For October 2023. The waning gibbous moon rises just north of bright Jupiter on October 1st, about 9 p.m.. The last quarter moon is on October 6th. The waning crescent moon passes just above brilliant Venus, with the star Regulus in Leo sandwiched between them (great photo op!).
The big event is of course the partial solar eclipse at new moon on Saturday, October 14. The eclipse begins at 10:41 a.m. 70% of the Sun will be covered about noon, and the moon leaves the sun’s disk about 1:50 p.m.. You will need to use safe filters, such as eclipse viewers, to visually or photographically observe this event.
But farther west, in Texas and New Mexico, the moon will pass directly in front of the Sun. But this time it is not a total eclipse, since the moon is near apogee in its orbit, too distant and small to over the whole sun. Next April 8, the closer moon will give much of the central US up to four minutes of totality. As about 10% of the Sun is still visible round the rim of the moon, this ring of fire is called an annular solar eclipse.
The most dramatic of all is the broken annular eclipse, such as Merry photographed on May 30, 1984, then the sizes match so closely that only tiny bits of sunlight (Bailey’s Beads) leak through the lunar valleys, while the rest of the Sun was blocked. This perfect alignment only lasted eleven seconds, so Merry was delighted to take this shot that made the cover of the Astronomical League’s Reflector magazine in June 1984.
Mercury lies too close to the Sun for visibility from Earth this month. Venus by contrast is at its greatest brilliancy as a waxing crescent in the dawn as October begins. It reaches greatest elongation west of the Sun on October 23rd at 48 degrees in front of the rising sun. On the edge of her orbit, Venus will then appear exactly half lit. Mars is now lost behind the Sun as well. Jupiter and Saturn are both well placed for evening observing. Jupiter reaches opposition in early November, and rises about 10 PM in the northeast in Taurus at midmonth. But Saturn is well up in the SE at sunset in Capricorn. Its rings are now tilted about six degrees to our line of sight, and closing become edge on at its equinox in May 2025, almost invisible from earth for weeks.
The Big Dipper falls lower each evening. By the end of October, it will be only the three stars in the handle of Dipper still visible in the northwestern twilight. By contrast, the Little Dipper, while much fainter, is always above our northern horizon here along the Gulf Coast.
To the southwest, Antares and Scorpius also set soon after twilight, and will be gone by month’s end. East of the Scorpion’s tail is the teapot shape of Sagittarius, which marks the heart of our Milky Way galaxy. Saturn lies above of the pour spout now. Looking like a cloud of steam coming out of the teapot’s spout is the fine Lagoon Nebula, M-8, easily visible with the naked eye.
The brightest star of the northern hemisphere, Vega dominates the sky overhead. To the northeast of Vega is Deneb, the brightest star of Cygnus the Swan. To the south is Altair, the brightest star of Aquila the Eagle, the third member of the three bright stars that make the Summer Triangle so obvious in the NE these clear autumn evenings. To the east of Altair lies tiny Delphinus, a rare case of a constellation that does look like its namesake.
To the south, Saturn is in the head of Capricornus, and Jupiter above its tail. Aquarius and Pisces are among the faintest of the zodiacal constellations, and need dark skies to pick out. Fomalhaut is the only first magnitude star of the SE fall sky, and stands alone above the SE horizon now.
To the east, the square of Pegasus is a beacon of fall. If the southern skies of Fall look sparse, it is because we are looking away from our Galaxy into the depths of intergalactic space. The constellation Cassiopeia makes a striking W, rising in the NE as the Big Dipper sets in the NW. Polaris lies about midway between them. She contains many nice star clusters for binocular users in her outer arm of our Milky Way, extending to the NE now. Her daughter, Andromeda, starts with the NE corner star of Pegasus’’ Square, and goes NE with two more bright stars in a row. It is from the middle star, beta Andromeda, that we proceed about a quarter the way to the top star in the W of Cassiopeia, and look for a faint blur with the naked eye. M-31, the Andromeda Galaxy, is the most distant object visible with the naked eye, lying 2.5 million light years distant.
Look closely at this superb star city. Bigger than our own Milky Way, it too has companions like our own Large and Small Magellanic Clouds. The one closest to it, M-32, lies above the core in this shot, while larger M-110 lies to the left of the disk here. All three are visible in small telescopes. The core appears redder, due to aging population II stars near its core, but the outer regions are rejuvenated by continuous star birth of bright population I is the hot pink H-II regions that outline the leading edges of the spiral arms. Because we see this great galaxy almost edge on (as it would also see US), we also note the dark clouds of gas and dust mixed among the spiral arms and providing the fuel that make new stars (and with the dark carbon dust) and new life (?) form in the H-II regions. All the critical elements and basic amino acids needed for life here have ben found in these stellar nurseries, so the building blocks of
us are indeed out there. It is moving toward us, and may sideswipe our smaller spiral in perhaps three billion years, so be sure your galactic collision insurance is paid up now.
South of M31 is the other great spiral in our Local Group of Galaxies. M-33 in Triangulum is seen from a higher viewing angle, so the spiral arms are even more striking. It too is about three million light years distant. About 50 smaller elliptical and irregular galaxies accompany the three big spirals in our own cluster of galaxies.
Below the head of Pegasus is Aquarius, the Water Carrier. Below his western foot is the only bright star of the southern fall sky, Fomalhaut. It means the "mouth of the fish", and carries on the watery grouping of Pisces the Fish (home to Jupiter now), Capricornus the sea goat (with Saturn in its tail), Cetus the Whale in the SE, and Grus the Crane due south now.
Below Andromeda is her hero, Perseus. In his hand is a star most appropriate for Halloween, Algol. This star "winks" at us for six out of every 70 hours, which Arabic astronomers centuries ago found spooky, hence naming it "the ghoul". We know today it is an eclipsing binary system, an orange giant covering most of its blue companion.
At the foot of Perseus, the hero of "Clash of the Titans" is the fine Pleiades star cluster, the "seven sisters" that reveal hundreds of cluster members in large binoculars. This might be the best object in the sky for binocular users. The giant planet Jupiter now sits just west of this famous group in early evenings.
Winter will be coming soon, and in the NE we see yellow Capella rising. It is the brightest star of Auriga the Charioteer, and pair of giant stars the same temperature as our sun, but at least 100X more luminous and about 10X larger than our sun. It lies about 43 light-years distant. A little farther south, below the Pleiades, orange Aldebaran rises. It is the eye of Taurus the bull, with the V shaped Hyades star cluster around it making the head of the bull. This colorful giant star is only 2/3 as hot as our yellow sun, but 44X times larger and at 65 light years distant, one of the closest of these monster stars.
