Nova Cassiopeiae 2021 carries on, fluctuating unpredictably as it remains in binocular view six months after its March explosion. As of September 21st it was back up to magnitude 6.7, more than twice as bright as its original March eruption from its 15th-magnitude baseline. Charts and comparison stars.


FRIDAY, SEPTEMBER 24

■ Bright Jupiter and fainter Saturn continue to dominate the southern evening sky, 16° apart. All week Jupiter shines just above or upper right of 3rd-magnitude Delta Capricorni, Deneb Algedi (the name means "Tail of the Young Goat"). The scene is shown below for late twilight this evening.

Farther to the upper right of Saturn, look for Alpha and Beta Capricorni. Both are binocular double stars. Alpha is a wide pair of yellow-orange giants that the smallest binoculars easily resolve; so does our chart below. The components of Beta are half as far apart, much more unequal, and oriented roughly the same way as the Alpha pair.

As the stars come out this week, look for 3rd-magnitude Delta Capricorni just below or lower left of Jupiter. Tonight they're 1.5° apart, about a finger's width at arm's length. Jupiter is 175 times brighter! How early (or more likely, late) in twilight can you first make out Delta Cap?

Delta Cap is an interesting star: a magnetic white subgiant, spectral class A7m, nine times brighter than the Sun and closely orbited by a small, dim orange dwarf almost exactly once a day. The dwarf passes in front of the bright star every orbit from our point of view, dimming it by 0.24 magnitude. That's theoretically discernable by eye but without near-match comparison stars nearby, good luck. The system is only 39 light-years away.

■ Jupiter's Great Red Spot should cross Jupiter's central meridian around 9:04 p.m. Eastern Daylight Time. For full timetables of the Red Spot's transits as well as the doings of Jupiter's moons and their shadows, see the Celestial Calendar section of Sky & Telescope magazine.

SATURDAY, SEPTEMBER 25

■ Cygnus the Swan floats just about straight overhead these evenings. Its brightest stars form the big Northern Cross. When you face southwest and crane your head way, way up, the cross appears to stand upright. It's about two fists at arm's length tall, with Deneb as its top. Or to put it another way, when you face that direction the Swan appears to be diving straight down.

The waning gibbous Moon doesn't rise now until about an hour after dark. So take this opportunity to look for the Milky Way running straight up from the west-southwest horizon, along the backbone of Aquila and just to the right of bright Altair high in the south; then along the shaft of the Northern Cross overhead, and straight down through Cassiopeia and northern Perseus to the east-northeast horizon.

SUNDAY, SEPTEMBER 26

■ Bright Arcturus, pale yellow-orange, shines ever lower in the west-northwest at nightfall. The narrow kite shape of its constellation, Bootes, extends two fists at arm's length to Arcturus's upper right. Arcturus is where the kite's downward-hanging tail is tied on.

To the right of the top of the kite, the Big Dipper is turning more level.

And this is the time of year when, during the evening, the dim Little Dipper "dumps water" into the bowl of the Big Dipper way down below. The Big Dipper will dump it back in the evenings of spring.

■ Tonight Jupiter's Great Red Spot should cross the planet's central meridian around 10:42 p.m. EDT (7:42 p.m. Pacific). It remains in good view for about an hour before and after that time.

MONDAY, SEPTEMBER 27

■ Arcturus shines in the west in late twilight these evenings. Capella, equally bright, is just rising in the north-northeast (depending on your latitude; the farther north you are the higher it will be). They're both magnitude 0.

Later in the evening, Arcturus and Capella shine at equal heights in their respective compass directions. When will this happen? That depends on both your latitude and longitude.

When it does, turn around and look low in the south-southeast. There will be 1st-magnitude Fomalhaut at the about same height too — exactly so if you're at latitude 43° north (about the latitude of Boston, Buffalo, Milwaukee, Boise, Eugene). Seen from south of that latitude, Fomalhaut will appear higher than Capella and Arcturus are. Seen from north of there, it will be lower.

TUESDAY, SEPTEMBER 28

■ Last-quarter Moon tonight (exact at 9:57 p.m. Eastern Daylight Time). The Moon rises around 11 or midnight in Gemini, down below Capella and the rest of Auriga.

An hour later look off to the Moon's right, and there's Orion stepping up over the eastern horizon (for viewers at mid-northern latitudes).

