(10/2021) For October 2021, the crescent moon wanes in the dawn until new moon on October 6th. It makes a striking pairing with brilliant Venus in the dusk on the weekend of October 8-9. The star close to Venus is delta Scorpii, the north claw of Scorpius. Note the earthshine for a nice photo with even your smartphones! The moon is first quarter on October 12th, and just south of Saturn on the next evening. It passes below bright Jupiter on October 14-15. The full moon for October, the Hunter’s Moon, is on October 20th, so alas, no moon for the pumpkin patch this Halloween! In fact, the last quarter moon will rise about midnight on the 28th, and will be a waning crescent in the dawn on Halloween morn.

We can’t see Mercury well this month, being too close to the Sun, but Venus dominates the evening skies for the rest of 2021. It passes 1.4 degrees north of Antares in Scorpius on October 14th, and moves into Sagittarius by month’s end. Telescopically it is a bright waning gibbous disk, with no details in its cloud deck, alas. Mars, like Mercury, lies too close to the Sun now. But Jupiter and Saturn are still well placed for fall sky observers. They lie at opposite ends of Capricornus, in the SE. Saturn’s fine rings are still well open and spectacular in the head of the sea goat. Jupiter is much brighter, right above the tail our sea goat. Its four huge moons are visible even in binoculars, and belts, zones, and famed Great Red Spot make a constantly changing tableau for large scopes. Yet another comet or asteroid fit it on September 14th, creating a video record of two second flash near the center of the disk…always the promise of excitement!

While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere skies visit the www.skymaps.com website and download the map for October; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. Also available as the next month begins is wonderful video exploring the October 2021 sky, available from the Hubble Space Telescope website at: http://hubblesite.org/explore_astronomy/tonights_sky/.

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.

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 South East 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 North West. 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 North East now. Her daughter, Andromeda, starts with the NE corner star of Pegasus’’ Square, and goes North East with two more bright stars in a row. It is from the middle star, beta Andromeda, that we precede 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 about 2.5 million light years distant. It is a bigger version of our own Galaxy, which it may collide with about three billion years from now. Note companions, M-32 near left center, and M-110 at bottom right.

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, with the larger, cooler orange star covering 80% of its smaller, hotter neighbor during the "wink". 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.

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.