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Last updateTue, 18 Sep 2018 1pm

Venus becomes ever more prominent in the evening, while Jupiter, and then Saturn, sink into the southwest twilight glow in December. Mars, slowly brightening, appears in the southeast morning sky, with bright Mercury below it in the first half of the month.

Do not miss Venus and Saturn within 5 degrees Dec. 7-14 (see right), with their closest pairing 1.8 degrees apart on Dec. 10; and the spectacular Venus-moon conjunction on Dec. 28.

Three planets span 18 degrees in the southwest at dusk in early December. On Dec. 1, find Venus, magnitude -3.9, with Jupiter, magnitude -1.8, just 8 degrees to the lower right, and Saturn, magnitude +0.6, 11 degrees to Venus’ upper left. Venus is now on the far side of its orbit, with its light taking 12 minutes to reach us, compared to the sun’s eight minutes. Light reflected from Jupiter and Saturn takes 51 and 90 minutes, respectively, to travel to Earth on Dec. 1.

As stars appear at dusk, find the Summer Triangle of Vega, Altair and Deneb dropping downward from high in the west; Fomalhaut, mouth of the Southern Fish, crossing through south; Capella, the mother goat star, ascending in the northeast; and Aldebaran, eye of Taurus, climbing in the east-northeast to east. In twilight before month’s end, Orion’s bright stars Rigel and Betelgeuse, and his three-star belt midway between them, appear in the east, followed by Gemini’s twin stars, Castor and Pollux, rising farther north along the horizon.

Note the first-magnitude star Aldebaran, eye of Taurus, low in the east at dusk on Dec. 1. Visualize: As Earth passes between Aldebaran and sun, the star is at opposition and up all night. The revolution of Earth and other planets around the sun is counterclockwise, from the viewpoint of an observer above the north side of our solar system. So Earth on Dec. 1 is moving directly away from a point 90 degrees east of the sun and 90 degrees west of Aldebaran; that’s 2 degrees west of the third-magnitude star Lambda in Aquarius, in the southern sky at nightfall. Inner planets move faster, so Venus, now on the far side of its orbit and gaining on us, continues to move farther out from last August’s place on far side of the sun, until reaching greatest elongation, 46 degrees east of the sun, on March 24, 2020. Venus will overtake us 10 weeks later, when it passes inferior conjunction, nearly between the Earth and the sun, on June 3.

We’re leaving Jupiter and Saturn behind. Earth’s faster revolution around the sun will cause Jupiter to pass behind the sun on Dec. 27, and Saturn to do so on Jan. 13. During this month, before these solar conjunctions, when will you last spot Jupiter low in the southwest at dusk? When will you last see Saturn? Pick a spot where nearby mountains won’t block your view. Using binoculars can help you delay these planets’ departures by a few days.

In morning sky, on Dec. 2, Earth is heading toward Leo, 10 degrees east of Regulus. Speedy Mercury, a few days past greatest elongation on Nov. 28, is leaving us behind and heading toward superior conjunction on the far side of the sun, on Jan. 10. When will you last see Mercury before then? Mars begins December at faint magnitude +1.7. We’re gaining on the red planet, so watch it brighten until its closest approach and opposition in October 2020, when it will gleam at magnitude -2.6.

Follow the moon and planets: The earliest sunsets of the year in December provide a convenient opportunity for families to enjoy the night sky, and this year, the planets provide much to see. In the southwest, the brightest planet, Venus, is easy to spot by half an hour after sunset. In early December, find bright Jupiter to Venus’ lower right, and Saturn to Venus’ upper left. In December’s first week, Jupiter and Saturn are 18 degrees apart, with brilliant Venus between them, while the waxing moon moves farther from the planets nightly. Each evening in early December, Venus moves farther from Jupiter and closer to Saturn. On Dec. 2, foreground Venus appears nearly midway between the distant giants. On Dec. 3, the moon reaches first-quarter phase, when it appears half-full. On the evenings of Dec. 10 and 11, Venus will pass less than 2 degrees to the lower left of Saturn. Can you still spot Jupiter those evenings, before it sinks into even brighter twilight? Find Jupiter 17 degrees to the lower right of the Venus-Saturn pair on Dec. 10.

By then, the moon, shifting its place eastward by an average of 13 degrees per day against background stars, has moved into the constellation Taurus, the Bull. On Tuesday, Dec. 10, note the first-magnitude star Aldebaran, eye of the Bull and follower of the Pleiades, to the lower left of the moon. On the next evening, find Aldebaran to the upper right of the full moon. Continue to follow the moon for several more evenings after Dec. 11—if you’re OK with staying up later each night.

Alternatively, early risers can shift their moon-watching time to mornings, one hour before sunrise. At that time on Dec. 11, the moon and Aldebaran are within 3 degrees and about to set in the west-northwest, while Orion is setting in west, and Sirius, the brightest star, is low in the west-southwest. Mercury, just risen in the east-southeast, is in the head of Scorpius on the morning of Dec. 11, while the moon is just above the head of Taurus—opposite to Scorpius in the zodiac, the belt of constellations where the sun, moon and planets are always found. Look in the southeast for faint Mars, 18 degrees to the upper right of Mercury on Dec. 11, and for a first magnitude star, Spica, nearly 21 degrees to the upper right of Mars. Spica is in Virgo, another zodiac constellation. Note that Mercury, Mars and Spica are in a nearly straight line.

Mornings the next two weeks, watch the waning moon pass several bright stars and planets in the zodiacal band: Pollux and Castor of Gemini on Dec. 14; Regulus, heart of Leo, on Dec. 17; Spica in Virgo on Dec. 20 and 21; Mars in Libra on Dec. 22 and 23; and Antares in Scorpius on Dec. 24. By then, Mercury has moved closer to the sun and may be too difficult to observe in bright twilight.

The new moon is invisible as it passes the sun late on Christmas Day. At dusk on Dec. 27, the young crescent can be seen low in the southwest to the lower right of Venus. Using binoculars, can you spot Saturn within 7 degrees to the lower right of the moon?

Whatever you plan for Saturday, Dec. 28, be sure to include time for views of the southwest sky at dusk! At sunset, Venus will be within 2 degrees above and slightly to the right of the moon. Can you spot Venus before sunset? By 40 minutes after sunset, the view of Venus just to the upper right of the crescent moon will be spectacular! Keep watch as the moon and Venus sink toward the horizon. They’ll be little more than one degree apart as they set.

For a preview of sky events through August 2020, with monthly all-sky charts for dusk and dawn, visit the Sky Calendar extra content page at www.abramsplanetarium.org/msta.

Check the website of the Astronomical Society of the Desert at www.astrorx.org, and come to our free evening star parties, offered monthly at two locations.Our primary, more accessible venue is 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. Our next session there will be on Saturday, Dec. 21, from 5 to 8 p.m.Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will next host a session on Saturday, Dec. 28, starting at dusk.

At various locations, some members of the Astronomical Society of the Desert will host observing sessions for special events, including gatherings of moon and planets. These might be announced on short notice, so periodically check the link to Impromptu Star Party Dates, on the society’s website.

You can also pre-register for one of the Stargazing Parties offered several times each month at the Rancho Mirage Library Observatory. Visit www.ranchomiragelibrary.org/observatory.html; click on Stargazing Parties, then sign up for their eNewsletter to receive registration information. If you go farther afield, check out the Sky’s the Limit Observatory and Nature Center in Twentynine Palms, at www.skysthelimit29.org.

Wishing you clear skies!

