This Week’s Sky at a Glance, November 5 – 13 – Sky & Telescope

Nova Cassiopeiae 2021 was still hanging in at magnitude 8.3 as of November 4th, more than 7 months after it erupted. Charts and comparison stars.


■ At dusk this week, the Jupiter-Saturn line in the southern sky tilts only mildly, as shown below. Look far to their lower right for bright Venus.

As evening progresses, Venus sets and the tilt of the giants steepens.

Jupiter and Saturn have passed the stationary points in their retrograde loops and have begun moving eastward (leftward) again with respect to the background stars. This is most noticeable as Jupiter moves past Delta Capricorni, the constellation’s left corner, shown here. Keep watch; the planets’ eastward motion is speeding up.

The Summer Triangle Effect. Here it is early November, but Deneb still shines right near the zenith as the stars come out. And brighter Vega is still not far from the zenith, toward the west. The third star of the “Summer” Triangle, Altair, remains very high in the southwest (high upper right of Jupiter and Saturn). They seem to have stayed there for a couple months! Why have they stalled out?

What you’re seeing is the result of sunset and darkness arriving earlier and earlier during autumn. Which means if you go out and starwatch soon after dark, you’re doing it earlier and earlier by the clock. This counteracts the seasonal westward turning of the constellations.

Of course this “Summer Triangle effect” applies to the entire celestial sphere, not just the Summer Triangle. But the apparent stalling of that bright landmark inspired Sky & Telescope to give the effect that name many years ago, and it has stuck.

Of course, as always in celestial mechanics, a deficit somewhere gets made up elsewhere. The opposite effect makes the seasonal advance of the constellations seem to speed up in early spring. The spring-sky landmarks of Virgo and Corvus seem to dash away westward from week to week almost before you know it, due to darkness falling later and later. Let’s call this the “Corvus effect.”

■ New Moon (exact at 5:15 p .m. Eastern Daylight Time).


■ I don’t know why I get confused trying to find the open cluster NGC 7789 in Cassiopeia, a.k.a. Caroline’s Rose, with a finderscope or binoculars. I mean it’s right there a simple, short star-hop from the bright end of the Cassiopeia W. Maybe it’s because the cluster is a very dim, smooth glow despite being respectably large; it’s rich with stars but they’re all too faint for the swarm to look speckly, and I do have light pollution. Use the nice, clear finder chart with Matt Wedel’s Binocular Highlight column in the November Sky & Telescope, page 43.

■ Daylight-saving time ends at 2 a.m. tonight for most of North America. Clocks fall back an hour.


■ Catch Venus and the crescent Moon in the southwest as twilight fades, as shown below. How low can you follow them down after dark?

The Moon poses right of Venus at dusk Sunday. They’re only about 2° to 4° apart depending on where you are in North America. On Monday, the Moon hangs farther to Venus’s upper left. These are the two brightest celestial objects after the Sun.


■ Now the Moon is farther upper left of Venus, as shown above.

■ When night arrives, the Great Square of Pegasus is still balanced on its corner high in the southeast. But within two hours it turns around to lie level like a box high in the south.

A sky landmark to remember: The west (right-hand) side of the Great Square points far down almost to 1st-magnitude Fomalhaut. The east side of the Square points down toward Beta Ceti not as directly, and not as far.


■ Around 10 p.m., depending on where you live, zero-magnitude Capella rises exactly as high in the northeast as zero-magnitude Vega has sunk in the west-northwest.

■ As Wednesday’s dawn brightens, bring binoculars to try for Mercury and Mars in conjunction, 1° apart, very low above the eastern horizon. Look for Mars, a mere magnitude +1.6, 1° south (lower right) of Mercury. Mercury is magnitude –0.9, ten times brighter. Your best chance might be 30 or 40 minutes before sunrise.

■ Happy 87th birthday, Carl Sagan (November 9, 1934 – December 20, 1996). If only.

Moon passing Saturn and Jupiter, Nov. 10-11, 2021
When the Moon passes Saturn, then Jupiter, consider how near and far they actually are. Saturn is 4,000 times farther from us than the Moon is just now, and it’s physically 35 times larger in diameter. Jupiter is 1,900 times more distant than the Moon and 41 times larger.


