Sky at a Glance | October 26th, 2007

Some daily events in the changing sky for October 26 – November 3.

Naked-eye comet over Tehran
On the evening of October 24th, through bright moonlight and light pollution over Tehran, Iran, Babak Tafreshi took this wide-field panorama. "This is unbelievable!" he writes. "I was amazed to find Comet Holmes so easily with the naked eye in the light-polluted skies." Click image for full view.
Babak Tafreshi
Naked-eye Outburst of Comet Holmes. On Wednesday October 24th, faint little Periodic Comet Holmes (17P) underwent a gigantic outburst to shine as bright as magnitude 2.5, easily visible to the unaided eye. That day the ejection of gas and dust was still so close to the comet's nucleus as to appear starlike, as if this were a nova. Within the next day the cloud was beginning to enlarge visibly, at least in telescopes.

Comet Holmes is in Perseus, excellently placed high in the northeast in late evening. This is an extraordinary event not to be missed! Full story.

Friday, October 26

  • Halloween is approaching, and this means that Arcturus, the star sparkling low in the west-northwest in twilight this week, is taking on its role as "the Ghost of Summer Suns." What does that mean? Every year around October 29th, Arcturus occupies a special place in your local sky. It closely marks the spot above your horizon where the Sun stood at the same time (according to your watch) during June and July, back when it was broad daylight at this hour. So when you see Arcturus at this season of the year, you can think of it as the Halloween ghost of the departed summer Sun.

    Saturday, October 27

  • The Moon occults the northern edge of the Pleiades for northeastern North America in early evening (see the October Sky & Telescope, page 70) and for Europe later in the night.

    Sunday, October 28

  • Venus is at greatest elongation, 46° west of the Sun in the dawn.

    Monday, October 29

  • Bright Mars shines below the waning Moon once they rise late this evening.

    Tuesday, October 30

  • Mars is now upper right of the waning Moon in late evening, as shown below.

    Wednesday, October 31

  • While you're out using binoculars on Comet Holmes in Perseus. . . did you know there's a third star cluster close to the Perseus Double cluster? It's not obvious, but once you're familiar with it, you'll always recognize it. See Gary Seronik's "Binocular Highlight" in the November Sky & Telescope, page 54.

    Thursday, November 1

  • Last-quarter Moon (exact at 5:18 p.m. Eastern Daylight Time).

    Friday, November 2

  • The waning Moon occults (covers) the 1st-magnitude star Regulus before or during dawn — or even in broad daylight — on Saturday morning across the southern and western US, the Caribbean, Mexico, and Central America. The star's disappearance happens on the Moon's bright edge, so you'll need a telescope to watch it even if the event happens in darkness for your location. See the article and maps on page 70 of the November Sky & Telescope.

    Saturday, November 3

  • Daylight saving time ends at 2 a.m. Sunday morning. Now, starry nights will really start coming early. And be sure to make the appropriate change in your local settings for our online almanac (uncheck the Daylight Saving Time box).

    Looking east-northeast in very late evening
    For the second time this month, the waning Moon shines with Mars late at night. But this time Mars is brighter, and they're up nearly two hours earlier. (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. 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 somewhat 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

    Vic
    Sky & Telescope
    Mercury is only about magnitude +1 when it emerges into view late this week, very low in the glow of sunrise. Using binoculars, look for it about 30 minutes before sunrise just above the east horizon, very far lower left of bright Venus. Spica glimmers a little to Mercury's right or upper right. On what date will you see them first?

    To find your local sunrise time (and much else), make sure you've put your location into our online almanac. If you are on daylight saving time, make sure the Daylight Saving Time box is checked.

    Venus (magnitude –4.5, in eastern Leo) blazes high in the east before and during dawn. Well above it now, and a bit right, are much fainter Saturn and (even higher) Regulus. A telescope shows that Venus is reaching dichotomy, its half-lit phase.

    Vic
    Sky & Telescope
    Mars (magnitude –0.6, in Gemini) now rises as early as 9:30 p.m. daylight saving time. It shines very high toward the south before dawn — near the zenith, in fact, for mid-northern observers.

    In a telescope, Mars appears 12 arcseconds in diameter. It will reach 15.9" diameter around its Christmas-season opposition. The Martian dust storms of July and August have abated, and while the planet's atmosphere is still bright and hazy with dust, surface features are showing through better. But they're still low-contrast.

    Jupiter (magnitude –1.9, in southern Ophiuchus) is sinking low in the southwest in twilight. It sets soon after dark.

    Saturn (magnitude +0.8) is the brightest "star" above brilliant Venus in the dawn. Fainter Regulus (magnitude +1.4) is there too, upper right of Saturn.

    Uranus (magnitude 5.8, in Aquarius) and Neptune (magnitude 7.9, in Capricornus) are well placed in the south during early evening. Finder charts for them are in the July Sky & Telescope, page 60, and online. With a big scope you can shoot for their faint moons! See the October Sky & Telescope, page 69.

    Vic
    Sky & Telescope
    Pluto (magnitude 14.0 in Sagittarius, above Jupiter) is disappearing into the sunset.

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

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