct. 8 and Oct. 25-Nov. 7, the moon changes from a thin crescent low in the southwestern sky, and moves through first quarter phase. By the final date of each set, Oct. 8 and Nov. 7, the moon will have just passed through full phase and will rise north of east, in waning gibbous phase—a little less than full—within an hour after sunset.

Our evening twilight all-sky chart above depicts the sky at dusk (mid-twilight), when the sun is 9 degrees below the horizon, about 40 minutes after sunset at this time of year. Those plotted on our evening chart are the first to appear as twilight fades after sunset. October’s brightest stars at dusk are Arcturus in the west, and Vega nearly overhead. Also high in the sky are Altair and Deneb, completing the Summer Triangle with Vega. Mars lingers in the southwest all month, while Antares, just 4 degrees from Mars on Oct. 1, sinks into the southwest as the month progresses. Saturn, on its way to conjunction beyond the sun in mid-November, sinks into the west-southwest. Fomalhaut, mouth of the Southern Fish, climbs into the southeast.

On Oct. 25, use binoculars to catch Saturn within 5 degrees to the lower right of the thin crescent moon, and Antares 8 degrees to the lower left of the moon on the next evening. On Oct. 27 and 28, find Mars 9 degrees to the left of the moon on the first evening, and about the same distance to its lower right on the next.

2. Watch the moonrise each day when it occurs between sunset and 10 p.m.

In October 2014, this happens Oct. 8-12. On Oct. 8, the moon rises just after sunset. (The full moon and the total lunar eclipse will have occurred earlier on the same date, before sunrise.) Thereafter, the moon rises later each evening. Pick a spot with a good view of the eastern horizon, and enjoy the show. Note the color of the rising moon, and—if you can observe from the same location each evening—note the time and the place along your horizon panorama where the moon rises.

3. Look for the moon each morning, about one hour before sunrise.

With daylight saving time still in effect in October, this shouldn’t be too much to ask. The dates this month 2014 are Oct. 8 (soon after the lunar eclipse has ended in California) through Oct. 22.

During these 15 mornings, the waning moon changes from full, low in the west on Oct. 8, and moves through last quarter phase, half full and 90 degrees west of the sun, on Oct. 15, to a thin crescent old moon, just risen within 10 degrees south of east, on Oct. 22.

While you’re out, use our morning twilight all-sky chart below to find these bright objects in morning twilight: Jupiter (magnitude -2); Sirius (-1.5); and Canopus(-0.7), very low in the south for Southern Californians. Mercury ranks next after it brightens past magnitude 0 on Oct. 28; Arcturus (mag 0.0), after it emerges late in month; and Capella (0.1).

As for morning planets: Jupiter climbs very high through the southeastern sky. One week after passing inferior conjunction on Oct. 16, nearly between Earth and the sun, backlit Mercuryemerges south of east as a faint +1.5 magnitude object on Oct. 23, and brightens rapidly to magnitude -0.6 by month’s end.

As for morning stars: The huge Winter Hexagon reaches its highest position in morning twilight this month. In clockwise order, its stars are Sirius, Procyon, Pollux (and Castor, not quite bright enough to be plotted), Capella, Aldebaran and Rigel. Betelgeuse is inside the figure, and bright Jupiter and faint Regulus pursue the hexagon across the sky. Arcturus, Mercury and Spica, in that order, appear above the eastern horizon in late October.

An hour before sunup, skies are dark enough to allow viewers to follow the moon’s changing place against background stars. On Oct. 11, the moon is 8 degrees south (to the lower left) of the Pleiades cluster, and on the 12th, just 1 to 2 degrees above Aldebaran, eye of Taurus.

On Oct. 13, the waning gibbous moon has moved 14 degrees east of Aldebaran and stands 12 degrees to the upper right of Betelgeuse, Orion’s shoulder.

On Oct. 15, the nearly last quarter moon—just more than half full and just more than 90 degrees from the sun—stands nearly equidistant from Procyon, the “Little Dog” star, and Pollux, the brighter of the “Twin” stars of Gemini. On the 17th, the crescent moon stands 7 to 8 degrees to the upper right of Jupiter.

On Oct. 18, the moon, a crescent one-quarter full, stands 8 to 9 degrees to the lower right of Jupiter and 6 to 7 degrees to the lower right of Regulus, heart of Leo, the Lion. On the next morning, the moon is 8 to 9 degrees below Regulus.

Finally, on the morning on Oct. 22, the old moon, less than 2 percent full, is just 2 degrees up an hour before sunrise, and 8 degrees south of due east. A partial solar eclipse occurs on the afternoon of the next day, Thursday, Oct. 23.

4. Observe moon in the morning.

At 9 a.m., follow the moon daily from Oct. 11 (88 percent full, low in the west to west-northwest), through last quarter phase on Oct. 15, just over half full and more than halfway up to overhead in the west-southwest. Your last easy morning daytime view at that hour may occur on Oct. 20, when the moon will be a 10 percent crescent located 37 degrees to the upper right of the sun.

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.

