In February 2018, the predawn sky hosts all three bright outer planets, spanning 44 degrees. After the total lunar eclipse at dawn on Jan. 31, follow the waning moon each morning in the first half of February, and watch it pass Jupiter on Feb. 7; Mars on Feb. 9; and Saturn on Feb. 11.
Evenings offer the challenge of spotting Venus low in the western twilight glow, getting easier as its setting time improves from 24 to 56 minutes after sunset. Follow the waxing moon evenings from Feb 16, as a thin crescent near Venus, until March 1, when it’s full. Until Venus emerges from bright twilight, the evening’s most prominent point of light is Sirius, the brilliant “Dog Star,” in the southeast at dusk in February.
Our morning twilight chart for February shows bright Jupiter nearly 40 degrees up in the southern sky. On Feb. 1, Mars is 12 degrees to Jupiter’s lower left, with Saturn another 31 degrees to the lower left of Mars. On Feb. 1, note the moon, two bright stars and the three planets lie in a long straight line across the sky, from the moon in west, to Saturn in southeast. In order that morning, they are: the moon, Regulus, Spica, Jupiter, Mars and Saturn. Note also the reddish star Antares, heart of the Scorpion, to the lower left of Mars on Feb. 1. Look about an hour before sunrise each morning through Feb. 13, and watch for these events:
Feb. 2: Regulus is 11 degrees to the lower right of the moon.
Feb. 5: Spica is 6 to 7 degrees to the lower left of the moon.
Feb. 7: Jupiter is 5 degrees to the lower left of the last-quarter moon—half full and 90 degrees, or a quarter-circle, west of the sun. Mars appears within 6 degrees of Antares for 10 mornings, Feb. 7-16. Compare them in color and brightness. At closest approach in late July 2018, Mars will outshine Jupiter!
Feb. 8: Jupiter is within 9 degrees to the right of the fat crescent moon. Mars is within 9 degrees to the moon’s lower left, while Antares is 5.5 degrees below Mars.
Feb. 9: Mars is 5 degrees to the lower right of the moon, with Antares 9 degrees to the lower right of the moon, and 5.3 degrees to the lower right of Mars. Saturn is within 24 degrees to the lower left of the moon. Jupiter is 20 degrees to the moon’s upper right.
Feb. 10: Visualize our dynamic solar system as you observe the planets in the morning sky. Today, Jupiter lies directly ahead of Spaceship Earth in our orbital motion around the sun. We’ll curve around the sun to pass between Jupiter and the sun in early May, and that planet will appear at opposition, 180 degrees from the sun. We’ll similarly overtake Saturn in late June, and Mars in late July, each taking its own turn at opposition.
Feb. 11: Saturn is within 2 degrees to the lower right of a striking lunar crescent, with earthshine illuminating the moon’s dark (non-sunlit) side. Mars and Antares, now 26 to 27 degrees to the moon’s upper right, appear closest together, just 5.1 degrees apart this morning and tomorrow. Mars, moving 0.6 degrees east daily against background stars, will appear midway between Jupiter and Saturn, 22 degrees from each, on Feb. 19.
Feb. 12: The waning crescent moon, only 10 percent full, is low in the east-southeast to southeast, 12 degrees to the lower left of Saturn.
Feb. 13: The last easy-to-see crescent moon, 5 percent full, is 24 degrees to the lower left of Saturn. The Mars-Antares pair is 5.2 degrees apart, within 19 degrees to the lower left of Jupiter.
Feb. 14: You have one last chance to catch the waning moon: Just 25 minutes before sunrise, if the sky is very clear, look 2 degrees up in the east-southeast for the hairline old crescent, 2 percent full and 31 hours before the invisible new moon, which occurs on Feb. 15 at 1:05 p.m.
February’s evening twilight sky chart plots Venus barely above the horizon 40 minutes after sunset, just south of west, in the last 10 days of month. Improve your chances to spot Venus and begin seeing it earlier in month by using binoculars and looking closer to the time of sunset. Find a spot where mountains won’t block your view! The brightest stars are Sirius in the southeast, and Capella, very high, northeast to north of overhead. They mark the southern and northern vertices of the huge Winter Hexagon, in clockwise order from Capella: Aldebaran, Rigel, Sirius, Procyon, the Twins (Pollux and Castor) and back to Capella. Orion’s shoulder, Betelgeuse, sits inside. Regulus, heart of Leo in the east, chases the Winter Hex across the sky.
