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01 Feb 2014

February Astronomy: Jupiter, Sirius Dominate at Dusk—Plus a Note on a Possible New Moon Record

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February 2014 at dusk: The two brightest “stars” at dusk in February are, by a wide margin, steady yellowish Jupiter, high in the east, and blue-white, madly twinkling Sirius, the dog star, in the southeast. The only other evening planet is Mercury, very low south of west, but it will fade and is on its way to conjunction with the sun.

The waxing gibbous moon, four days before full, appears near Jupiter on the evening of Feb. 10.

Surrounding Jupiter is the huge Winter Hexagon of Sirius-Procyon-Pollux-Capella-Aldebaran-Rigel. The noticeably red star Betelgeuse is also within the hexagon. Find the three-star belt of Orion, the hunter, midway between Betelgeuse and bluish Rigel. The belt, extended southeastward, locates Sirius. Extend the belt in the opposite direction, and turn 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! Rising in the eastern sky, Regulus, heart of Leo, is at opposition to the sun on Feb. 18, and chases the Winter Hexagon across the sky.

February 2014 at dawn: This month, Venus attains the peak brilliance of its current morning apparition, which began in mid-January and continues until September. Telescopes and even binoculars reveal Venus now as a crescent, back-lit by the sun. Find Venus before sunrise, and keep track of it—and you can have a daytime sighting! It’ll be especially easy on Feb. 25 and 26, when the crescent moon appears nearby.

For most of February, in morning twilight, you can observe three planets: Venus in the southeast; Saturn in the south; and Mars in the southwest. In the last days of February, a fourth planet appears, once Mercury emerges from its Feb. 15 solar conjunction on near side of sun into the east-southeast twilight glow. Back-lit Mercury is faint at first, but continues to brighten.

Look for these stars within the zodiacal belt: Antares, heart of Scorpius, to the upper right of Venus and lower left of Saturn; Spica near Mars; and Regulus, heart of Leo, in the west far to lower right of Mars and Spica.

In the latter half of February, the waning moon in the morning sky will pass all of these, in west-to-east order: Regulus, Spica, Mars, Saturn, Antares, Venus and Mercury.

Other bright stars at dawn are Arcturus, high above Mars; Spica, in the southwest sky; and the Summer Triangle of Vega-Altair-Deneb, climbing in the eastern sky. The brightest objects visible at morning mid-twilight at start of the month, in order of brilliance, are Venus, Arcturus, Vega and Mars. The red planet nearly doubles in brightness and clearly outshines stars Arcturus and Vega after mid-February.

On Feb. 11, the revolution of spaceship Earth around the sun will be carrying us toward Saturn. A week later, on Feb. 18, Earth passes between the sun and Regulus, and that star appears at opposition—180 degrees from the sun. On Feb. 28, Earth is heading toward a point less than 5 degrees above Antares.

Looking ahead, on April 8, Mars takes its turn at opposition as our planet passes between that planet and the sun. On May 30-31, three weeks after Saturn appears at opposition, Antares will appear at opposition and be above the horizon nearly all night.


A Note on the Sighting of Opposing Crescent Moons, Dec. 31, 2013 and Jan. 1, 2014: A New Record?

On the very clear morning of Tuesday, Dec. 31, Alexander Seidler and I drove to a high spot in a residential area in the northwest corner of Palm Springs. From that site, we had an excellent view of the Coachella Valley below—and spotted the old crescent moon soon after its rising in the east-southeast shortly before 6 a.m. Pacific Standard Time.

We saw it first with 8x42 binoculars, then immediately with unaided eye; we then enjoyed the view through an Orion SkyQuest XT4.5 Dobsonian Reflector at 45x. Alex was able to hold the moon in view with unaided eye until 6:34 a.m., when it was 20 hours and 40 minutes before new. We remained at the site until sunrise and observed a spectacular green flash.

That day, I examined some topographical maps to help me select a different site to provide us with an unobstructed view of the young moon on the evening of Jan. 1. I picked a site in a residential area on the upper-northern part of Desert Hot Springs with a clear view toward Banning Pass in the west-southwest. I visited the site on the evening of Dec. 31 to make timed observations of Venus. Doing so helped me predict, within narrow limits, where the very thin young moon would appear at earlier stages of twilight on Jan. 1.

We returned to the Desert Hot Springs site with two others on Jan. 1, equipped with two pairs of 8x42 binoculars, a pair of 15x70’s, and two Orion SkyQuest 4.5-inch Dobsonian reflectors: one at 36x and the other at 45x. As we looked through some thin streaks of cirrus cloud, Alex was the first to spot the extremely thin crescent, through the 4.5-inch at 36x, at 5:11 p.m. PST, when its age was 13 hours, 57 minutes.

Another observer in our party of four, Andrew Smith, spotted it through the same scope within a few minutes, and I finally caught a brief glimpse using the other telescope at 45x.

A fourth member of our evening party, Misti Rausch, never did see the moon that evening. It may have been because she lost her eyeglasses and had difficulty adjusting the telescope to the appropriate focus. When I tried to refocus my telescope with my eyeglasses on immediately after I saw the crescent to enable others to have a look, I was unable to see the moon and never did recover it. None of us observed the moon with the binoculars or with unaided eye that evening.

The time interval between Alex's last observation of the waning moon on Dec. 31 and his first observation of the waxing moon on Jan. 1 was 34 hours and 37 minutes. As far as I know, this may be a new record for the shortest time interval between sightings of opposing crescents. Stephen J. O’Meara spotted opposing crescents 35.7 hours apart exactly 19 years earlier, on Dec. 31 and Jan. 1, 1994-1995 (see his account in the May 1995 issue of Sky and Telescope, Page 105), but he was observing from the big island of Hawaii, where winter days are longer than in Southern California—so it would not have been possible for him to see the opposing Moons as close together in time as we did.

We are eagerly awaiting our next opportunity to see opposing moons on consecutive days, on Feb. 28 and March 1. At civil twilight here in the Coachella Valley, the crescent at dawn on Feb. 28 and at dusk on March 1 will both be just over 18 hours from the new moon, which happens to occur at 12 a.m. on March 1.

Robert C. Victor was a staff astronomer at the 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.

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