This Week's Sky at a Glance, October 29 – November 6

Nova Cassiopeiae 2021 was still hovering around magnitude 7.6 as of October 29th, after nearly a dozen rises and dips since it first exploded from mag 15 to 7.7 last March. Charts and comparison stars.

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FRIDAY, OCTOBER 29

■ Jupiter and Saturn continue to steepen their tilt in the southern evening sky this week, as shown below. Meanwhile, they are gradually creeping toward Venus — which shines at nightfall far to their lower right.

■ Spot bright Capella sparkling low in the northeast these evenings. Then look for the Pleiades cluster off to Capella's right, by about three fists at arm's length. These harbingers of the cold months rise higher as evening grows late — and watch for Aldebaran coming up below the Pleiades.

Upper right of Capella, and upper left of the Pleiades, the stars of Perseus lie astride the Milky Way.

■ A small telescope is all you need to watch Jupiter's big moon Ganymede slowly reappear from eclipse out of Jupiter's shadow around 8:31 p.m. EDT. It will come into view a little east of the planet.

Then Callisto emerges from eclipse, a little farther from Jupiter and even more gradually, 1¼ hours later: at about 9:47 p.m. EDT. (Convert the times to your own time zone.)

SATURDAY, OCTOBER 30

■ Spot bright Altair high in the southwest soon after dark. Brighter Vega is far to its right.

Above Altair lurk two distinctive little constellations: Delphinus the Dolphin, hardly more than a fist at arm's length to Altair's upper left, and smaller, fainter Sagitta the Arrow, slightly less far to Altair's upper right. Light pollution too bright? Use binoculars!

SUNDAY, OCTOBER 31

■ Halloween evening is moonless this year. But as twilight turns to night, bright Jupiter and lesser Saturn look down on trick-or-treaters from the south, and Venus blazes far to their lower right in the southwest.

The brightest star high in the evening is Vega, watching from very high in the west. And look two fists at arm's length lower left of Jupiter for Fomalhaut, the Autumn Star. Their eyes are upon you, and they say nothing.

MONDAY, NOVEMBER 1

■ Draw a line from Altair, the brightest star very high in the southwest after dark, to the right to Vega, very high in the west and even brighter. Continue the line onward by half that far, and you hit the Lozenge: the pointy-nosed head of Draco, the Dragon. Its brightest star is orange Eltanin, the tip of the Dragon's nose, always pointing toward Vega.

■ Just to Altair's upper right, by a finger-width at arm's length, is orange Tarazed (Gamma Aquilae), looking like Altair's little sidekick but actually a much bigger and brighter star far in the background. Altair is 17 light-years away. Tarazed is about 360 light-years away, and it puts out 100 times as much light!

TUESDAY, NOVEMBER 2

■ 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. How accurately can you time this event? Sextant not required. . . but it would help.

■ This week Jupiter crosses the meridian (is highest due south) around 7 or 8 p.m. daylight-saving time, depending how far east or west you live in your time zone. And when Jupiter crosses the meridian now, so does the nose star of upside-down Pegasus: Enif, aka Epsilon Pegasi. "Enif" is from the Arabic for nose, a designation adopted from the Greeks' take on Pegasus.

At magnitude 2.4, Enif is easy to spot 25° above Jupiter. That's about 2½ fists at arm's length. Sharp eyes or binoculars reveal that it's yellow-orange; it's a K3 supergiant.

Enif is your starting point for finding the fine fall globular cluster M15, Queen Anne's Lace per Josh Urban, located 5° to the star's northwest (upper right these evenings). At 6th magnitude M15 is within binocular range as a tiny glowball, and a 6-inch telescope may begin to resolve some of its sugarpile starspecks. Use the finder chart with Matt Wedel's Binocular Highlight column in the October Sky & Telescope, page 43.

■ In early dawn Wednesday morning, have a try for the thin Moon, Mercury, and Spica forming a triangle very low in the east-southeast, as shown above. Bring binoculars in case you don't catch just the right, brief time window between the triangle being too low and the sky becoming too bright for Spica, the faintest of the three.

WEDNESDAY, NOVEMBER 3

■ Got a really big scope and a dark-sky location? With the Moon gone from the evening sky, bring your deep-sky atlas and check out "The Odd World of Peculiar Galaxies" in the October Sky & Telescope starting on page 57, with photos and visual drawings. The ten featured galaxies are magnitudes 12 to 14.

■ Low in bright dawn Thursday morning, the thin waning Moon hangs in a triangle with Mercury and faint Spica below it, as shown above. Look low in the east-southeast about 40 or 30 minutes before sunrise, and bring binoculars.

The triangle is 4° or 5° on a side. The Moon is thin indeed; it's only 1½ days from new as dawn breaks in the Americas.

THURSDAY, NOVEMBER 4

■ After dark this week Capella shines well up in the northeast, and the Pleiades are well up in the east-northeast three fists to Capella's right. As evening grows later, you'll find orange Aldebaran climbing up below the Pleiades. By about 10 p.m. (depending on your location), Orion is clearing the eastern horizon below Aldebaran.

■ Uranus is at opposition.

FRIDAY, NOVEMBER 5

■ 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).

SATURDAY, NOVEMBER 6

■ I don't know why I always 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 it's a very dim, smooth glow despite being respectably large; the cluster is rich with stars but they're all very faint. 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 — and some of them do it all by themselves, this being the 21st century.

 

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This Week's Planet Roundup

Mercury, in Virgo, is still in its best morning apparition of the year. Look for it low above the east-southeast horizon in early dawn, about 50 to 40 minutes before your sunrise time. It remains bright at magnitude –0.8 all week. Passing through its vicinity is fainter Spica, magnitude +1.0.

On the morning of November 3rd the thin Moon stands close above them, as shown two illustrations above.

Venus, a brilliant magnitude –4.6, shines in southwest during and after twilight, right or lower right of the vastly fainter Sagittarius Teapot. Venus now stays up for nearly an hour after dark. It will continue to get a little higher and brighter into early December.

Mars remains out of sight deep in the glow of sunrise.

Jupiter and Saturn continue to shine in the south during evening, 15° apart in Capricornus. Jupiter is the bright one at magnitude –2.5. 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 as they move westward. Saturn sets around 11 or midnight daylight-saving time, Jupiter about an hour later.

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

By the way, fantastically precise velocity measurements of the Juno spacecraft orbiting Jupiter have just shown (via its gravitational perturbations) that the Great Red Spot extends about 300 km below Jupiter's visible cloudtops. This is deeper than was expected, but still very shallow compared to the spot's width of 16,000 km; the great storm is about 50 times wider than deep, a little thinner than two DVDs stacked.

Still, the bottom is below the depth when sunlight penetrates or water condensation occurs. See The Roots of Jupiter's Great Red Spot Run Deep. "For context, Jupiter’s stripes, the brown-red belts and whitish zones, extend much deeper, down to about 3,000 km, or about 4% of the way to the core."

Uranus (magnitude 5.7, in southern Aries) is well up in the east by 9 p.m. It's at opposition this week, exactly so on November 4th. See Bob King's Uranus Queues Up for Opposition.

Neptune (magnitude 7.9, at the Aquarius-Pisces border) is high in the southeast by nightfall. It went through opposition almost two months ago, but at Neptune's distance that hardly matters.

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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 minus 4 hours. Universal Time is also known as UT, UTC, GMT, or Z time. To become more expert about time systems than 99% of the people you'll ever meet, see our compact article Time and the Amateur Astronomer.

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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.

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 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."

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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.

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"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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