This Week’s Sky at a Glance, November 20 – 28 – Sky & Telescope


■ Whenever Fomalhaut, the Autumn Star, is “southing” (crossing the meridian due south, which it does around 7 p.m. this week), the first stars of Orion are just about to rise above the east horizon in the world’s mid-northern latitudes. And, the Pointers of the Big Dipper stand upright low due north, straight below Polaris.

From then, it takes Orion’s figure about an hour and a half to completely clear the horizon.


■ First-quarter Moon (exact at 11:45 p.m.). The Moon shines between dim Aquarius and Capricornus. Look to its lower left for Fomalhaut.

■ The bowl of the Little Dipper is descending in the evening at this time of year, left or lower left of Polaris. By about 11 p.m. it hangs straight down from Polaris.

■ As dawn brightens on Sunday morning the 22nd, Mercury is still nicely visible in the east-southeast. Look for it lower left of Venus as shown below. Day by day it will descend toward the dawn horizon and out of sight.

Mercury is still in good view as dawn brightens if you have a low view to the east-southeast. The 3rd-magnitude star about 1° to Mercury’s right (use binoculars!) is Alpha Librae. Look too for Beta Librae farther off to the left. The visibility of the faint objects in bright twilight is greatly exaggerated here. Even Mercury, and then Venus, become difficult as day approaches.


■ Today we’re two thirds of the way through fall, so Capella shines in the northeast as soon as the stars come out. As night grows dark, look to Capella’s right by about three fists at arm’s length for the frosty little Pleiades cluster, the size of your fingertip at arm’s length.


■ Two faint fuzzies naked-eye: The Andromeda Galaxy (M31) and the Perseus Double Cluster are two of the most famous deep-sky objects. They’re both cataloged as 4th magnitude, and in a fairly good sky you can see each with the unaided eye. Binoculars make them easier. They’re only 22° apart, very high toward the east early these evenings — to the right of Cassiopeia and closer below Cassiopeia, respectively.

But they look rather different, the more so the darker your sky. See for yourself. You can find them with the all-sky constellation map in the center of the November or December Sky & Telescope.


■ Mars shines about a fist-width to the upper left of the waxing gibbous Moon this evening, as shown below. Mars has lost two thirds of the brightness it displayed around opposition in early October. But at magnitude –1.4 it’s still as bright as Sirius, which will be up and shining low in the southeast after midnight. At that time, Mars will be very high in the southwest.

The waning gibbous Moon passes 5° below Mars on Wednesday the 25th. The Moon here is drawn about three times its actual apparent size.

■ Around 8 p.m. the Great Square of Pegasus stands level very high toward the south (straight overhead if you’re as far south as Miami). Its right (western) edge points very far down toward Fomalhaut. Its eastern edge points less directly toward Beta Ceti, less far down.

Now descending farther: If you have a very good view down to the south horizon, and if you’re not much farther north than latitude 40° (roughly Denver, New York, or Madrid), picture an equilateral triangle with Fomalhaut and Beta Ceti as its top two corners. Near where the third corner would be (a bit to the right of that point) is Alpha Phoenicis, or Ankaa, in the constellation Phoenix. It’s magnitude 2.4, not very bright but the brightest thing in its area. It has a yellow-orange tint; binoculars help confirm this. Have you seen anything of the constellation Phoenix before?


■ Mars shines about 5° above the waxing gibbous Moon high in the southeast in early evening, as shown above. These are currently the two closest large celestial bodies, 1.3 light-seconds and 5 light-minutes away. Next is the Sun at 8.3 light-minutes. Mercury and Venus are both currently on the far side of the Sun.


The early Thanksgiving sunset. Does the Sun already seem to be setting about as early as it ever will? You’re right! We’re still nearly a month away from the winter solstice on December 21st — but the Sun sets its earliest around December 7th if you live near latitude 40° north. And already the Sun sets within only two minutes of that time.

A surprising result of this: The Sun actually sets a trace earlier on Thanksgiving than on Christmas — even though Christmas is around solstice time!

This offset from the solstice date is balanced out by the opposite happening at sunrise: The Sun doesn’t come up its latest until January 4th. Blame the tilt of Earth’s axis and the eccentricity of Earth’s orbit.


■ Bright Jupiter and Saturn are almost as close together now (2.6° apart) as modest, 3rd-magnitude Alpha and Beta Capricorni above them (2.3° apart); see below. Wait for full dark to catch the faint stars.

Jupiter and Saturn continue in the southwest during and after twilight. This evening they’re 2.6° apart. Above them, once the sky grows dark, are the 3rd-magnitude binocular double stars Alpha and Beta Capricorni. Alpha is the wider one; maybe you can split it with your bare eyes.


■ This evening the bright, almost-full Moon shines between Aldebaran below it and the Pleiades above it. Off to their left, bright Capella looks on.


