Friday, October 26 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? 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. The eclipsing variable star Algol in Perseus should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 1:14 a.m. Saturday morning EDT; 10:14 p.m. Friday evening PDT.
The Moon appears to pair up with Jupiter on November 1st. The Moon here is shown three times its actual apparent size, and is positioned for a viewer near the middle of North America.
Saturday, October 27 The bright Moon shines below the Great Square of Pegasus's bottom corner early this evening. From the Square's left corner extends a big, slightly downward line of three stars (including the corner). These form the backbone and leg of Andromeda.
Sunday, October 28 Plucked from obscurity to make astronomical history, the star 51 Pegasi will be known for all ages as the first Sun-like star discovered to host a planet beyond our solar system (in 1995). At 5th magnitude it's an easy binocular target next to the Great Square of Pegasus, even in moonlight. Can you spot it, and show it to others? Use the chart with Gary Seronik's Binocular Highlight column in the November Sky & Telescope, page 45.
Monday, October 29 Full Moon (exact at 3:49 p.m. Eastern Daylight Time). Look a fist-width above the Moon for the brightest stars of Aries, lined up nearly horizontally. Algol should be at minimum light for a couple hours centered on 10:03 p.m. EDT. Algol takes several additional hours to fade and to rebrighten. Jupiter's Great Red Spot (pale orange-tan) crosses Jupiter's central meridian around 11:32 p.m. Eastern Daylight Time.
Tuesday, October 30 The "Summer Star" Vega is still the brightest star in the west during fall evenings. Higher above it is Deneb. Farther off to Vega's left or lower left is Altair, the third star of the Summer Triangle.
Wednesday, October 31 The Halloween Moon, waning gibbous, rises around the end of twilight. The Pleiades are above it. Once it rises higher, Aldebaran sparkles is below it and bright Jupiter shines to its lower left, as shown here. Just after dark, the faint, slow-moving asteroid 35 Leukothea should occult a 10.6-magnitude star in Aquarius fairly high in the south for up to 39 seconds, for observers along a track from Florida through Michigan. Charts and details.
Thursday, November 1 The bright "star" above the Moon this evening is Jupiter. Although they look close together, Jupiter is 1,500 times farther away. Aldebaran, to their right, is 930,000 times more distant than Jupiter!
Friday, November 2 Once the waning gibbous Moon rises high late this evening, look lower right of it for wintry Orion making his sparkly appearance.
Saturday, November 3 Fomalhaut, the "Autumn Star," culminates (reaches its highest point due south) around 9 p.m. daylight saving time. The western side of the Great Square of Pegasus, high above, points almost down to it. Can you see any of the rest of Fomalhaut's dim host constellation Piscis Austrinus, the Southern Fish? Standard Time returns (for most of North America) at 2 a.m. tonight. Clocks "fall back" an hour.
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 guide to 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 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 the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope effectively.
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.
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 certainly not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). 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
Mercury (magnitude 0.2) is having a poor evening apparition. Using binoculars, look for it about 30 minutes after sundown very low in the southwest, to the lower right of Mars and Antares.
The Great Red Spot's side of Jupiter is busy indeed. On October 29th when Christopher Go
shot this image from the Philippines, bright orange Oval BA and the little dark red dot following it had finished passing south of (above) the Great Red Spot. Huge turbulence roils the South Equatorial Belt behind the Great Red Spot, and in the midst of this, notice the tiny dark marking next to a bright little white outbreak.
The South Temperate Belt is barely visible along some of its length but prominent elsewhere. Four white ovals dot the South South Temperate Belt. On the north (lower) side of the planet, the North Equatorial and North Temperate belts have become cleanly separated by the North Tropical Zone's return to whiteness. An extremely wide blue festoon intrudes into the bright Equatorial Zone north of the Great Red Spot.
Venus (magnitude 4.0, in Virgo) rises in darkness more than an hour before the first glimmer of dawn. By dawn it's shining brightly in the east.
Mars (magnitude +1.2, in Ophiuchus) remains low in the southwest in evening twilight. It's upper left of similar-looking Antares; they widen from 6° to 10° apart this week.
Jupiter (magnitude 2.7, in Taurus) rises in the east-northeast shortly after dark, with Aldebaran to its right. Above Aldebaran are the Pleiades.
Saturn is buried deep in the glow of sunrise.
Uranus (magnitude 5.8, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are in in good view in the south during evening. Finder charts for Uranus and Neptune.
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. Eastern Standard Time is UT minus 5 hours.
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