Monday, May 8
With the Moon rising later, there’s a widening dark window after sunset to begin enjoying faint objects once more. The western sky holds many targets for this week — remember Venus and Mars? We’re still coming back for them! But tonight, look a little higher above the horizon for Leo the Lion. His brightest star, Regulus, is still 50° high two hours after sunset.
We’re going to look a little higher still, moving east to locate the tip of the Lion’s tail, 2nd-magnitude Denebola. This is our anchor point for finding tonight’s two targets: the dwarf planet 1 Ceres and the spiral galaxy M99.
First, let’s locate Ceres. From Denebola, use binoculars or a telescope to scan just a little east. Eighth-magnitude Ceres lies within 2.5° of Denebola, to the star’s east-northeast. There aren’t many bright background stars here, so it should be a relatively easy ID, particularly with the chart at right. Ceres is drifting slowly, so you’ll need to come back every few nights to really catch any movement.
From the main-belt world, slide about 5° east-southeast this time (or just over 7° due east of Denebola). This will bring you to M99, a spiral galaxy in Coma Berenices. M99 is a face-on galaxy that shines at 10th magnitude, best seen with a telescope — particularly a larger aperture if you want to bring out some detail. Even in large instruments, however, its spiral arms are a bit hard to make out. Clearest is the southern arm, which is brighter than the others thanks to large clumps of star formation.
Sunrise: 5:52 A.M.
Sunset: 8:02 P.M.
Moonrise: 11:54 P.M.
Moonset: 7:44 A.M.
Moon Phase: Waning gibbous (89%)
Tuesday, May 9
Uranus is in conjunction with the Sun at 4 P.M. EDT; it will reappear in the morning sky just before sunrise in late May, so we’ll make sure to catch this distant world once it’s visible again.
Very visible, though, is Venus. The bright planet still dominates the western sky after sunset and reaches its farthest declination north (26°) today, as well as its highest point above the ecliptic. Venus doesn’t set until nearly midnight for most of the U.S. and appears almost circumpolar from Alaska, remaining in the sky as both an evening and a morning star.
Venus now lies roughly due north of Eta Geminorum and hangs within 2° of the glittering open cluster M35, visible to the naked eye under good conditions at magnitude 5.3. The pair looks stunning in binoculars or a wide-field scope. Astrophotographers may want to take advantage of the juxtaposition.
Venus is now 63 percent lit and 18" across; its phase will shrink throughout the month to roughly half-lit by the end of May, while its angular size will grow to more than 20" at the same time.
Sunrise: 5:51 A.M.
Sunset: 8:03 P.M.
Moonrise: —
Moonset: 8:43 A.M.
Moon Phase: Waning gibbous (81%)
Wednesday, May 10
Now let’s enjoy the other glorious evening planet: Mars passes 5° south of Pollux at 4 P.M. EDT. Catch it in this same position after sunset tonight, appearing to Pollux’s lower left. Mars sits 30° directly above Betelgeuse, the red giant that marks Orion’s shoulder, now sinking toward the horizon. The Red Planet shows off its small disk through a telescope, appearing just 5" wide, thanks to its vast distance from Earth. If we were to look down on the solar system from above, Earth is quickly pulling away from Mars as our planet’s faster orbital speed carries us around the Sun. Mars is about a quarter-orbit away after our planets came closest late last year.
While you’re enjoying this region of the western sky, take some time to enjoy the sight of both Pollux and nearby Castor through a telescope. Pollux is the cooler of the two stars, glowing orange-yellow. It is slightly cooler than the Sun, thanks to its more advanced age. Castor, which lies 4.5° northwest of Pollux, is a beautiful multiple star with two bright components separated by several arcseconds. Another member lies some 1.2' to their south. In truth, each of these three stars is also a binary, though optical instruments cannot split them further and their true nature was discovered spectroscopically.
Sunrise: 5:50 A.M.
Sunset: 8:04 P.M.
Moonrise: 12:53 A.M.
Moonset: 9:52 A.M.
Moon Phase: Waning gibbous (71%)