Tuesday, September 28
As the Moon approaches Last Quarter this evening at 9:57 P.M. EDT, the best time to view it will actually be early this morning before sunrise. At that time, our satellite will still be a little more than 50 percent lit, hovering between the horns of Taurus the Bull.
You can enjoy the Moon in many ways with little or no magnification. Getting a close-in view with binoculars or a telescope, though, will let you better study features along the terminator, which divides lunar night from day. This morning, several round, rugged craters are visible along this line of shadow in the lunar south, while larger, darker seas dominate its northwestern side (which appears east in our sky).
As long as you’re in the area of the sky, Taurus is also home to two famous and easy-to-spot star clusters: the Hyades and the Pleiades (M45). Both look best at low magnification — and in fact, many observers enjoy them using no observing tools at all. Your telescope’s low-power finder scope is also an excellent way to take in these young star clusters. The Hyades, which are dusted across Taurus’ nose near bright red Aldebaran, are some 625 million years old. The Pleiades are much younger: only about 100,000 million years old.
Sunrise: 6:54 A.M.
Sunset: 6:47 P.M.
Moonrise: 11:24 P.M.
Moonset: 2:17 P.M.
Moon Phase: Waning gibbous (54%)
Wednesday, September 29
Venus is located in Libra tonight, setting in the west about two hours after the Sun. But that’s still plenty of time for evening observers to catch it — and in fact, it’ll be the first thing to pop out in the twilight sky, given its bright magnitude of –4.2.
Once darkness falls, you’ll see that the planet is located between and below Zubenhakrabi (Gamma [γ] Librae) and brighter Zubenelgenubi (Alpha [α] Librae). Together with Zubenesh (Beta [β] Librae), the four form a diamond in the sky. Venus also sits roughly 0.5° from magnitude 4.5 Iota (ι) Librae, far outshining this star.
Zoom in on Venus with a telescope and you’ll see the planet is just 63 percent lit, spanning 19″ in apparent size on the sky. It currently sits about 0.9 astronomical unit (AU) from Earth, where 1 AU is the average Earth-Sun distance of 93 million miles (150 million km).
Sunrise: 6:55 A.M.
Sunset: 6:45 P.M.
Moonrise: —
Moonset: 3:09 P.M.
Moon Phase: Waning crescent (44%)
Thursday, September 30
Mercury passes 1.7° south of Spica at 11 A.M. EDT. Of course, the Sun is high in the sky by then, so step outside right after sunset to catch them this evening. You’ll want to be quick, though — just 10 minutes after sunset, Mercury is only 1.5° high, with Spica not yet visible to the naked eye, still roughly 1.7° to the planet’s north. Once you’re sure the Sun has set, try finding them with binoculars or a small telescope, hugging the western horizon. Don’t pull out your optics until the Sun is completely gone from the sky, however, to avoid accidentally damaging your eyes.
Even if you aren’t able to catch Mercury before it sets, there’s another planet you’ll want to hunt down tonight: Uranus. Rising around 8 P.M. local time, the ice giant is up all night and glows at magnitude 5.7. That’s bright enough for keen-eyed observers to spot from a dark observing site, or for anyone to easily snag in binoculars or any telescope.
Tonight, Uranus sits less than 0.5° northeast of magnitude 5.8 Omicron (ο) Arietis. If you’re able to use high magnification, you’ll see the planet’s 4″-wide disk, which often appears a flat, pale blue. It’s also sitting just 16″ from a close pair of 12th-magnitude field stars.
Sunrise: 6:56 A.M.
Sunset: 6:43 P.M.
Moonrise: 12:17 A.M.
Moonset: 3:54 P.M.
Moon Phase: Waning crescent (35%)
Friday, October 1
Asteroid (40) Harmonia reaches opposition at 3 P.M. EDT. This space rock spans about 66 miles (107 km) across and was discovered in 1856. It circles the Sun, along with its main-belt brethren, between Mars and Jupiter and takes about 3.4 years to complete a single orbit.
Today, you’ll find it in Cetus the Whale. Because it’s at opposition, Harmonia will rise around sunset and set around sunrise, so you can opt to view it either in the morning or the evening. The crescent Moon won’t interfere. Harmonia glows softly at magnitude 9.5 — well within the range of binoculars or a small scope. As the constellation is rising, you’ll find Harmonia about 8.8° directly above (northwest of) 3rd-magnitude Eta (η) Ceti and 7.7° to the left (northeast) of 3rd magnitude Iota Ceti. Zoom in on the asteroid, and you’ll see it’s only about 0.1° from a slightly brighter (magnitude 7) field star, HIP 3385.
Sunrise: 6:57 A.M.
Sunset: 6:42 P.M.
Moonrise: 1:18 A.M.
Moonset: 4:34 P.M.
Moon Phase: Waning crescent (25%)
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