#astronomy This Week’s Sky at a Look, April 16 – 24 – Sky & Telescope

April 16, 2021 - Comment

This has become a crackling month for novae! The most recent is Nova Scorpii 2021. It popped up and peaked round magnitude eight.6 on April 13th, then shortly dropped to 10.zero by the 15th. Will it rebound? See Bob King’s A Bouquet of Novae Brightens April Nights. Nova Cassiopeiae 2021 (V1405 Cas) was, in the

This has become a crackling month for novae! The most recent is Nova Scorpii 2021. It popped up and peaked round magnitude eight.6 on April 13th, then shortly dropped to 10.zero by the 15th. Will it rebound? See Bob King’s A Bouquet of Novae Brightens April Nights.

Nova Cassiopeiae 2021 (V1405 Cas) was, in the meantime, nonetheless holding regular at about magnitude eight.1 as of April 15th. It has been about like that for 4 weeks now. See Vivid Nova Erupts in Cassiopeia.

Comet ATLAS, at ninth magnitude, is crossing Hercules excessive within the early-morning sky, awaiting 6-inch and bigger telescopes. See Make the Most of Comet ATLAS.

On the finish of that article are information and charts for Nova Sagittarii 2021 No. 2 (V6595 Sgr), simply off the spout of the Sagittarius Teapot in good view earlier than the primary gentle of daybreak. Within the final two weeks this one has light steadily from magnitude eight.zero to 10.5.



■ This night the waxing crescent Moon kinds a quadrilateral with Mars above it and Taurus’s horntip stars, Beta and fainter Zeta Tauri, to the edges as proven under.

Each Mars and the Moon cross upward between the horntips of Taurus.


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

■ Vivid Arcturus ascends within the jap sky throughout night whereas Capella, its shut match for brightness, descends within the northwest. They stand at precisely the identical altitude across the finish of twilight, relying in your location.

■ And at the moment, the Sickle of Leo stands upright 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.

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


■ The Moon shines in central Gemini this night below Pollux and Castor, forming an extended, tall triangle with them. Farther left of the Moon is Procyon. A lot farther proper of the Moon is Capella.

■ Right now of 12 months, the 2 Canine Stars stand vertically aligned in late twilight. Look straight southwest. Good Sirius in Canis Main is under, and Procyon in Canis Minor is excessive above. They’re roughly two fists aside.

■ That is additionally when, because the final of twilight fades away, the bowl of the dim Little Dipper extends straight to the proper of Polaris within the north.

■ And excessive above the end-stars of the Little Dipper’s bowl, you may discover the end-stars of the Massive Dipper’s bowl. That pair is nearly twice as broad aside.


■ First-quarter Moon (precise at 2:59 a.m. EDT). Look excellent of the Moon for Pollux and Castor practically lined up with it. Decrease left of the Moon shines Procyon.


■ This night, use binoculars to pick M44, the Beehive star cluster, about four° or so under the Moon. That is roughly two-thirds or three-quarters the width of a typical binocular’s subject of view. This a lot moonlight is hardly excellent for viewing a deep-sky object, however the Beehive stars aren’t tough in binocs, and the Moon does make a really helpful reference level to begin from.

■ Arcturus shines brightly within the east these evenings. It is the sharp finish of an extended, slim 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 pinnacle of the kite, on the far left, is bent barely upward. The kite is 23° lengthy: about two fist-widths at arm’s size.


■ The Moon this night kind an isosceles triangle with Regulus and Algieba (Gamma Leonis), the second-brightest star of Leo’s Sickle, as proven under. The precise peak of the isosceles triangle will rely in your longitude, for the reason that Moon strikes eastward by an considerable quantity every hour.

The scenes listed here are all the time plotted precise for an observer close to the center of North America, at latitude 40° N, longitude 90° W. If you happen to’re close to the East Coast the Moon might be just a bit to the proper of the place it is plotted under. On the West Coast the Moon will seem slightly left of the place plotted.

By how a lot? Measure by the truth that the hole between the 2 Moons under is 24 hours of lunar movement.