Friday, 19 September 2014 14:20

Astronomy: Get Ready for Two October Eclipses!

There are two eclipses in October 2014!

The first is a total lunar eclipse, in the predawn hours of Wednesday, Oct. 8. You’ll want to set your alarm when you turn in for the night on Tuesday.

Here are the times for the various stages of the Oct. 8 lunar eclipse for the Pacific time zone, with the moon’s position in Palm Springs.

  • Moon enters umbra at 2:15 a.m. (moon’s azimuth is at 227 degrees; altitude is 52 degrees).
  • Total eclipse begins at 3:25 a.m. (245°; 41°).
  • Deepest eclipse is at 3:55 a.m. (251°; 35°).
  • Total eclipse ends at 4:24 a.m. (256°; 29°).
  • Moon leaves umbra at 5:34 a.m. (267°; 16°).

During totality in Palm Springs, Uranus (magnitude 5.7) should be visible in binoculars nearly 1 degree to the left or lower left of the center of the eclipsed moon. A medium to high power telescope reveals the planet’s disk, 3.7 arcseconds across.

October’s second eclipse is a partial solar event, in the afternoon on Thursday, Oct. 23.

A solar eclipse can be viewed indirectly, by looking at a projected image. Take a postcard or 3-by-5-inch index card; puncture a small pencil point hole in the center of the card; and allow the projected image of the sun to fall on a second white card, held 3 or 4 feet away, in the shadow of the first card. You can improve the view by using a long cardboard box: Cut a large hole at one end, and cover that hole with the first index card with the small puncture hole. Then tape a sheet of white paper inside the box at the opposite end, to serve as a screen.

You can also stand in the shade of a tree and look for projected images of the eclipsed sun, on the ground or on a sheet you have spread on the ground, or on the side of a light-colored building. Try this method a few days before the eclipse, at the same time of day, and look for round projected images of the full disk of the sun.

Groups organizing a solar eclipse watch can also order a quantity of solar eclipse viewers for participants. Both hand-held safe eclipse viewers and eclipse glasses (to be worn like regular eyeglasses) are available from Rainbow Symphony. Both styles are identically priced and employ the same filter materials. The minimum quantity for those items is 25, at 85 cents each, with bigger discounts for larger quantities. To order, go to www.rainbowsymphonystore.com, and click on eclipse shades.

The viewers can be kept for use during future eclipses! In the next 10 years, there will be three more solar eclipses visible from California. These filters can also be used to check for sunspots; very large ones would be visible through the filter.

In Palm Springs, the eclipse on Thursday, Oct. 23, begins at 2:12 p.m., as the moon’s disk makes first contact with the upper right edge of the sun’s disk. Greatest eclipse for Palm Springs occurs at 3:31 p.m., as the moon’s disk covers the upper right portion of the sun’s disk—45 percent of the solar diameter, or 33 percent of the disk area. The eclipse ends at 4:41 p.m., as the moon’s disk makes last contact with the upper left edge of the solar disk.

During the eclipse in Palm Springs, the sun will be sinking through the southwestern sky, at an altitude ranging from 38 degrees at the start of the event, to 15 degrees at the end.

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.

Mars forms colorful pairs with other objects in the southwest evening sky in September, as the red planet moves from just more than 5 degrees from yellowish Saturn on Sept. 1, to within 5 degrees of red Antares from Sept. 22 through Oct. 3.

Saturn, with its rings tipped 22 degrees from edge-on, is impressive through a telescope, if you catch it before it sinks low.

The crescent moon near a planet is an attractive sight. Catch a waning crescent near Jupiter at dawn on Sept. 20, and a waxing crescent very near Saturn on Sept. 27. On Sept. 27 and 28, Mars passes 3 degrees above Antares, and on the 29th, the lunar crescent passes above the red pair.

September 2014 at dusk: The five brightest objects in evening mid-twilight (ignoring Mercury, near magnitude 0, but very low in the west to west-southwest), are Arcturus and Vega (0.0); Saturn (+0.6); Mars (+0.6 to +0.8); and Altair (+0.8).

Saturn is in the southwest to west-southwest, lower as the month progresses. Mars starts this month just more than 5 degrees to the lower left of Saturn, and 18 degrees to the right of Antares, heart of Scorpius the scorpion. Watch Mars move! On Sept. 5 and 6, look for a nearly vertical “fence” of three stars about midway between Mars and Antares; it marks the head of the scorpion. By Sept. 12, Mars is equidistant from Saturn and Antares, 11 degrees from each. On Sept. 17, Mars passes just a half-degree north of second-magnitude Delta Scorpii, the middle star of the “fence.” Mars passes 3 degrees north of Antares on Sept. 27 and 28, with a crescent moon nearby on the next evening. Compare color and brightness of Mars and Antares (“rival of Mars”) for several evenings around their closest approach. Mercuryis highest at midmonth, but only 3 degrees up in mid-twilight from Southern California in this poor apparition. It passes 0.6 degrees south of Spica on Sept. 20. Binoculars, very clear skies and an unobstructed horizon are needed to observe this event.

