This Week’s Sky at a Glance, April 9 – 17

Nova Cassiopeiae 2021 (V1405 Cas) was nonetheless holding on at about magnitude 8.3 as of April ninth. See Bright Nova Erupts in Cassiopeia.

Comet ATLAS, at the moment ninth or tenth magnitude, is excessive within the early-morning sky transferring from Aquila towards Hercules, awaiting 6-inch and bigger telescopes. See Bob King’s Make the Most of Comet ATLAS.

And at the top of that article is data and a chart for the brand new Nova Sagittarii 2021 No. 2 simply off the spout of the Sagittarius Teapot. It’s at the moment eighth magnitude and pretty effectively up within the south-southeast earlier than the start of daybreak.



■ As the stars start to come back out in late twilight, Arcturus, the brilliant Spring Star climbing up within the east, stands simply as excessive as Sirius, the brighter Winter Star descending within the southwest. They’re each about 20° or 25° excessive for skywatchers at mid-northern latitudes.

These are the 2 brightest stars within the sky at the time. But Capella is a very shut runner-up to Arcturus. Spot it a lot increased within the northwest in early night.


■ By late night the Sickle of Leo stands practically vertical excessive within the south. Its backside star is Regulus, the brightest of Leo. Leo himself is strolling westward. The Sickle types his entrance leg, chest, mane, and a part of his head. Off to the left, a lengthy proper triangle types his hind finish and lengthy tail.

Spot brighter Procyon practically 4 fists to the suitable of Regulus and a bit decrease. About midway alongside that line and simply a bit under, search for the dim head of Hydra, the Sea Serpent.


■ At this time of year, the 2 Dog Stars stand vertically aligned in late twilight. Look southwest. Brilliant Sirius in Canis Major is under, and Procyon in Canis Minor is excessive above. They’re roughly two fists aside.

■ This can also be the time of year when, because the final of twilight fades away, the bowl of the dim Little Dipper extends straight to the suitable of Polaris within the north.

High above the end-stars of the Little Dipper’s bowl, you will discover the end-stars of the Big Dipper’s bowl. That pair is nearly twice as broad aside.

■ New Moon (actual at 10:31 p.m. EDT).


■ Mars is crossing the road between the horntips of Taurus, Beta and Zeta Tauri, this night and tomorrow night.

Mars is just a bit brighter than Beta. But evaluate their colours: Beta is a bluish-white B7 star.


■ Vega, the brilliant “Summer Star,” rises within the northeast in mid-evening. Exactly the place do you have to look ahead to it to come back up? Spot the Big Dipper very excessive within the northeast. Look at Mizar at the bend of its deal with. If you may see Mizar’s tiny, shut companion Alcor (binoculars present it simply), observe a line from Mizar by means of Alcor all of the way all the way down to the horizon. That’s the place Vega will make its look.


■ Arcturus shines brightly within the east these evenings. It’s the sharp finish of a lengthy, slender kite-shaped asterism shaped by the brightest stars of Bootes, the Cowherd. The kite is at the moment mendacity on its aspect, extending to Arcturus’s left. The head of the kite, at the far left, is bent barely upward. The kite is 23° lengthy, about two fist-widths at arm’s size.


■ The waxing crescent Moon shines close to Aldebaran and the Pleiades this night, as proven under.

This week each Mars and the Moon move upward between the horntip stars of Taurus.


■ The waxing crescent Moon this night types a quadrilateral with Mars above it and Beta and fainter Zeta Tauri to the perimeters, as proven above.


■ Now the Moon shines higher left of tiny Mars, as proven above.

■ As Arcturus ascends the japanese sky, Capella (its shut match for brightness) is coming down within the northwest. They stand at precisely the identical top above your horizon at some second between about 9 and 10 p.m. daylight-saving time, relying totally on how far east or west you reside in your time zone.


This Week’s Planet Roundup

Mercury, Venus, Uranus, and Neptune all stay out of sight within the glare of the Sun.

Mars (magnitude +1.4, in Taurus) shines excessive within the west after darkish. Watch it move between Beta and Zeta Tauri, the horntips of Taurus, on April twelfth and thirteenth. Mars is visibly fainter than orange Aldebaran down under it, to not point out brighter orange Betelgeuse to Mars’s left or decrease left. In a telescope Mars is a mere 5 arcseconds broad: a tiny, shimmering blob.

Jupiter and Saturn (each in Capricornus) are low within the southeast simply earlier than and through early daybreak. Saturn is barely the upper of the 2 (relying in your latitude), however it’s a lot dimmer at magnitude +0.7. Jupiter shines at magnitude –2.1, about 13° to Saturn’s decrease left.

Jupiter’s Great Red Spot aspect, imaged on April third by Christopher Go from his tropical latitude of 10° north. The darkish dot just isn’t a moon’s shadow however darkish Callisto itself, caught in a uncommon equatorial transit throughout Jupiter.

South right here is up. The northern two thirds of the Equatorial Zone are pale orange tan slightly than white. It’s bordered on the north by the darkish red fringe of the North Equatorial Belt.

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 often known as UT, UTC, GMT, or Z time. To change into extra knowledgeable about time programs than 99% of the folks you will ever meet, see our compact article Time and the Amateur Astronomer.

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

This is an out of doors nature passion. For an easy-to-use constellation information overlaying the entire night sky, use the large month-to-month map within the heart of every situation 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 primary customary is the Pocket Sky Atlas (in both the original or (*17*)), 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 laborious covers and enlarged for simpler studying open air 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 already know 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, akin 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 substitute charts? Not for freshmen, I do not assume, and never on mounts and tripods which can be lower than top-quality mechanically, which 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 underneath 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

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