We can't look away. Long-lasting, ever fluctuating Nova Cassiopeiae 2021 was finally down to about magnitude 8.2 as of October 14th. That's still barely fainter than when it exploded last March. Charts and comparison stars.

The gibbous Moon lingers with Jupiter on Friday evening the 15th, before moving ever eastward to turn full on the 20th under the Great Square of Pegasus.


■ Bright Jupiter and fainter Saturn continue to dominate the southern evening sky from their home in dim Capricornus, as shown above. They remain 15° apart; both are nearly stationary at the west end of their retrograde loops.

■ Spot Venus low in the west in twilight. Just lower left of it, by 1½° (about a finger's width at arm's length), look for orange Antares, less than 1% as bright. Venus stays about this close to Antares for the next two days, but watch their orientation change.


■ It's International Observe the Moon Night, with more than 1,960 events worldwide inviting you to show up! Or, put on your own event and add it to the map. All you need to host a Moon-observing event is a telescope, a place to put it, and a readiness to welcome visitors for a look. Or you can just invite friends and family, and it still counts.

The Moon is waxing gibbous. Its terminator crosses Oceanus Procellarum, which shows off the dramatic crater Copernicus and countless other features.

To the naked eye, the Moon forms a roughly equilateral triangle with bright Jupiter to its right or upper right, and Fomalhaut to the Moon's lower right.

Cloudy where you are? Gianluca Masi of the Virtual Telescope Project plans a narrated live feed of the Moon from Rome, starting at 17:30 UT (3:30 p.m. EDT).


■ This is the time of year when, in early evening, W-shaped Cassiopeia stands on end high in the north-northeast — and when, lower left of Cas in the north, the dim Little Dipper extends leftward from Polaris.

Below or lower right of Cassiopeia is star-scattered Perseus. Look lower left from Perseus, or far below Cas, for bright (zero-magnitude) Capella.


■ Vega is the brightest star very high west of the zenith after dark. Less high in the south-southwest is Altair, not quite as bright. Still near the zenith is the third and least bright star of the Summer Triangle, Deneb.

Look lower left from Altair by three or four fists at arm's length, and you hit can't-miss-it Jupiter. Extend that line two fists farther on, and you hit Fomalhaut.


■ Look two fists left of the brilliant Moon this evening for the brightest stars of Aries, not far apart. Through the moonlight, can you see one of them, or two, or three? Hamal is magnitude 2.0. Sheratan to its right or upper right is is mag 2.6. Mesarthim, closer to the lower right of Sheratan, is more challenging at mag 3.9. Averted vision helps.


■ Full Moon (exactly so at 10:57 a.m. EDT). The Moon rises in the east about 20 minutes after sunset for the mid-latitudes of North America. Right after dark, look three fists above the Moon for Alpheratz, the 2nd-magnitude head of Andromeda and the leftmost corner of the Great Square of Pegasus.

■ It's a busy evening at Jupiter. At 8:41 p.m. EDT the tiny black shadow of Io starts crossing Jupiter's face, entering on the east limb, followed by Io itself about an hour later. The shadow leaves Jupiter's western limb at 10:58 p.m. EDT, followed by Io an hour after that.

Meanwhile, Jupiter's Great Red Spot should transit the planet's central meridian around 10:37 p.m. EDT. Features on Jupiter remain closer to the central meridian than the limb for 50 minutes before and after they transit.


■ Once the Moon is well up in the east tonight, look left of it by about a fist and a half for the little Pleiades cluster. Can you pick out this sparkle-patch through the moonlight? Binoculars make it easy.

Look a little more than a fist below the Pleiades for orange Aldebaran on the rise.


■ The waning gibbous Moon shines in the east after dark this evening. You may need binoculars to pick out the Pleiades few degrees to its left or upper left, as shown below. Much easier is bright Capella many times farther left of the Moon.

As night advances, Aldebaran comes up below or lower left of the Moon. And by midnight, Orion is clearing the eastern horizon far below them all.


■ Tonight the waning Moon shines near Aldebaran, as shown below.

In October every year, the Moon commits its passage through Taurus when it's waning gibbous.

■ This is the time of year when the Big Dipper lies down horizontal low in the north-northwest after dark. How low? The farther south you are, the lower. Seen from 40° north (New York, Denver, Madrid) even its bottom stars twinkle nearly ten degrees high. But at Miami (26° N) the entire Dipper skims along out of sight just below the northern horizon.


