Monday, January 10
Early-morning observers up before the Sun can enjoy a full view of Hydra the Water Snake this morning. Covering roughly 1,303 square degrees, this is the largest of the officially recognized 88 constellations in our sky. That may seem intimidating to observe, so let’s zoom in on only its head, which covers a smaller, more manageable 20°.
The Water Snake’s head lies adjacent to Cancer the Crab and some 15.5° east of bright Procyon in Canis Minor. The head itself is depicted by the stars Zeta (ζ), Epsilon (ϵ), Delta (δ), Sigma (σ), and Eta (η) Hydrae. First, focus in on Epsilon with your telescope — this is not a single luminary but in fact a double star, also cataloged as Struve (STF) 1273. Its components are magnitude 3.5 and 6.7, and sit a mere 2.9" apart. You’ll need steady seeing and about a 5-inch scope to split them. Can you do it?
If you want an easier double to observe, slide over to Delta and then look 1° north to spot STF 1245. These are both fainter at magnitude 6.0 and 7.2, but separated by a wider 10.1". Their different spectral classes — F8 and G5 — mean that close attention may reveal differing colors.
Several other double stars sit in or near Hydra’s head, including STF 1255 and STF 1290. The former is easy to split, but the latter is more challenging than Epsilon.
Sunrise: 7:22 A.M.
Sunset: 4:54 P.M.
Moonrise: 12:08 P.M.
Moonset: 12:45 A.M.
Moon Phase: Waxing gibbous (60%)
Tuesday, January 11
The Moon passes 1.5° south of Uranus at 6 A.M. EST. By sunset this evening, they are a respectable 5.7° apart high in the southern sky, making it easier to pick up Uranus’ dim light once darkness falls.
To locate the distant ice giant, which is now southwest of the Moon, look for 2nd-magnitude Hamal, the Ram’s brightest star. Drop 10.7° to its lower left (southeast) to spot Uranus’ magnitude 5.8 glow in binoculars or a telescope. The planet’s disk spans nearly 4" and should appear like a “flat,” greenish-blue star. Uranus currently sits some 19.4 astronomical units (AU) from Earth, where 1 AU is the average Earth-Sun distance. That means sunlight reflecting off its surface must travel back through the solar system for nearly 3 hours to reach our eyes.
Asteroid 3 Juno is in conjunction with the Sun at 5 P.M. EST tonight.
Sunrise: 7:21 A.M.
Sunset: 4:55 P.M.
Moonrise: 12:33 P.M.
Moonset: 1:46 A.M.
Moon Phase: Waxing gibbous (69%)