Sky at a Glance | January 25th, 2008

Some daily events in the changing sky for January 25 – February 2.

Comet Holmes remains near Algol, dimming and widening more and more; it's well over 1½° across. Now that the Moon is gone from the early-evening sky, keep trying for the comet both with your naked eyes and with binoculars. When will you last be able to see it? Dim as it may become, Holmes will remain in the evening sky through April; see chart.

While you're checking in on Comet Holmes with binoculars, look also for the two Messier objects nearby in Perseus: M34 (which is easy) and M76 (much tougher). See Gary Seronik's Binocular Highlight column and chart in the January Sky & Telescope, page 58.


Looking southeast in early dawn
Watch the configuration of Venus and Jupiter change each morning this week! The views here are for 1 hour before sunrise. To find your local sunrise time, make sure you've put your location into our online almanac (and make sure the Daylight Saving Time box is unchecked).
Sky & Telescope diagram
Friday, January 25

  • Venus and Jupiter are drawing closer together in the dawn each morning, low in the southeast. Watch as they approach their conjunction a week from today.

  • A small telescope will always show Titan, Saturn's largest moon. Tonight and tomorrow night Titan is four ring-lengths to Saturn's west. A 6-inch telescope will begin to show the orange color of its atmospheric haze. (A guide to identifying all six of Saturn's satellites that are visible in amateur scopes is in the January Sky & Telescope, page 66.)

    Saturday, January 26

  • Winter is almost halfway through — as you can see from the ascent of the Big Dipper. The Dipper is highest in late spring and early summer, but already it stands upright on its handle in the northeast as early as 8 or 9 p.m. (The exact center of winter this year is on February 4th at 12:58 p.m. Eastern Standard Time. The center of winter is celebrated, approximately, as Groundhog Day, also known as Candlemas or Imbolc.)

    Sunday, January 27

  • This is also the time of year when the Little Dipper hangs straight down from Polaris right at nightfall. As the evening, and winter, advance, the Little Dipper begins curling upward toward its summer height.

    Monday, January 28

  • Mira, the brightest long-period variable star in the sky, should be nearly at its peak brightness of about magnitude 3.4 this week. So it should be easy to spot with the unaided eye. Follow Mira's doings with the article and comparison-star chart on page 71 of the March Sky & Telescope (now arriving in subscribers' mailboxes).

  • Another red long-period variable star, U Orionis at the top of Orion's Club, should also be at maximum this week. Though it's no match for Mira, U Ori is still one of the brightest long-period variables, typically peaking at around magnitude 6.3.

    Tuesday, January 29

  • Last-quarter Moon tonight (exact at 12:03 a.m. Wednesday morning Eastern Standard Time).

    Wednesday, January 30

  • Mars halts its retrograde (westward) motion and begins creeping eastward again through the stars of Taurus.

    Looking southeast in early dawn
    Bent like a bow, the crescent Moon points to Venus and Jupiter in conjunction on the morning of Friday, February 1st.
    Sky & Telescope diagram
    Thursday, January 31

  • Venus and Jupiter, the two brightest planets, are in close conjunction tomorrow morning in early dawn, as shown here. The arc of the waning crescent Moon, far to their upper right, points the way; if it were a bow it would be shooting an arrow at them. Also: can you see Antares sparkling near the Moon?

    Friday, February 1

  • The bright eclipsing variable star Algol should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 11:16 p.m. Eastern Standard Time; 8:16 p.m. PST. Algol takes several additional hours to fade and to rebrighten. (For all times of Algol's minima this month, good worldwide, see the February Sky & Telescope, page 73.)

    At any random time you glance up at Algol, you have a 1-in-30 chance of catching it at least 1 magnitude fainter than normal.

    Saturday, February 2

  • In early dawn Sunday morning, the thin crescent moon hangs a fist-width at arm's length to the right of Venus and Jupiter, as shown below.

    Looking southeast in early dawn
    As Venus and Jupiter start drawing apart, the thinning Moon passes by them. (These scenes are always drawn for the middle of North America, at latitude 40° north, longitude 90° west. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. For clarity, the Moon is shown three times actual size.)
    Sky & Telescope diagram

    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 foldout map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of maps; the standard is Sky Atlas 2000.0) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the enchanting though increasingly dated Burnham's Celestial Handbook). Read how to use them effectively.

    More beginners' tips: "How to Start Right in Astronomy".

    This Week's Planet Roundup

    Mercury drops down from its good evening apparition this week, while also fading from magnitude 0 to +2. Early in the week you can still catch it above the west-southwest horizon about 45 minutes after sundown. (Don't confuse it with twinklier Fomalhaut, far to the left in the southwest, or Altair, even farther to Mercury's right.)

    NASA's Messenger probe recently made its first flyby of Mercury — and its views verified the reality of what Earthbound amateurs have been imaging! See our article.

    Venus (magnitude –3.9, in Sagittarius) is the brighter of the two "Morning Stars" low in the southeast during dawn. The other is Jupiter, which closes in on Venus day by day (from the lower left) until their conjunction on the morning of February 1st.

    Mars (about magnitude –0.5, in eastern Taurus) shines high in the southeast after dark and highest toward the south around 9 or 10 p.m., high above Orion. The fairly bright star near it is Beta (β) Tauri, also known as El Nath, magnitude +1.6 and pale blue-white.

    Mars diminishes from 12.8 to 11.9 arcseconds in apparent diameter this week; it's falling farther behind us as Earth moves ahead in our faster orbit around the Sun. See the telescopic observing guide and surface-feature map in the November Sky & Telescope, page 66, or the short version online.

    Jupiter (magnitude –1.9, in Sagittarius) is closing in on brighter Venus low in the dawn. They have a close conjunction, 0.6° apart, on the morning of February 1st.

    Saturn, Titan, and Rhea on Jan 22, 2008
    Titan and Rhea, Saturn's two brightest satellites, stood north of the planet when S&T's Sean Walker took this image at 6:17 UT January 22nd through mediocre atmospheric seeing.
    S&T: Sean Walker
    Saturn (magnitude +0.4, in Leo) rises in the east around 7 or 8 p.m. and is highest in the south after midnight. Fainter Regulus (magnitude +1.4) is 7° west of Saturn: to its upper right after they rise. Only a little dimmer than Regulus is Gamma (γ) Leonis (magnitude +2.1), located 8° to Regulus's north. The three make an eye-catching triangle.

    Uranus (magnitude 5.9, in Aquarius) is sinking low in the southwest after dark.

    Neptune is hidden in the glow of dusk (in the vicinity of Mercury).

    Pluto is hidden in the glow of dawn (above Venus and Jupiter).

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

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