This Week's Planet Roundup

Mercury is heading toward its best morning apparition of the year. By about Monday October 18th, look for it low above the east horizon about 50 minutes before sunrise. On that morning it's still only magnitude +0.7, so you may want binoculars.

But it brightens and gets a little higher every day. Just four days later, on Friday morning the 22nd, Mercury is more than twice as bright at magnitude –0.2. Next week it will nearly double in brightness again.

Don't confuse Mercury with Arcturus, which is above the east-northeast horizon (depending on your latitude) off to Mercury's left.

Mars remains out of sight behind the glare of the Sun.

Venus, brilliant at magnitude –4.4, shines in southwest during twilight, crossing from Scorpius into the feet of Ophiuchus. It sets about a half hour after twilight's end.

On Saturday the 16th Venus is passing 1.4° north (upper right) of Antares, which is much fainter, orange, and twinkling. Every evening thereafter, Antares falls away farther to Venus's lower right. By the 22nd they're a good 6° apart.

Jupiter and Saturn continue to shine in the south during evening, 15° apart on opposite sides of Capricornus. Jupiter is the eye-grabber at magnitude –2.6. Saturn, to its right or lower right, is a twentieth as bright at mag +0.6.

In twilight they shine equally high. As the evening progresses watch them tilt as they move to the right, with Saturn becoming the lower one. Saturn sets around midnight or 1 a.m. daylight-saving time, followed by Jupiter about an hour later.

After dark look 23° (two fists at arm's length) lower left of Jupiter for 1st-magnitude Fomalhaut, as shown at the top of this page.

Here's a beginner's telescopic guide to Jupiter.

Jupiter on October 6th, imaged by S&T's Sean Walker with a 12-inch reflector in New Hampshire. North is up. "We were treated to some excellent seeing conditions." he writes. "I spent hours shooting and observing the planet, watching the GRS transit, as well as the dark barges in the NEB, and the series of white ovals south of the SEB. It was a magical night of observing -- I was seeing the first diffraction ring around Io and Europa; don't think I can ever recall seeing that before. Wish I could have shared it with others."

Uranus (magnitude 5.7, in southern Aries) climbs high in the east by 10 p.m.

Neptune (magnitude 7.8, at the Aquarius-Pisces border) is already well up in the in the southeast at twilight's end.

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 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."

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



Image of Rod


October 15, 2021 at 1:56 pm

After more than a week of clouds, light rain, and more clouds at my location in MD, I was able to do some viewing the evening of 13-Oct. From my stargazing log. [Observed 1930-2045 EDT/2330-0045 UT. First Quarter Moon 13-Oct-2021 0325 UT so the Moon tonight was just past First Quarter or waxing gibbous. I used the 90-mm refractor with 14-mm eyepiece for 71x views and true FOV a bit more than 60 arcminutes or 1-degree across. Jupiter's Great Red Spot crossed central meridian near 0149 UT, 14-Oct or 2149 EDT tonight. Io transit ended near 2353 UT tonight so when I viewed, Io very close to Jupiter's limb, < 20 arcseconds. Many cloud bands visible on Jupiter, the NEB and SEB, along with some others tonight. At Saturn, I could see some cloud bands, rings, and the moon Titan distinct. When observing the Moon, many craters along terminator line or near the terminator line like Archimedes visible, excellent details visible. After a period of clouds and light rain, this was enjoyable to view the Moon, Jupiter, and Saturn tonight. I used a Moon filter when observing the Moon. The Moon’s angular size tonight according to Virtual Moon Atlas, 31.94 arcminutes. The 4 Galilean moons were visible at Jupiter and the moon Titan visible at Saturn. Along with our Moon, that makes 6 moons viewed tonight. Jupiter retrograde in Capricornus, Saturn retrograde ended 11-Oct-2021 according to Starry Night.]

You must be logged in to post a comment.

Image of mary beth

mary beth

October 17, 2021 at 1:02 am

Hello Rod, I am glad you finally got some clear skies, sounds like you made good use of the night and you caught up pretty well, especially lunar-wise. Most of the nights have been clear here in the past for five days. The first quarter moon was beautiful and I watched it until it set. The color with gorgeous. I’ve also been enjoying watching Venus and Antares draw closer. Antares and Arcturus were sparkling beautifully, we had very low humidity. I saw Aldebaran in the East a couple of days ago and it took me by surprise. It was gorgeous and had a very distinct red color. The planets have certainly made this an interesting season!