This Week’s Planet Roundup

Last week on the morning of November 13th, Gianluca Masi shot this image of Venus, the crescent Moon, Spica and low Mercury from his balcony in Rome. Click here for full view. Writes Masi, “Enjoying this really mitigated the sad feeling of these months. ‘Breathing’ the beauty, the vastness of space made my start of the day simply amazing. Of course, the Moon (with its earthshine) and Venus were shining so beautifully paired, but later Mercury joined the show.”

This week the Moon is gone, you’ll now find Spica to Venus’s upper right, and Mercury will be even lower.

Mercury (magnitude –0.7) sinks low into the glow of sunrise this week. About 45 to 30 minutes before sunrise, look for it below or lower left of bright Venus by about 15° (roughly a fist and a half at arm’s length), as shown near the top of this page. The earlier in the week the better.

Venus (magnitude –3.9, in the feet of Virgo) is also moving lower in the dawn, but it’s higher and much more obvious as the bright “Morning Star.”

Look for Spica, only 1% as bright at magnitude +1.0, increasingly far to Venus’s upper right.

Mars (about magnitude –1.3, in Pisces) shines bright yellow in the east-southeast at dusk. Above it is the Great Square of Pegasus. Mars is six weeks past opposition and shrinking into the distance but still 16 or 15 arcseconds wide in a telescope, quite big enough to show surface detail during steady seeing. The South Polar Cap has shrunk to a tiny white speck. Yellow dust storm activity has begun in the Chryse region and has since spread south.

Mars with Gomer Sinus and Gale Crater
Mars on November 2nd, imaged by Christopher Go. South is up. The great diagonal dark streak is mostly Mare Cimmerium. From its lower right part, two little dark prongs point down. The larger one is Gomer Sinus, a very good catch in large amateur telescope.

These classical names refers to the albedo (bright/dark) markings, which mostly have to do with surface dust and rock exposure. In terms of physical geography, on the other hand, the bottom of Gomer Sinus is Gale Crater, home of the Curiosity rover for the last five years.

Mars on Oct. 10, 2020
A different side of Mars. Here, Mare Cimmerium runs off the right limb, and dark Syrtis Major extends from left of center to the upper left. Between them is dark Mare Tyrrhenum. South is to the lower right. “Mars with ‘the Face,’ ” writes imager Jim Militello of Tucson, referring to the markings in the large bright region in and around Hellas between Tyrrhenum and the South Polar Cap. Militello took this image on October 9th with a 14.5-inch Starmaster scope and a Skyris video camera.

To get a map of the side of Mars facing Earth at the date and time you observe, you can use our Mars Profiler. The map there is square; remember to mentally wrap it onto the side of a globe. (Features near the map’s edges become very foreshortened.)

Jupiter and Saturn (magnitudes –2.1 and +0.6, respectively) tilt ever farther down in the southwest during and after twilight. Look early. Jupiter is the bright one; Saturn is upper left of it. Watch their separation shrink from 3.3° to 2.3° this week, from November 20th to 27th. They’ll pass 0.1° apart at conjunction on December 21st.

Don’t expect a decent view in a telescope; they’re farther and smaller than they were last summer, and the low-altitude seeing will be poor.

Uranus (magnitude 5.7, in Aries) is high in the east in early evening, about 22° east (lower left) of Mars. Uranus is only 3.7 arcseconds wide, but that’s enough to appear as a tiny fuzzy ball, not a point, at high power in even a good small telescope.

And while you’re there, find the 9th-magnitude asteroid 8 Flora about 11° away. See Bob King’s Tiny Asteroid Flora and Mighty Uranus Team Up with finder charts and more about both.

Neptune (magnitude 7.9, in Aquarius) is equally high in the south in early evening. Neptune is 2.3 arcseconds wide, harder to resolve than Uranus except in very good seeing. Check in on all three of these faint targets when you’re done with Mars. Finder charts for Uranus and Neptune.

All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world’s mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

Eastern Standard Time, EST, is Universal Time minus 5 hours. (Universal Time is also known as UT, UTC, GMT, or Z time.)

Want to become a better astronomer? Learn your way around the constellations. They’re the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy.

Once you get a telescope, to put it to good use you’ll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown here is the Jumbo Edition, which is in hard covers and enlarged for easier reading outdoors at night. Sample charts. More about the recent new editions.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And be sure to read how to use sky charts with a telescope.

You’ll also want a good deep-sky guidebook, such as Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope replace charts? Not for beginners, I don’t think, and not on mounts and tripods that are less than top-quality mechanically, meaning heavy and expensive. And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer’s Guide, “A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand.”

Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty’s monthly
podcast tour of the heavens above. It’s free.

“The dangers of not thinking clearly are much greater now than ever before. It’s not that there’s something new in our way of thinking, it’s that credulous and confused thinking can be much more lethal in ways it was never before.”
            — Carl Sagan, 1996

“Facts are stubborn things.”
            — John Adams, 1770


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