Robert C. Victor was staff astronomer at Abrams Planetarium at Michigan State University. Now retired, he often collaborates in producing new issues of the Sky Calendar he originated in 1968, and enjoys providing sky watching opportunities for a variety of groups. 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.

Published in Astronomy

The sky’s highlights in November include Mars and Spica forming a colorful pair before dawn on Nov. 10. Mercury crosses the sun Nov. 11 to join Spica and Mars a week later. Venus and Jupiter form a brilliant pair at dusk Nov. 23-24. The moon passes three bright evening planets Nov. 27-29.

Our evening twilight chart for November shows Venus higher each evening at the same stage of twilight, while Jupiter and Saturn, dragged westward along with the starry background, appear lower. The Abrams Planetarium Sky Calendar highlights the resulting spectacular gatherings of Nov. 24, Nov. 28 and Dec. 10 involving these planets.

Planets at dusk: Begin looking low in the southwest about a half-hour after sunset to catch the two brightest planets, Venus (magnitude -3.9), and Jupiter (-1.9, only one-sixth as bright). They are 20 degrees apart on Nov. 4; 10 degrees apart on Nov. 14; and within 5 degrees, fitting within a binocular field, Nov. 19-28. Don’t miss this spectacular pair at its closest, 1.5 degrees apart, on Nov. 23 and 24.

Saturn, of magnitude +0.6, one-tenth as bright as Jupiter, is 22 degrees to the upper left of Jupiter on Nov. 1; 19 degrees to the upper left of the Venus-Jupiter pair on Nov. 24; and 12 degrees to the upper left of Venus on Nov. 30. Venus will pass 1.8 degrees from Saturn on Dec. 10; by then, Jupiter will be almost gone.

The first, young crescent moon of a new cycle appears within 6 degrees to the lower right of Jupiter on Nov. 27. Don’t miss the crescent moon within 3 degrees to the upper left of Venus on Thanksgiving, Nov. 28, and even closer to Saturn on the next evening.

Mornings: About one hour before sunrise, enjoy dim red Mars (magnitude +1.8) and blue Spica (+1.0), low in the east-southeast within a five-degree binocular field Nov. 4-16. They’ll appear closest on Nov. 10, as Mars passes 2.8 degrees north (to the upper left) of Spica. The next two Mars-Spica pairings, in 2021 and 2023, will be lost in the glare of the sun. Their next visible pairing after this one: They’ll be 2.2 degrees apart on Sept. 13, 2025.

Mercury transits across the face of the sun on Nov. 11. The disk of Mercury is tiny, only 10 arcseconds across, little more than 1/200th of the sun’s diameter. Use a telescope magnifying 50x to 100x with a solar filter securely installed over its front end, or use equipment to project an image of the sun on a white screen or paper 1-2 feet from the eyepiece. Mercury will appear as a tiny black dot already near the center of the solar disk at 7:20 a.m., just more than an hour after sunrise in the Coachella Valley. The leading edge of Mercury’s disk reaches the edge of the sun near 10:03 a.m.; egress from the solar disk is complete 1.7 minutes later. The next transit of Mercury visible in U.S. won’t be until May 7, 2049, so you might want to catch this one!

In the days after the transit, Mercury rises before sunrise, but is in a thin crescent phase, too faint to be seen for several mornings. Mercury brightens quickly, reaching magnitude +0.7 by Nov. 19, within 12 degrees to the lower left of Mars, and -0.1 by Nov. 22, within 10 degrees to the lower left of Mars. Once Mercury emerges from the solar glare, follow the striking lineup of Spica, Mars and Mercury. Watch the waning, old crescent moon slide downward past Spica, Mars and Mercury, in order, Nov. 23-25, while Mercury pauses 9.5 degrees to Mars’ lower left. On Nov. 28, only 17 days after its transit, Mercury shines at magnitude -0.6 and stands at greatest elongation, 20 degrees from the sun.

The morning twilight chart for November below shows Spica and Mars getting higher daily, while Mercury ascends to its highest position before month’s end. The panel of Sky Calendar illustrations also shows Mars passing Jupiter and Saturn in late March 2020, after the giant planets have emerged from behind the sun to join Mars in the morning sky. For a summary of planetary visibility in 2019-20, visit www.abramsplanetarium.org/msta.

Check the website of the Astronomical Society of the Desert at www.astrorx.org and come to our free evening star parties offered monthly at two locations. Our primary, more-accessible venue is 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). Our next session there will be on Saturday, Nov. 2, from 6-9 p.m. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will next host sessions on Saturday, Nov. 23, starting at dusk. At various locations, some members will host observing sessions for special events, including the transit of Mercury and gatherings of planets. These might be announced on short notice, so periodically check the link to Impromptu Star Party Dates. You can also pre-register for one of the stargazing parties offered several times each month at the Rancho Mirage Library Observatory by visiting www.ranchomiragelibrary.org/observatory.html. Click on Stargazing Parties, then sign up for their eNewsletter to receive registration information.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

As October both begins and ends, the moon will be sweeping through an evening lineup of four planets.

On October evenings, bright Jupiter is in the south-southwest to southwest at dusk, with Saturn to its left in the south to south-southwest; both remain outstanding for telescopic viewing, Jupiter with its cloud belts and four bright moons, and Saturn with its rings now tipped 25 degrees from edgewise. These giant planets appear 26 degrees apart on the sky’s dome on Oct. 1, narrowing to 22 degrees apart by Oct. 31. Follow their eastward motions against background stars, until the seasonal westward drift of the constellations drags both slow-moving planets to the southwest horizon before year’s end. Note reddish twinkling Antares, heart of Scorpius, 10 to 14 degrees to the lower right of Jupiter during October. Watch Jupiter pass 2.1 degrees north of a third-magnitude star on Oct. 22.

Look early in the evening twilight to catch Venus; binoculars are indispensable for nearby Mercury. From the Coachella Valley, Venus sets only 37 minutes after sunset on Oct. 1, improving to 64 minutes by month’s end. Mercury, near magnitude 0 almost all month, sets a maximum of 60 minutes after the sun Oct. 18-24; reaches greatest elongation, 25 degrees to the upper left of the sun on the 19th; and appears highest in twilight for a few days around then. But this is the year’s poorest evening apparition of Mercury, because the zodiac belt where the planets are found makes its shallowest angle with the evening horizon when the southernmost zodiac constellation Sagittarius is in southern sky. Using binoculars, find Mercury to the upper left of Venus during the first three weeks—by 7 degrees Oct. 2-3; 8 degrees Oct. 8-16; and back to 7 degrees Oct. 20-21. On Oct. 23, Mercury is 6 degrees to the upper left of Venus. Next, Mercury passes left of Venus, by 5.2 degrees on Oct. 25, and 4.6 degrees on Oct. 26. Then Mercury appears to Venus’ lower left, by 4 degrees on the 27th, and 3.4 degrees on the 28th. On Oct. 30, Mercury passes within 2.6 degrees south of Venus, but has begun its rapid fade.

Follow the moon at dusk through Oct. 13, and again Oct. 27-Nov. 12. On Oct. 3, find bright Jupiter within 3 degrees to the lower right of the moon. On Oct. 4, the fat (44 percent) crescent moon is 15 degrees to the upper left of Jupiter and 10 degrees to the lower right of Saturn. On Oct. 5, the moon, 54 percent full, is just past its first-quarter phase, when it’s half full and 90 degrees—a quarter of the way around the sky—from the sun.

On Oct. 13, watch the full moon rise some 20-25 minutes after sunset, just north of due east. As you looked daily in evening twilight through Oct. 13, the moon took two weeks to travel through a half-dozen zodiac constellations, from western horizon to eastern horizon, passing four planets along the way. In the first five evenings its next time around, Oct. 29-Nov. 2, the moon will pass the same four planets.

