Sky This Month: January 2023

Jupiter shines brightly within the southwest these winter evenings. It begins the month at magnitude –2.4 and slips by solely 0.2 magnitude by Jan. 31. It treks eastward throughout the faint stars of Pisces the Fish. Look ahead to the beautiful four-day-old crescent Moon to reach Jan. 25, when the pair stand 3° aside.

Jupiter’s disk spans 39″ on Jan. 1 and shrinks by about 8 % by Jan. 31. Begin your observing in late twilight, when Jupiter’s brilliance is tempered by the background sky. The 2 darkish equatorial belts straddling the equator first become visible, with extra refined options following with affected person observing.

Io undergoes an occultation the night of Jan. 1, opening a month of high quality occasions. The moon disappears behind the western limb of Jupiter round 7:45 P.M. EST. The next night on the identical time, Io has made half an orbit and its shadow is in the midst of transiting Jupiter’s face. The shadow leaves simply earlier than 8:40 P.M. EST.

West Coast observers can see Callisto partially occulted by Jupiter’s northern limb Jan. 7, starting round 8:30 P.M. PST and lasting practically an hour. The occasion repeats Jan. 24, this time for the japanese half of the U.S., beginning round 7:10 P.M. EST.

Two occasions happen Jan. 9, when Io begins a transit round 7:05 P.M. EST. Ganymede slips out from behind Jupiter shortly after, round 7:09 P.M. EST. The large moon takes about 5 minutes to totally reappear.

Europa begins a transit on Jan. 19 at about 7:45 P.M. EST. Its shadow doesn’t seem till simply after 10:10 P.M. EST, lower than 10 minutes earlier than Europa itself leaves the other facet of the disk. The Royal Astronomical Society of Canada’s 2023 Observer’s Handbook lists different occasions all through the month.

Uranus lies in sparse southern Aries, a straightforward binocular goal at magnitude 5.7. Search for a pair of Fifth-magnitude stars, Sigma (σ) and Pi (≠) Arietis, making a 2.5°-long north-south line. Uranus is rather less than halfway between these stars on Jan. 1, a bit nearer to Sigma. The planet drifts barely west of a line becoming a member of the celebrities all through January. Uranus steadily slows to a stationary level Jan. 22, 1° northwest of Sigma Arietis.

The planet is seen all night and units quickly after 1 A.M. native time by January’s finish. By way of a telescope, its 4″-wide disk seems blue. On Jan. 28/29, search for Uranus near the gibbous Moon within the late night. Uranus stands solely 0.5° due south of the Moon’s southern limb quickly after midnight on the twenty ninth for East Coast observers (nonetheless the twenty eighth in all different U.S. time zones). Earlier within the night, Uranus is southeast of Luna’s southern limb.

Mars is a spectacular object in Taurus, shining at magnitude –1.2 on Jan. 1. That evening, the Crimson Planet is sort of 70° excessive round 8:30 P.M. native time. Mars lies about 9° east of the Pleiades star cluster (M45) and eight.5° north-northwest of Aldebaran. The planet slows to a halt Jan. 12, ending its retrograde movement and resuming an easterly trek, reaching 10° east of M45 by Jan. 31, when Mars units simply earlier than 3:30 A.M.

Watch Mars and the waxing gibbous Moon shut in on one another Jan. 30. For northern states, the 2 lie very shut, only a few arcminutes between them. From areas south of about 37° north latitude, the Moon occults Mars; the time is determined by your location. From Miami, Mars is occulted at 12:38 A.M. EST on Jan. 31 and reappears at 1:27 A.M. EST. In Dallas, Mars disappears at 11:18 P.M. CST on Jan. 30 and reappears practically 4 minutes after native midnight on the thirty first. Los Angeles observers see Mars vanish at 8:36 P.M. PST and reappear at 9:29 P.M. PST. Mars takes practically a minute to vanish and reappear, so put together your scope half-hour earlier than the occasion and start observing not less than 5 minutes earlier than the occultation is about to begin.

By way of a telescope, Mars is properly previous its greatest. On Jan. 1, it spans 15″ and is 97 % lit, giant sufficient for reasonable telescopes to see floor options. By the top of January, it shrinks to 11″ broad and floor options develop into tougher. The phase slims to 92 %. Mars additionally fades to magnitude –0.3.

At about 9 P.M. Central time, the next options are seen (for the mid-U.S.): Jan. 1: Sinus Meridiani with Syrtis Main leaving the disk; Jan. 10: Syrtis Main, Hellas, and Elysium; Jan. 23: Olympus Mons, Tharsis Ridge, and Mare Sirenum; Jan. 30: Tharsis, Valles Marineris, Solis Lacus, and Mare Erythraeum. Options and their positions differ relying on the time and your location.