This Week’s Sky at a Glance, June 25 – July 3

Nova Cassiopeiae carries on… and on… It’s been 3½ months since Nova Cas 2021 erupted on March nineteenth to magnitude 7.7. Surprisingly, it has stayed roughly that vibrant ever since apart from swelling to five.3, faint naked-eye visibility, for a week in May earlier than dropping again to about 7.7. It’s been wavering barely since then. As of June twenty fourth it was 7.6.

The nova is reasonably low within the north-northeast after darkish relying in your latitude. It climbs greater later within the night time. Charts and comparison stars.

But not Nova Herculis. This one leapt as much as 6.3 on June twelfth after which pale quick. As of June twenty fourth it was all the way down to 11.8 visually. See Bright Nova in Hercules on a Roller Coaster Ride.


■ Leo is usually a constellation of late winter and spring. But he is not gone but. As twilight ends look due west, considerably low, for Regulus, the Lion’s brightest and now lowest star: the forefoot of his stick determine. You’ll discover Regulus higher left of Venus and Mars.

The Sickle of Leo extends higher proper from Regulus, by about a fist at arm’s size. The remainder of the Lion’s constellation determine runs higher left from there for a couple of fists, to his tail star Denebola, the best. Leo will quickly tread offstage into the sundown.


■ On the jap facet of the sky, the massive Summer Triangle holds sway after darkish. Its high star is Vega, the brightest in all of the east. The brightest star to Vega’s decrease left is Deneb. Farther to Vega’s decrease proper is Altair.

■ Look south in early daybreak on Sunday morning the twenty seventh, and there is Saturn over the waning gibbous Moon, as proven under. Jupiter watches from their higher left.

Moon with Jupiter and Saturn at dawn, June 27-28, 2021
Very early risers on Sunday morning June twenty seventh will discover Saturn over the waning gibbous Moon, with Jupiter off to their higher left.


■ Star colours are largely delicate, and totally different individuals have a neater or tougher time seeing them. To me, the tints of vibrant stars present a little higher on a late-twilight sky background than in a totally darkish sky.

For occasion, the 2 brightest stars of summer time are Vega, excessive within the east in late twilight, and Arcturus, even greater within the southwest. Vega is white with simply a contact of icy blue. Arcturus is a yellow-orange big. Do their colours stand out a little higher for you in late twilight than in darkish night time?

Binoculars, in fact, at all times make star colours a lot simpler.

■ The waning gibbous Moon rises in late night. Once it is up, search for Jupiter to its left and dimmer Saturn to its higher proper.

By daybreak on Monday morning the twenty eighth, this Jupiter-Moon-Saturn association is greater and rotated clockwise as proven above.


■ After dusk, search for the Big Dipper hanging straight down excessive within the northwest. Its backside two stars, the Pointers, level decrease proper towards modest Polaris, the top of the Little Dipper’s deal with.

Examine the center star of the Big Dipper’s deal with, Mizar. Can you see its faint little companion Alcor nestled subsequent to it? It’s simply higher proper of Mizar — pointing, as at all times, within the course from Mizar to Vega.


■ This is the time of year when, after darkish, the dim Little Dipper floats straight upward from Polaris — like a helium balloon on a string, escaped from some summer-evening get together. Through mild air pollution, nonetheless, all you might even see of the Little Dipper are Polaris at its backside and Kochab, the lip of the Little Dipper’s bowl, at the highest.


■ Now that July is about to reach, Antares and the starry head of Scorpius are at their highest within the south shortly after the lengthy summer time twilights lastly surrender the ghost.

The “head of Scorpius” is the near-vertical row of three stars higher proper of Antares. Three positive doubles await you right here. The high star of the row is Beta Scorpii or Graffias, a positive binary for telescopes, separation 13 arcseconds, magnitudes 2.8 and 5.0.

