Skywatcher's Guide: October and November 2023

Skywatcher's Guide written by: Lucas Snyder (Flandrau Planetarium Technician)



Stars and Constellations

In October, only a small portion of the spring sky is still visible at the beginning of the night.  The Big Dipper (Ursa Major) is low in the north-northwest.  As always, the last two stars in the bowl point to Polaris, our north star, in the Little Dipper (Ursa Minor).  You can also still follow the arc of the handle of the Big Dipper to Arcturus, the bright star in Boötes, now low in the west-northwest.  The summer constellations are also visible for a good portion of the night, starting the night in the middle of the sky.  The Summer Triangle is almost directly overhead, with Vega closest to the west-northwest, Deneb closest to the northeast, and Altair closest to the south.  The summer Milky Way is still prominently streaking across the sky, cutting from the northeast to the southwest.  Scorpius with the bright star Antares is now getting low in the southwest, and the nearby "teapot" of Sagittarius in the south-southwest.  The fall sky is now very prominent, taking up most of the eastern sky at the beginning of the night.  The "W" of Cassiopeia is easy to spot in the northeast, with Perseus just below.  The Great Square of Pegasus is up in the east, and Andromeda nearby in the east-northeast.  There is also a fairly bright star called Fomalhaut in the southeast, though its constellation Piscis Austrinus is not easy to distinguish.

In November, all but a few of the spring stars are now gone, and the summer constellations are starting to get lower in the west.  Deneb is the highest point of the Summer Triangle, with Vega below to the west, and Altair towards the southwest.  The brightest part of the summer Milky Way is now gone, but a good portion of it is still easy to distinguish.  Scorpius is now gone, but the "teapot" of Sagittarius is still above the horizon in the southwest.  The fall sky is now a little higher, but still in the eastern half of the sky.  We can now begin to see a few winter stars coming up along the eastern horizon, namely the bright Capella in the northeast and Aldebaran in the east-northeast.  Also look for the Pleiades (aka the Seven Sisters or Subaru) star cluster just above Aldebaran.

Interesting Stars Visible in October and November (between 7 and 10 pm)

Name / Designation Apparent Magnitude
(lower = brighter)
Arcturus -0.05 36.7  
Vega 0.03 25  
Capella 0.08 42  
Rigel 0.18 770  
Betelgeuse 0.45 427  
Altair 0.76 17  
Aldeberan 0.87 65  
Pollux 1.16 38  
Fomalhaut 1.16 25  
Markab 1.25 140  
Deneb 1.25 3230  
Castor 1.58 52  
Polaris 1.97 431  
Alpheratz or Sirrah 2.07 97  
Mirach 2.07 199  
Algol 2.09 93 variable star
Enif 2.38 670  
Almak 2.1 / 5.0 & 6.3 355  triple star system w/ 64 yr orbit
Albireo 3.2 / 5.8 & 5.1 390 / 380  possibly a triple star system
Eta Cassiopeiae 3.5 / 7.4 19 480 yr orbit

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Solar System

Mercury slips out of view in the morning sky in early October and passes behind the Sun later in the month.  It then re-emerges in the evening sky in early-mid November and remains visible for the rest of the month.

Venus is easily visible in the morning sky throughout October and November as it reaches its largest angle from the Sun in late October.

Mars might still be visible in the evening sky in early October but soon becomes lost in the Sun's glare as it will be passing behind the Sun in November.

Jupiter is in Aries, coming up in the early evening during October and eventually rising before sunset in early November.

Saturn is in Aquarius, starting the night in the southeast in early October but gradually making its way to the southwest by the middle of November.

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Jupiter Great Red Spot Transits visible during October and November (between 7 and 10 pm)

Note: The GRS is visible on the disk of Jupiter for 50 minutes before and after meridian transit time.

Date Meridian Transit Time
10/02/23 08:54 PM
10/09/23 09:39 PM
10/14/23 08:46 PM
10/19/23 07:53 PM
10/21/23 09:31 PM
10/26/23 08:37 PM
10/31/23 07:44 PM
11/02/23 09:22 PM
11/07/23 08:29 PM
11/12/23 07:37 PM
11/14/23 09:15 PM
11/19/23 08:22 PM
11/21/23 10:00 PM
11/24/23 07:29 PM
11/26/23 09:07 PM

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Calendar of Night Sky Events

Date Event
10/06/23 Last Quarter Moon.
10/14/23 New Moon and Annular Solar Eclipse. — Partially visible from Tucson. Learn more!
10/19/23 Mercury at superior conjunction. — Passing behind the Sun.
10/21/23 Peak of Orionids meteor shower.
10/21/23 First Quarter Moon.
10/23/23 Venus at greatest western elongation. — Visible in the morning sky.
10/28/23 Full Moon and Partial Lunar Eclipse. — Not visible from Tucson.
10/29/23 Appulse of Mercury and Mars. — Separated by 0.3°.
11/02/23 Jupiter at opposition. — Best time to see our largest planet.
11/05/23 Last Quarter Moon.
11/05/23 Peak of Southern Taurids meteor shower.
11/13/23 New Moon.
11/13/23 Uranus at opposition. — Best time to see this gas giant.
11/17/23 Mars at conjunction. — Passing (directly) behind the Sun.
11/17/23 Peak of Leonids meteor shower.
11/20/23 First Quarter Moon.
11/27/23 Full Moon.