Other bright stellar markers not in the zodiac are Fomalhaut, mouth of the Southern Fish, climbing in the southeast, and golden Arcturus, the “Bear-watcher” star, sinking in the west to west-northwest.

By Oct. 16, moonrise is late enough to allow at least a brief interval of dark skies unaffected by moonlight. This “window” of darkness lasts longer each evening as the moon rises later. If you’re in a dark place, enjoy the Milky Way passing through the Summer Triangle of Vega, Altair and Deneb overhead, and the Andromeda Galaxy above the curved chain of stars starting at one corner of the Great Square of Pegasus in the east.

Follow the moon at dawn from when it is full, low in the west on Oct. 13, through last quarter (half full and 90 degrees west of the sun) on Oct. 21, to a thin crescent, low and south of east, on Oct. 26. The brightest star in October’s morning twilight is Sirius, in the southern sky, as dawn brightens. Confirm by noting that the three-star belt of Orion, with stars bluish Rigel marking his foot and reddish Betelgeuse his shoulder, points directly to Sirius. Extend the belt in the opposite direction, and you’ll pass near Aldebaran, eye of Taurus the Bull, and farther to the Pleiades or Seven Sisters star cluster, a wonderful target for binoculars.

Four days after it’s full and low in the west on Oct. 13, the moon is within 6 degrees to the lower right of Aldebaran on Oct. 17. For the next three mornings, Oct. 18-20, the waning gibbous moon moves through the huge Winter Hexagon. Next, on Oct. 21, the last-quarter moon, half full, is 7 degrees southeast of Pollux, and in line with the “Twin” stars, Castor and Pollux of Gemini. Our Spaceship Earth is heading in the direction of the half-lit moon in our orbit around the sun. If the moon stood still, it would take us only about 3 1/2 hours to reach it.

Our view of the peak of the Orionid meteor shower, in the predawn hours of Oct. 22, is affected by moonlight. On Oct. 23, the crescent moon will pass 4 degrees north of Regulus, heart of Leo, the Lion. In just three more mornings, on Oct. 26, look for the last easy old crescent moon, 4 percent full, just south of east, with Mars 5 degrees to its lower right. The dim red planet is now at magnitude +1.8, as faint as it ever gets. In just less than a year, in October 2020, the Earth will pass between Mars and the sun, and it will appear at opposition, and shine at magnitude -2.7, some 60 times brighter than now. At the end of October, Spica will be emerging out of the morning twilight glow, 7 degrees below Mars.

Notice the star Arcturus rising on the morning twilight chart. Arcturus is equally visible low in the west-northwest at dusk on Oct. 29 as it is in the east-northeast at dawn on Oct. 30. At this time of year, Arcturus leads the procession of stars and constellations through the night, and brings up the rear.

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. The calendar illustrates many of the present and future events described above. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly. For a preview of evening and morning planet gatherings through August 2020, visit the Sky Calendar Extra Content Page at www.abramsplanetarium.org/msta.

Would you enjoy telescopic views of Jupiter, Saturn and an assortment of deep sky objects? Check the website of the Astronomical Society of the Desert at www.astrorx.org and come to our free evening star parties offered monthly at two locations.Our primary, more accessible venue is 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. Our next sessions there will be on Saturday, Oct. 5, from 7 to 10 p.m., and on Saturday, Nov. 2, from 6 to 9 p.m. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will next host a session on Saturday, Oct. 26, starting at dusk.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

From Sagittarius to Gemini and back, the moon swings! And the crescent rocks!

Enjoy watching moonrises? The harvest moon on Friday the 13th is the first of a half-dozen moonrises in a row taking place in the early evening, through Sept. 18. Meanwhile, Jupiter shines steady and brightest at dusk, and Sirius, the “Dog Star,” twinkles brightest at dawn.

Overnight on Sept. 22—actually at 12:50 a.m., Monday, Sept. 23—the sun is directly over Earth’s equator, marking the start of autumn for residents of the Northern Hemisphere. On the date of an equinox, the sun rises in the east, and sets in the west 12 hours later. (Well, this is not precisely true, because of the way sunrise and sunset are defined—when the top of the solar disk, rather than its center, appears on an ideal, flat horizon; refraction by our atmosphere uplifts the sun’s disk and lengthens the day by several minutes.)

The moon travels around the Earth in an orbit inclined 5 degrees to the Earth’s orbital plane, traveling through the same belt of the zodiac and returning to the same stars after only 27.3 days, the sidereal period of the revolution of the moon. So in less than four weeks, the moon’s rising and setting places on the horizon and height at mid-path range from southern to northern extremes and back.

On Saturday, Sept. 7, the moon “rides low,” reaching the southernmost part of its 27.3-day trip around the zodiac, in the constellation Sagittarius, the Archer. From Palm Springs, the moon rises nearly 28 degrees south of east at 3:10 p.m. It reaches its highest point in south at 8:16 p.m., only 33 degrees above the horizon.

As the moon passes south on Sept. 7, look for Saturn 5 degrees to its left; Jupiter 23 degrees to the moon’s right; and the third-magnitude star Kaus Borealis, northern star of the Archer’s bow, within 3 degrees to Luna’s lower right. September’s southernmost moon sets nearly 28 degrees south of west later that night.

Might we call the lunar event of Sept. 7-8 a “Lunastice”? There are two solstices each year, when the “sun stands still” directly over the Tropic of Capricorn and the Tropic of Cancer at the southern and northern extremes of the sun’s annual journey around the zodiac. But the moon takes just 27.3 days to make the same circuit. That’s about two days less than the moon’s 29.5-day cycle of phases, so each successive time the moon “rides low” (or “rides high,” or returns to the same star background) occurs 2.2 days earlier in its phase cycle. Since the moon makes just more than 13 trips around the zodiac annually, there are 26 or 27 “Lunastices” each year, spaced at intervals averaging just less than two weeks.

After Sept. 7, the moon rises farther north, getting later each day. By Sept. 11, the moon rises 19 degrees south of east at 6:04 p.m., some 55 minutes before sunset, so it’s still possible from some places in the Coachella Valley to view sun and moon simultaneously. On Sept. 12, the moon rises 15 degrees south of east at 6:37 p.m., just 20 minutes before sunset. For the next five nights through Sept. 17, moonrise occurs only about a half-hour later on each successive night. Short daily delays in the time of moonrise, significantly less than the long-term average of 50 minutes per day, always happen around the full moon near the beginning or autumn, and is called the Harvest Moon Effect.On Friday, Sept. 13, the full moon rises 10 degrees south of east at 7:07 p.m., just 11 minutes after sunset.

This month’s full moon also happens to be the most distant of this year. It’s also the faintest of all the full moons (except for those eclipsed by Earth’s shadow)—not only because of its distance, but also because it passes 5 degrees south of the point opposite the sun and reflects less of its light back toward Earth. (Look up “opposition effect.”) By Sept. 15, the moon rises about one degree north of east at 8:05 p.m., and by the 17th, 12 degrees north of east at 9:04 p.m. September’s northernmost moonrises occur on Saturday evening, Sept. 21, at 11:44 p.m., and on the next night, Sunday, Sept. 22—actually Monday morning, Sept. 23, at 12:40 a.m., some 27 degrees north of east. On both occasions, the moon “rides high” in Gemini, passing within 12 degrees south of overhead on Sept. 22 at 7:04 a.m., and on Sept. 23 at 8:01 a.m., setting 7 hours and 20 minutes later.

