Some daily events in the changing sky for January 15 – 23.

Friday, January 15

  • An annular eclipse of the Sun occurs for parts of Africa, the Indian Ocean, southernmost India, northern Sri Lanka, Burma, and China. A partial eclipse occurs for most of the rest of the Eastern Hemisphere. See zoomable map of the zone of annularity, and other information on the rest of the eclipse. Seen from its center point in the Indian Ocean, this is the longest annular eclipse until the year 3043.
  • The solar eclipse corresponds to this month's new Moon (which for the center of the Earth occurs at exactly 2:11 a.m. on this date Eastern Standard Time).
  • Algol should be at its minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 11:10 p.m. EST; 8:10 p.m. PST.

    With Jupiter lighting the way, watch for this month's return of the waxing crescent Moon.

    Sky & Telescope diagram


    Saturday, January 16

  • As twilight fades, look for the very thin waxing crescent Moon low in the west-southwest far to the lower right of Jupiter, as shown here.

    Sunday, January 17

  • The waxing crescent Moon is thicker and higher than it was yesterday evening, and it's closer to Jupiter, as shown here.

    Monday, January 18

  • The Moon now shines above Jupiter during and after dusk.
  • Algol should be at minimum light for a couple hours centered on 8:00 p.m. EST.

    Tuesday, January 19

  • By mid-evening, bright Mars is well up in the east. Notice the gigantic, flattened letter M that it forms with (to its right) Pollux, Procyon, Betelgeuse, and Rigel — like an enormous Cassiopeia, enlarged five times. The real Cassiopeia is high in the northwestern sky, tipped on end.

    Wednesday, January 20

  • This evening the Great Square of Pegasus poses to the right of the Moon. It's tilted on one corner.

    Thursday, January 21

  • Late tonight and tomorrow night, once Saturn climbs reasonably high, a telescope will show Saturn's largest satellite, Titan, about four ring-lengths to the planet's east.

    Friday, January 22

  • By 9 p.m., the Big Dipper is already standing nearly upright on its handle in the northeast. This means we're a third of the way through winter!

    Saturday, January 23

  • First-quarter Moon (exact at 5:53 a.m. on this date EST).

    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 magazine of 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 Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.

    Can a computerized telescope take their place? I don't think so — not for beginners, anyway (and especially not on mounts that are less than top-quality mechanically). As Terence Dickinson and Alan Dyer say in their 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 and a curious mind." Without these, "the sky never becomes a friendly place."

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

    This Week's Planet Roundup

    Mercury is having a good morning apparition. Look for it low in the southeast about an hour before your local sunrise time. Don't confuse it with Antares roughly 30° to its upper right, or Altair a similar distance to its left.

    Venus is hidden behind the glare of the Sun.

    Mars, shining fiery bright at magnitude –1.2, rises in the east-northeast in twilight and shines high in the east by late evening. It's at the border of Leo and Cancer, with dimmer Regulus about a fist-width below it during evening. Mars is highest due south around 1 a.m.

    Dark Syrtis Major was almost dead center on Mars when Ian Sharp in Britain took this image at 0:54 UT January 4, 2010. The North Polar Cap is huge and obvious. The slightly bright region on the southern limb (top) is the dusty Hellas basin. The central meridian longitude was 280°. South is up.

    Stacked-video images like this will generally show much more detail on a planet than can be seen by eye even through the same telescope.

    Ian Sharp

    In a telescope Mars is 14 arcseconds wide, essentially as large as it will become this year. The big, white north polar cap is in fine view, bordered by a very wide dark zone. Identify other surface features using the Mars map and observing guide in the December Sky & Telescope, page 57. Mars is closest to Earth on January 27th, when it will be 14.1 arcseconds wide, and it's at opposition on the 29th.

    Jupiter (magnitude –2.1, at the Capricornus-Aquarius border) shines low in the southwest in twilight and sets fairly soon after dark.

    Saturn (magnitude +0.8, in Virgo) rises in the east around 10 or 11 p.m. and stands highest in the south around 4 a.m. In earliest dawn, notice the huge, horizontal line of Pollux, Mars, Regulus, Saturn, and Spica running all the way from west-northwest to south. In a telescope Saturn's rings are tilted 5° from edge-on to us, their maximum tilt until next August.

    Uranus (magnitude 5.9, just south of the Circlet of Pisces) is still in view right after dark well to the upper left of Jupiter. Use our finder chart.

    Neptune, lower right of Jupiter, is sinking away into the sunset.

    Pluto is behind the glare of the Sun.

    All descriptions that relate to your horizon or zenith — 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, World Time, or GMT) minus 5 hours.

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