■ This evening, look for Jupiter upper left of the Moon and for lesser Saturn roughly half as far to the Moon’s right, as shown above. Watch through the evening as this pattern moves lower toward the west-southwest, gradually rotating a bit clockwise as it goes.


■ First-quarter Moon (exact at 7:46 a.m. EST). Jupiter shines brightly about 5° upper right of the Moon as shown above. Saturn shines more modestly to their right in twilight tonight, and to their lower right later as shown above.


■ At nightfall Jupiter, Saturn, the Moon, and Venus form a long, ragged diagonal line in the south to southwest, in that order from upper left to lower right.

■ The largest asteroid, 1 Ceres, is currently passing through the Hyades near Aldebaran this week. At magnitude 7.3 Ceres is faintly in binocular range. Its path is mapped in the November Sky & Telescope, page 50 (where the date ticks are for 0:00 Universal time, which falls on the evening of the previous date for North America.)

Aldebaran and the Hyades are well up in the east by 9 p.m. standard time. Robert C. Victor points out to us that on the nights of November 11-12 and 12-13 , “Ceres is passing north of the naked-eye pair Theta-1 and Theta-2 Tauri,” a landmark pair of Hyads just west of Aldebaran. “These stars are 5.5 arcminutes apart, magnitudes 3.8 and 3.4. The 5.0-mag. star 75 Tauri is 24 arcminutes north of Theta-1. On November 12, Ceres passes within 9 arcminutes north of 75 Tauri. This conjunction takes place in the afternoon in North America, with Ceres moving west by 12 arcminutes per day.”


■ Look high above the Moon for the Great Square of Pegasus.

■ Vega is the brightest star high in the west on November evenings. Its little constellation Lyra extends to its left, pointing as always to Altair, the brightest star in the southwest.

Three of Lyra’s stars near Vega are interesting doubles. Barely above Vega is 4th-magnitude Epsilon Lyrae, the Double-Double. Epsilon forms one corner of a roughly equilateral triangle with Vega and Zeta Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm’s length.

Binoculars easily resolve Epsilon. And a 4-inch telescope at 100× or more should resolve each of Epsilon’s wide components into a tight pair.

Zeta is also a double star for binoculars; much tougher, but plainly resolved in a telescope.

And Delta Lyrae, upper left of Zeta by a similar distance, is a much wider and easier binocular pair.


This Week’s Planet Roundup

Mercury is deeper down in the sunrise glow every morning. Look for it low above the east-southeast horizon about 30 or 40 minutes before sunrise. At least it’s currently bright, about magnitude –0.9. By the end of the week it’ll probably be out of sight.

Don’t confuse Mercury with Arcturus sparkling some 30° (three fists) to its upper left.

Venus, a brilliant magnitude –4.7, shines in southwest during and after twilight. It’s now encroaching into the vastly fainter Sagittarius Teapot. Venus doesn’t set now until about an hour after dark. It will continue to shine a little higher and brighter through the end of November.

Mars, a mere magnitude +1.6, is emerging deep in the sunrise in the vicinity of Mercury, which is ten times brighter at magnitude –0.9. Catch them in conjunction on the morning of November 10th, when Mars is 1° south (lower right) of Mercury. Bring binoculars.

Jupiter and Saturn continue to shine in the south during evening, 16° apart in Capricornus. Jupiter is the bright one at magnitude –2.4. Saturn, to its right or lower right, is mag +0.6.

In twilight they’re just beginning to tilt. As evening advances they tilt more steeply and move westward. Saturn sets around 10 p.m. standard time, Jupiter about an hour later.

Look 23° (two fists at arm’s length) lower left of Jupiter for Fomalhaut, magnitude +1.2.

Jupiter in the news: The Roots of Jupiter’s Great Red Spot Run Deep.

Uranus (magnitude 5.7, in southern Aries) is well up in the east by 7 p.m. standard time. See Bob King’s Uranus Queues Up for Opposition.

Neptune (magnitude 7.9, at the Aquarius-Pisces border) is already high in the southeast at nightfall.

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 Daylight Time, EDT, is Universal Time (also called UT, UTC, or GMT) minus 4 hours. Eastern Standard Time, EST, is Universal Time minus 5 hours. Standard time begins Sunday Nov. 7th for most of North America.

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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