#astronomy This Week’s Sky at a Look, March 19 – 27 – Sky & Telescope

March 21, 2021 - Comment

FRIDAY, MARCH 19 ■ 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 night within the longitudes of the Americas). ■ Pollux and Castor in


■ 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 night within the longitudes of the Americas).

■ Pollux and Castor in Gemini cross almost 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, Houston and the US Gulf Coast, in addition to northernmost Africa, Tibet, and Shanghai.

The “twin” heads of the Gemini figures are fraternal twins at greatest. 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 large. Castor is a binary pair of two smaller, hotter, white main-sequence stars, a effective double in novice telescopes. If Pollux had been a basketball, Castor A and B can be a tennis ball and a baseball a couple of half mile aside.

Furthermore, every Castor star is intently orbited by an unseen purple dwarf — a marble in our scale mannequin only a foot or so from every of the two vivid primaries.

And a really distant tight pair of purple dwarfs, Castor C, is seen in novice scopes as a single, 10th-magnitude speck 70 arcseconds south-southeast of the principle pair. In our scale mannequin, they’d be a pair of marbles about three inches aside not less than 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 a protracted rectangle with Mars and Aldebaran: a short lived asterism particular to mid-March 2021.

■ Earth crosses 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 begins within the Northern Hemisphere, fall within the Southern Hemisphere. And no, eggs do not stability right this moment any higher than they normally do, in case somebody tries to let you know that.


■ First-quarter Moon. The Moon shines within the toes 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 below Pollux and Castor in early night. Far beneath the Moon is the massive Winter Triangle: Procyon on the left, orange Betelgeuse on the fitting 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 fitting pf Leo.

And now the waxing gibbous Moon works its manner throughout Leo, on its technique 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 might be primarily 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).

This line of three turns vertical, with the Moon nonetheless close to its center, by about 1 a.m.

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


■ Now that spring is below manner, 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 relies on the place you reside east-west in your time zone, and in your latitude. How effectively are you able to time this occasion? For those who’re close to your time zone’s normal longitude, anticipate it round eight:40 this night (daylight-saving time). . . roughly.


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

By 9 or 10 p.m. daylight-saving time, look two or three fists beneath the Moon for Spica now 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 utterly. 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 together with the Solar.

Mars (magnitude +1.2, in Taurus) shines excessive within the west after darkish. Mars is almost the dual of Aldebaran to its decrease left, in each brightness and in colour. 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 vast: a tiny vivid blob too small for any floor element.

Jupiter and Saturn 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 upper of the 2, but it surely’s a lot dimmer at magnitude +zero.7. Jupiter shines at magnitude –2.zero (not counting the atmospheric extinction for one thing so low); search for it some 11° to Saturn’s decrease left. That is a couple of fist at arm’s size.

Uranus (magnitude 5.eight, in western Aries) is sinking away low within the west proper after the tip 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 Daylight Time, EDT, is Common Time minus four hours. Common Time is often known as UT, UTC, GMT, or Z time. For all of the down-and-dirty particulars see Time and the Beginner Astronomer.

Wish to grow to be a greater astronomer? Be taught your manner across the constellations. They’re the important thing to finding every thing fainter and deeper to hunt with binoculars or a telescope.

That is an out of doors nature pastime. For an easy-to-use constellation information overlaying the entire night sky, use the large month-to-month map within the middle of every concern 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 fundamental normal is the Pocket Sky Atlas (in both the unique or Jumbo Version), which reveals stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo editionThe Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and a whole bunch of telescopic galaxies, star clusters, and nebulae amongst them. Proven right here is the Jumbo Version, which is in onerous covers and enlarged for simpler studying open air by purple flashlight. Pattern charts. Extra concerning the present editions.

Subsequent up is the bigger and deeper Sky Atlas 2000.zero, plotting stars to magnitude eight.5; almost 3 times as many. The following up, as soon as you understand your manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And remember to learn the best way to use sky charts with a telescope.

You may additionally need a good deep-sky guidebook, comparable to Sky Atlas 2000.zero Companion by Robust and Sinnott, or the larger (and illustrated) Evening Sky Observer’s Information by Kepple and Sanner.

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

Audio sky tour. Out below the night sky along with your
earbuds in place, take heed 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 will be way more deadly in methods it was by no means earlier than.”
            — Carl Sagan, 1996

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


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