This Week’s Sky at a Glance, March 26 – April 3

Eighth-magnitude Nova in Cassiopeia. Nova Cassiopeiae 2021, now also called V1405 Cassiopeiae, has light a hint to about magnitude 8.1 as of March twenty sixth, after it was found at 9.6 on March 18th and shortly peaked round 7.7. For finder charts and extra information, see Bright Nova Erupts in Cassiopeia. Moonlight provides you with hassle with binoculars, even massive ones, however the moonlight will probably be gone from the early-evening sky beginning on the thirtieth.

To get a gentle curve with probably the most up-to-date brightness measurements, go to and in “Pick a Star”, enter “V1405 Cas” and select “Plot a light curve”. There, visible observers’ estimates are the open black circles, and photoelectric V magnitudes are the green squares. (You can see calendar dates as a substitute of Julian Days utilizing “Preferences”.)

And the place’s Cassiopeia itself? Catch it sinking within the north-northwest proper after the top of twilight. Look early earlier than it will get too low.


■ Now that spring is beneath way, Orion has taken up his early-spring posture within the southwest throughout night. He’s tipping westward, and his Belt is popping horizontal as proven under.

Orion in early spring tips toward the right, and his three-star Belt turns horizontal. As always, the Belt points roughly toward orange Aldebaran and the V-shaped Hyades. Akira Fujii
Orion in early spring ideas towards the proper, and his three-star Belt turns horizontal. As at all times, the Belt factors roughly towards orange Aldebaran and the V-shaped Hyades.
Akira Fujii

When does Orion’s Belt seem precisely horizontal? That depends upon 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 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 full. After darkish look far to its decrease left, by three or 4 fists at arm’s size, for vivid Arcturus, pale yellow-orange, making its way up the japanese sky. By about 9 p.m. daylight-saving time, look two or three fists under the Moon for Spica on the rise.


■ Full Moon (precisely full at 2:48 p.m. EDT). Spica is now about one fist under it come night. Arcturus is greater than twice that far to the Moon’s left.


■ This night Spica shines to the proper of the Moon low within the east, by lower than a fist at arm’s size. Arcturus is three or 4 instances as far to the Moon’s higher left.

All week and actually all April, Jupiter and Saturn edge increased within the southeast throughout early daybreak.


■ We now have an hour of moonless darkish sky after the top of twilight (these of us on the planet’s mid-northern latitudes). This is a good time to test in on Nova Cassiopeiae! See the highest of this web page.

■ Also whereas the sky continues to be darkish: Spot the Big Dipper “dumping water” very excessive within the northeast. The Dipper is the hindquarters and lengthy tail of Ursa Major, the Great Bear.

Nearly crossing the zenith are three pairs of dim naked-eye stars, all third or 4th magnitude, marking the Bear’s ft. They’re also called the Three Leaps of the Gazelle, from early Arab lore. They kind a lengthy east-west line roughly halfway between the Bowl of the Big Dipper and the Sickle of Leo; see the night constellation chart within the heart of the April Sky & Telescope.

According to the Arabian story, the gazelle was consuming at a pond — the large, dim Coma Berenices star cluster — and bounded away when startled by a flick of Leo’s close by tail, Denebola. Leo, nonetheless, appears fairly unaware of his potential prey at the water hole; he is dealing with the opposite way.


■ Castor and Pollux shine collectively practically overhead within the south after darkish. Pollux is barely the brighter of those “twins.” Draw a line from Castor by way of Pollux, comply with it farther out by a huge 26° (about 2½ fist-widths at arm’s size), and also you’re at the dim head of Hydra, the Sea Serpent. In a moonless darkish sky it is a refined however distinctive star grouping, concerning the width of your thumb at arm’s size. Binoculars present it simply by way of gentle air pollution or moonlight.

Continue the road farther by a fist and a half and also you hit 2nd-magnitude Alphard, Hydra’s orange coronary heart.

Another way to seek out Hydra’s head: It’s nearly halfway from Procyon to Regulus.

■ The waning gibbous Moon shines within the hours earlier than daybreak Thursday morning, within the head of Scorpius now making its late-night look. Below or decrease left of the Moon you will discover orange Antares.


■ This is the time of year when the dim Little Dipper juts to the proper from Polaris (the Little Dipper’s handle-end) throughout late night. The a lot brighter Big Dipper curls over excessive above it, “dumping water” into it. They do the reverse water dump within the fall.


■ Shortly after the top of twilight round this time of year, Arcturus, the brilliant Spring Star climbing within the east, stands simply as excessive as Sirius, the brighter Winter Star descending within the southwest (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 excessive within the northwest.


■ The enormous, vivid Winter Hexagon continues to be in view early after darkish, filling the sky to the southwest and west.

Start with good Sirius within the southwest, the Hexagon’s decrease left nook. High above Sirius is Procyon. From there look increased higher proper for Pollux and Castor (lined up practically horizontal), decrease proper from Castor to Menkalinan after which vivid Capella, decrease left from there to Aldebaran (previous Mars), decrease left to Rigel at the underside of Orion, and again to Sirius.

The Hexagon is considerably distended. But should you draw a line by way of its center from Capella to Sirius, the “Hexagon” is pretty symmetric with respect to that axis.


This Week’s Planet Roundup

Mercury, Venus, and Neptune are out of sight within the glare of the Sun.

Mars (magnitude +1.3, in Taurus) shines excessive within the west after darkish. Mars is now visibly fainter than orange Aldebaran under or decrease left of it. In a telescope Mars is a mere 5 arcseconds broad: a tiny, shimmering vivid blob too small for any floor element.

Jupiter and Saturn have been slowly rising into daybreak view for the final month. Look for them low within the 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 +0.8. Jupiter shines at magnitude –2.1 (not counting the atmospheric extinction for one thing so low). Find Jupiter some 12° to Saturn’s decrease left, roughly 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.

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 develop 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 masking 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.

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 commonplace 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 exhausting covers and enlarged for simpler studying outdoor by red flashlight. (*26*). 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 understand your way round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And remember to learn how to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, comparable 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 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

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