As for stars, Spica departs in the west-southwest. Arcturus remains prominent in the west, and Antares sinks toward the southwest. Vega, the lead star of the Summer Triangle, passes nearly overhead, with Altair and Deneb remaining east of the meridian (north-south line overhead) at mid-twilight through September. Fomalhaut rises in the southeast at month’s end.

Moon in the evening sky is found near Mars and Saturn on Aug. 31; near Antares on Sept. 1; near Saturn on Sept. 27; and near Mars and Antares on Sept. 29. On evenings following the full moons of late summer and early fall, we usually get a “Harvest Moon effect,” when the moon rises not very much later each evening. But this year, the perigee on Sept. 7 and the low inclination of the moon’s orbit increase the daily time delay over what it can be for the Harvest Moon in most years.

September 2014 at dawn: The brightest objects are Venus, near magnitude -4, but in bright twilight and sinking out of sight at our mid-twilight viewing time during third week; and Jupiter, near magnitude -1.8 and climbing in the east. Next in brightness are Sirius, in the southeast to south-southeast, and Capella, nearly overhead.

The latter two are the southernmost and northernmost stars of the huge “Winter Hexagon,” in clockwise order, Sirius, Procyon, Pollux (and Castor, not shown), Capella, Aldebaran, Rigel and back to Sirius. Betelgeuse, Orion’s shoulder, resides within the hexagon. Regulus, the heart of Leo the lion, follows the hexagon across the sky, as if to chase his next meal, with the twins of Gemini, Orion, two dogs, Auriga the charioteer, Capella the mother goat, and Taurus the bull as possible menu options. Find emerging Regulus just 0.8 degrees south (to the lower right) of Venus on Sept. 5. The only other star of first magnitude visible in September’s dawns is Deneb in the northwest, the last star of the Summer Triangle to set.

Before morning twilight brightens, use binoculars to find the Beehive star cluster, 3 degrees above Jupiter on Sept. 1, widening to 8 degrees to the upper right of Jupiter at month’s end.

The moon in morning sky appears near Aldebaran on Sept. 14 and 15; widely (11 degrees) north of Betelgeuse on Sept. 16; between Procyon and Pollux on Sept. 17; south of Jupiter on Sept. 20; and within 5 degrees south of Regulus on Sept. 21.

Check the website of the Astronomical Society of the Desert for dates, maps and directions to our “star parties,” where everyone is welcome to look through our telescopes at the moon, planets and “deep sky objects.” Year-round monthly sessions begin at dusk at Sawmill Trailhead, elevation 4,000 feet. This month’s session will be on Sept. 20, if sky conditions permit. Our monthly star parties at the more-convenient Santa Rosa and San Jacinto Mountains National Monument’s Visitor Center will resume on Oct. 4.

Enjoy 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, who provided the twilight charts, 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.

The full moon occurs on Sunday, Aug. 10, at 11:09 a.m. The moon passes perigee—221,765 miles from Earth, the closest approach of the year—at the same hour.

But this “supermoon,” visible at dawn and dusk on that date, is not the brightest moon of 2014, because of the phase effect, which makes the moon’s brightness decrease sharply when it’s a few degrees away from being exactly 180 degrees from the sun. You can duplicate this effect one night by standing between a stationary bright-light source and a highly reflective road sign, so that the shadow of your head is cast upon the sign. Note how the sign really lights up around your head’s shadow, giving the shadow a brilliant “halo.” However, if you take a step or two to left or right, you’ll notice how quickly the road sign fades away.

August's full moon passes four to five degrees north of Earth’s shadow center, causing the moon to set after sunrise and rise before sunset on Aug. 10. Further, the timing of the full moon, during the daytime, places the moon widely northwest of the Earth’s shadow at sunrise, and northeast of it at sunset.

Even with the moon not as bright as could be, there are no truly dark skies between dawn’s first light on Aug. 8 and nightfall on Aug. 14. This fact will largely spoil this year’s Perseid meteor shower, which would otherwise be at its best in the predawn darkness hours of Wednesday, Aug. 13.

If you’re outdoors that morning as twilight brightens, watch for Jupiter rising in the east-northeast, 5 degrees to the lower left of Venus. Venus goes east against background stars by 1.2 degrees per day compared to Jupiter’s 0.2 degrees; watch their separation narrow by about 1 degree daily.

Don’t miss the spectacular pairing of Venus and Jupiter on Monday, Aug. 18, within 0.4 degrees. Five days later, on Saturday, Aug. 23, the old crescent moon joins the brilliant planets in a beautiful scene.

Evening planets: Find the planets Mars and Saturn in the southwest at nightfall, and compare them in brightness and color to each other; to bluish Spica, to their lower right; and to reddish Antares, to Saturn’s left. The stars will twinkle noticeably.

Watch the Mars-Saturn gap shrink until they’re 3.4 degrees apart on Aug. 25, and then widen to 5.0 degrees apart by Aug. 31. The moon will appear near these planets on Aug. 31.

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.