Here are some of this month’s evening events:
Feb 16: Around 5:22 p.m., or 22 minutes after sunset, the sun is 5 degrees below the horizon, while the young crescent moon, only 1 percent illuminated, is 6 to 7 degrees up and 16 degrees south of due west. Very clear skies and an unobstructed horizon are essential for success within the next 10-minute window, and binoculars will greatly increase your chances. Venus appears as a point of light within 3.4 degrees to the lower right of the illuminated lower right limb of the moon. You’re likely to spot Venus first, since its light is concentrated within a tiny disk. If so, look to the upper left of Venus for the faint arc of the nearly 29-hour-old crescent.
Feb. 17: About 25 minutes after sunset, the sun is 6 degrees below the horizon (civil twilight), while the moon is 17 degrees up, 9 degrees south of due west. At 5 percent, the crescent should be easy to see in clear skies. Can you spot Venus 15 degrees to the moon’s lower right and just 3 degrees up? Venus is just beginning its evening apparition, lasting until early October.
Feb. 18: Regulus is at opposition as Earth passes between that star and the sun. Tonight, Regulus is visible all night.
Feb. 22: The moon, nearing first-quarter phase when it’s 90 degrees east of the sun and appearing half-full, is 9 degrees south of the Pleiades (Seven Sisters) star cluster this evening, and 9 degrees west of Aldebaran, eye of Taurus. By moonset tonight, the moon will appear 6 degrees to the lower right of Aldebaran.
Feb. 23: At dusk, the slightly gibbous moon is high in the south, with Aldebaran 5 degrees to its lower right. Note Betelgeuse 17 degrees to the moon’s lower left.
Feb. 24: The moon and Betelgeuse, 12 degrees to its lower right, lie near the center of the Winter Hexagon.
Feb. 25:Between tonight and tomorrow, the moon moves from inside to outside the Hexagon, jumping over the line joining Pollux, the brighter and more southerly Gemini Twin, and Procyon, the Little Dog Star.
Feb. 26: The moon is 10 degrees southeast of Pollux, in line with Pollux and its fainter Twin Castor.The Twins are 4.5 degrees apart, with Castor northwest of Pollux and farther from the moon.
Feb. 27: Find Regulus, the heart of Leo, 16 degrees to the moon’s lower left.
Feb. 28: As evening twilight deepens, use binoculars to spot Regulus only about 1 degree to the moon’s lower right. Check every half hour; shortly after 9 p.m., the moon will pass closely north of the star, with less than a moon’s width of clearance between them. From the Arctic, the moon will occult or cover the star. At dawn on March 1, the moon will have moved 4 degrees east (to the upper left) of the star.
On Friday, Feb. 2, Bruce M. Gottlieb, president of the Astronomical Society of the Desert, will be speaking on “The Total Solar Eclipse of August 21, 2017.” Gottlieb will explain why eclipses happen, and share photos from his trip to Casper, Wyo., to view the eclipse. On Friday, March 2, Dennis Mammana, author of six books on astronomy and the “Stargazer” syndicated newspaper column, will present a lecture on an astronomy topic to be determined. Both lectures will be held at the Portola Community Center, 45480 Portola Ave., in Palm Desert. Doors open at 6:30 p.m., and the talks begin at 7 p.m.
The website of the Astronomical Society of the Desert has a listing of our lectures and of our evening star parties at two locations. The 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). A sky viewing session is scheduled there on Saturday, Feb. 10, from 6 to 9 p.m. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have a star party starting at dusk on Saturday, Feb. 17. Star parties can be cancelled in poor observing weather. Also find the link to “Impromptu Star Parties” on the website.
Finally, check out the Sky’s the Limit Observatory and Nature Center in Twentynine Palms, at skysthelimit29.org.
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.