This Week’s Sky at a Glance, December 3 – 11


Comet Leonard (C/2021 A1) is getting into its finest week! It’s about sixth magnitude or fainter, excessive within the east earlier than the very first mild of daybreak within the neighborhood of Arcturus. The morning of December 4th finds it 9° higher left of Arcturus as seen from North America.

The comet ought to peak round fifth magnitude — nonetheless needing binoculars or a telescope or a very darkish sky (a comet is extra diffuse than a star) — round December tenth or eleventh. By then it’s going to be a lot decrease at the start of daybreak, beginning to lose its battle with morning twilight.

Online article: See Comet Leonard at its Best. But for extra detailed, useful charts given the comet’s dimness, see “Comet Leonard Races Across the Sky” within the December Sky & Telescope, web page 48; the charts there’ll allow you to pinpoint the precise location among the many stars to look at with binoculars at your time and date. (The date ticks on the comet’s observe there are for 0:00 UT, which is 7:00 p.m. on the earlier date EST.)

Update: Using 10 x 50 binoculars on the morning of December 4th by way of suburban mild air pollution, I discovered the comet with out a lot issue utilizing the chart within the journal. Seen although this relatively mediocre, all-too-ordinary sky, the comet was a delicate, diffuse glow with little or no central condensation; spherical, and with no signal of a tail. Compared to the globular cluster M3 nearly in the identical area, the comet was dimmer by greater than a magnitude, considerably bigger, and missing the cluster’s focus towards the middle. Be cautious to not confuse the 2; M3 is extra seen.

Far behind Jupiter and Saturn tons of of hundreds to tens of millions of occasions farther than the 2 planets what number of faint stars of the Capricornus sample are you able to make out as soon as the sky is darkish?

■ Venus and Jupiter, the 2 brightest celestial objects after the Sun and Moon, proceed to blaze throughout and after twilight this week. Venus dazzles within the southwest. Jupiter shines some 30° to Venus’s higher left, excessive within the south to south-southwest. As twilight fades, dimmer Saturn emerges halfway between them.


■ This night Saturn seems precisely midway between Jupiter and Venus; look throughout late twilight or shortly after. Although Saturn is a very respectable magnitude +0.7, the opposite two fairly overpower it.

■ For West Coasters, Algol in Perseus ought to be in eclipse at its minimal brightness, magnitude 3.4 as a substitute of its normal 2.1, for a couple hours centered on 11:49 p.m. PST. Algol takes a number of further hours to fade and to rebrighten.

■ New Moon (precise at 2:43 a.m. on this date Eastern Standard Time).

■ Total eclipse of the Sun for elements of West Antarctica. A partial eclipse happens for all of Antarctica and far of the Southern Ocean, and it nicks South Africa. See the December Sky & Telescope, web page 50.


■ Vega nonetheless shines brightly properly up within the west-northwest after darkish. The brightest star above it’s Deneb, the top of the massive Northern Cross shaped by the brightest stars of Cygnus. At dusk the shaft of the cross extends decrease left from Deneb. By about 11 p.m., it vegetation itself kind of upright on the northwest horizon.

■ Now that it is December, Orion is striding up away from the east-northeast horizon by 7 or 8 p.m. By 9 or 10 he is displaying himself excessive within the southeast in his full wintry glory. Have you regarded in on the Great Orion Nebula but this season? Here’s your probability earlier than moonlight begins to flood the sky once more. Orion is highest within the south round midnight.


■ The waxing crescent Moon hangs with Venus low within the southwest early this night, as proven beneath.

The Moon under Venus and Saturn, December 6-7, 2021
The Moon dangles like a bauble beneath Venus, then Saturn, then decrease proper of Jupiter, which is simply outdoors the highest left of this body.

■ What’s the subsequent most engaging star cluster in Taurus after the Pleiades and Hyades? Maybe it is NGC 1647, between the horns of Taurus simply a few levels from Aldebaran and the Hyades. Matt Wedel calls it “a wonderful object for binoculars” in a actually darkish sky. It’s largish however free.

The cluster’s location is simple: It types a roughly equilateral triangle with Aldebaran and the opposite tip of the Hyades V. (The cluster is definitely centered 1° southeast of, i.e. presently beneath, the purpose that makes the equilateral triangle good.) Just off the cluster’s south edge you may discover “a fine optical double star,” Matt writes, very extensive and unequal, each orange, magnitudes 6.0 and seven.5. Have a cautious look utilizing the chart along with his Binocular Highlight column within the December Sky & Telescope, web page 43.

Some, nonetheless, would as a substitute bestow the rank of third-place Taurus cluster on NGC 1746, additionally between the Taurus horns. It’s bigger and a little extra photogenic and attention-grabbing, situated 3/5 of the way from Aldebaran to Beta Tauri. (NGC 1647 is 1/5 of the way alongside that very same line.) The two clusters usually get confused not least as a result of their NGC numbers are the identical digits rearranged.


■ Now the Moon hangs beneath distant Saturn, between Venus to their decrease proper and Jupiter to their higher left.


