The Sky this Week

October 14–23, 2011

Your daily digest of celestial events coming soon to a sky near you. By Richard Talcott n

Friday, October 14 

Jupiter’s colorful atmosphere proves visually
stunning through a telescope of any size.
NASA/ESA/H. Hammel (SSI)/Jupiter Impact Team

Brilliant Jupiter rises around 7 p.m. local daylight time this week, while twilight still glows in the west. The giant planet climbs the eastern sky during the evening hours and appears highest in the south around 2 a.m. Shining at magnitude –2.9, Jupiter is the night’s brightest celestial object with the exception of the waning gibbous Moon, which appears about 15° from the planet this evening. When viewed through a telescope, Jupiter’s disk spans 49" and shows incredible detail in its cloud tops.

Saturday, October 15

Comet C/2009 P1 (Garradd) shines
at 7th-magnitude this week as it moves
westward through southeastern Hercules.
Astronomy: Kellie Jaeger

The waning gibbous Moon lies near the Pleiades star cluster (M45) this morning. At 4 a.m. local daylight time, the cluster stands 4° directly above the Moon. Use binoculars for the best views of this exquisite conjunction.

Sunday, October 16

Comet C/2009 P1 (Garradd) remains the sky’s brightest comet this week. The 7th-magnitude object moves westward against the background of southeastern Hercules. This evening, the comet passes a fraction of a degree due south of a similarly bright star (SAO 103110), although the pointlike star will appear brighter than the fuzzy comet. You can find this region high in the west shortly after darkness falls.

Monday, October 17

If you like observing challenges, head outside this evening without any optical aid. Uranus glows at magnitude 5.7, bright enough to glimpse with naked eyes under a dark sky. The planet reached opposition and the peak of its 2011 apparition in late September, and it remains a fine sight. Around 9 p.m. local daylight time, Uranus lies about halfway from the southeastern horizon to the zenith. To find it, start your search with Alpheratz and Algenib, the two stars that form the eastern edge of the Great Square of Pegasus. Draw an imaginary line between these two and then extend it an equal distance to the lower right. Uranus is the brightest object in this region. If you can’t see it with naked eyes, or if you live in a light-polluted area, binoculars will bring the planet into view.

Tuesday, October 18 

Asteroid Ceres glows at 8th magnitude
as it slides westward against the backdrop
of southeastern Aquarius.
Astronomy: Kellie Jaeger

Binoculars also will reveal the asteroid 1 Ceres this week as it moves slowly westward against the backdrop of southeastern Aquarius. The 8th-magnitude object lies about 1° southwest of the 5th-magnitude star 106 Aquarii, which serves as a convenient guide for finding the solar system’s largest asteroid. This region lies in the southeast after darkness falls and appears highest in the south around 11 p.m. local daylight time.

Wednesday, October 19

Last Quarter Moon occurs at 11:30 p.m. EDT. Our celestial neighbor will rise around midnight and appear almost exactly half lit. The Moon resides on the border between the constellations Gemini the Twins and Cancer the Crab.

Thursday, October 20

Around 6 a.m. local daylight time, just as twilight starts to paint the morning sky, Mars lies about halfway from horizon to zenith in the east-southeast. The Red Planet crossed from Cancer the Crab into Leo the Lion a couple of days ago and is making a beeline toward the Lion’s brightest star, Regulus. The two will have a close conjunction in November. Mars shines at magnitude 1.2 and stands out by virtue of its orange-red color.

Friday, October 21

Look low in the west-southwest early this evening and you might glimpse Venus. From 40° north latitude, the brightest planet lies just 2° above the horizon 30 minutes after sunset (from 25° north latitude, it appears 5° high). Even though it shines at magnitude –3.8, Venus will be hard to pick out of the twilight glow. If you can’t spot it with naked eyes, binoculars will help bring it into view.

Saturday, October 22 

The Orionid meteor shower
must compete with a waning crescent Moon
at its peak October 21/22.
Astronomy: Kellie Jaeger

If you’re out between midnight and dawn, you’ll likely see a number of bright streaks peppering the sky. These are Orionid meteors, which belong to an annual shower that peaks the night of October 21/22. The best views this year should come around 2 a.m. local daylight time on the 22nd, shortly before the waning crescent Moon rises. At its peak, the shower produces about 20 meteors per hour radiating from the northern part of the constellation Orion the Hunter.

Sunday, October 23

The variable star Algol in Perseus reaches minimum brightness at 3:53 a.m. EDT. If you start watching it late yesterday evening, you can see its brightness diminish by 70 percent (its magnitude drops from 2.1 to 3.4) over the course of about 5 hours. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days. Algol appears in the northeast during evening hours and passes nearly overhead around 2 a.m. local daylight time.

Quoted from Astronomy