Periodic Comet Hartley 2 is at its best early this week — before moonlight becomes a problem late in the week. At 6th magnitude the comet is visible in binoculars in a moderately dark sky, well placed in the evening high in Perseus. It has a small central condensation and a large, dim coma. As a result of this, what you'll see of it depends strongly on the quality of your sky; in the last few days different observers have reported the comet as anywhere from magnitude 5.3 to 7.2 overall. Use the finder chart below, and see our article.
Friday, October 8
Saturday, October 9
Sunday, October 10
In twilight, look for twinkly little Antares upper left of the crescent Moon low in the southwest, as shown here. Binoculars help.
Monday, October 11
Tuesday, October 12
Wednesday, October 13
Thursday, October 14
Update Thursday morning: David Dunham writes: "The star is b Persei (small "b", NOT beta; after Greek letters ran out, Bayer used small Roman letters) or SAO 24531, spectral type A2, a tight spectroscopic binary with a period of only 1.527 days; it is an elliptical variable, and radio flaring has been observed, indicating that there is probably active mass exchange between the components....
"In spite of the visible coma, the area around comets is an almost perfect vacuum; you have little chance to detect any dimming of the star's light, with the odds being not much better than finding a satellite of an asteroid, unless you are within perhaps 40 km of having an occultation by the nucleus. One of the few occultations by a comet ever observed was seen by Richard Nolthenius when IRAS-Araki-Alcock occulted an 8th-mag. star.... He saw the star fade, then brighten again over a period of less than a second, as I remember. Many have tried to look for dimmings during predicted close appulses by comets with almost no success...."
Friday, October 15
Saturday, October 16
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 in the glare of the Sun.
Venus, though bright at magnitude –4.6, is approaching inferior conjunction with the Sun. Even early in the week, it's barely above the west-southwest horizon just 10 or 15 minutes after sunset. Sweep for it with binoculars.
In a telescope, however, Venus is taking on its most interesting form: a lengthening, thinning crescent. The time to view it in a telescope is in daylight long before sunset — but don't accidentally sweep up the Sun! In mid-afternoon, place your scope in the shadow of a building or other obstacle where you have a clear view of the sky 28° to 21° to the Sun's left, while the Sun will remain hidden.
Mars, way dimmer at magnitude +1.5, continues to linger low in the southwest after sunset (7° to 10° above Venus). You'll need those binoculars.
Jupiter (still a brilliant magnitude –2.9, at the Pisces-Aquarius border) shines low 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 or midnight daylight saving time.
Jupiter is having an unusually close apparition; it continues to appear 49 arcseconds wide. (In fact its opposition three weeks ago was closer than any other of Jupiter from 1963 to 2022, though only 1% or 2% closer than in any year when opposition occurs from mid-August through October, including last year and next. See article.)
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 (times and dates in UT) for the rest of this observing season.
Saturn is deep in the glow of sunrise.
Uranus (magnitude 5.7) is 2° to 2½° east of Jupiter this week.
Neptune (magnitude 7.8, at the Aquarius-Capricornus border) 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 northwestern Sagittarius) remains in the south-southwest right 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.
To be sure to get the current Sky at a Glance, bookmark this URL:
If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of the URL to any other character and try again.