This Week’s Sky at a Glance, April 2 – 10 – Sky & Telescope

Eighth-magnitude Nova in Cassiopeia. Nova Cassiopeiae 2021, now often known as V1405 Cassiopeiae, was holding on at about magnitude 8.2 as of April 1st, after it was found at 9.6 on March 18th and rapidly peaked round 7.7. For finder charts and extra information, see Vibrant Nova Erupts in Cassiopeia.

To get a light-weight curve with probably the most up-to-date brightness measurements, go to and in “Choose a Star”, enter “V1405 Cas” and select “Plot a light-weight curve”. There, visible observers’ estimates are the open black circles, and photoelectric V magnitudes are the inexperienced squares. (You’ll be able to 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!


■ Shortly after the top of twilight round this time of 12 months, Arcturus, the intense 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 on the time. However Capella is a really shut runner-up to Arcturus! Spot it excessive within the northwest.

Jupiter and Saturn edge ever larger within the southeast throughout early daybreak all April. . .


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

Begin with sensible Sirius within the southwest, the Hexagon’s decrease left nook. Excessive above Sirius is Procyon. From there look larger 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 on the backside of Orion, and again to Sirius.

The Hexagon is considerably distended. However if you happen to draw a line by its center from Capella to Sirius, the “Hexagon” is pretty symmetric with respect to that axis.

■ Final- Moon tonight (precisely final quarter at 6:02 a.m. Sunday morning EDT). The Moon rises tonight very late, round 2 or Three a.m. Earlier than daybreak on Sunday morning the you will discover it shining on the deal with of the Sagittarius Teapot.


■ Proper after it is totally darkish, Sirius shines brilliantly within the south-southwest. Decrease left of Sirius, by about one fist, is the triangle of Adhara, Wezen, and Aludra, from proper to left. They kind Canis Main’s hind foot, rear finish, and tail, respectively. Or, alternatively, the decrease finish and deal with of the Meat Cleaver.

A bit higher left of them, forming a Third- and 4th-magnitude arc 7° lengthy, are the three uppermost stars of the constellation Puppis. No, that is not a pet, regardless of following proper behind the Massive Canine. It is the Poop Deck (stern) of the large historical constellation Argo Navis, the ship of Jason and the Argonauts. These three are the one stars of Argo which might be readily seen naked-eye from mid-northern latitudes.

Simply 1.5° higher proper of the center of the three, binoculars on a darkish evening will present the Sixth-magnitude open cluster M93. It is elongated northeast-southwest.


■ Shortly after the top of twilight round this time of 12 months, Arcturus, the intense 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).

■ Early in Tuesday’s daybreak the crescent Moon shines underneath Saturn, as proven under. Then in Wednesday’s daybreak, the Moon shines underneath Jupiter.

. . .And on April Sixth and seventh, the waning Moon poses underneath the large planets.


■ The brilliant star excessive within the west-northwest throughout and after nightfall is Capella. Its pale-yellow shade matches that of the Solar, that means they’re each about the identical temperature. However in any other case Capella could be very totally different. It consists of two yellow-giant stars orbiting one another each 104 days.

Furthermore, for telescope customers, it is accompanied by a distant, tight pair of crimson dwarfs: Capella H and L, magnitudes 10 and 13. Article and finder charts.


■ 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 Pollux, observe it farther out by an enormous 26° (about 2½ fists at arm’s size), and also you’re on the dim head of Hydra, the Sea Serpent. In a moonless darkish sky it is a delicate however distinctive star grouping, concerning the width of your thumb at arm’s size. Binoculars present it simply by gentle air pollution or moonlight.

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

One other method to discover Hydra’s head: It is nearly halfway from Procyon to Regulus.


■ Presently of 12 months, the 2 Canine Stars stand vertically aligned across the finish of twilight. Look southwest. Good Sirius in Canis Main is under, and Procyon in Canis Minor is excessive above.


■ Vega, the intense “Summer season Star,” rises within the northeast late these evenings. Precisely the place must you look ahead to it to return up? Spot the Massive nearly overhead within the northeast. Have a look at Mizar on the bend of its deal with. When you can see Mizar’s tiny, shut companion Alcor (binoculars present it simply), observe a line from Mizar by Alcor all the best way all the way down to the horizon. That is the place Vega makes its look.


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


This Week’s Planet Roundup

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

Mars (magnitude +1.3, in ) shines excessive within the west after darkish. It is visibly fainter now than than orange Aldebaran under it, to not point out brighter orange Betelgeuse farther to Mars’s left. 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 rising into daybreak view for the final month. Search for them low within the southeast about 60 to 40 minutes earlier than your native dawn time. Saturn is the upper of the 2, but it surely’s a dimmer at magnitude +0.8. Jupiter shines at magnitude –2.1 (these values do not depend the atmospheric extinction). Discover Jupiter some 12° to Saturn’s decrease left: roughly a fist at arm’s size.

Jupiter continues to be down low within the daybreak, however at Christopher’s Go‘s tropical latitude of simply 10° north (Cebu Metropolis, Philippines) it stands larger than for these of us at north temperate latitudes. He obtained this shot on March 26th even by the poor seeing and a vivid sky. “Listed below are my first pictures of Jupiter for this season,” he writes. “Jupiter was solely 25 deg above the horizon. It was nearly dawn.” He subtracted out the intense blue-sky foreground in the course of the picture processing, which essentially degraded the signal-to-noise ratio considerably.

South right here is up, celestial west is left. “Oval BA [well above center and a bit left] could be seen simply after the central meridian. It’s nonetheless very pale,” he notes. The South Equatorial Belt “seems very ” with its very slender darkish strains and skinny pale middle. The Equatorial Zone “has a really robust ochre shade” in its central and north components. “The North Equatorial Belt has a really darkish shade.”

Uranus (magnitude 5.8, in western Aries) units within the west simply 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.

Japanese Daylight Time, EDT, is Time minus Four hours. Common Time is often known as UT, UTC, GMT, or Z time. To develop into extra professional about time methods than 99% of the folks you will ever meet, see our article Time and the Newbie Astronomer.

Wish to develop into a greater astronomer? Study your method across the . They’re the important thing to finding every thing fainter and deeper to hunt with binoculars or a telescope.

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

When you get a telescope, to place it to good use you will want an in depth, large- sky atlas (set of charts). The essential customary 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 galaxies, star clusters, and nebulae amongst them. Proven right here is the Jumbo Version, which is in arduous covers and enlarged for simpler studying outside by crimson flashlight. Sample charts. Extra concerning the present editions.

Subsequent up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; practically thrice as many. The following up, as soon as you understand your method 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 learn how to use sky charts with a telescope.

You will additionally desire a good -sky guidebook, comparable to Sky Atlas 2000.0 Companion by Sturdy and Sinnott, or the larger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope substitute charts? Not for learners, I do not assume, 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 can’t come with out creating the talents to seek out issues within the sky and understanding how the sky works. This information comes solely by spending time underneath the celebs with star maps in hand.”

Audio sky tour. Out underneath the night sky together with your
earbuds in place, take heed to Kelly Beatty’s month-to-month
podcast tour of the heavens above. It is free.

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

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


Read More


Recent Articles

Related Stories

Leave a Reply