WEDNESDAY, SEPTEMBER 29

■ The starry W of Cassiopeia stands high in the northeast after dark. The right-hand side of the W (the brightest side) is tilted up.

Look at the second segment of the W counting down from the top. Notice the dim naked-eye stars along that segment (not counting its two ends). The brightest of these, on the right, is Eta Cassiopeiae, magnitude 3.4. This is a remarkably Sun-like star just 19 light-years away, and it has a orange-dwarf companion, magnitude 7.3, separation 13 arcseconds a lovely binary in a telescope.

Left of it, and fainter, is a naked-eye pair in a dark sky: Upsilon1 and Upsilon2 Cassiopeiae, a good 0.3° apart. They're yellow-orange giants unrelated to each other, 200 and 400 light-years distant from us. Upsilon2 is slightly the brighter of the pair. It's also the closer one.

■ Night owl? Look east any time from 1 or 2 a.m. to early dawn Thursday morning, and you'll find the waning Moon near Pollux in Gemini. Above Pollux is Castor.

THURSDAY, SEPTEMBER 30

■ The big asteroid 2 Pallas, almost three weeks past opposition, stands high in the southeast by 9 or 10 p.m. It's still in small-telescope reach at magnitude 8.4. This week Pallas is 8° or 9° upper right of Neptune, magnitude 8.7, which also is past opposition. Read about both and hunt them down using the finder charts in Asteroid Pallas Makes a Point in Pisces.

FRIDAY, OCTOBER 1

■ Vega is the brightest star just west of the zenith after dark. Face west and look to Vega's right by 14° (nearly a fist and a half at arm's length) for Eltanin, the nose of Draco the Dragon. The rest of Draco's fainter, lozenge-shaped head is a little farther behind. Draco always eyes Vega as they wheel around the sky.

The main stars of Vega's own constellation, Lyra — faint by comparison — extend to its left (by 7°).

■ Before and during early dawn Saturday morning October 2nd, look below the crescent Moon by about a fist at arm's length for Regulus, forefoot of Leo already making his early-apparition appearance, as shown below.

Leo announces spring when it's on the rise in the early evening sky. But Leo's arrival in the east at the beginning of dawn? That announces October.

SATURDAY, OCTOBER 2

■ During evening, look just above the northeast horizon — far below high Cassiopeia — for bright Capella on the rise. How soon Capella rises, and how high you'll find it, depends on your latitude. The farther north you are, the sooner and higher.

■ Vega is the brightest star very high in the west, and Arcturus is getting low in the west-northwest. The brightest star in the vast expanse between them, about a third of the way from Arcturus up toward Vega, is Alphecca, magnitude 2.2 — the crown jewel of dim Corona Borealis. Alphecca is a 17-day eclipsing binary, but (like most variable stars!) its brightness dips are too slight for the eye to see reliably.

■ Before and during early dawn Sunday morning October 3rd, the waning crescent Moon forms a flat, almost isosceles triangle with Regulus and Algieba (Gamma Leonis) to Regulus's left or upper left, as shown above (for North America).

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This Week's Planet Roundup

Mercury is hidden deep in the glare of the Sun.

Venus, brilliant at magnitude –4.2, shines low in the southwest during twilight. And it still sets around twilight's end.

Jupiter and Saturn continue to shine in the southeast to south during evening. They're magnitudes –2.7 and +0.5, respectively, 16° apart on opposite sides of dim Capricornus.

During twilight bright Jupiter, on the left, is slightly the lower of the two. They level out soon after dark, and later they tilt the other way, with Saturn now the lower one. Saturn sets around 2 a.m. daylight-saving time, followed down by Jupiter about an hour later.

In the evening look for 1st-magnitude Fomalhaut 23° (two fists) lower left of Jupiter. And less than 2° below or lower left of Jupiter is 3rd-magnitude Delta Capricorni, described in the caption above.

Also, see Amateurs Spot New Impact Flash at Jupiter. With videos of it taken by two amateur Jupiter-impact monitors.

Uranus (magnitude 5.7, in southern Aries) climbs high in the east by midnight.

Neptune (magnitude 7.8, at the Aquarius-Pisces border) is high in the southeast by 9 or 10 p.m.


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.


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 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 at the 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."