Follow the moon at dusk through Sept. 14, and again Sept. 29-Oct. 13. Follow the moon at dawn Sept. 13-27. Note the “tipped bowl” orientation of the waxing lunar crescents in the western sky at dusk through Sept. 3 and Sept. 29-Oct. 2, preceding the nearly first-quarter (half) moons found low in the southern sky around sunset on Sept. 5 and on Oct. 4 and 5. Note the “upright bowl” waning lunar crescents in the eastern sky at dawn Sept. 25-27, following the nearly half-moon close to last-quarter phase found high in the southern sky around sunrise on Sept. 21 and 22. Best views of zodiacal light (reflected off comet and asteroid dust in the plane of the solar system) can be had from dark places free of light pollution just before start of morning twilight, 90 minutes before sunrise, Sept. 27-Oct. 11. All these observations are related!

The only planets easy for the unaided eye to see in September are both conveniently placed in the southern sky in the early evening: Bright Jupiter, in the south-southwest at dusk; and Saturn, in the south-southeast to south, 29 to 26 degrees east (left) of Jupiter. Telescopes show Jupiter’s disk, now just over 0.01 degrees in apparent diameter, usually with two dark equatorial belts, and the four bright Galilean satellites. Since their orbits lie nearly in plane of Jupiter’s equator, and Jupiter’s south pole is tipped more than 2 degrees toward Earth for rest of 2019, it’s often possible to mentally work out whether a satellite of Jupiter is on the near or far side of its orbit. Currently, if a moon is displaced north of a line through Jupiter’s center parallel to its equator, then that moon must be on the near side of Jupiter. If displaced south, it must be on far side of its orbit. Jupiter’s equator will appear edge-on in early 2021, and so, nearly, will the orbits of the satellites, making them appear in a straight line.

Saturn’s rings span slightly wider than Jupiter’s apparent size. Saturn’s north pole is now tipped toward Earth by more than 25 degrees, giving us our best view of the rings until 2030, when the south pole will be tipped toward us by a similar angle. Before then, the rings will be edgewise to the Earth and sun during spring 2025. Maximum tilt of rings, nearly 27 degrees with north face visible, occurred in 2017; the maximum with south face visible will occur in 2032.

There are no naked-eye planets in September’s morning sky, but the brightest star visible is Sirius, in the southeast to east-southeast as dawn brightens. Confirm by noting that the three-star belt of Orion—between bluish Rigel marking his foot and reddish Betelgeuse his shoulder—points directly to Sirius.

For a preview of the wonderful gatherings of the moon and planets in 2019-2020, visit www.abramsplanetarium.org/msta. Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. The calendar illustrates many of the present and future events described above. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties at two locations: Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have its next monthly sessions starting at dusk on Saturday, Aug. 31 and Sept. 28. Monthly sessions resume Saturday, Oct. 5, at our primary, more accessible location, 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).

But don’t wait until then! You can pre-register for one of the Stargazing Parties offered several times each month at the Rancho Mirage Library Observatory. Visit www.ranchomiragelibrary.org/observatory.html; click on Stargazing Parties, then sign up for their eNewsletter to receive registration information. If you go farther afield, check out the Sky’s the Limit Observatory and Nature Center in Twentynine Palms, at www.skysthelimit29.org.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

Evenings this month feature the gas-giant planets, Jupiter and Saturn, and on dark moonless nights, the Milky Way. Predawn skies include the bright stars we’ll meet again on winter evenings—and a brief visit by our solar system’s smallest planet, Mercury.

In the evening, bright Jupiter gleams in the south to south-southwest at dusk, while Saturn is in the southeast to south-southeast, 31 to 29 degrees east (to the left) of Jupiter. Note Antares, heart of Scorpius, twinkling to Jupiter’s lower right. Jupiter lingers 7 degrees from this red supergiant star from mid-July through first week of September; their least separation of 6.7 degrees occurs Aug. 8-15 as Jupiter ends retrograde on Aug. 11.

Follow the moon at dusk Aug. 2-15. On Aug. 2, the thin crescent moon is easy to see, though very low, a little north of due west. Don’t miss a striking pairing of the moon and Jupiter, within 3 degrees, at dusk on Aug. 9, and the moon and Saturn, just 3 degrees apart on Aug. 11. By the evening of Aug. 12, the moon has moved 9 degrees east of Saturn. On Aug. 15, the moon, past full, is rising in the east-southeast. The moon returns to the evening sky as a crescent low in the west on Aug. 31.

The year’s best Milky Way viewing after evening twilight occurs through Aug. 2, and Aug. 20-Sept. 1. Go to a dark place to enjoy these with the unaided eye and binoculars: the Cygnus Star Cloud, along axis of the Northern Cross or neck of the Swan, within the Summer Triangle; the Great Sagittarius Star Cloud, above the spout of the Teapot; the Great Rift, a dark lane of dust dividing the Milky Way into two streams southward from Cygnus; Lagoon Nebula M8 (Messier 8), above the tip of the spout; star clusters M7 and M6, near the end of the tail of Scorpius; and much more.

As for the mornings: Mercury makes a brief visit to the a.m. sky. It brightens past first magnitude (to +0.9) by Aug. 5 to become visible low in the east-northeast morning twilight. During Aug. 5-10, it lingers 9 degrees to the lower right of Pollux while brightening another magnitude to -0.1. Mercury reaches greatest elongation, 19 degrees west of the sun, on Aug. 10, and on Aug. 11, a line from Castor to Pollux, 4.5 degrees apart, extended nearly 10 degrees, locates Mercury. Late in the month, Mercury sinks into bright twilight; superior conjunction beyond the sun will occur Sept. 3. The “Dog Star” Sirius, the brightest star, emerges in the east-southeast morning twilight before mid-August. Sirius rises 4 minutes earlier each morning, climbing higher as the month progresses. Note Orion’s belt points almost directly to Sirius.

Follow the moon in morning sky Aug. 15-29: On Aug. 15, the moon is full, setting in the west-southwest. The moon passes last quarter phase on Aug. 23, while 9 degrees south of Pleiades. On Aug. 24, the fat crescent moon is 2 degrees north of Aldebaran, eye of the Bull. On Sunday, Aug. 25, the 30 percent crescent moon occults third-magnitude Zeta Tauri, tip of southern horn of Taurus. From the Coachella Valley, the star disappears behind the bright edge of the moon at 3:46 a.m., and reappears from behind the dark, earthlit side at 4:41 a.m. It’s best viewed with a telescope.

Absent in August are Venus, in superior conjunction on night of Aug. 13, and Mars, in conjunction on Sept. 2. When passing beyond the sun, Venus and Mars remain out of sight for longer than other planets, because their motions most closely match that of Earth; Venus is the next planet inward from Earth, and Mars is the next planet beyond Earth’s orbit. Venus goes faster than Earth and so emerges from beyond the sun into the evening sky. Mars goes more slowly and emerges into the morning sky. During the 2019-20 school year, each participates in a spectacular gathering: Venus, with Jupiter and Saturn at dusk in late November-early December; and Mars, with Jupiter and Saturn at dawn in late March 2020. Stay tuned!

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. The calendar illustrates many of the present and future events described here. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues, mailed quarterly.

