This Week’s Sky at a Glance, November 25 – December 4 – Sky & Telescope


■ Does the Sun already seem to be setting about as early as it ever will? You’re right! We’re still almost a month from the winter solstice — but the Sun sets its earliest each year around December 7th, if you’re near latitude 40° north. And already the Sun sets within only about 3 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!

But in celestial mechanics, every seeming abnormality is balanced out by an equal abnormality somewhere else. The offset of the earliest sunset from the solstice date is balanced out by the opposite happening at sunrise: The Sun doesn’t come up its latest until January 4th, well after the solstice. Blame the tilt of Earth’s axis and the eccentricity of Earth’s orbit.

■ As dawn begins on Friday morning the 26th, the waning Moon shines at the Sickle of Leo, as shown below.

When the waning Moon goes through last-quarter phase this month, it’s passing through Leo high in early dawn.


■ Venus and Jupiter, the two brightest celestial objects after the Sun and Moon, continue to blaze during and after twilight. Venus is in the southwest, now at its highest and brightest of this apparition. Jupiter is is very far to Venus’s upper left, high in the south to south-southwest.

Spot dimmer Saturn between them. It’s less than halfway from Jupiter to Venus early in the week, exactly halfway on December 4th.

■ The last-quarter Moon rises in Leo around 11 p.m. tonight. By dawn on Saturday the 27th it’s high in the south below Leo’s belly, as shown above. The Moon is exactly last-quarter at 7:28 a.m. Saturday morning EST.


■ Around 7 or 8 p.m. this week, the Great Square of Pegasus rests in its level position very high toward the south. (It’s straight overhead if you’re as far south as Miami.) Its western (right) side points very far down toward Fomalhaut. Its eastern side points down toward Beta Ceti, also known as Deneb Kaitos or Diphda, less far down and less directly.

Now descending farther: If you have a very good view down to a dark south horizon — and if you’re not much farther north than roughly New York, Denver, or Madrid — picture an equilateral triangle with Fomalhaut and Beta Ceti as its top two corners. Near where the third corner would be (just a bit 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 check). Have you ever seen anything of the constellation Phoenix before?


■ Jupiter’s Great Red Spot should transit the planet’s central meridian around 7:02 p.m. EST. Features on Jupiter are in fine view (closer to the central meridian than to the limb) for 50 minutes before and after they transit. A light blue or green filter helps a bit.

During this time, the tiny black shadow of Io will be crossing Jupiter. Bright little Io itself enters Jupiter’s eastern edge at 7:16 p.m. EST. The shadow departs Jupiter’s western edge at 8:34 p.m. EST.


■ What’s the next most attractive star cluster in Taurus after the Pleiades and Hyades? Gotcha there, I bet! Maybe it’s NGC 1647, between the horns of Taurus just a few degrees from Aldebaran and the Hyades. Matt Wedel calls it “a wonderful object for binoculars,” at least under a really dark sky. It’s fairly large as open clusters go and rich in faint stars. At a total magnitude of 6.4 Matt calls it “visible to the naked eye under clear, dark skies,” but for an extended object? I’d say he means the clear dark sky from a high desert mountaintop 50 miles from the nearest town, seen with a 20-year-old’s wide pupil and more than an hour’s dark adaptation. Hence, binoculars or a scope.

The cluster’s location is easy: it forms a roughly equilateral triangle with Aldebaran and the other tip of the Hyades V. Just off its south edge you’ll find “a fine optical double star,” Matt writes, very wide, both orange, magnitudes 6.0 and 7.5. Have a good inspect using the chart with his Binocular Highlight column in the December Sky & Telescope, page 43.

Some, however, would instead give the rank of third-place Taurus cluster to NGC 1746, also between the Taurus horns. It’s larger and perhaps a little more photogenic and eye-catching, located 3/5 of the way from Aldebaran to Beta Tauri. The two clusters often get confused not least because their NGC numbers are the same digits rearranged.


■ Mars is taking its sweet time emerging from behind the Sun’s glare into the morning sky, as always. But on Wednesday and Thursday mornings the curve of the crescent Moon points down to show where to look, as shown below.

