This Week's Sky at a Glance

Some daily events in the changing sky for October 17 – November 25.

All week, Venus is getting higher and easier to spot after sunset. Look for Antares, much fainter, moving in toward Venus from the left. Binoculars will help.

Friday, October 17

Venus is starting to come into its own as the "Evening Star" low in the sunset, as shown at right. It outshines Antares, the brightest real star in its vicinity, by a factor of 100 (five magnitudes).

From now through late October, little Mercury has its best dawn apparition of 2008 for skywatchers at mid-northern latitudes. Look for it low in the east far below Saturn as dawn brightens, as shown below.

Saturday, October 18

Right around nightfall at this time of year, you'll find Arcturus sparkling low in the west-northwest at the same height above the horizon as Capella is sparkling low in the northeast. Arcturus is sinking lower, and Capella is rising higher. How accurately can you time when they're at exactly the same altitude? (The time will vary depending on where you are in your time zone.)

Sunday, October 19

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 10:25 p.m. EDT. Algol takes several additional hours to fade and to rebrighten.

Mercury is up before sunrise and brightening day by day. Look for it low in the dawn, far below Saturn.

Jupiter's moon Europa reappears out of eclipse by Jupiter's shadow around 10:43 p.m. Pacific Daylight Time, just east of the planet.

Monday, October 20

The annual Orionid meteor shower should be at its peak between midnight and dawn for the next few mornings, but the waning Moon will brighten the sky. You may see a dozen or so meteors per hour of steady watching before dawn.

Tuesday, October 21

Last-quarter Moon (exact at 7:55 a.m. EDT).

Wednesday, October 22

Mercury is at greatest elongation, 18° west of the Sun in the dawn sky.

Algol should be at minimum light for a couple hours centered on 7:14 p.m. EDT.

Thursday, October 23

Jupiter's inner moon Io casts its tiny black shadow onto the planet's face from 8:42 to 10:57 p.m. EDT.

Watch the Moon waning from morning to morning is it passes Saturn and, later, low Mercury. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. For clarity, the Moon is shown three times actual size.)

Tomorrow morning as dawn begins to brighten, the Moon hangs upper right of Saturn (and below Regulus). Use them to guide your way down to Mercury, as shown at right.

Friday, October 24

During dawn tomorrow, look for Saturn to the upper left of the Moon, as shown here.

Saturday, October 25

Venus is passing 3½ from Antares at dusk. See the illustration under "Venus" below.

During dawn tomorrow, Saturn, the Moon, and Mercury form a tall tableau in the eastern sky.

This Week's Sky at a Glance

Some daily events in the changing sky for October 10 – 18.

All week, Venus is getting higher and easier to spot after sunset. Look for Antares, much fainter, moving in toward Venus from the left. Binoculars will help.

Friday, October 10

The red long-period variable star W Lyrae should be about at its peak brightness (8th magnitude) this week. Follow its doings with binoculars or a small telescope and the star chart.

Saturday, October 11

For western-U.S. observers, Jupiter's moon Ganymede disappears into eclipse by Jupiter's shadow around 9:39 p.m. Pacific Daylight Time. A small telescope will show it gradually fading away a little east of the planet.

Sunday, October 12

The Dumbbell Nebula, M27, is the brightest planetary nebula in the sky as seen in most instruments. Binoculars usually show it fairly easily.

Monday, October 13

Shortly after dark at this time of year, Deneb crosses nearly straight overhead (for skywatchers at mid-northern latitudes). West of Deneb shines brighter Vega.

Tuesday, October 14

Full Hunter's Moon (exact at 4:02 p.m. EDT).

Wednesday, October 15

The large asteroid 2 Pallas, magnitude 7.3, is 17 arcminutes east of the 2.8-magnitude star Beta Leporis during the predawn hours Thursday morning. At high power, watch for its very gradual motion with respect to the background stars.

Thursday, October 16

Early Friday morning, telescope users in western North America can watch the waning gibbous Moon crossing the Pleiades. Stars will disappear on the Moon's bright limb and reappear from behind its narrow dark limb. Of the six brightest Pleiads, only Maia gets occulted for most viewers. Local predictions.

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 1:37 a.m. Friday morning EDT; 10:37 p.m. Thursday evening PDT. Algol takes several additional hours to fade and to rebrighten.

Mercury is brightening day by day. Look for it low in the dawn far below Saturn.

Friday, October 17

For the next two weeks, little Mercury has its best dawn apparition of 2008 for skywatchers at mid-northern latitudes. Look for it low above the horizon due east (far below Saturn) as dawn brightens.

Saturday, October 18

Right around nightfall at this time of year, you'll find Arcturus sparkling low in the west-northwest — at the same height above the horizon as Capella is sparkling low in the northeast. Arcturus is sinking lower, and Capella is rising higher. How accurately can you time when they're at exactly the same altitude? (The time will vary depending on where you are in your time zone.)

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