For a preview of evening and morning planet viewing through August 2020, see Jeffrey Hunt’s two-page graphic summary of moon and planet setting and rising times, relative to the times of sunset and sunrise, exact for Palm Springs, below. The graph of evening planet setting times shows the departure of Jupiter and Saturn in December 2019, and Venus improving until its very favorable evening appearance in March 2020, when it will set 3 1/2 hours after sunset, followed by its rapid departure from the evening sky in May. The graph of morning-planet-rising times shows the gradual emergence of Mars before dawn in autumn 2019; the emergence of Jupiter and Saturn in January-February 2020; and the sudden rise of Venus into predawn prominence in June-July 2020. The charts also make it easy to pick out the best dates to see Mercury in evening and morning skies.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet—wear warm clothes), will have its next monthly sessions starting at dusk on Saturdays, Aug. 31 and Sept. 28. Our primary, more-accessible location is 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). Monthly sessions there will resume on Saturday, Oct. 5.

But don’t wait until then! You can pre-register for one of the Stargazing Parties offered several times each month at the Rancho Mirage Library Observatory at www.ranchomiragelibrary.org/observatory.html. (Click on Stargazing Parties, then sign up for their eNewsletter to receive registration information.) If you go farther afield, check out the Sky’s the Limit Observatory and Nature Center in Twentynine Palms, at www.skysthelimit29.org.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

June evenings will be wonderful for viewing the skies, especially if you stay up late enough until the sky fully darkens. With daylight saving time in effect on these longest days of the year, that might be a tall order!

Mercury starts 16 degrees to the lower right of Mars on June 1, climbing to 0.3 degrees above Mars on June 18, at their closest pairing. Mercury and Mars remain within 3 degrees June 14-24. Mercury decreases in brightness, from magnitude -1.0 on June 1, through 0.0 on June 16, to +1.0 on June 30. Mercury fades rapidly in first days of July, but in June, it remains much brighter than Mars’ magnitude +1.8—as faint as Mars ever gets.

Elsewhere in the west to northwest, Procyon and Capella drop out of sight, but the Gemini Twins, Pollux and Castor, 4.5 degrees apart, hold on. During June 18-21, first Mercury, then Mars, pass 5.5 degrees south (to the lower left) of Pollux for two nights each, while the Mercury-Mars pair widens from 0.3 to 1.8 degrees apart. Mercury is the brightest member of this gathering of two planets and two stars.

In June, Regulus slides down the western sky on its way to its conjunction with the sun on Aug. 23. Spica and Arcturus pass their highest positions in the south. Golden Arcturus, at magnitude -0.1, is the brightest star on June evenings, but the planet Jupiter, at magnitude -2.6 in the southeast, appears 10 times brighter. Note red, twinkling Antares within 12 degrees to Jupiter’s upper right on June 1, and within 9 degrees to its right at dusk on June 30. Jupiter is at opposition to the sun on June 10, and is retrograding, or appearing to move westward against the background stars.

By mid-June, Altair rises north of east to complete the Summer Triangle with Vega and Deneb, just in time for the new season. Summer begins at 8:54 a.m. on June 21, with the sun directly over the Tropic of Cancer. The highest sun of the year, only 10 degrees south of overhead for Palm Springs, occurs that day at 12:48 p.m.

Saturn rises in time for mid-twilight in the last days of June. Watch for it in the east-southeast, 31 degrees to the lower left of Jupiter. Saturn’s opposition will occur on July 9.

On the morning twilight chart below, you’ll find the stars, but not fast-moving Venus, in roughly the same positions they’ll occupy in evening twilight in November. On June mornings (and November evenings), the Summer Triangle moves west of overhead. Bright Jupiter, with Saturn to its upper left, will be sinking into the southwest. Fomalhaut, Mouth of the Southern Fish, will be low in the south-southeast to south. Capella, the “Mother Goat” star, will be rising in the northeast. Aldebaran, eye of Taurus, rises in the east-northeast late in month. By getting up before dawn, you’ll get a preview of the evening sky of the next season!

Alignments: On May 31, Earth and Aldebaran are on opposite sides of the sun. As seen from Earth, Aldebaran appears in conjunction with the sun, hidden from our view until it emerges in the east-northeast morning twilight in late June. Also on May 31, Earth passes between Antares and the sun, and that star appears at opposition to the sun, visible almost all night.

On June 10, Jupiter will be at opposition, 180 degrees from the sun and visible all night. Jupiter that night is low in the southeast at dusk, and reaches its highest in the south in the middle of the night, and is low in the southwest at dawn. On July 9, Saturn will be at opposition.

For nearly all of June, Mercury has a favorable evening appearance, including a close approach to Mars for several evenings around June 18. In morning twilight on June 1, Venus is very low in the east-northeast, with the old moon nearby. Jupiter is low in the southwest, 150 degrees from Venus, while Saturn is 29 degrees to Jupiter’s upper left. On July 1, the old moon is again near Venus, but Jupiter has already set. Instead, Saturn will be low in the southwest nearly 160 degrees from Venus. In June, the gap between Venus and these giants widens toward 180 degrees, at mutual oppositions reached by Venus-Jupiter on June 23, and Venus-Saturn on July 17.

There are evening pairs of planets at mutual opposition: Mercury (setting) and Jupiter (rising) on May 30; Mars (setting) and Saturn (rising) on June 14; and Mercury (setting) and Saturn (rising) on June 16. Jean Meeus, in his Mathematical Astronomy Morsels IV, wrote about planets in mutual opposition: “Certainly this is a matter of almost zero observational interest. Somebody who likes to observe weird things might be interested in the near-simultaneous rise/set of two planets in opposition, but it’s far from the mainstream.”

Mercury, Mars and the Twins of Gemini: These four objects are visible in the west-northwest at dusk throughout June, but Mercury is very low at start of month, and all are low in the closing days. I already mentioned Mercury’s fading brightness and Mars’ relative faintness. Watch these changing arrangements of Mercury and Mars with Pollux and Castor, the “Twin” stars of Gemini, 4.5 degrees apart. Binoculars enhance the view, especially late in month, when all will be low in bright twilight. June 5: Mars forms an isosceles triangle with Pollux-Castor, 11 degrees from each. June 12: Mercury forms an isosceles triangle with Pollux-Castor, 10-11 degrees from each. June 18: Mercury-Mars appear closest, 0.3 degrees apart, within 6 degrees to the lower left of Pollux. June 18 and 19: Mercury is 5.5 degrees south (to the lower left) of Pollux. June 20 and 21: Mars is 5.5 degrees south of Pollux. June 25: A line from Castor to Pollux, extended 8.7 degrees, locates Mercury. (The three objects appear to be in a straight line.) June 28: A line from Castor to Pollux, extended 7.2 degrees, locates Mars.

The moon on June evenings: On June 4 at dusk, look low in the west-northwest for the young crescent moon with earthshine, with bright Mercury 7 degrees to the lower right, and faint Mars 7 degrees to the upper left. Jupiter rises about one hour before Mercury sets. Try to view Mercury, Mars and Jupiter simultaneously, within an hour after sunset. On June 5, find Mars 7 degrees to the moon’s lower right, and Pollux 8 degrees to moon’s upper right. On June 6, use binoculars to find the Beehive Cluster within 3 degrees to moon’s upper left after nightfall. Find Regulus near the moon on June 8. The moon passes first quarter phase on June 9. Spica is fairly near the moon on June 11 and 12. From June 12 and for the rest of Mercury’s evening apparition, Mercury and Mars are no more than 4 degrees apart. On June 14 at dusk, find Antares 14 degrees to the moon’s lower left. On June 15, find bright Jupiter 8 degrees to the moon’s lower left, and Antares 7 degrees to moon’s lower right. On evening of June 16, the moon is 6 degrees to the lower left of Jupiter. The full moon later that night, at 1:31 a.m. on June 17, is the fourth during spring 2019. On the evening of June 17, the moon, past full, rises 18 degrees lower left of Jupiter.

