天使之路写真视频:This Week's Sky at a Glance for November 11 – 19

This Week's Sky at a Glance
Some daily events in the changing sky for November 11 – 19
by Alan M. MacRobert
Use binoculars to try for this lineup not long after sunset. The visibility of objects in bright twilight is exaggerated here.
Sky & Telescope diagram
Friday, Nov. 11 Spot Venus low in the southwest in bright twilight, and then little Mercury 2° beneath it. Use binoculars to try for twinkly Antares, even fainter, below Mercury as shown here.
Much easier: binoculars show the Pleiades above the bright waning gibbous Moon in the east after dark. Below the Moon, Aldebaran sparkles orange.
Saturday, Nov. 12
Jupiter's satellite Io crosses Jupiter's face from 8:15 to 10:24 p.m. EST, followed by Io's tiny black shadow (easier to see in a telescope) from 8:39 to 10:49 p.m. EST. Meanwhile, Jupiter's Great Red Spot transits the planet's central meridian around 8:21 p.m. EST. (For listings of all Red Spot transits and events among Jupiter's moons this month, visible worldwide, see "The Jupiter Watch" in theNovember Sky & Telescope, page 54.)
Sunday, Nov. 13
The Great Andromeda Galaxy, M31, crosses near your zenith in mid-evening if you're in the mid-northern latitudes. The exact time (sometime around 9 p.m. this week) depends on how far east or west you are in your time zone. Lie on the ground with binoculars, look straight up, and examine the sky just off Andromeda's upraised knee for a dim little elongated glow among the pinpoint stars.
To piece out the Andromeda constellation, use the monthly evening sky map in the center ofSky & Telescope. Or, the galaxy is just below the "E" in "Andromeda" on the chart farther below.
Io reappears from eclipse out of Jupiter's shadow around 8:08 p.m. Eastern Standard Time. With a small telescope, you can watch it gradually swell into view just off Jupiter's eastern limb.
Monday, Nov. 14
The two brightest points on the eastern side of the sky are Jupiter, high in the southeast, and Capella, in the northeast. Find the midpoint between them, and look just below that for the little Pleiades star cluster. The Pleiades are the size of your fingertip at arm's length.
Ganymede, Jupiter's biggest moon, crosses the face of the planet from 7:13 to 8:46 p.m. EST. Then Ganymede's tiny black shadow, easier to see, crosses the planet from 8:50 to 10:45 p.m. EST.
Tuesday, Nov. 15
The two brightest stars in the November evening sky are Vega in the west-northwest and Capella in the northeast. Sometime around 8 p.m. tonight, depending on your location, they will be at precisely the same height. How accurately can you time this event? Welcome to medieval astronomy.
Wednesday, Nov. 16
All star atlases show the loose open cluster M39 in Cygnus, which is high in the west these evenings. But what about the "finger of darkness" nearby: the long dark nebula Barnard 168? "Under good (though not pristine) skies," writes Gary Seronik, even his image-stabilized 10×30 binoculars "suffice to show the dark nebula quite well." It's east of M39, about 3° long, and runs east-west. See his Binocular Highlights column and chart in theNovember Sky & Telescope, page 45.
Thursday, Nov. 17
The bright eclipsing variable star Algol should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:13 p.m. EST (7:13 p.m. PST). Algol takes several additional hours to fade and to rebrighten. The chart below gives the magnitudes of three stars near Algol. Memorize them, and you can use them forever after to judge Algol's changing brightness.
Algol (Beta Persei) was the first eclipsing variable star discovered. Good comparison stars are Gamma Andromedae to its west, magnitude 2.1, and Epsilon Persei to its east, magnitude 2.9.
Sky & Telescope diagram
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The modest Leonid meteor shower should be most active in the hours before dawn Friday morning. Last-quarter moonlight will interfere somewhat.
Friday, Nov. 18
Last-quarter Moon (exact at 10:09 a.m. EST). The Moon shines near Mars and Regulus this morning and tomorrow morning.
Saturday, Nov. 19
Jupiter's moon Io crosses the face of the planet tonight from 10:00 p.m. to 12:09 a.m. EST, with its tiny black shadow following 34 minutes behind. (Subtract 3 hours to get PST.)