■ Now the Moon hangs decrease proper of Jupiter. Look farther to their decrease left for sparklier Fomalhaut.

■ As the stars come out, the Cassiopeia W stands on finish (its fainter finish) excessive within the northeast. Watch Cas flip round to develop into a flattened M, even increased within the north, by late night.

■ This is the time of year when M31, the Andromeda Galaxy, passes your zenith after dinnertime (should you reside within the mid-northern latitudes). The precise time depends upon your longitude; it occurs at 7:30 p.m. should you occur to reside at your time zone’s customary longitude. Binoculars, or your eyes alone below a darkish sky, will present M31 simply off the upraised knee of the Andromeda constellation’s stick determine. See the massive night constellation chart within the middle of Sky & Telescope.


■ Orion is up after dinnertime low within the east-southeast, and meaning Gemini can also be coming as much as its left (for the world’s mid-northern latitudes). The head stars of the Gemini twins, Castor and Pollux, are at the left finish of the Gemini constellation — one over the opposite, with Castor on prime.


■ First-quarter Moon (precisely so at 8:36 p.m. EST). The half-lit Moon shines far off the upper-left finish of the Venus-Saturn-Jupiter line, turning it into an immense, gently curving line of 4 objects.

■ Algol ought to be at minimal mild for a couple hours centered on 8:27 p.m. EST.


■ At this time of year the Big Dipper lies shyly down at its lowest simply after darkish, due north. It’s totally beneath the north horizon should you’re as far south as Miami.

But by midnight the Dipper stands straight up on its deal with in high-quality view within the northeast whereas Cassiopeia has wheeled over to the northwest to face practically upright on the intense finish of its W form.

■ Seen any early Geminid meteors but? The bathe is because of peak in two days, late on the night time of December 13-14.


This Week’s Planet Roundup

Mercury is out of sight within the glare of the Sun.

Venus, a dazzling magnitude –4.9, shines within the southwest throughout and after twilight.

Mars, far and faint at magnitude +1.6, is rising low within the dawn. Look simply above the east-southeast horizon about 50 minutes earlier than sunup, way down beneath Arcturus and Spica.

Jupiter with Great Red Spot and two dark barges on Nov. 22, 2021.
Jupiter on November twenty second, imaged by Christopher Go within the Philippines. South is up. Because Jupiter is way previous opposition, its following (jap) edge is barely shaded. Jupiter has shrunk to 37 arcseconds extensive now however continues to be price watching! Get your scope on Jupiter and Saturn in twilight earlier than they transfer decrease. Moreover, the seeing usually steadies in twilight.

The South Equatorial Belt, with the Great Red Spot in its southern edge, is usually pale. The North Equatorial Belt is comparatively darkish red alongside its south edge and sports activities two darkish red barges within the picture above.

Color and brightness contrasts are exaggerated right here, in comparison with Jupiter’s whiter, flatter visible look. This is completed in just about each photograph of the planet you ever see, to carry out particulars.

Jupiter, in Capricornus, shines within the south to southwest throughout night far higher left of Venus. At magnitude –2.3 Jupiter is second in brightness solely to Venus.

Look two fists decrease left of Jupiter for sparkly Fomalhaut, magnitude +1.2.

Saturn, additionally in Capricornus, is halfway between Jupiter and Venus. At magnitude +0.7, Saturn is just one/16 Jupiter’s brightness.

Saturn units round 8 or 9 p.m. Jupiter follows it down a little greater than an hour later.

Uranus (magnitude 5.7, in southern Aries) could be very excessive within the east-southeast after darkish. See Bob King’s story and finder chart.

Neptune (magnitude 7.9, at the Aquarius-Pisces border) is excessive within the south after darkish.

All descriptions that relate to your horizon — together with the phrases up, down, proper, and left — are written for the world’s mid-northern latitudes. Descriptions and graphics that additionally depend upon longitude (primarily Moon positions) are for North America.

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

Want to develop into a higher astronomer? Learn your way across the constellations. They’re the important thing to finding all the things fainter and deeper to hunt with binoculars or a telescope.

This is an out of doors nature interest. For an easy-to-use constellation information overlaying the entire night sky, use the massive month-to-month map within the middle of every challenge of Sky & Telescope, the journal of the American Astronomical Society.

Once you get a telescope, to place it to good use you may want a detailed, large-scale sky atlas (set of charts). The fundamental customary is the Pocket Sky Atlas (in both the original or Jumbo Edition), which reveals stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and tons of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in onerous covers and enlarged for simpler studying open air by red flashlight. Sample charts. More about the current editions.

Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; practically 3 times as many. The subsequent up, as soon as you already know your way round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And you should definitely learn How to Use a Star Chart with a Telescope.

You’ll additionally need a good deep-sky guidebook, akin to the massive Night Sky Observer’s Guide set by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for rookies, I do not suppose, and never on mounts and tripods which can be lower than top-quality mechanically, which means heavy and costly. And as Terence Dickinson and Alan Dyer say of 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 below the night sky along with your
earbuds in place, take heed to Kelly Beatty’s month-to-month
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

Leave a Comment

Your email address will not be published. Required fields are marked *

Shopping Cart