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Deep Sky

There are many deep sky objects we can see since the summer Milky Way is high in the sky.  There are many open star clusters that can be seen with only binoculars scanning this part of the sky.  For example we have the Butterfly Cluster (M6) and Ptolemy's Cluster (M7) near the tail of Scorpius.  Further north there is the Wild Duck Cluster (M11) in the faint constellation of Scutum between Sagittarius and Aquila.  There is also the asterism of the Coathanger between Aquila and Cygnus in the fainter constellation of Vulpecula.  Next, heading towards the west we can see the Coma Star Cluster in the constellation of Coma Berenices, which is even visible naked-eye.  The Pleiades (M45) will be visible later in the night, after midnight.

There are a several globular clusters we can see as well, as the center of our galaxy is the highest it gets for the year.  Near the bright star Antares in Scorpius lies the globular cluster M4.  In Sagittarius we also have the Teapot Cluster (M22).  Of course we have the famous Hercules globular (M13) high in the east.  Also, M15 is visible in the east near the head of Pegasus.

For nebulae, we have several in the plane of the galaxy, one of which is the Swan Nebula (M17) in Sagittarius, also known as the Omega Nebula.  There is also the Lagoon Nebula (M8) nearby and the North America Nebula (C20) further north in Cygnus.  For planetary nebulae we have the Ring Nebula (M57) in Lyra, the Dumbell Nebula (M27) in Vulpecula, and the Blue Snowball (C22) in Andromeda.

And now the galaxies:  Although the Big Dipper is getting lower in the sky, you may still be able to find some of the galaxies in this part of the sky.  We have the Whirlpool Galaxy (M51) and the Pinwheel Galaxy (M101) near the handle, and the Cigar Galaxy (M82) and Bode's Galaxy (M81) near the bowl.  The spectacular Andromeda Galaxy (M31) is now coming up in the northeast, along with the nearby Triangulum Galaxy (M33).

Interesting Deep Sky Objects to Observe during October and November (between 7 and 10 pm)

Designation Name Apparent Magnitude Apparent Size Distance
Messier 45 Pleiades 1.6 110' 440 open cluster
Messier 31 Andromeda Galaxy 3.4 3° x 1° 2,900,000 spiral galaxy
Messier 42 Orion Nebula 4 85' x 60' 1400-1600 diffuse nebula
Messier 33 Triangulum Galaxy 5.7 67' x 42' 3,000,000 spiral galaxy
Messier 3 (in Canes Venatici) 6.2 18' 34,000 globular cluster
NGC 7293 Helix Nebula 7.3 16' 450 planetary nebula
Messier 27 Dumbbell Nebula 7.4 8' × 6' 1,250 planetary nebula
NGC 7009 Saturn Nebula 8 36" 2,400 planetary nebula
Messier 81 Bode's Galaxy 8.5 21' 1,200,000 spiral galaxy
Messier 57 Ring Nebula 8.8 1' 2,300 planetary nebula
Messier 82 Cigar Galaxy 9.5 14' 1,200,000 galaxy

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Frequently Asked Questions

How many stars are there?

Have you ever tried to count the stars?  Where do you even begin?  Especially if you are looking at the sky from a dark location, there are way too many to keep track of.  And beyond what our eyes can see there are countless stars in other galaxies throughout our universe.  But even though there is no way to come to an exact number, we are able to make estimates based on what we can see.

First, the number of stars you can see with your naked eye depends on how dark your location is.  If you're in a big city you may not be able to see more than a handful of the brightest stars, but from a very dark location there are probably somewhere between three to four thousand above the horizon at any given time.

Our home galaxy, the Milky Way, is estimated to contain around 200 billion stars.  Even though we haven't gone very far in the scale of the universe, this is already beyond what we can see with our telescopes.  We've been able to catalog maybe a billion stars at most due to the dust, gas, and other stars that block our view of the rest of the galaxy.  But we can figure out the mass of our galaxy by other means and therefore make an educated guess as to how many stars there are.

As we start to move farther out in our universe the number of stars quickly goes up.  There are estimated to be a couple trillion galaxies in our visible universe (the part of our universe that we could ever hope to detect through even the most sophisticated telescopes).  Our Milky Way is a little bigger than the average-sized galaxy, but even a rough calculation tells us that there are at least a sextillion stars in our visible universe.  That's a one with 21 zeroes after it!

Finally, if we try to consider the entire universe, not just the visible portion, that number might go up to infinity.  We don't know if the universe is finite or if it goes on forever in all directions.  And we assume that the universe is fairly uniform in terms of density at large scales, but there's no way for us to verify that.

It's humbling to think about how little we can actually see compared to the full expanse of the universe.  When you look up at the stars at night, just remember that you're only seeing the tip of the iceberg, and the universe is vastly bigger than we can even imagine.

If you have any questions you'd like me to answer in the next issue of SWG, please let me know.  I'm also happy to take suggestions or comments, and also pictures if you'd like to send them.  Happy viewing!

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Date of publication: 2023