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January's top 10 targets

ChapleGlenn

As we start 2017, the biggest astronomical event to look forward to (at least in the United States) is the August 21 total solar eclipse that will traverse the country. But for now, I’d like to stay in the moment and draw your attention to 10 must-see cosmic sights you can enjoy this month. The deep-space selections (items four through 10) are all plotted on the StarDome map at the center of the magazine.

Earth

Yes, Earth is a cosmic sight — every bit as much a planet as Mars or Jupiter. It’s an important point of departure for novices trying out their first telescope or veterans test-driving a newly purchased instrument. There’s no better way to get the feel of a telescope than to use it to explore our planet’s fascinating landscapes and wildlife.

The Moon

Arguably the most spectacular celestial sight for the telescopist is Earth’s lone natural satellite. The Moon remains visible throughout January except for a few days around its New phase on the 27th. Luna is conveniently positioned in the early evening sky from January 1, when it’s a thin crescent low in the southwest, through Full Moon on the 11th, when it rises in the east at sunset. During this period, sunlight exposes more and more of the rugged surface, revealing an ever-changing, jaw-dropping panorama of craters, mountains, and plains. Don’t bother trying to identify features — just gaze and enjoy!

Venus

January’s brightest evening planet is Venus, which begins the year high above the southwestern horizon after sunset. If you view it once a week (any magnification above 30x will do), the planet’s phase changes noticeably as its orbit around the Sun brings more of the nightside into view. On the 1st, Venus takes on the appearance of a slightly gibbous Moon, then a half Moon (First Quarter phase, to be astronomically correct) around greatest elongation from the Sun on the 12th, and finally a fat crescent as January closes. During this time, the planet’s apparent diameter grows from 22" to 31" as it wanders closer to us in advance of inferior conjunction in late March.

Sirius

It’s time to reach for the stars, and there’s no better starting point than Sirius. A backyard scope won’t magnify the Dog Star (stars are too far away for that), but it will make it brighter. The night sky’s brightest luminary, Sirius is a hypnotic telescopic sight — a dazzling, pure-white diamond that dominates the field. It’s a binary star, but the 8th-magnitude companion is impossible to see in small-aperture telescopes.

ASYGC0117_01copy
A small telescope reveals the sparkling gems of the Double Cluster (NGC 869 [right] and NGC 884) in Perseus.
Thomas V. Davis

Almach

(Gamma [γ] Andromedae)

Unlike Sirius, Almach is a double star with an easy-to-see companion through small scopes, and it’s a beauty. A glimpse of its topaz-yellow and sapphire-blue components evokes gasps of wonder from first-time viewers. Almach is a cosmic gem in every sense of the word.

Castor

(Alpha [α] Geminorum)

Many astronomers consider Castor to be one of the finest double stars in the northern sky. Its magnitude 1.9 and 3.0 components, separated by a little more than 5", are easy to split with a magnification of 75x. A 9th-magnitude star 72" away orbits the main two. All three are spectroscopic binaries, making Castor a sextuple system!

Pleiades (M45)

One of the loveliest naked-eye sights on a winter’s night is this beautiful cluster of some six stars (more if you view from a dark-sky site). Binoculars add even more stars, while a telescope brings out dozens. The Pleiades spans 2°, so use low power to see them all at once.

Orion Nebula (M42)

A telescope transforms a naked-eye glow in Orion’s Sword into a majestic glowing cloud. Fix your eye on the Orion Nebula, and you’re looking at a stellar nursery. Near its heart is a beautiful quartet of newborn 5th- to 8th-magnitude stars (the Trapezium), best seen with magnifications of 60x and up. At once, the Orion Nebula gives us one of the heaven’s grandest nebulae and its finest multiple star!

Double Cluster (NGC 869 and NGC 884)

If you gaze at a spot midway between Cassiopeia and Perseus, you’ll see a nebulous patch. Point your telescope at it, and you’ll be greeted by a pair of rich star clusters. This twofer can be viewed together at low magnification or examined individually with high power. Either way, the Double Cluster won’t disappoint.

Andromeda Galaxy (M31)

We complete our list with a 2.5 million-light-year voyage to the Andromeda Galaxy. As remote as it is, the galaxy is so vast that its apparent length spans several Moon diameters. To capture the entire galaxy and its two brightest satellites, M32 and NGC 205, wait for a dark night and use the lowest magnification your scope provides. The best view I ever had was with a 4-inch f/4 rich-field telescope at just 16x.
Questions, comments, or suggestions? Email me at gchaple@hotmail.com. Next month: Messier “birthday” objects. Clear skies!
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