Sky at a Glance | October 25th, 2013

Friday, October 25

  • Staying out late tonight? Keep an eye low to the east-northeast for Jupiter rising around 11 or midnight (depending on your location). Lesser Castor and Pollux shine to its left. About 45 minutes later, the waning gibbous Moon follows Jupiter up. And then once the Moon is well up, look to the Moon's lower right for Procyon.

    Saturday, October 26

  • Last-quarter Moon (exact at 7:40 p.m. EDT). The Moon rises around midnight or 1 a.m. local time tonight, in dim Cancer below Jupiter and Gemini. To the right of the Moon and Jupiter, Procyon forms a nearly equilateral triangle with them.

    By dawn on Sunday they're all high in the southeast to south, with Procyon now on the bottom and Regulus and Mars off to their lower left.

    Sunday, October 27

  • The Ghost of Summer Suns. Halloween is approaching, and this means that Arcturus, the star sparkling low in the west-northwest in twilight, is taking on its role as "the Ghost of Summer Suns." For several days centered on October 29th every year, Arcturus occupies a special place above your local landscape. It closely marks the spot in your sky where the Sun stood at the same time, by the clock, during warm June and July — in broad daylight, of course. So, in the last days of October each year, you can think of Arcturus as the chilly Halloween ghost of the departed summer Sun.

    Pre-dawn view
    If you're up before dawn, watch the waning Moon pass Regulus and Mars in the east.
    Sky & Telescope

    Monday, October 28

  • Algol in Perseus, the prototype eclipsing binary star, should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 1:46 a.m. Tuesday morning EDT (10:46 p.m. Monday evening PDT). Algol takes several additional hours to fade and to rebrighten. Use the comparison-star chart at right.

  • Through the early morning hours and into dawn Tuesday morning, the waning crescent Moon forms a triangle with Mars and Regulus in the eastern sky — for the second time this month. By dawn it's high in the southeast.

    Tuesday, October 29

  • Look high in the northeast after dark for Cassiopeia standing on end. With the Moon out of the evening sky, now's a fine time to hunt some of Cassiopeia's star clusters and nebulae; see Sue French's Deep-Sky Wonders column, chart, and photos in the November Sky & Telescope, page 54.

    Wednesday, October 30

  • Have a really big scope? Have you ever really explored the Great Andromeda galaxy? Now you can; see Alan Whitman's Going Deep column and detailed photo-charts in the November Sky & Telescope, page 59, including dozens of open and globular clusters to 15th magnitude and fainter. Even a 6-inch scope can show one of them, NGC 206.

    Thursday, October 31

  • Halloween is moonless this year. Spot Venus in the southwest as twilight fades, and Vega very high in the west after dark. Higher above Vega is Deneb. A greater distance to Vega's left, look for Altair.

  • Algol, the Demon Star, is at minimum light in eclipse for a couple hours centered on 10:35 p.m. EDT.

    Friday, November 1

  • Fomalhaut, the Autumn Star, shines at its highest in the south after dinnertime at this time of year. Fomalhaut is often called "lonely" because it's so far from any other 1st-magnitude star. It's in the bottom right of the Great Water: the enormous expanse of autumn sky filled with dim water-themed constellations.

    November 3rd's partial solar eclipse at sunrise
    Weather permitting, early risers along the Eastern Seaboard can see a partial solar eclipse at sunrise on November 3, 2013.
    Sky & Telescope illustration / source: Stellarium

    Saturday, November 2

  • A partial eclipse of the Sun will be in progress at sunrise Sunday morning for the Eastern Seaboard of North America and points inland, as shown at the top of this page. The partial eclipse happens in the daytime on Sunday for Africa, the Middle East, southernmost Europe, and elsewhere. The eclipse is total for a narrow band crossing the Atlantic and Equatorial Africa. See our article: Partial Solar Eclipse Sunday Morning, Nov. 3.

  • WARNING: Daylight-saving time ends just hours earlier, at 2 a.m. Sunday morning for most of North America. Clocks fall back an hour.


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

    This is an outdoor nature hobby. 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).

    Pocket Sky Atlas
    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 once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

    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 not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means heavy and expensive). 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

    Jupiter on Sept. 9, 2013
    Above (south of) center is Jupiter's Oval BA, "Red Spot Junior." S&T's Sean Walker took this stacked video image on September 9th at 9:54 UT with a 12.5-inch reflector through poor to fair seeing.
    S&T: Sean Walker

    Mercury and Saturn are lost in the sunset.

    Venus (magnitude –4.5) shines brightly in the southwest during dusk. It sets nearly an hour after dark now.

    In a telescope Venus appears very close to half-lit. When will it — or did it — it appear exactly so? Visually, the dichotomy of Venus comes about a week or ten days before Venus wanes to be geometrically half-lit, which happens on October 30th. We see this offset timing because of the dim lighting at Venus's terminator combined with fuzzy seeing in a telescope and a (usually) bright-sky background.

    Mars (magnitude 1.5) rises around 2 or 3 a.m. near Regulus (magnitude 1.4) in Leo. By dawn they're high in the east. Mars and Regulus are moving farther apart now, from a separation of 6° on October 26 to 11° on November 2nd. In a telescope Mars is just a tiny blob 5 arcseconds wide.

    Comet ISON is below Mars, in the hind feet of Leo, before the first light of dawn, still a telescopic target at 9th or 10th magnitude. Use the finder chart for it in the November Sky & Telescope, page 50. Check for news at skypub.com/ISON.

    Jupiter (magnitude –2.2, in Gemini) rises in the east-northeast around 10 or 11 p.m. and blazes high in the south by early dawn. About 8° left of it after it rises are Castor and Pollux. In a telescope Jupiter has grown to 41 arcseconds wide, as it heads toward its January 5th opposition. Its Great Red Spot has turned an unusually strong shade of orange.

    Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are high in the southeast and south, respectively, by 8 or 9 p.m. Finder charts for Uranus and Neptune. See also the October Sky & Telescope, page 50.


    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 Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.


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