Sky at a Glance | January 11th, 2013

Friday, January 11

  • In early evening at this time of year, the Great Square of Pegasus balances on one corner high in the west. The vast Andromeda-Pegasus constellation complex runs all the way from near the zenith (Andromeda's foot) down through the Great Square (Pegasus's body) to low in the west (Pegasus's nose).

    evening sky January 2013
    The crescent Moon marches higher each evening as it waxes thicker farther away from the Sun. Use the Moon to locate faint little Mars.
    Sky & Telescope diagram

    Saturday, January 12

  • As twilight turns to night, look low in the northwest for Vega. To its upper left, by two or three fists at arm's length, shines Deneb. Deneb is the head of the big Northern Cross, which is now swinging down and soon will stand nearly upright on the northwest horizon (as seen from mid-northern latitudes).

    Sunday, January 13

  • In twilight this evening, look below the waxing crescent Moon in the west to see if you can still spot faint little Mars, as shown here. Mars has been hanging in there in twilight ever since August (!) but is now gradually creeping lower week by week.

    Monday, January 14

  • Before moonlight returns in force to wash out low-surface-brightness telescopic objects, try tonight for the Bubble and Pac-Man Nebulae in Cassiopeia using Ken Hewitt-White's "Hot Gas in Cass" article with finder chart and photos in the January Sky & Telescope, page 65.

    Tuesday, January 15

  • In this coldest time of the year, the dim Little Dipper hangs straight down from Polaris after dinnertime, as if (per Leslie Peltier) from a nail on the cold barn wall of the sky.

    Highlight of the Evening Sky
    Jupiter is moving with respect to the stars, though slowly. It has now crept just to the right (as seen in early evening) of the upward line from Aldebaran through Epsilon Tauri, the other tip of the Hyades V pattern.
    Sky & Telescope

    Wednesday, January 16

  • Of course you often turn your telescope to Jupiter, high and bright this season. But how well do you know all that you can actually look for? See "Observing Dynamic Jupiter" in the January Sky & Telescope, page 52 — including all of Jupiter's satellite events for January.

    Thursday, January 17

  • Bright Capella high overhead and bright Rigel in Orion's foot, both magnitude 0, have almost the same right ascension — so they transit your north-south meridian at the almost same time. Capella passes closest to the zenith around 9 or 10 p.m. this week, depending on how far east or west you live in your time zone. (It goes exactly through the zenith if you're at latitude 46° north: Portland, Oregon; Montreal; central France.) So, whenever Capella is closest to the zenith, Rigel always marks true south over your landscape.

    Friday, January 18

  • First-quarter Moon. The Moon is exactly half lit at 6:45 p.m. EST. In early evening, look above the Moon by about about a fist-width at arm's length for the brightest two or three stars of Aries. These are aligned more or less vertically.

    Saturday, January 19

  • In twilight, bright Jupiter comes into view well to the lower left of the Moon. By 8 p.m. things have turned around and Jupiter is shining to the Moon's upper left. Closer to the Moon's lower left now is the big, dim head of Cetus with its one 2nd-magnitude star, orange Alpha Ceti (Menkar).


    Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

    For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.
    Alan MacRobert

    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope effectively.

    You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? Not for beginners, I don't think, and certainly not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). As Terence Dickinson and Alan Dyer say in their invaluable Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


    This Week's Planet Roundup

    Mercury is hidden in conjunction with the Sun.

    Venus (magnitude –3.9) is getting lower in the dawn each morning. Look for it above the southeast horizon about 30 minutes before your local sunrise.

    Mars (magnitude +1.2) still glimmers very low in the west-southwest in the fading glow of sunset. Don't confuse it with Fomalhaut far to its left.

    Jupiter on Jan. 1, 2013
    The white turbulence following Jupiter's Great Red Spot, and unusual amounts of activity in the Equatorial Zone, are evident in this exquisite image taken on January 1st by Christopher Go in the Philippines. South is up.

    Jupiter (magnitude –2.7, in Taurus) is the first "star" to appear in the eastern sky after sundown. It dominates the high southeast after dusk, with orange Aldebaran below it and the Pleiades over it as shown above. They tilt around and pass highest in the south around 8 or 9 p.m. local time. In a telescope Jupiter is still about 45 arcseconds wide.

    Saturn (magnitude +0.6, in Libra) rises in the east-southeast around 1 or 2 a.m. local time. By the beginning of dawn it's fairly high in the southeast. That's the best time to get your telescope on it. Saturn's rings are tilted 19° to our line of sight, the widest open they've been for seven years.

    Uranus (magnitude 5.8, in Pisces) is still in good view in the southwest right after dark. Finder chart.

    Neptune (magnitude 8.0, in Aquarius) is sinking away low in the west-southwest after dark.


    All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Standard Time (EST) equals Universal Time (also known as UT, UTC, or GMT) minus 5 hours.


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