Friday, October 29

  • 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." What does this mean? Every year for several days around October 29th, Arcturus occupies a special place in the sky above your local landscape. It closely marks the spot there 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 every year, you can think of Arcturus as the chilly Halloween ghost of the departed summer Sun.
  • Venus is at inferior conjunction, 6° south of the Sun and basically unobservable.
  • The last-quarter Moon shines very late tonight. (It's exactly last-quarter at 8:46 a.m. Eastern Daylight Time Saturday morning.)

    Cetus rising

    Now at naked-eye visibility, Mira in Cetus climbs the eastern sky in late evening — in this case, over hills in Iran.

    Babak A. Tafreshi


    Saturday, October 30

  • The tiny black shadows of both Europa and Ganymede fall on Jupiter's face from 9:16 to 11:59 p.m. Pacific Daylight Time.
  • Mira, the brightest long-period red variable star, should soon be starting to fade from the unusually bright maximum it's been having. As of October 27th observers were still reporting it at about magnitude 3.0, obvious to the unaided eye. Mira is up in good view in the east-southeast by 9 or 10 p.m. daylight saving time. A comparison-star chart is in the September Sky & Telescope, page 58.

    Sunday, October 31

  • Halloween evening this year is moonless, with brilliant Jupiter lording it over the southern sky.

    Comet Hartley 2, big and round but very dim, crosses the feet of Gemini early this week rapidly heading south. Click image for larger map.

    Sky & Telescope diagram


    Monday, November 1

  • Periodic Comet Hartley 2 is once again becoming visible in a more-or-less moonlight-free morning sky. This week the comet crosses from Gemini into Canis Minor, as shown at right (larger chart). That means the time to observe is before the first light of dawn at your location. The comet is fading now as it starts moving away from both Earth and Sun; see predicted light curve (scroll to bottom). Read more in our article Encounters with Comet Hartley 2.
  • The long-lasting Taurid meteor shower runs throughout the first half of November or longer. Taurids are few in number but sometimes unusually bright, traveling slowly away from the direction of Taurus. The shower is active in the evening as well as the early-morning hours.

    Tuesday, November 2

  • Will there be a "Hartley-id" meteor shower this evening or tomorrow evening? We'll only find out by watching! If there is, the shower's radiant will be in Cygnus — high overhead in early evening. See NASA article.
  • By mid-evening, bright Capella is shining well up in the northeast. Look off to its right, in the east, for the little Pleiades star cluster — and, below the Pleiades by about a fist-width at arm's length, the orange giant star Aldebaran.

    Early risers can catch the waning crescent Moon guiding the way to Saturn, Spica, and Venus as dawn grows bright. bring binoculars; the visibility of objects in bright twilight is exaggerated here. The blue 10° scale is about the size of your fist held at arm's length.(These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date.)

    Sky & Telescope diagram


    Wednesday, November 3

  • During dawn Thursday morning, spot Venus very low in the east-southeast starting about a half hour before your local sunrise time. The waning crescent Moon is about a fist-width at arm's length to Venus's upper right. Use binoculars to pick out Saturn and Spica too, as shown at right.

    Thursday, November 4

  • This morning is when NASA's EPOXI mission flies within about 450 miles of the nucleus of Comet Hartley 2, taking pictures all the way. The best resolution should be just 7 meters per pixel on the nucleus's landscape. Full details. Watch the coverage on NASA TV.
  • During dawn Friday morning, skywatchers in North America can use binoculars to try spotting an extremely thin waning crescent Moon. Look 2° to 5° below and perhaps a bit left of Venus, very low in the east-southeast, starting about 20 minutes before your sunrise time.

    Friday, November 5

  • By 11 p.m. this week, Orion is sparkling in the east-southeast, with Aldebaran and the Pleiades high above it.

    Saturday, November 6

  • Vega is still the brightest star shining high in the west these evenings. The brightest star above Vega is Deneb, marking the head of the Northern Cross — the brightest part of the constellation Cygnus.
  • New Moon (exact at 12:52 a.m. on this date Eastern Daylight Time).
  • If you're on daylight-saving time in North America, clocks "fall back" an hour to standard time at 2 a.m. Sunday morning.


    Sky at a Glance is now an iPhone app! Put S&T SkyWeek on your iPhone, iPad, or iPod Touch and get the above listings anytime, anywhere — with interactive sky maps! Tap a button to see the scene described, customized for your location worldwide. From there you can scroll the view all around the sky, zoom in or out, change to any time or date, and turn on animation! Go to Apple's iTunes store from your device and buy S&T SkyWeek — for just 99 cents!

    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).

    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 must have a detailed, large-scale sky atlas (set of charts). The standards are the     Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper Uranometria 2000.0 (stars to magnitude 9.75). And read how to use your charts effectively.

    You'll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.

    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."

    This Week's Planet Roundup

    Mercury and Venus are still deep in the glow of the Sun. Late in the week Venus begins emerging into view very low in the east-southeast in bright dawn, as shown above.

    Mars, dim at magnitude +1.4, continues to linger very low in the southwest after sunset. Use binoculars to scan for it early in twilight. Look also for fainter Antares twinkling to Mercury's left or lower left.

    Jupiter on Nov. 3, 2010

    The non-Red-Spot side of Jupiter is interesting too, as seen in this image taken at 11:35 UT November 3rd. South is up. The South Equatorial Belt is still missing. The North Temperate Belt remains broad and dark with diagonal disturbances. Below it, is the North Temperate Belt broken into pieces, or are we seeing lots of red-brown "barges" merging together?

    Don't expect an eyepiece view this sharp and steady any telescope, no matter how big! Planetary imager Christopher Go continues to demonstrate the extraordinary power of stacked-video imaging done with years of experience.

    Christopher Go


    Jupiter (magnitude –2.8, at the Pisces-Aquarius border) shines high in the southeast to south during evening. It's by far the brightest starlike point in the sky. In a telescope it's still a big 47 arcseconds wide.

    Jupiter's Great Red Spot is near System II longitude 157°. Assuming it stays there, here's a list to print out of all the Great Red Spot's predicted transit times for the rest of this observing season.

    Saturn (magnitude +0.9, in Virgo) is low in the east-southeast in early dawn. Don't confuse it with brighter Arcturus far to its left. The best time to try observing Saturn with a telescope is in moderately bright morning twilight, perhaps an hour before your local sunrise time, when the planet will be less blurred by the low-altitude atmospheric mess. Saturn's rings have widened to 8° from edge-on.

    Uranus (magnitude 5.8) is 3° east of Jupiter.

    Neptune (magnitude 7.9, in Capricornus) is highest in the south in early evening. See our finder charts for Uranus and Neptune online, or with article in the September Sky & Telescope, page 56. Can you see any color in Uranus and/or Neptune?

    Pluto (magnitude 14.0, in Sagittarius) is disappearing in the 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 Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.

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