Follow the moon in morning sky through the latter half of June. On the 16th, the moon, not quite full, sets in the west-southwest shortly before sunrise, 5 degrees to the lower right of Jupiter. On the next morning, June 17, the full moon appears 8 degrees to the upper left of Jupiter and 22 degrees to the lower right of Saturn. On June 18, the moon will have moved more than two-thirds of the way from Jupiter toward Saturn, and on June 19, the moon will appear 4 degrees to the upper left of Saturn. On June 25, the moon will reach last quarter phase, half full in the morning sky. On June 29, a beautiful crescent moon with earthshine will appear low, north of east, accompanied by the Pleiades cluster, 10 degrees to the upper left, and bright Aldebaran, eye of Taurus, 15 degrees to the lower left. On the 30th, a thinner crescent moon will appear with Aldebaran within 2 degrees below.

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. The calendar illustrates many of the events described in this article. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties.Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have its next monthly session starting at dusk on Saturday, June 1.

Wishing you clear skies!

Robert Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. Robert 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.

Published in Astronomy

A thin crescent moon low in the west-northwest at dusk on May 5 marks the start of Ramadan, with a month-long daytime fast beginning the next day. Nearly two weeks later, a “blue moon”—the third of four full moons within the season—is visible through all nighttime hours of May 18. Late in the month, bright Jupiter begins rising in southeast during early evening hours.

The May evening twilight chart shows that Rigel, Aldebaran, Sirius and Betelgeuse disappear this month, leaving four winter stars—Procyon, Pollux, Castor and Capella—forming an arch in the western sky through month’s end, when Mercury is just starting an evening appearance very low in the west-northwest.

Regulus in Leo crosses high in the south into the west-southwest. Golden zero-magnitude Arcturus rises high in the eastern sky, with blue-white first-magnitude Spica in Virgo to its lower right. Zero-magnitude Vega, the brightest member of the Summer Triangle and first to appear, rises into view in the northeast, with Deneb eventually trailing to its lower left. Red Antares, heart of Scorpius, rises in the southeast late in May. Bright Jupiter follows 12 degrees to Antares’ lower left, just in time for the end of May.

Nearly all the events described here are illustrated on the Abrams Planetarium Sky Calendar. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues, mailed quarterly. A free, printable copy of the May 2019 issue is available at the site.

May 2 at dawn: The old moon is very low in the east, 4 degrees to the lower right of Venus.

Sunday, May 5, at dusk: The sighting of the young crescent moon low in the west-northwest, perhaps by half an hour after sunset, marks the start of Ramadan.

On May 6 at dusk: Look for the crescent moon with earthshine 3 degrees to the upper right of Aldebaran. Follow the moon nightly at dusk through May 18, watching it pass Mars on May 7, Pollux on May 9, the Beehive on May 10 (use binoculars), Regulus on May 11 and 12, and Spica on May 15.

On May 18 at dawn: The moon, some 8-9 hours before full, is low in the west-southwest. Today’s full moon is the third of four within the same season, spring 2019, so by one definition (Maine Farmers’ Almanac, 1937), it is called a “blue moon.” This definition predated the now widespread use of the term “blue moon” to refer to the second full moon within a single calendar month.

At dusk on May 18: Some 5-6 hours after full, the moon is very low in the east-southeast. From the Coachella Valley on May 18, the moon sets in the west-southwest about 5 minutes after sunrise, and rises in the east-southeast about a minute after sunset, but unless you’re at a site higher than your surroundings, it will not be possible to view the sun and moon simultaneously.

Two hours after sunset on May 18: Find Antares 11 degrees below the full moon; on May 19, find Jupiter 7 degrees to the moon’s lower left; and on May 20, see the moon rising 6 degrees to the lower left of Jupiter. Rather than stay up late, you can switch to mornings to catch the waning gibbous moon passing Antares, Jupiter and Saturn May 19-23. The last quarter occurs May 26. Finally, catch the last old crescent near Venus on June 1.

(Almost) opposing planets: On May 20, Jupiter rises about one hour before Mars sets. About two hours after sunset, both planets are about 5 degrees above opposite horizons. It’ll get easier to view both planets simultaneously in coming weeks, as Jupiter rises earlier.

Mars fades from magnitude +1.6 to +1.8 in the west-northwest at dusk. Watch Mars pass between Beta and Zeta Tauri, tips of Bull’s horns, on May 6. Crossing into Gemini on May 16, Mars goes 2 degrees north of Eta and Mu, third-magnitude stars 1.9 degrees apart in Castor’s foot, May 21-24. On May 31, Mars is 0.9 degrees south of third-magnitude Epsilon Gem.

Late evening until dawn: Bright Jupiter, in Ophiuchus, on May 1 rises within 15 degrees to the lower left of Antares, three hours and 10 minutes after sunset, as Mars sets. Saturn in Sagittarius rises within two hours later. Jupiter rises half an hour earlier each week, and by May 31 rises 12 degrees to the lower left of Antares 40 minutes after sunset, with Saturn still following by two hours. Jupiter (magnitude -2.5 to -2.6) and Saturn (+0.5 to +0.3) brighten slowly and stay 27-29 degrees apart, as both retrograde, by 3.0 degrees and 0.8 degrees, respectively. Jupiter passes 2.5 degrees north of 3.3-magnitude Theta Oph May 23-24.

On May 24, best in the darkness hours before dawn: Jupiter, moving retrograde, or westward against the stars, passes 2.5 degrees north of the 3.3-magnitude star Theta in Ophiuchus. Jupiter passed that star while going eastward on Feb. 27.

In the morning twilight, find bright Jupiter in the south-southwest to southwest, getting lower as the month progresses, with red Antares, heart of Scorpius, 15 to 12 degrees to its lower right; and Saturn, passing through the south during May; and Venus, very low in the east to east-northeast in brightening twilight. Binoculars may show Mercury to the lower left of Venus for the first few days. The morning twilight chart below shows all that, plus the Summer Triangle of Vega, Altair and Deneb passing overhead; golden Arcturus sinking in the west to west-northwest; and Fomalhaut, Mouth of the Southern Fish, low in the southeast.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have sessions starting at dusk on Saturdays, May 4 and June 1. Our primary, more-accessible location is 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). Our final one for the season will be on Saturday, May 11, from 8 to 10 p.m.

Also, remember to check the Impromptu Star Parties link on the Astronomical Society’s webpage. I’ll be offering a Ramadan Young Moon Watch on Sunday, May 5, at a yet-to-be-selected site with a view toward the west-northwest horizon, and other sky watches in Palm Springs at the pedestrian bridge over Tahquitz Creek at North Riverside Drive and Camino Real.

Wishing you clear skies!

Robert Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. Robert 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.

Published in Astronomy

My lifelong interest in sky-watching began in the school year 1951-52, a year after our sixth-grade teacher led us to create a mural of the solar system, with the planet sizes to scale.

When I was in seventh-grade, our school library included two books which really changed my life: A Dipper Full of Stars, by Lou Williams Page, originally published by in 1944—and revised and republished as a California state textbook in 1959! The other book was The Friendly Stars, by Martha Evans Martin, published in 1907.

On the first page of A Dipper Full of Stars is a quote from Harlan T. Stetson’s Man and the Stars: To acquire some appreciation of the meaning of the skies, one must make the friendship of the stars; watch their majestic march through the night, and the slow seasonal advance of constellation after constellation from east to west throughout the year. To know Orion, Sirius, Taurus, and the Pleiades as leading roles of the winter skies; or Lyra, with its Vega, Cygnus, with its Northern Cross, the Scorpion and Antares as the quieter leaders of the softer skies of summer, gives one a sense of kinship with nature which makes a knowledge of their movements more significant, and even life a bit more worthwhile.”

