The Sky This Week, 2012 October 16 - 23
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Orion Rising, Autumn, 2004 |
The Moon waxes in the evening sky this week, wending her way up from the southern reaches of the ecliptic toward the sparse starfields of the autumnal constellations. First Quarter occurs on the 21st at 11:32 pm Eastern Daylight Time. Look for Luna’s crescent just over five degrees east of ruddy Mars in the southwest at dusk on the 18th. As twilight deepens, look a few degrees south of Mars for the bright star Antares which will form a nice triangle with the Moon and the planet.
Despite the encroachment of the brightening Moon, summer’s brighter stars and constellation patterns still hang tough in the early evening sky. You should have no trouble picking out the three bright stars of the Summer Triangle, Vega, Deneb, and Altair, just west of the meridian at the end of evening twilight. As the Moon washes out the star clouds of the Milky Way in this part of the sky you can still enjoy some of the stellar delights within the Triangle’s bounds. One of my favorite targets for small telescopes may be found almost smack-in-the-middle of the Triangle in the form of the third-magnitude star Albireo, which marks the "head" of Cygnus the Swan. To the naked eye it appears as a single star, but almost any small telescope will reveal it to be a beautiful double star made up of a brighter yellow primary star and a deep blue-tinted secondary. Here is a case where less is more since the color contrast is best seen in smaller instruments. In large telescopes the hues begin to wash out due to the brighter appearance of the components. I like to call Albireo the "Navy Double" since its component colors are that of my favorite Service. Nearby is another famous multiple star system, Epsilon Lyrae. If you look at the bright star Vega in binoculars you’ll see a pair of stars nestled close to the bright star. Now point your telescope to this "pair", and if you have good optics of three inches aperture or more you’ll notice that each component is itself a close double star. The so-called "Double-Double" is widely used by amateur astronomers to judge the stillness of the atmosphere from night to night.
Later in the evening the Summer Triangle heels over in the west, and the relatively sparse stars of autumn take over the nightscape. A prominent geometrical figure approaches the meridian at 10:00 pm high in the southern part of the sky. While its brightest stars are all second magnitude, the "Great Square" of Pegasus should be easy to spot from suburban locations. Joining Pegasus in the northeastern sky are several other constellations which are all related in mythology. Andromeda, Cassiopeia, Cepheus, Cetus, and Perseus all figure in one of the most enduring legends handed down to us from ancient time in a story filled with vanity, deceit, evil, bravery, and a little bit of magic. The story plays out every clear night at this time of the year.
If you’re looking for planets in the evening sky, you can see two with the naked eye. One sets in the early evening, the other rises a bit later.
Mars has been with us in the evening sky for most of the year. He was at his best at opposition way back in early March, and now he lingers in the southwest for a short time after sunset. The red planet passes by an aptly-named star this week as he glides north of Antares, the heart of Scorpius, the Scorpion. "Antares" translates as "rival of Mars", and this week you have a good chance to see why the star bears that name. Mars passes just over three degrees north of Antares on the evening of the 20th; binoculars should provide a nice view of their similar hues.
Jupiter rises just before 9:00 pm, and I now see him peeking through the trees in my neighborhood before turning in for the night. Jupiter heralds the rising stars of the Great Winter Circle, and you will find him prominently placed between the bright stars Aldebaran and Alnath in the constellation of Taurus. By midnight you’ll see the rising figure of Orion striding over the horizon, and by then Old Jove should be a splendid sight in the telescope.
Bright Venus still greets early risers with her dazzle in the pre-dawn sky. This week she is drifting under the stars that form the hindquarters of Leo the Lion as she wends her way into the rising stars of spring. She will continue to welcome you before the Sun rises through the end of the year.
