This Week’s Sky at a Glance, October 1 – 9

Nova Cassiopeiae 2021 was again all the way down to magnitude 7.7 as of October 1st, and it might be reddening once more. Charts and comparison stars.


■ Vega is the brightest star simply west of the zenith after darkish this week. Face west, crane your head up, and look to Vega’s proper by 14° (practically a fist and a half at arm’s size) for 2nd-magnitude Eltanin, the nostril of Draco the Dragon. The remainder of Draco’s fainter, lozenge-shaped head is a little farther behind. Draco all the time eyes Vega as they wheel across the sky.

The predominant stars of Vega’s personal constellation, Lyra — faint by comparability — prolong to Vega’s reverse aspect by half so far as the space from Vega to Eltanin.

■ Bright Jupiter and fainter Saturn proceed to dominate the southeast to south these evenings, 16° aside.

Look higher proper of Saturn, by 6° or 8°, for Third-magnitude Alpha and Beta Capricorni. Both are binocular double stars. Alpha, the higher one, is a vast pair of yellow-orange giants that the smallest binoculars simply resolve. The parts of Beta are considerably tougher; they’re half as far aside and rather more unequal. They’re oriented roughly the identical way because the Alpha pair. For extra on these stars and their environment, see “Capricious Capricornus” within the the October Sky & Telescope, web page 45.

■ Tonight Jupiter’s Great Red Spot ought to cross Jupiter’s central meridian round 9:54 p.m. EDT. The Red Spot stays nearer to the central meridian than to the planet’s edge for 50 minutes earlier than and after it transits.

■ Before and through early daybreak Saturday morning October 2nd, look under the crescent Moon by about a fist at arm’s size for Regulus. It’s the forefoot of Leo, who’s already making his early-apparition daybreak arrival as proven under.

Leo proclaims spring when he is on the rise within the early-evening sky. But Leo’s rise within the east at the start of daybreak? That proclaims October.


■ During night, look simply above the northeast horizon — far under excessive Cassiopeia — for brilliant Capella on the rise. How quickly Capella rises, and the way excessive you may discover it, rely in your latitude. The farther north you might be, the earlier and better.

■ Vega is the brightest star very excessive within the west, whereas Arcturus is getting low within the west-northwest. The brightest star within the huge expanse between them, about a third of the way from Arcturus up towards Vega, is Alphecca, magnitude 2.2 — the crown jewel of dim Corona Borealis. Alphecca is a 17-day eclipsing binary, however (like most variable stars!) its brightness dips are too slight for the attention to see reliably.

■ Before and through early daybreak Sunday morning October Third, the waning crescent Moon varieties a flat, nearly isosceles triangle with Regulus and Algieba (Gamma Leonis) to Regulus’s left or higher left, as proven above (for North America).


■ Globular clusters are at their most ample on summer time evenings. In this primary week of October, with moonlight gone from the night sky, arrange your telescope to look in on 4 that Josh Urban calls The Last Wildflowers: Globular Clusters Greet Autumn. There’s “Sagittifolia,” the Arrowhead Flower M71 in Sagitta; “Queen Anne’s Lace,” M15 sneezed from the nostril of Pegasus; “Watercress by the Stream,” M2 in Aquarius a little farther south; and “Seaflower of the Deep,” M30 in Capricornus down under Jupiter.


■ Jupiter’s moon Io enters onto the planet’s face at 9:19 p.m. EDT, adopted by its tiny black shadow one hour later. Io leaves Jupiter’s western aspect at 11:36 p.m. EDT, once more adopted by its shadow an hour later. See the “Action at Jupiter” timetables for the entire month, good worldwide, within the October Sky & Telescope, pages 50-51.


■ Arcturus shines within the west in late twilight these evenings. Capella, equally brilliant, is arising within the north-northeast (relying in your latitude; the farther north you’re the increased it is going to be). They’re each magnitude 0.

Later within the night, Arcturus and Capella shine at equal heights of their respective compass instructions. When will this occur? That is dependent upon each your latitude and longitude.

When it does, flip round and look low within the south-southeast. There will probably be 1st-magnitude Fomalhaut at the about similar peak too — precisely so for those who’re at latitude 43° north (concerning the latitude of Boston, Buffalo, Milwaukee, Boise, Eugene). Seen from south of that latitude, Fomalhaut will seem increased than Capella and Arcturus are. Seen from north of there, it is going to be decrease.


■ Now that it is October, Deneb has changed Vega because the zenith star of early darkish night (for skywatchers at mid-northern latitudes). Accordingly, Capricornus has changed Sagittarius because the zodiacal constellation low within the south. This year, in fact, Capricornus is overwhelmed by its two brilliant short-term residents: Jupiter and Saturn.