The crescent Moon points the way to low Mars at dawn, Dec. 1-2, 2021
The waning crescent Moon points the way down to low little Mars in early dawn. The blue 10° scale is about the width of your fist at arm’s length.


■ As the stars come out, the Cassiopeia W stands on end (its fainter end) high in the northeast. Watch Cas turn around to become a flattened M, even higher in the north, by late evening.

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 located only 22° apart, very high toward the east early these evenings — to the right of Cassiopeia and closer below Cassiopeia, respectively. Later in the evening they pass more overhead.

Though similar in brightness 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.


Comet Leonard passes M3. Comet Leonard (C/2021 A1) has probably brightened to 6th magnitude by tonight, crossing from Canes Venatici into Bootes high in the east before the very first light of dawn. North Americans late tonight will find it less than 1° below the 7th-magnitude globular cluster M3. Quite an interesting comparison to be made, and think photo opportunity!

The comet should peak around 4th or 5th magnitude (meaning it’ll only be a dim binocular object; a comet is more diffuse than a star) around December 10th or 11th. By then it’ll be much lower at the beginning of dawn, starting to lose its battle with morning twilight. See “Comet Leonard Races Across the Sky” in the December Sky & Telescope, page 48.


■ Vega still shines brightly well up in the west-northwest after dark. The brightest star above it is Deneb, the head of the big Northern Cross, formed by the brightest stars of Cygnus. At nightfall the shaft of the cross extends lower left from Deneb. By about 11 p.m., it plants itself more or less upright on the northwest horizon.


■ Saturn is now exactly halfway between Jupiter and Venus during and shortly after dusk. Although Saturn is a very respectable magnitude +0.7, the other two quite overpower it.

■ For West Coasters, Algol in Perseus should be in eclipse at minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 11:49 p.m. PST. Algol takes several additional hours to fade and to rebrighten.

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

■ Total eclipse of the Sun for parts of West Antarctica. Partial eclipse for all of Antarctica, the Southern Ocean, and nicking South Africa. See the December Sky & Telescope, page 50.



This Week’s Planet Roundup

Mercury is out of sight in conjunction with the Sun.

Venus, a dazzling magnitude –4.9, shines in the southwest during and after twilight. Venus has reached its greatest height and greatest brilliancy for this apparition.

Mars, far and faint at magnitude +1.6, is gradually emerging low in the sunrise. Try for it with binoculars just above the east-southeast horizon about 45 minutes before sunup. See the graphic for Dec. 1-2 above. You’re catching Mars at the start of its new apparition, which will run for almost two years.

Jupiter with Great Red Spot and two dark barges on Nov. 22, 2021.
Jupiter on November 22nd, imaged by Christopher Go in the Philippines. South is up. Jupiter, being far past opposition, shows shade on its following (eastern) edge, the right edge here. Jupiter has shrunk to 38 arcseconds wide now but is still worth watching! The seeing often steadies in twilight, when Jupiter and Saturn are currently at their highest.

The South Equatorial Belt, with the Great Red Spot in its southern edge, is mostly pale. The North Equatorial Belt is dark red along its south edge and sports two dark red barges.

Jupiter and Saturn, both in Capricornus, shine in the south to southwest during evening far upper left of Venus. Jupiter is the bright one at magnitude –2.3. Saturn, 16° to Jupiter’s lower right, is mag +0.7, only 1/16 as bright.

Look 22° (two fists at arm’s length) lower left of Jupiter for Fomalhaut, the Autumn Star, magnitude +1.2.

Saturn sets around 9 p.m. Jupiter sets a little more than an hour later.

Uranus (magnitude 5.7, in southern Aries above the head of Cetus) is high in the east after dark. See Bob King’s story and finder chart.

Neptune (magnitude 7.9, at the Aquarius-Pisces border) is high in the south after dark.

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 and graphics that also depend on longitude (mainly Moon positions) are for North America.

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

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 magazine of the American Astronomical Society.

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 by red flashlight. Sample charts. More about the current 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 a Star Chart with a Telescope.

You’ll also want a good deep-sky guidebook, such as the big Night Sky Observer’s Guide set 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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