This Week's Sky at a Glance
Some daily events in the changing sky for September 2 10
Supernova in M101. The Type Ia supernova in M101 off the Big Dipper's handle seems to have reached its peak. Supernova 2011fe was discovered on August 24th at magnitude 17.2, reached 13.8 on the 25th and 11.6 on the 29th. By then it was easier to see than the galaxy itself in amateur telescopes through suburban light pollution. By the evening of September 7th it was about magnitude 10.0 and almost ceasing to brighten.
Judge its brightness using the comparison-star charts you can generate courtesy of the American Association of Variable Star Observers (AAVSO).
A normal Type Ia supernova at M101's distance, 23 million light-years, would reach magnitude 10.0 at its peak, assuming none of its light is lost to interstellar absorption in M101 itself. It's well within visual reach in a 4-inch scope. You'll be using the supernova to find the galaxy, not the other way around! Especially with moonlight now returning. See our article, Supernova Erupts in M101.
Friday, Sept. 2
Saturday, Sept. 3
Sunday, Sept. 4
Monday, Sept. 5
Tuesday, Sept. 6
Wednesday, Sept. 7
Thursday, Sept. 8
Friday, Sept. 9
Saturday, Sept. 10
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 sky charts effectively.
You'll also want a good deep-sky guidebook, such as Sue French's new Deep-Sky Wonders collection, Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger 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 having a good dawn apparition, brightening from magnitude 0.2 to 0.9 this week. Look for it low in the east-northeast about an hour before sunrise. It's far below Mars, Castor, and Pollux.
(To find your local time of sunrise, you can use our online almanac for your location. If you're on daylight saving time, make sure the Daylight Saving Time box is checked.)
Venus is hidden in the glare of the Sun.
Mars (magnitude +1.4, crossing Gemini) rises around 2 a.m. daylight saving time. By the beginning of dawn it's in good view well up in the east, to the right or lower right of Castor and Pollux. In a telescope Mars is a tiny blob only 4.7 arcseconds in diameter.
Jupiter (magnitude 2.6, in southern Aries) rises in the east-northeast around 10 p.m. daylight saving time. Look above it for the stars of Aries and (once Jupiter is well up) closer below it for the head of Cetus, rather dim. Jupiter shines highest in the south before dawn, making this the best time to examine it with a telescope. It's a big 45 arcseconds wide.
Saturn (magnitude +0.9) is disappearing into the sunset. Look for it low above the western horizon as twilight fades, far below Arcturus. Left of Saturn by 10° twinkles Spica. Binoculars help.
Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.8, in Aquarius) are well placed in the south and southeast before midnight. Use our printable finder chart for both.
Pluto (magnitude 14.0, in northern Sagittarius) is 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.
NEW BOOK: Sue French's DEEP-SKY WONDERS! This long-awaited observing guide by Sky & Telescope's own Sue French is now available for pre-order from Shop at Sky. This lavishly illustrated book contains Sue’s 100 favorite sky tours (25 per season) from her 11 years of writing the Celestial Sampler and Deep-Sky Wonders columns for S&T. Pre-order now, and your book will ship on September 26th. Don’t miss it!
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