■ New Moon (actual at 7:05 a.m. EDT).


■ The Great Square of Pegasus balances on its nook excessive within the east by a lot of the night. Away from the Great Square’s left nook extends the primary line of Andromeda, three 2nd-magnitude stars about as brilliant as these of the Square and spaced equally far aside. (The three embody the Square’s nook.) This entire dipper-shaped sample was named the Andromegasus Dipper by the late Sky & Telescope columnist George Lovi becoming a member of the Big and Little Dippers, the Milk Dipper of Sagittarius (these days normally subsumed into the Teapot), and the tiny dipper sample of the Pleiades.


■ Spot Venus low within the southwest as early in twilight as you possibly can. Then look decrease proper of it by some 12° (about a fist at arm’s size) for the skinny crescent Moon. Binoculars assist.

If you discover the best time of compromise between the sky nonetheless being too brilliant and the Moon sinking too low, you must get a effective view of earthshine dimly lighting the Moon’s nightlands contained in the crescent. And the Moon is at perigee right this moment, so it is going to seem a hint bigger than common: a supercrescent moon.


■ Now the Moon shines solely about 3° above Venus in twilight (for North America), simply whereas Venus is passing ¾° decrease left of 2nd-magnitude Delta Scorpii, as proven under. Bring binoculars.

Crescent Moon with Venus in the head of Scorpius, Oct. 9, 2021
Set your calendar for nightfall on the ninth to catch the Moon together with Venus whereas Venus is in nearer conjunction with Delta Scorpii. Bring your binoculars.



This Week’s Planet Roundup

Mercury and Mars are out of sight together with the Sun.

Venus, sensible at magnitude –4.3, shines low in southwest throughout twilight, in Libra. It units a little after twilight’s finish.

Look to Venus’s left as twilight deepens for orange Antares in Scorpius. Between them for a lot of the week is Delta Scorpii, not an excessive amount of fainter than Antares. Binoculars will enable you to pick each stars within the deepening blue.

Watch Venus shut in on Delta Sco daily. They cross simply ¾° aside on October ninth, with the skinny crescent Moon proper shut by as proven above. A week afterward the sixteenth, Venus will cross 1½° above Antares.

Jupiter and Saturn proceed to shine within the southeast to south throughout night, 16° aside on reverse sides of dim Capricornus. Jupiter is the eye-grabber at magnitude –2.7. Saturn, to its proper, is a twentieth as brilliant at magazine +0.5.

By the tip of twilight they sit equally excessive within the south-southeast. As night progresses watch them tilt to the proper, with Saturn the decrease one. Saturn units round 1 or 2 a.m. daylight-saving time, adopted by Jupiter about an hour later.

After darkish look 23° (two fists at arm’s size) decrease left of Jupiter for 1st-magnitude Fomalhaut. About 2° decrease left of Jupiter, spot Third-magnitude Delta Capricorni.

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

Uranus (magnitude 5.7, in southern Aries) climbs excessive within the east by 11 or midnight.

Neptune (magnitude 7.8, at the Aquarius-Pisces border) is already properly up within the within the southeast by the point darkness is full.

All descriptions that relate to your horizon — together with the phrases up, down, proper, and left — are written for the world’s mid-northern latitudes. Descriptions that additionally depend upon longitude (primarily Moon positions) are for North America.

Eastern Daylight Time, EDT, is Universal Time minus 4 hours. Universal Time is also referred to as UT, UTC, GMT, or Z time. To develop into extra knowledgeable about time programs than 99% of the folks you may ever meet, see our compact article Time and the Amateur Astronomer.

Want to develop into a higher astronomer? Learn your way across the constellations. They’re the important thing to finding all the things fainter and deeper to hunt with binoculars or a telescope.

This is an outside nature passion. For an easy-to-use constellation information protecting the entire night sky, use the massive month-to-month map within the heart of every subject of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you may want a detailed, large-scale sky atlas (set of charts). The primary normal is the Pocket Sky Atlas (in both the original or Jumbo Edition), which exhibits stars to magnitude 7.6.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and a whole bunch of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in exhausting covers and enlarged for simpler studying outdoor by red flashlight. Sample charts. More about the current editions.

Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; practically thrice as many. The subsequent up, as soon as you realize your way round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And you should definitely learn How to Use a Star Chart with a Telescope.

You’ll additionally need a good deep-sky guidebook, reminiscent of the massive Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for learners, I do not suppose, and never on mounts and tripods which might be lower than top-quality mechanically, that means heavy and costly. And as Terence Dickinson and Alan Dyer say of their (*9*), “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 beneath the night sky together with your
earbuds in place, hearken to Kelly Beatty’s month-to-month
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

Leave a Comment

Your email address will not be published. Required fields are marked *

Shopping Cart