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


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

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

■ Pollux and Castor in Gemini cross almost overhead round 7 p.m. this week in case you stay on this planet’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’re 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 tremendous double in newbie telescopes. If Pollux had been a basketball, Castor A and B could be a tennis ball and a baseball about a half mile aside.

Moreover, every Castor star is intently orbited by an unseen red dwarf a marble in our scale mannequin simply a foot or so from every of the 2 vibrant primaries.

And a very distant tight pair of red dwarfs, Castor C, is seen in newbie scopes as a single, Tenth-magnitude speck 70 arcseconds south-southeast of the principle pair. In our scale mannequin, they’d be a pair of marbles about 3 inches aside at least 10 miles from Castor A and B.

Read extra in Fred Schaaf’s “Gemini’s Like and Unlike Twins” within the March Sky & Telescope, web page 45.


■ Now the Moon shines between the horn suggestions of Taurus, Beta and Zeta Tauri, as proven above. These two stars kind a lengthy rectangle with Mars and Aldebaran: a non permanent 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 Sun 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 don’t balance as we speak any higher than they normally do, in case somebody tries to inform you that.


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

The brightest asteroid, 4 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 precise 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 Dog Star. Even farther beneath Procyon is vibrant white Sirius, the unique Dog Star itself.


■ The vibrant 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 precise pf Leo.

And now the waxing gibbous Moon works its way throughout Leo, on its way to full on the twenty eighth.

■ 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 at the Sickle of Leo, kind of 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.

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


■ Now that spring is below way, Orion has taken up his early-spring posture within the southwest throughout night. He’s 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 properly are you able to time this occasion? If you are close to your time zone’s normal longitude, anticipate it round 8:40 this night (daylight-saving time). . . kind of.


■ 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 vibrant yellow Arcturus making its way 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.

■ Meanwhile on the opposite aspect of the sky, the signature fall-and-winter constellation Cassiopeia retreats down after darkish. Look for it pretty low within the north-northwest. It’s 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 along side the Sun.

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 coloration. Mars this week is passing north of Aldebaran, giving it a large 7° berth for a number of days working. They’re closest (6.9°) on March twentieth.

In a telescope Mars is a mere 5½ arcseconds large: a tiny vibrant 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, 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); search for it some 11° to Saturn’s decrease left. That’s about a 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 Sun.

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 rely on longitude (primarily 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. For all of the down-and-dirty particulars see Time and the Amateur Astronomer.

Want to turn out to be a higher astronomer? Learn your way across the constellations. They’re the important thing to finding the whole lot fainter and deeper to hunt with binoculars or a telescope.

This is an outside nature interest. For an easy-to-use constellation information protecting the entire night sky, use the large month-to-month map within the middle of every challenge of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you will want a detailed, large-scale sky atlas (set of charts). The fundamental normal is the Pocket Sky Atlas (in both the original or Jumbo Edition), which reveals 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 galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in onerous 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; almost 3 times as many. The subsequent up, as soon as you recognize 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’ll want to learn how to use sky charts with a telescope.

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

Can a computerized telescope exchange charts? Not for newcomers, 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 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 below the night sky together with your
earbuds in place, take heed to Kelly Beatty’s month-to-month
(*27*) 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