Some daily events in the changing sky for February 15 – 23.
Friday, February 15
Saturday, February 16
Sunday, February 17
Monday, February 18
Tuesday, February 19
Wednesday, February 20
And take advantage of the dark sky during the total eclipse to have a look for Comet Holmes, very big but very dim, as described at the bottom of this page.
Thursday, February 21
At any random time you glance up at Algol, you have a 1-in-30 chance of catching it at least 1 magnitude fainter than normal.
Friday, February 22
Saturday, February 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 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 increasingly 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
Mercury is emerging from deep in the glow of sunrise. Late in the week, use binoculars to look for it a little left of bright Venus.
Venus (magnitude –3.9, moving from Sagittarius into Capricornus) is getting lower every morning. Look for it above the southeast horizon about 30 or 40 minutes before sunrise, well to the lower left of Jupiter.
Mars (about magnitude –0.1, in eastern Taurus) shines very high in the south during evening, high above Orion. The fairly bright star near it is Beta (β) Tauri, or El Nath, magnitude +1.6 and pale blue-white. In a telescope, Mars dwindles from 10.4 to 9.6 arcseconds in apparent diameter this week. See the observing guide and surface-feature map in the November Sky & Telescope, page 66, or the short version online.
Jupiter (magnitude –2.0, in Sagittarius) shines low in the southeast before and during dawn. It's moving ever farther to the upper right of Venus.
Saturn (magnitude +0.3, in Leo) comes to opposition on the night of the 23rd. It glows low in the east as twilight fades, rises higher all evening, and stands highest in the south around midnight. Fainter Regulus (magnitude +1.4) is 6° west of Saturn: to its upper right after they rise. Only a little dimmer than Regulus is Gamma (γ) Leonis (magnitude +2.1), located 8° to Regulus's north. The three make an eye-catching triangle.
In a telescope, watch this week for the Seeliger effect, a brightening of Saturn's rings for several days around oppposition. The reason for this? The ice particles making up the rings "backscatter" sunlight (reflect it back the way it came) more efficiently than the material in Saturn's cloud tops. When Saturn is at opposition, Earth is in the line of backscattering. A daily series of images will show this particularly well.
Uranus and Neptune are hidden in the glare of the Sun.
Pluto (magnitude 14.0, in Sagittarius) is low in the southeast before the first light of dawn.
Comet Holmes continues to grow ever bigger and dimmer. At the Winter Star Party in the dark Florida Keys, says Sean Walker, "Comet Holmes was still naked eye, but only just — it was an averted-vision object as of February 7th. Ghostly through 8x50 binoculars." On February 11th through suburban light pollution, Dennis di Cicco could not see it with the naked eye at all when he took the picture at right. The comet is between the feet of Perseus; chart.
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 Standard Time (EST) equals Universal Time (UT, UTC, or GMT) minus 5 hours.
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