Astronomy - The Sky This Week for November 18 to 27

A globular star cluster, the Summer and Winter triangles visible, and other beautiful things to look for in the sky this week.

This image shows the center of the globular cluster Messier 22, also known as M22, as observed by the NASA/ESA Hubble Space Telescope

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Friday, November 18

Brilliant Venus stands out in the southwest during early evening. The planet lies 15° above the horizon a half-hour after sunset and doesn’t set until 7 p.m. local time, well after twilight comes to a close. At magnitude –4.1, Venus is the brightest object on view. Under a clear, dark sky this evening, binoculars will show you the 5th-magnitude globular star cluster M22 just 1.6° north of the planet. A telescope also reveals the planet’s 16"-diameter disk, which appears about three-quarters lit.

Saturday, November 19

Neptune’s westward motion against the background stars comes to a halt tonight (officially at 5 a.m. EST on the 20th). The distant planet appears highest in the south at the end of evening twilight and doesn’t set until shortly after midnight. The magnitude 7.9 world lies in Aquarius, 2.6° southwest of the 4th-magnitude star Lambda (l) Aquarii. (Don’t confuse the planet with a 7th-magnitude star that lies 0.7° to its north.) You’ll need binoculars to spy Neptune and a telescope to see its blue-gray disk, which spans 2.3".

Sunday, November 20

The Moon rises in the eastern sky just before 11:30 p.m. local time this evening (the exact clock time depends on how far east or west you live in your time zone). Our satellite reaches Last Quarter phase early tomorrow morning, at 3:33 a.m. EST, and it appears half-lit from the time it rises until it climbs highest in the south shortly before dawn. The Moon lies among the background stars of Leo, less than 2° south of 1st-magnitude Regulus, the Lion’s brightest star.

An artist's rendering of Jupiter and its four moons.

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Monday, November 21

Mars continues to put on a nice show these November evenings. The magnitude 0.6 Red Planet lies among the background stars of Capricornus and appears nearly 30° high in the south-southwest after darkness falls. A telescope reveals the world’s 7"-diameter disk, though you’ll be hard-pressed to see much surface detail except under exceptional viewing conditions.

Tuesday, November 22

Uranus reached opposition more than a month ago, but it remains a tempting target. The outer planet appears in the southeast after darkness falls and climbs highest in the south around 9 p.m. local time. The magnitude 5.7 world lies in southern Pisces just 1.1° due east of the 5th-magnitude star Zeta (z) Piscium. Although Uranus shines brightly enough to glimpse with the naked eye under a dark sky, binoculars make the task much easier. A telescope reveals the planet’s blue-green disk, which spans 3.7".

Wednesday, November 23

Although the Leonid meteor shower peaked before dawn November 17, observing conditions have improved significantly since then. The gibbous Moon of last week has now waned to a crescent that doesn’t interfere much with viewing a few last-minute stragglers. To tell a Leonid meteor from a sporadic, trace the shooting star’s path backward. If it points toward the constellation Leo the Lion, it likely is a shower member.

Thursday, November 24

While Venus dominates the evening sky, Jupiter rules the predawn hours. The giant planet rises four hours before the Sun and climbs 25° high in the southeast by the time twilight starts to paint the sky. Jupiter shines brilliantly at magnitude –1.8 and shows a 32"-diameter disk when viewed through a telescope. A small scope also reveals an unusual alignment of the planet’s moons this morning. Callisto, the outermost major satellite, passes due north of Jupiter. For North American observers, this is the first time in 3.5 years that Callisto’s orbit has not carried the moon in front of the planet.

The Big Dipper constellation

Flickr/ christianreimer

Friday, November 25

The variable star Algol in Perseus appears faintest at 12:13 a.m. EST tomorrow morning, when it shines at magnitude 3.4. If you start watching it immediately after darkness falls, you can see it dim from its peak brightness (magnitude 2.1) to minimum and then rise back to maximum all in a single night. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days, but the drop from peak brightness and subsequent rise lasts only about 10 hours. Algol appears in the east-northeast after sunset and passes nearly overhead around 11 p.m. local time. 

Saturday, November 26

Although Thanksgiving weekend signifies autumn to many people, the stars of both summer and winter appear prominent in late November’s evening sky. If you head out around 9 p.m. local time and look toward the west, you’ll see the bright stars of the Summer Triangle. These three luminaries — Vega, Deneb, and Altair — stand out nicely against the fainter stars in their vicinity. Deneb appears highest (nearly halfway to the zenith), while the brightest, Vega, lies farthest to the right. Now, if you turn around and face east, you’ll find stars normally associated with winter. Betelgeuse, Rigel, Aldebaran, and Capella all clear the horizon before 8 p.m. and appear conspicuous an hour later.

Sunday, November 27

While the stars of summer and winter remain on view on late November evenings, the stars of spring are not so lucky. The Big Dipper swings low in the north at this time of year. Although this conspicuous asterism never sets from much of the United States and Canada, it does come close. And the star at the end of the handle — magnitude 1.9 Eta (h) Ursae Majoris — does dip below the horizon around 9 p.m. local time for viewers south of 40° north latitude.

The Moon reaches apogee, the farthest point in its orbit around Earth, at 3:08 p.m. EST. It then lies 252,621 miles (406,554 kilometers) from Earth’s center.