You must be logged in to post a comment.

Image of padmanva


October 17, 2021 at 3:53 am

Hi. I'm new to this so forgive me for any ignorance. I've just started observing the skies and with the naked eye probably saw the conjunction of moon, Jupiter & Saturn yesterday night 16th October, 2021 at 9.30pm ist. Is there a way to upload the pic?

You must be logged in to post a comment.

Image of Monica Young

Monica Young

October 18, 2021 at 8:56 am

Absolutely, you can share astrophotos here: https://skyandtelescope.org/communities/online-gallery/

You must be logged in to post a comment.

Image of Rod


October 17, 2021 at 10:13 pm

mary beth, good stargazing report and viewing Venus along with Antares. Where I stand in my pastures, about 150 yards away is a tree line that blocks objects like Venus near 15 degrees or lower in SW sky. I can see Venus if I go farther away into another large pasture area nearby. Tonight I spent a bit more than an hour looking at the Moon, Jupiter, and Saturn. Here is my report 🙂 [Observed 2000-2100 EDT/0000 UT - 0100 UT. Full Moon 20-Oct-2021 1457 UT. Tonight I viewed using the 90-mm refractor with 14-mm eyepiece and 1.8x Barlow lens. Moon filter used for viewing the Moon and Jupiter. 129x views very good with true FOV ~ 33.6 arcminutes. The Virtual Moon Atlas shows the Moon's angular size 30.81 arcminutes. Virtual Moon Atlas, Starry Night, and Stellarium indicated the Moon's distance ~ 387800 km. The telescope resolved ~ 2.33 arcseconds so the angular size on the Moon ~ 4.4 km diameter craters could be viewed. I enjoyed lunar craters, Aristarchus, Herodotus, Kepler, Copernicus, and Byrd in the northern limb. Kepler and Copernicus craters, many lunar rays visible. At Jupiter the cloud bands visible along with the 4 Galilean moons. Even using the Moon filter, I could see plenty of cloud bands on Jupiter, so I did not need to remove the filter when switching between Jupiter and the Moon views. At Saturn, the rings, Cassini division visible, some cloud bands, and Titan moon visible. < 4 arcminutes angular separation from Saturn in the FOV was the star TYC6338-789-1. Starry Night shows apparent magnitude + 10.25. Stellarium reports the same. SIMBAD portal reports the star name is HD 196311 also. Apparent magnitude 10.073. Stellar parallax 4.5495 mas and spectral type F3/5V D. The star's distance ~ 717 LY or close to 220 pc. Earlier in the evening while viewing the Moon, altocumulus clouds passed by providing an ethereal view in the telescope. A lovely time observing tonight under the bright, waxing gibbous moonlight all around the pastures, and woods. Winds from the west near 8 knots, temperature 11C with mostly clear skies.]

You must be logged in to post a comment.

Image of Rod


October 18, 2021 at 8:16 pm

mary beth post prompted me to view early this evening, shortly after sunset. Very lovely skies here now with NW winds 6 knots and temperature 14C when I was out. Observed 1845-1915 EDT/2245-2315 UT. Sunset 1824 EDT/2224 UT. Full Moon 20-Oct-2021 1457 UT. I used unaided eyes and 10x50 binoculars. Lovely evening with the Moon rising, Jupiter, Saturn, Venus, and Antares visible. 3 planets tonight along the ecliptic and the Moon. Antares visible below Venus in SW sky. Venus and Antares fit into the 10x50 binocular FOV.

You must be logged in to post a comment.

Image of mary beth

mary beth

October 19, 2021 at 11:34 am

Hi Rod! i’m glad you went out and enjoyed some early evening stargazing. I realize you are kind of a late night/early morning sky guy. I wish I had a situation where I could be outside a few hours before dawn. But I would have to go away from my house to really be able to see things well. I’m enjoying the earlier darkness for that reason. I read your first post and I really did not know the moon had so many named craters.

I’ve been thoroughly enjoying Antares and Venus. We’ve only had one cloudy night while they have been doing their little dance so I was able to catch most of it. Probably my imagination but Antares seemed extra vibrant. At any rate it was definitely truly the ‘rival of mars’ this month!

Don’t forget to keep your eye on Arcturus, it gets real spooky this time of year!!

You must be logged in to post a comment.

You must be logged in to post a comment.