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

 


Comments


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Anthony Barreiro

September 24, 2021 at 5:07 pm

In the item for Thursday September 30, the digits for Neptune's magnitude are reversed. Neptune is magnitude 7.8, not 8.7.

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Rod

September 24, 2021 at 11:42 pm

mary beth, Anthony, New Jersey Eclipse Fan. Some enjoyable early fall viewing tonight. Observed 1930-2200 EDT/2330 UT-0200 UT. Waning gibbous Moon rise 2103 EDT in Aries tonight. I could see portions of the Milky Way running from Cygnus through Sagittarius tonight, especially after 2030 EDT. I used Delphinus to test limiting magnitude, about 5.5 or so. In Delphinus, I could see Eta Delphini at 5.37 and Iota Delphini at 5.40 apparent magnitude. About 2115 EDT, I observed a meteor streak SE near Aquarius, about 2nd magnitude I estimate. A 5th magnitude polar orbiting satellite passed heading SSE/S direction. I used the 90-mm refractor with 9-mm and 1.8x Barlow lens for 200x views of Jupiter and Saturn. The Great Red Spot crossed Jupiter central meridian near 2104 EDT as reported. Using the 10-inch Newtonian with 35-mm (2-inch eyepiece), Jupiter was very bright with cloud bands visible. The Galilean moons visible and Saturn was bright, the rings bright. The view was about 34x with true FOV near 1.8-degrees or a bit larger. The 90-mm refractor at 200x provided very good views of Saturn. Cassini division, some cloud bands visible, and Titan and Rhea moons visible. This was a goodtime to view Saturn. Saturn transit 2129 EDT. A treat tonight was viewing Neptune just a bit more than 2 arcminute angular separation from the star, HIP115953. Stellarium shows apparent magnitude 6.25 and spectral class K3-III and about 149 light years distance. Starry Night shows spectral class K1 III. This is a red giant star and the 10-inch at 34x presented a very good and bright image of the orange red giant and blue Neptune, close together in the FOV. The 90-mm refractor at 111x did a good job too but the 10-inch brighter image, very enjoyable color contrast. Temperature tonight dropped quickly to 13C with humidity and dew forming on the fields. By the time I went back in, my feet were soaking wet, and my telescopes were very wet too. There were some owls out hooting in the woods and I could see the waning gibbous Moon rising in the East behind some trees farther away. A very lovely sight. I found Neptune easily using 10x50 binoculars in Aquarius. Neptune in a field of distinct stars, HIP115953, HIP116106, HIP116225, HIP116402, and HIP116266. All 7th apparent magnitude stars. Stellarium and Starry Night provided good charts for locating Neptune.

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mary beth

September 25, 2021 at 11:51 am

Hello Rod, Anthony and all! Happy Autumn!

Rod, it sounds like you had a very delightful evening! The color contrast of the Red Star with blue Neptune must be striking! I did not know that Neptune looked blue. I thought you would probably be out watching the Jupiter’s red spot. Glad conditions were favorable. The moon and the owl sound a little spooky…and very seasonally fun!!

Anthony, are there any interesting reports from your club?

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Anthony Barreiro

September 25, 2021 at 3:58 pm

Sorry, not much to report. On Monday evening I watched the Harvest Moon rise over the east bay hills and San Francisco Bay. The sky was clear and calm and the moonlight twinkled on the water of the bay. It was lovely.

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mary beth

September 25, 2021 at 11:23 pm

That actually sounds ideal! What are used to live on the coast of Galveston Bay and could see the moon rise over the water. I love that first hint of orange on the horizon! Glad you have such a nice place to see the moon. How far do you have to go to see the sunset?

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Anthony Barreiro

September 26, 2021 at 4:51 pm

I walk about a mile up to the top of Bernal Hill. You can see the Sun and Moon rise over the east bay hills and set over Twin Peaks or the Pacific, depending how far north or south they set. It's a lovely spot.

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mary beth

September 26, 2021 at 10:51 pm

Excellent! And the fact you can walk, what a blessing. If I was in the area I would practically live on the hill! I’ve always dreamed of having a good unobstructed view of both the eastern and western horizons.

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Anthony Barreiro

September 27, 2021 at 3:59 pm

Sometimes I feel like Julie Andrews in The Sound of Music.

