This Week’s Sky at a Glance, March 19 – 27 – Sky & Telescope


■ The Moon this night shines with Mars and Aldebaran, which look nearly similar as proven beneath.

The waxing Moon shines with Aldebaran and Mars on Friday night the 19th, then between the horn-tips of Taurus on the 20th (for evenings within the longitudes of the Americas).

■ Pollux and Castor in Gemini move practically overhead round 7 p.m. this week for those who dwell on the earth’s mid-northern latitudes. They go smack overhead as seen from close to latitude 30° north: Austin, , the US Gulf Coast, northernmost Africa, Tibet, Shanghai.

The “twin” heads of the Gemini figures are fraternal twins at finest. Pollux is visibly brighter than Castor and pale orange. And as for his or her bodily nature? They are not even the identical species.

Pollux is a single orange big. Castor is a binary pair of two smaller, hotter, white main-sequence stars, a high quality in newbie telescopes. If Pollux have been a basketball, Castor A and B can be a tennis ball and a baseball a few half mile aside.

Furthermore, every Castor star is carefully orbited by an unseen pink dwarf a marble in our scale mannequin with a interval of just some days.

And a really distant shut pair of pink dwarfs, Castor C, is seen in newbie scopes as a single, 10th-magnitude speck 70 arcseconds south-southeast of the primary pair in our scale mannequin, a pair of marbles about three inches aside at the very least 10 miles from Castor A and B.

Learn extra in Fred Schaaf’s “Gemini’s Like and Not like Twins” within the March Sky & Telescope, web page 45.


■ Now the Moon shines between the horn ideas of Taurus, Beta and Zeta Tauri, as proven above. These two stars kind an extended rectangle with Mars and Aldebaran: a short lived asterism particular to mid-March 2021.

■ Earth the March equinox level on its orbit at 5:37 a.m. EDT on this date. This when the Solar crosses the equator (each Earth’s equator and, equivalently, the celestial equator), heading north. Spring within the Northern Hemisphere, fall within the Southern Hemisphere. And no, eggs don’t balance immediately any higher than they normally do, in case somebody tries to inform you that.

, MARCH 21

■ First-quarter Moon. The Moon shines within the ft of Gemini, excessive above Orion in early night.

The brightest asteroid, four Vesta, continues creeping throughout the rear flank of Leo this week at a binocular-easy magnitude 6.1. Use the finder chart with the article about Vesta within the March Sky & Telescope, web page 48.


■ Now the Moon, simply previous first quarter, shines excessive beneath Pollux and Castor in early night. Far beneath the Moon is the large Winter Triangle: Procyon on the left, orange Betelgeuse on the appropriate in Orion’s shoulder, and sensible Sirius beneath them.


■ After darkish look proper of the Moon for Pollux, then Castor. Farther beneath the Moon is Procyon, the Little Canine Star. Even farther beneath Procyon is vivid white Sirius, the unique Canine Star itself.


■ The brilliant gibbous Moon shines higher proper of Leo’s Sickle asterism in early night, as proven beneath. By 10 or 11 p.m. the Moon shines on to the appropriate pf Leo.

And now the waxing gibbous Moon works its throughout Leo, on its to full on the 28th.

■ Algol shines at its minimal brightness in early night, whereas it is nonetheless pretty excessive within the northwestern sky, for the Mountain and Pacific time zones of North America. Its mid-eclipse is predicted for 7:55 p.m. Pacific Daylight Time. In one other month Algol will probably be basically gone for the season.


■ This night the gibbous Moon shines on the Sickle of Leo, roughly between Regulus to its decrease proper and Algieba (Gamma Leonis) to its higher left, as proven above (relying in your location).

■ Additionally this night, a line drawn from Aldebaran by Mars factors straight to Capella far past.


■ Now that spring is beneath method, Orion has taken up his early-spring posture within the southwest throughout night. He is tipping westward, and his three-star Belt is popping horizontal.

When does Orion’s Belt seem precisely horizontal? That is dependent upon the place you reside east-west in your time zone, and in your latitude. Are you able to time this occasion? In case you’re close to your time zone’s commonplace longitude, count on it round 8:40 this night (daylight-saving time). . . roughly.


■ The Moon this night is lower than a day from being precisely absolutely. After darkish, look far to its decrease left, by three or 4 fists at arm’s size, for vivid yellow Arcturus making its method up the jap sky.

By 9 or 10 p.m. daylight-saving time, look two or three fists beneath the Moon for Spica on the rise.

■ In the meantime on the opposite facet of the sky, the signature fall-and-winter constellation Cassiopeia retreats down after darkish. Search for it pretty low within the north-northwest. It is standing roughly on finish.

For skywatchers at mid-northern latitudes and above, Cassiopeia is circumpolar, by no means going away fully. After midnight it is at its lowest due north, mendacity not fairly horizontally.


This Week’s Planet Roundup

Mercury has sunk out of sight into the glow of dawn.

Venus is out of sight at the side of the Solar.

Mars (magnitude +1.2, in Taurus) shines excessive within the west after darkish. Mars is sort of the dual of Aldebaran to its decrease left, in each brightness and in coloration. Mars this week is passing north of Aldebaran, giving it a large 7° berth for a number of days operating. They’re closest (6.9°) on March 20th.

In a telescope Mars is a mere 5½ arcseconds extensive: a tiny vivid blob too small for any floor element.

Jupiter and have been slowly rising into daybreak view for the final three weeks. Look low within the east-southeast about 50 or 40 minutes earlier than your native dawn time. Saturn is the of the 2, nevertheless it’s a lot dimmer at magnitude +0.7. Jupiter shines at magnitude –2.0 (not counting the atmospheric extinction for one thing so low), some 11° to Saturn’s decrease left. That is a few fist at arm’s size.

Uranus (magnitude 5.8, in western Aries) is sinking away low within the west proper after the top of night twilight.

Neptune is hidden within the glare of the Solar.

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.

Jap Commonplace Time, EST, is Common Time minus 5 hours. Jap Daylight Time, EDT, is UT minus four hours. (Common Time is also called UT, UTC, GMT, or Z time. For all of the down-and-dirty particulars see Time and the Amateur Astronomer.)

Wish to to be a greater astronomer? Study your method across the constellations. They’re the important thing to finding the whole lot fainter and deeper to hunt with binoculars or a telescope.

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

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

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and a whole bunch of telescopic , star clusters, and nebulae amongst them. Proven right here is the Jumbo Version, which is in exhausting covers and enlarged for simpler studying open air by pink flashlight. Sample charts. More about the current editions.

Subsequent 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 recognize your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And make sure you learn how to use sky charts with a telescope.

You may additionally need a good deep-sky guidebook, equivalent to Sky Atlas 2000.0 Companion by Robust and Sinnott, or the larger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for newbies, I do not suppose, and never on mounts and tripods which are lower than top-quality mechanically, that means heavy and costly. And as Terence Dickinson and Alan Dyer say of their Backyard Astronomer’s Guide, “A full appreciation of the universe can not come with out the talents to search out issues within the sky and understanding how the sky works. This data comes solely by spending time beneath the celebrities with star maps in hand.”

Audio sky tour. Out beneath the night sky along with your
earbuds in place, hearken to Kelly Beatty’s month-to-month
podcast tour of the heavens above. It is free.

“The risks of not pondering clearly are a lot better now than ever earlier than. It is not that there is one thing new in our mind-set, it is that credulous and confused pondering could be rather more deadly in methods it was by no means earlier than.”
            — Carl Sagan, 1996

“Information are cussed issues.”
            — John Adams, 1770




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