Periodic Comet Hartley 2 remains about 6th magnitude, appearing big, round, and dim in binoculars. This week it's crossing Auriga and passing its closest to Earth (on October 20th). But moonlight is returning; the waxing Moon sets later each night. You can have a Moon-free view through about the morning of the 19th if you observe in the pre-dawn hours; find your local moonset time using our online almanac. What you'll see of the comet, if anything, depends strongly on the quality of your sky. See our article Comet Hartley 2 At Its Closest, with finder charts.
Friday, October 15
Saturday, October 16
Sunday, October 17
Monday, October 18
Tuesday, October 19
Wednesday, October 20
Thursday, October 21
Friday, October 22
Saturday, October 23
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).
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 is hidden behind the glare of the Sun.
Venus is finally disappearing deep into the sunset.
Mars, dim at magnitude +1.5, continues to linger very low in the southwest after sunset. Look for it early in twilight with binoculars. Don't confuse it with twinklier Antares, well off to its left and a trace brighter.
Jupiter (magnitude –2.8, at the Pisces-Aquarius border) shines in the east-southeast in twilight and high in the southeast by mid-evening — by far the brightest starlike point in the sky. It's highest in the south around 11 p.m. daylight saving time. Jupiter is having an unusually close apparition; in a telescope it continues to appear 48 or 49 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 emerging from the glow of sunrise. Look for it very low in the east about an hour before your local sunrise time. It's within 1° of fainter Gamma Virginis.
Uranus (magnitude 5.7) is 2½° to 3° east of Jupiter this week.
Neptune (magnitude 7.8, in Capricornus) is highest in the south after dinnertime. See our finder charts for Uranus and Neptune online or in the September Sky & Telescope, page 56. Can you see any color in Uranus and/or Neptune?
Pluto (magnitude 14.0, in Sagittarius) is sinking 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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