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mary beth

September 27, 2021 at 10:31 pm

Instead of sound of music you have the sight of stars! Do a lot of people come up there to watch the sunset and moonrise?

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Anthony Barreiro

September 28, 2021 at 4:30 pm

Yes, the park is very popular around sunset and sunrise, and a lot of people come up for the full Moon.

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cyrtonyx

September 30, 2021 at 1:07 pm

I am fortunate in my location about 30 miles east of Albuquerque on the western edge of the Estancia Valley. Unobstructed views east and west. And dark. East of my location it is 100 miles to the nearest population center (Santa Rosa, NM) The sunrises are notable.

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Anthony Barreiro

September 30, 2021 at 8:43 pm

Northern New Mexico truly is the Land of Enchantment. I'm happy for your good fortune!

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mary beth

September 30, 2021 at 9:50 pm

Very nice! We live in Houston but we have a house near Cloudcroft. It’s a little too forested there to see things like you can see although it is very dark. A lot of the streets in Cloudcroft are named after things in astronomy lol. I think quite a few retired astronauts moved there in the 70s. Sounds like you are in a very remote area which is great! What is your elevation?

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New Jersey Eclipse Fan

September 26, 2021 at 12:05 am

As usual, I really enjoyed reading all of the above comments. The only contribution I can add is that Saturday night just after 9:30pm EDT as I drove my daughter and her friend from my house in Central Jersey to NYC, there was a striking moonrise over the city skyline. I told my daughter to snap some photos on her cellphone, but they don't do justice to the actual event. Still, it was quite a sight. I think the moon gets a bad rap sometimes.

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mary beth

September 26, 2021 at 12:05 pm

Nice New Jersey Eclipse Fan! Glad y’all had good scenery! Isn’t there a Christopher Cross song about the moon and New York City? And also some old song about a Bill Bower moon?? It was really the old Balboa moon I think, but people heard it wrong! My dad always sang us to us kids in the 60s and 70s whenever there was a full moon!

https://bilbaomoon.blogspot.com/2011/04/bilbao-song.html

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New Jersey Eclipse Fan

September 26, 2021 at 12:43 pm

Back in the day, I remember Cross explaining his inspiration for that part of "Arthur's Theme (Best That You Can Do)." He flew into NYC for a concert and the plane had to circle a few times before finally landing. As he looked out the window to see the lights of the city downward and the moon upward, he came up with the lyrics. Similarly, Karen & Richard Carpenter were in an airplane when they were inspired to write "Top of The World." I wonder if anyone has written a song about the Mile High Club. 😉

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mary beth

September 26, 2021 at 10:54 pm

Adam Ant, 1981 lol

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New Jersey Eclipse Fan

September 27, 2021 at 3:04 pm

OMG I thought you were joking until I Googled it! I graduated from college that year (Boston University) and there was a Punk Rock joint off-campus called the Rathskeller, but I never ventured inside. I wonder if he ever appeared there.

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mary beth

September 27, 2021 at 10:43 pm

Wow that sounds like a really neat place kind of like CBGB where a lot of punk bands got their start. Bet it was the next stop for a lot of bands. There was an excellent documentary on PBS in 1995 called The History of Rock and Roll. The best episode is the one called Punk - had a great interview with Jonathan Richman of the Modern Lovers. He was from Boston, I’m sure he played there!

https://youtu.be/v2zsMS8xwVQ

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Rod

September 27, 2021 at 6:48 am

Okay, some lively posts here 🙂 This morning near 0530 EDT, I was out and looked at the heavens, southern sky area. Lovely view! Temperature 9/10C with the waning gibbous Moon in Taurus, Auriga, Orion, Sirius in Canis Major and much more. Was I doing some early morning stargazing with my telescopes? No, I took out some trash but really enjoyed the view of the clear, cool, early morning sky 🙂

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mary beth

September 27, 2021 at 10:25 pm

Thanks to your recommendation, I looked at early morning Stellarium and saw the scene you saw….there’s a lot going on! I might have to get up early next clear day to enjoy! My husband saw Canopus Friday morning. Can you see it in Maryland?

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Rod

September 28, 2021 at 4:56 pm

mary beth, no on observing Canopus. Stellarium shows no problem in Houston area but my location in MD is no (never rises). Looks like Canopus according to Stellarium rises near 0420 local time at Houston.

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