April is an interesting month to start keeping a record of bright stars seen each evening, within the first hour after sunset. Seven of the 16 stars of first-magnitude or brighter observable from the Coachella Valley are gathered in the western sky, arranged as the huge Winter Hexagon—clockwise starting with its brightest member, Sirius, Procyon, Pollux (with Castor nearby), Capella, Aldebaran, Rigel and back to Sirius to complete the Hexagon—with a bright red star, Betelgeuse, inside. Nearly all these stars will depart between late April and late June, as a result of the Earth’s revolution around the sun.

The morning sky features the planets Venus, Jupiter and Saturn. Mercury has a horizon-hugging apparition low in the morning twilight in April, lingering closely to the lower left of Venus at dawn in middle two weeks of month.

In the morning, the stars—but not the fast-moving planets Mercury and Venus—are in roughly the same positions they will occupy in the evening sky a few months hence: Bright steady Jupiter is in the south to south-southwest, with red twinkling Antares, heart of Scorpius, to its lower right, and steady Saturn to left of Jupiter. Golden Arcturus is in the west, with blue-white Spica to its lower left in the west-southwest. The Summer Triangle of Vega, Altair and Deneb passes overhead, as in evenings in August. Getting up before dawn is a good way to preview the sky of the coming season!

Events to observe:

April 1 at dawn: Venus is 8 degrees to the lower left of the waning crescent moon (13 percent). Binoculars may show Mercury rising in twilight, 10 degrees to the lower left of Venus.

April 1-6 at dusk: Mars and the Pleiades, or Seven Sisters, star cluster are 3 to 5 degrees apart, making a fine sight in the same field of view of binoculars. Mars’ trek across Taurus, at nearly two-thirds of a degree per day this month, will be fun to watch.

April 2 at dawn: Venus is within 5 degrees above the crescent moon (8 percent). Using binoculars, try for Mercury, 9 degrees to the lower left of Venus and 7 degrees left of the moon.

April 7-9: Enjoy a fine gathering of the moon, Mars, Aldebaran, Hyades and Pleiades at dusk.

April 10: Jupiter begins retrograde, and ends nearly 10 degrees farther west on the evening of Aug. 10. Saturn undergoes nearly 7 degrees of retrograde motion from April 30 through Sept. 19. It was a very close conjunction involving Saturn retrograding past the third-magnitude star Gamma in Virgo in the spring of 1952 which caught the attention of this writer, not quite 13 years old at the time.

April 10-23, dawn: Mercury stays no more than 5 degrees to the lower left of Venus, making it easy to locate through binoculars in this otherwise poor, low apparition. Mercury approaches within 4.3 degrees to the lower left of Venus April 15-18. Since these planets approach within 5 degrees but don’t pass each other, this event is known as a quasi-conjunction.

April 12: The moon is 7-12 degrees from Pollux and Castor, a pair of stars 4.5 degrees apart, marking the heads of Gemini, the Twins.

Night of April 13: Around this date each year, as the Earth passes between Spica and the sun, the star appears at opposition, nearly 180 degrees from the sun, and is visible all night. Look for Spica, the brightest star in Virgo, low in the east-southeast at dusk, and low in the west-southwest at dawn.

April 13-15: Mars passes 6.5 degrees north of Aldebaran at dusk. Binoculars give a fine view of the Hyades cluster in the same field as Aldebaran. Note two stars 8 degrees apart, marking tips of the Bull’s horns, 15-17 degrees above Aldebaran.

April 14: The moon is 4 degrees from Regulus, heart of Leo, the Lion.

Night of April 18-19: The full moon is 7-8 degrees from Spica all night.

April 22-26: The waning moon passes Antares, Jupiter and Saturn at dawn. The moon is 7 degrees above Antares on April 22, with close pairings of the moon and Jupiter on April 23 (less than one degree) and the moon and Saturn on April 25 (less than 2 degrees).

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties at two locations:Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will next have sessions starting at dusk on Saturday, April 6 and May 4. Our primary, more accessible location is 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). Our next session there is on Saturday, April 13, from 8 to 10 p.m., with the final one for the season on Saturday, May 11.

Also, remember to check the Impromptu Star Parties link. I’ll be offering sky watches in Palm Springs at the pedestrian bridge over Tahquitz Creek at North Riverside Drive and Camino Real, including some in predawn for the stars of summer, plus telescopic views of Jupiter and its moons, and Saturn’s rings; and some at dusk to observe the moon, Mars and the mix of winter and spring stars. Tentatively, I have predawn sky-watches scheduled each Sunday, and evening sky watches each Monday. Check the link for updates.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

In March 2019, early risers can enjoy a widening panorama of planets in the southeast quadrant of the sky—from the lower left to the upper right, one hour before sunrise, they are Venus, Saturn and Jupiter.

A waning moon adds its beauty to this section of the sky through March 2, and again March 26 through April 2. Moon pairings with bright Jupiter, the westernmost of the three planets, occur on Feb. 27 and March 27. Since Saturn is currently 26 degrees (two days of moon travel) east of Jupiter, the moon will pass Saturn on March 1 and 29. Venus, the easternmost of the three planets and the brightest, is rapidly moving eastward, so Venus’ pairings with the moon occur on March 2 and on April 2.

After March, Coachella Valley residents won’t catch Venus in a dark sky (in the absence of twilight) again until mid-November, after the planet emerges from its mid-August passage through superior conjunction beyond the sun, and into the evening sky.

Bright stars visible in March’s morning twilight include the Summer Triangle of Vega-Altair-Deneb high in the east; Arcturus and Spica in the southwest to west; and Antares, heart of the Scorpion, in the south, to the right of Jupiter. On mornings in March, we preview all these stars and the slow-moving planets, Jupiter and Saturn, in about the same places in the sky where we’ll catch them on warm July evenings.

Evenings: Find slowly fading Mars in the west at dusk, and watch it approach the Pleiades (Seven Sisters) all month. On March 1, Mars is 20 degrees below the star cluster. On the 31st, the red planet passes only 3 degrees south of the cluster, providing beautiful views for binoculars for about five evenings before and after March 31.

Also in the evening, the Big Dipper’s curved handle, extended, leads the eye to the rising of golden Arcturus in the east-northeast, and blue-white Spica in the east-southeast. When both stars rise before the end of evening twilight, it’s a sure sign that spring has arrived. The season begins astronomically on March 20 at 2:58 p.m., when the sun stands directly over Earth’s equator. Just more than two hours earlier, at 12:54 p.m., midday in Palm Springs, the sun reaches its high point for that day—34 degrees south of overhead (because we’re 34 degrees north of the equator). At dusk in the early spring, all of winter’s brightest stars are still around for evening viewing—see a photo of the Winter Hexagon at https://apod.nasa.gov/apod/ap190117.html—but by early April, all have crossed into the western half of the sky.

Retrograding on the near side of the sun from evening into morning, Mercury still shines at magnitude zero at dusk on March 1, but fades to +1 by March 4 and even more rapidly in the following days, while dropping into the western evening twilight glow. By the 30th, Mercury recovers to first magnitude and begins a poor, horizon-hugging apparition in the morning twilight glow—keep binoculars handy!—low in the east, 12 degrees to the lower left of Venus. Mercury will approach within 5 degrees to the lower left of the brightest planet in a quasi-conjunction April 11-23.

