This Week’s Sky at a Glance

Comet PanSTARRS update: The incoming comet that we hoped would make a fine showing in March has been weakening. It may not even reach naked-eye visibility, what with its low altitude in the evening twilight. Follow our updates at SkyandTelescope.com/panstarrs.


Friday, February 8

Mercury appears less than ½° upper right of much fainter Mars shortly after sunset on Friday the 8th.
Sky & Telescope diagram
Sunday evening the 10th offers North Americans their best chance in a long time to catch an extremely young, thin crescent Moon soon after sunset. Bring binoculars. (The Moon is positioned here for the middle of North America. The visibility of faint objects in such bright twilight is exaggerated. The 10° scale is about the width of your fist at arm's length.)
The waxing, heightening crescent Moon continues to guide the way down to Mercury and Mars

  • Mercury-Mars Conjunction. Mars is less than ½° from Mercury low in the west-southwest in bright twilight, as shown at right (for North America). They'll certainly be an interesting pair through a telescope, though both will be tiny and blurred at such a low altitude. See Mercury Meets Mars.

    Saturday, February 9

  • Mars now appears 1.1° below brighter Mercury (for North America), low in the sunset glow.

    Sunday, February 10

  • New Moon; exact at 2:20 a.m. EST on this date (11:20 p.m. on the 19th PST).

  • Catch your record young Moon? Very low in the west shortly after sunset, if the air is very clear, binoculars may show an extremely thin crescent Moon well to the lower right of Mercury and Mars (viewed from North America), as illustrated at right. If you see the crescent from the Eastern time zone, you're seeing it when it's only 15 or 16 hours old — a remarkable record that you may not beat in a lifetime! Seen three hours later in twilight from the Pacific time zone, the Moon will be 18 or 19 hours old — still likely a record for your logbook. Record the time you detect the Moon to the minute, and calculate how long this is from the time of new Moon given above.

    Monday, February 11

  • Mercury shines lower left of the Moon, as shown below. And bring binoculars for a last shot at faint, low Mars.

    Tuesday, February 12

  • Mercury shines far below the crescent Moon as twilight fades.

  • The eclipsing binary star Algol should be at minimum light, magnitude 3.4 instead of its usual 2.3, for a couple hours centered on 11:23 p.m. EST. Algol takes several additional hours to fade and to rebrighten.

    Wednesday, February 13

  • Look to the right of the Moon soon after dark for Gamma (γ) Pegasi, the leftmost star of the Great Square of Pegasus. The Great Square is standing on one corner.

    Thursday, February 14

  • February is when Orion stands highest in the south in early evening. This season, Orion is framed by the two brightest points in the sky: Jupiter high to its upper right and Sirius down to its lower left.

    Friday, February 15

  • After dark, look right of the crescent Moon by roughly a fist-width at arm's length for the two or three leading stars of Aries, lined up almost vertically.

  • Close flyby of asteroid 2012 DA14. This gymnasium-sized asteroid will miss Earth by just 18,000 miles (28,500 km) around 19:25 Universal Time today. It will then be as bright as 8th magnitude, moving across the stars by 0.8° per minute — and it will be in nighttime view from easternmost Europe (in late evening) across Asia to Australia (before dawn on the 16th local date).

    By the time it's visible in Western Europe it will be a little fainter, and by its visibility in North America it will be down to 11th to 13th magnitude, receding into the distance near the Little Dipper. See our article Asteroid 2012 DA14 to Zip Past Earth, with detailed telescopic finding instructions.

  • Algol should be at minimum light for a couple hours centered on 8:12 p.m. EST.

    Saturday, February 16

  • Bright Jupiter shines upper left of the Moon. Aldebaran is to Jupiter's left, and the Pleiades are a little farther to Jupiter's right.

  • Mercury is at greatest elongation, 18° east of the Sun in evening twilight. A telescope shows (in reasonably good seeing) that this tiny little sphere, just 7 arcseconds wide, is now half-lit.


    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).

    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope

    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 peaks in the early evening sky from February 11th to 21st, while much fainter Mars appears lower each evening. The two planets pass spectacularly close to each other on February 7th and 8th. Their disks are shown in their correct shapes and orientations, but their sizes are exaggerated hugely, roughly matching their appearance through a telescope at high magnification.
    Sky & Telescope diagram

    Mercury (magnitude –1) is having an excellent apparition in the evening twilight. Look for it low in the west-southwest as the sky darkens. No other point in the area is nearly so bright. See Mercury in February 2013.

    Right there too is Mars, much fainter. They're less than 1° apart on Friday the 8th; after that Mars moves lower each day and becomes harder to spot.

    Venus (magnitude –3.9) is buried deep in the glow of sunrise.

    Mars (magnitude +1.2) is becoming a real challenge as it sinks lower low into the sunset. Brighter Mercury is your marker for finding it; as shown here.

    Mars is currently on the far side of the Sun from us, but Mercury is swinging around to the Sun's near side as shown by its growing size and diminishing phase.

    The shadow of Ganymede was passing the Great Red Spot when Christopher Go took this image of Jupiter at 10:59 UT February 6th. South is up. Note the white outbreaks in the South Equatorial Belt downstream from the Great Red Spot. Another is below them in the North Equatorial Belt.

    Jupiter (magnitude –2.4, in Taurus) dominates the high south in early evening and the southwest later. To its left is orange Aldebaran; to its right are the Pleiades. This whole group sets around 2 a.m.

    In a telescope, Jupiter is shrinking as Earth pulls farther ahead of it in our faster orbit around the Sun. This week it shrinks from 42 to 41 arcseconds wide.

    Saturn (magnitude +0.5, in Libra) rises in the east-southeast around midnight, well to the lower left of Spica. By the beginning of dawn Saturn is highest in the south — more or less between Spica, far to its right, and Antares farther to its lower left.

    Uranus (magnitude 5.9, in Pisces) is getting low in the west after dusk.

    Neptune is lost in the glare of the Sun.

    This extraordinary amateur image of Saturn was captured by Darryl Pfitzner Milika in Australia on January 26th. He used a 14-inch Celestron Schmidt-Cassegrain scope and an ASI120MM planetary video camera for frame-stacking. Just visible is the hexagonal shape of the storm that surrounds Saturn's north pole. The hexagon shape was first discovered by the Cassini spacecraft in 2007. South is up.

    Also visible in his image are four of Saturn's moons. From left: Dione, Enceladus, Mimas (!), and Tethys. Click for larger view.

    Darryl Pfitzner Milika

    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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