This Week's Sky at a Glance, September 30 – October 8

FRIDAY, SEPTEMBER 30

■ At dusk this evening the crescent Moon shines in the southwest only about 2° from Antares (for North American viewers), as shown below. As always, the Moon's configuration with stars nearby may differ a bit depending on your location and time.

SATURDAY, OCTOBER 1

■ The waxing Moon hangs in the southwest as twilight fades to darkness, off the left edge of the chart above. Use binoculars to look 10° below the Moon, and perhaps a bit left, for what will probably be your last sighting this year of the Cat's Eyes, the attractive pair of stars in the tail of Scorpius. At this late date the Cat's Eyes are tilted even more than usual, with the fainter one lower right of the brighter one. They're 0.6° apart.

Left of the Moon is the Sagittarius Teapot, also tilting ever further.

SUNDAY, OCTOBER 2

■ First-quarter Moon (exact at 8:14 p.m. EDT). The Moon shines inside the Sagittarius Teapot at about the farthest southern declination we can ever see it. Use binoculars to pick out the Teapot's stars through the moonlight if you need. Note: The Teapot is 14° wide, at least twice as wide as most binoculars' fields of view. So sweep around a bit.

MONDAY, OCTOBER 3

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

TUESDAY, OCTOBER 4

■ The Moon is two days day past first quarter. Which means its moving terminator has unveiled the unique Straight Wall, a giant fault crossing Mare Nubium casting a stark, linear black shadow. Explore it and its surroundings with Chuck Wood's "Exploring the Moon" article and photos in the October Sky & Telescope, page 52.

WEDNESDAY, OCTOBER 5

■ Vega is the brightest star very high toward the west these evenings. Face west and look way up.

To Vega's right or lower right by 14° (nearly a fist and a half at arm's length), look 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 at 3rd and 4th magnitude — extend to Vega's left by half as far as the distance from Vega to Eltanin.

■ Jupiter's Great Red Spot should transit Jupiter's central meridian (the line down the middle of its disk from pole to pole) around 11:10 p.m. EDT; 8:10 p.m. PDT. The spot should be visible almost as easily for about an hour before and after, in a good 4-inch telescope if the atmospheric seeing is sharp and steady.

Jupiter rotates fast; the Red Spot transits about every 9 hours 56 minutes. But not quite like clockwork! It drifts east or west in Jupiter's atmosphere somewhat irregularly. A change often becomes detectable to visual transit timers over a span of some months. Our transit-time predictions are based on fairly recent observations, but don't be surprised if the Red Spot has taken it into its head to move several minutes off schedule.

THURSDAY, OCTOBER 6

■ Vega is the brightest star very high in the west at nightfall. Arcturus, equally bright, is getting low far beneath it. The brightest star in the vast expanse between them, about a third of the way from Vega down to Arcturus, is Alphecca, magnitude 2.2, the crown jewel of Corona Borealis. Alphecca is a 17-day eclipsing binary, but its brightness dips are too slight for the eye to see reliably.

FRIDAY, OCTOBER 7

■ Perseus is up in the northeast after dark now, including the eclipsing variable star Algol, Beta Persei. This evening Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.3, for a couple hours centered on 11:12 p.m. EDT; 8:12 p.m. PDT. Algol takes several additional hours to fade and to rebrighten. Comparison-star chart.

■ Mercury is beginning its best week of 2022 as a dawn object. On Saturday morning look for it low due east about 60 to 40 minutes before your local sunrise, as shown below.

SATURDAY, OCTOBER 8

■ The Moon and Jupiter cross the sky together tonight. They start in the east-southeast, as shown below.

This Week's Planet Roundup

Mercury this week is on its way to a good morning showing. Look for it very low due east as dawn brightens. Binoculars help. Mercury brightens rapidly, from magnitude +1.0 to –0.5 from October 2nd through 9th. That's a four-fold increase in brightness.

Venus is lost much lower in the sunrise.

Mars, magnitude –0.7 in eastern Taurus, clears the east-northeast horizon around 10 p.m. and gains altitude for the rest of the night. Mars is four times as bright as Mars-colored Aldebaran, magnitude +0.9, sparkling to its upper right. Look a similar distance above Aldebaran for the Pleiades.

Mars is 12 arcseconds in diameter and growing. The best time to observe it telescopically is before dawn when it's highest. Mars will be 17.2 arcseconds across when closest to Earth on December 1st.

Jupiter is just past its opposition on September 26th. As twilight fades, spot it glaring low due east. After dark Jupiter dominates the east, blazing at magnitude –2.9 in dim Pisces. It climbs higher across the southeast and stands at its highest in the south around midnight.

In a telescope Jupiter is still a remarkable 49 or 50 arcseconds wide across its equator, its maximum possible; Jupiter this season is very close to the perihelion of its 12-year orbit around the Sun. See Jupiter's Exceptionally Close Opposition by Bob King.

Saturn, magnitude +0.5 in dim Capricornus, glows in the south these evenings. It's about four fists to the right of Jupiter at the end of twilight, and lower right of Jupiter as evening grows late. Saturn is highest due south around 9 or 10 p.m.

Uranus, magnitude 5.7 in Aries, is up in the east in good binocular or telescope view by late evening. See the Uranus finder charts in the November Sky & Telescope, page 49.

Neptune, magnitude 7.8 at the Aquarius-Pisces border, is about 10° west of Jupiter. See the Neptune finder charts in the September Sky & Telescope, page 49.

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 and graphics 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 called UT, UTC, GMT or Z time.)

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.

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. It applies just as much to charts on your phone or tablet as to charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) 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