Here is a selection of sights involving solar system bodies:

Through March 3: The waning moon passes Antares, Jupiter, Saturn and Venus at dawn. Watch for close moon-planet pairs. Can you spot the thin, old crescent moon for two more mornings, 8 degrees to the lower left of Venus, on March 3, and 18 degrees to the lower left of Venus on March 4?

The new moon occurs on March 6 at 8:04 a.m. On the following evening, March 7, about 30 to 40 minutes after sunset, can you spot the thin, 2 percent crescent moon, just 34 hours past new? Forty minutes after sunset, it’s only 5 degrees up and 8 degrees south of due west. In clear skies, from places where mountains don’t block your line of sight to the moon, binoculars give an excellent view. Follow the moon daily at dusk until it is full, on March 20.

Tuesday, March 12: Aldebaran, eye of Taurus, is 5 degrees to the upper left of the fat crescent moon at dusk. As the sky darkens, several stars of the Hyades star cluster become visible in the same binocular field. The “V” formed by Aldebaran and the Hyades form the head of the Bull, with Aldebaran at the top of the left side of the “V.” As the evening progresses, watch the moon close in on some of the cluster members. From the Coachella Valley, just a few seconds before 11 p.m., the moon’s leading dark edge will occult, or cover up, one of the Hyades stars, 3.8-mag. Delta-1 Tauri. The occultation will be best observed with a telescope.

March 14, about an hour before sunrise: As you look toward Jupiter in the southern sky, visualize the motion of our Spaceship Earth heading toward that planet at a speed of nearly 19 miles per second. Saturn and Venus also lie ahead of us. We are catching up to Jupiter and Saturn and will overtake them on June 10 and July 9 as we pass between those outer planets and the sun.

March 20: Spring begins at 2:58 p.m. The full moon occurs at 6:43 p.m., and today, the moon sets very near the time of sunrise and rises a few minutes before sunset. Watch the moon rise more than an hour later nightly for the next several evenings, farther south each time. Since this full moon occurs so early in the spring, Easter this year occurs not on March 24, the first Sunday after the first full moon of spring, but on April 21, after the April 19 full moon. This spring, we’ll have four full moons.

March 25-29: The moon passes Antares, Jupiter and Saturn at dawn. The moon and Jupiter are 5 degrees apart on March 27; the moon and Saturn are 4 degrees apart on March 29.

March 29-April 1: Mars passes 3 degrees south of Pleiades at dusk. It’s excellent through binoculars.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties at two locations:Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will next have sessions starting at dusk on Saturday, March 2 and April 6. Our primary, more-accessible location is 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). Our next session there is on Saturday, March 16, at 7 p.m.

Remember to check the Impromptu Star Parties link on the Astronomical Society’s webpage. I’ll be offering sky watches in Palm Springs at the pedestrian bridge over Tahquitz Creek at North Riverside Drive and Camino Real, including some in predawn to follow the three morning planets, and some at dawn or dusk to observe moon’s conjunctions with planets.

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

February offers beautiful sights for the unaided eye and the eye aided with binoculars—especially for early risers getting out an hour before sunrise.

There’ll be close pairings of the moon with bright Venus just before and after the shortest month of the year—on Jan. 31 and March 2—providing chances to spot Venus in the daytime with binoculars and even the unaided eye. Venus and Saturn will appear just 1.1 degrees apart on Feb. 18. It’ll be worthwhile to watch that pair for changes on several adjacent mornings.

Planets at dawn: The pairing of Venus and the crescent moon on Thursday, Jan. 31, will be unusually close and very striking, before dawn and even long after sunrise. From the Coachella Valley, Venus and the center of the moon’s disk will be just 1.5 degrees apart and closing at 5 a.m. Sunrise occurs in Palm Springs at 6:43 a.m., with Venus just more than a degree from the moon’s center, or three-quarters of a degree from the moon’s edge. The closest approach of the moon and Venus occurs in daytime, between 9:45 and 10 a.m., with Venus about 0.4 degrees—less than the moon’s half-degree width—from the moon’s northern cusp the (upper point of the crescent). From 8:30 a.m. through 11:15 a.m., Venus will appear no more than a moon’s width from the moon’s edge. A telescope at low power will fit Venus and the moon in the same field, with Venus showing a gibbous disk, 62 percent illuminated.

At the next, wider moon-Venus pairing on March 2, Venus will appear nearly 4 degrees to the lower left of the moon. A telescope then shows the planet’s phase increased to 73 percent full, but reduced in apparent size as it will be more distant from Earth.

Near the dates of these moon-Venus pairings, the moon can be seen close to two other planets in the morning sky: The moon will appear 5 degrees to the upper right of Jupiter on Jan. 30; 4 degrees to the lower left of Saturn on Feb. 2; within 2 degrees above Jupiter on Feb. 27; and 2 degrees to the upper right of Saturn on March 1.

Planets, stars and moon at dusk: Mars is high in the southwest to west-southwest, halfway or more from horizon to overhead. While fading slowly from magnitude +0.9 to +1.2, Mars is bright enough not to be confused with any star while the red planet passes through the background of Pisces and Aries. The brightest star nearby is second-magnitude Alpha in Aries, about 10 degrees north of the planet in late February. Begin looking for Mercury emerging from the far side of the sun around Feb. 10, when it shines at magnitude -1.3 and sets south of west at mid-twilight, about 40 minutes after sunset. Still bright at magnitude -0.3 when it climbs to 9 degrees up at mid-twilight on Feb. 26, Mercury then begins to fade more rapidly. It’s still magnitude 0.0 on March 1, but, moving to the near side of the sun and becoming a backlighted crescent, it fades beyond magnitude +1 by March 5 and drops back into bright twilight.

Stars and moon: The moon is visible at dusk from Feb. 5 (very low in the west-southwest in early dusk), through Feb. 19 (just past full, risen north of east). The moon passes 6 degrees south of Mars in Aries on Feb. 10; 1-2 degrees north of Aldebaran in Taurus on Feb. 13; 7 degrees south of Pollux on Feb. 16; and 7 degrees above Regulus in Leo at dusk on Feb. 18. That evening, the Earth passes between the sun and Regulus, and that star appears at opposition, 180 degrees from the sun. The direction of Earth’s orbital motion around the sun on this night is away from the Pleiades in the evening sky and toward a spot about 3 degrees west of the third-magnitude star Beta in the head of Scorpius in the morning sky. At the end of February, our planet is moving away from Aldebaran, eye of Taurus, and toward Antares, heart of Scorpius.

The huge Winter Hexagon occupies much of the southeast quadrant of the sky at dusk. Start with Sirius, its brightest star, and go clockwise around its perimeter, to Procyon, the Twins (Pollux and Castor), Capella, Aldebaran, Rigel and back to Sirius. Orion’s shoulder Betelgeuse is inside. Regulus rises into view at dusk during February and chases the Hexagon across the sky. Note Regulus about to set in the west on the morning twilight chart, available with the online version of this article.

Check the website of the Astronomical Society of the Desert at www.astrorx.org for dates and times of our evening star parties at two locations:Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have a star party starting at dusk on Saturday, Feb. 2. The primary, more-accessible location is 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). The next session there is on Saturday, Feb. 9, from 6 to 9 p.m. Listings of star parties on the website include maps and directions for both locations. Star parties can be cancelled in poor observing weather.

Also, remember to check the Impromptu Star Parties link on the webpage. I’ll be offering sky watches in Palm Springs at the pedestrian bridge over Tahquitz Creek at North Riverside Drive and Camino Real, including some at predawn to follow the three morning planets, and some at dawn or dusk to observe the moon’s conjunctions with planets.

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. 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.

Published in Astronomy

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