The Moon passes between Regulus and Algieba (the orange star above Regulus) between the North American evenings of Wednesday and Thursday, April 21st and 22nd. (The Moon is drawn about thrice its precise obvious measurement.)

■ Within the early-morning hours of Thursday the Lyrid meteor bathe, often weak however generally unpredictable, ought to at its most exercise. The sunshine of the waxing gibbous Moon will intervene till the Moon units about an hour earlier than the primary glimmer of daybreak. That darkish hour is the perfect window to plan for. See Robert Lunsford’s Viewing the Lyrids in 2021.


■ Now the Moon kinds a triangle with Regulus and Algieba on their left aspect quite than their proper aspect, as proven above.

This new triangle is nearly completely equilateral across the time twilight ends within the Jap and Central time zones.


The Arch of Spring. As evening descends, look excessive within the west for Pollux and Castor lined up virtually horizontally relying in your latitude. These two stars, the heads of the Gemini twins, kind the highest of the big Arch of Spring. To their decrease left is Procyon, the left finish of the Arch. Farther to their decrease proper is the opposite finish, shaped by Menkalinan (Beta Aurigae) after which good Capella.

This spring the Arch has an intruder: little Mars. Tonight you may discover Mars the identical distance decrease proper from the Castor-Pollux pair as it’s decrease left from Capella. The entire array sinks within the west by means of the night.

Trendy skywatchers aren’t alone in seeing the Arch of Spring as one large asterism. Lengthen it down previous Procyon so as to add Sirius, and you have the Hawai‘ian Canoe-Bailer of Makali‘i. Seems to be large enough to bail the ocean.

■ The Moon shines on the alternative aspect of the sky after darkish. Look higher left of the Moon by lower than fist at arm’s size for 2nd-magnitude Denebola, the tail star of Leo.

Almost 4 fists left of the Moon shines brighter Arcturus, magnitude zero, the main gentle of Bootes.


■ This night Arcturus shines about three fists left of the Moon.

And look under the Moon by hardly greater than half that distance, and maybe a bit left, to seek out Spica, the main gentle of Virgo.


This Week’s Planet Roundup

Mercury and Venus stay buried within the sundown, however not for lengthy. Subsequent week they’re going to begin rising into low twilight view collectively.

Mars (magnitude +1.four, crossing from Taurus into Gemini) shines within the west after darkish. In a telescope Mars is a mere 5 arcseconds broad, only a tiny shimmering blob.

Jupiter and Saturn (each in dim Capricornus) are low within the southeast simply earlier than and through early daybreak. Jupiter grabs the attention at magnitude –2.1. Saturn glows a thirteenth as brilliant at magnitude +zero.7. Catch Saturn slightly greater than a fist at arm’s size to Jupiter’s proper or higher proper earlier than daybreak grows too brilliant.

Jupiter’s Nice Pink Spot aspect, imaged on April third by Christopher Go from his tropical latitude of 10° north. The darkish dot shouldn’t be 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 quite than white. Bordering the Equatorial Zone on the north is the darkish purple fringe of the North Equatorial Belt.

Uranus and Neptune stay hidden low in night and morning twilight, respectively.

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 also referred to as UT, UTC, GMT, or Z time. To develop into extra skilled about time programs than 99% of the individuals you may ever meet, see our compact article Time and the Newbie Astronomer.

Wish to develop into a greater astronomer? Study your method across the constellations. They’re the important thing to finding all the things 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 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.

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 essential commonplace 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 lot 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 outdoor 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; practically thrice as many. The following up, as soon as you realize your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And make sure you learn learn how to use sky charts with a telescope.

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

Can a computerized telescope substitute charts? Not for newbies, 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 Yard Astronomer’s Information, “A full appreciation of the universe can not come with out growing the talents to seek out issues within the sky and understanding how the sky works. This data comes solely by spending time below the celebs with star maps in hand.”

Audio sky tour. Out below the night sky together with your
earbuds in place, hearken 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 is not that there is one thing new in our mind-set, it is that credulous and confused pondering could be rather 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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