Just 1° under it’s the very broad naked-eye pair Omega1 and Omega2 Scorpii, diagonal from higher proper to decrease left. They’re 4th magnitude and ¼° aside. Binoculars present their slight colour distinction; they’re spectral varieties B9 and G2.

Upper left of Beta by 1.6° is Nu Scorpii, separation 41 arcseconds, magnitudes 3.8 and 6.5. In truth that is a telescopic triple. High energy in good seeing reveals Nu’s brighter element itself to be a shut double, separation 2 arcseconds, magnitudes 4.0 and 5.3, aligned nearly north-south.

And extra: In the identical binocular subject with Antares, or practically so, are two very totally different globular star clusters for binoculars. M4 is a large, dim fuzzy comparatively close by. M80 is fainter and way more compact, even tiny; in reality it may be arduous to differentiate in binoculars from an Eighth-magnitude star. It’s a greater and denser cluster than M4 however greater than 4 occasions as far-off. Use the chart for them with Matt Wedel’s Binocular Highlight column within the July Sky & Telescope, web page 43.


■ Last-quarter Moon (actual at 5:11 p.m. EDT). The Moon rises round 1 a.m. tonight daylight-saving time, shining at the Cetus-Pisces border.

Any time from then till early daybreak, look excessive above the Moon for the Great Square of Pegasus standing on one nook.


■ Venus shines low within the west-northwest throughout twilight, with vastly fainter Mars now simply 6° to its higher left. They set earlier than twilight’s finish.

Venus hardly strikes now with respect to your panorama from week to week, however its background stars are sliding proper alongside, towards the decrease proper. On July 2nd the Beehive Cluster, M44, passes behind Venus. Try binoculars or a wide-field scope, however this might be a troublesome remark if it is attainable at all! You’ll should catch the slim time window between the sky being too vibrant and Venus and the Beehive getting too low and setting. That window might or might not exist, relying in your optics, the sharpness of your eyes for faint stars in twilight, and the readability of the air.

Venus and Mars level a line to Regulus within the western twilight. The stars of the Beehive, behind Venus this night, are way too faint to be plotted. But they’re there. . . .
Mercury and Aldebaran low at dawn, July 3, 2021.
All week, Mercury has been brightening and creeping up a little much less low within the daybreak. Can you see it but? Its visibility in vibrant twilight is exaggerated right here!


■ Low within the northwest or north at the top of those lengthy summer time twilights, would you acknowledge noctilucent clouds should you noticed them? They’re probably the most astronomical of all cloud varieties, what with their excessive altitude and formation on meteoric mud particles. And they’re pretty uncommon — although changing into extra frequent in current years because the environment and climate phenomena change. See Bob King’s Nights of Noctilucent Clouds.



This Week’s Planet Roundup

Mercury glimmers very faintly very low within the east-northeast as daybreak grows vibrant. If you need to strive for it with binoculars or, higher, a wide-field telescope, do not confuse it with twinklier Aldebaran to its higher proper. See the illustration above.

Venus (magnitude –3.8) shines low within the west-northwest throughout twilight. Tiny Mars, practically 200 occasions fainter at magnitude +1.8, is closing in on Venus from the higher left. They’re separated by 10° on June twenty fifth, shrinking to six° by July 2nd. Both set earlier than twilight ends. They’ll be in conjunction, ½° aside, on July twelfth and thirteenth.

Venus hardly strikes now with respect to your panorama from week to week, however the background stars are shifting proper alongside. On July 2nd the Beehive Cluster, M44, slides behind Venus. You can strive for the brightest Beehive stars with binoculars or a wide-field scope, however this might be a troublesome remark if it is attainable at all. You’ll must catch the slim time window between when the sky is just too vibrant and the Venus-Beehive combo will get too low and units. That window might not exist if the air is not super-clear.

Jupiter and Saturn (in Aquarius and Capricornus, respectively) rise in late night: first Saturn, then brighter Jupiter about an hour later. They shine at their highest and telescopic greatest within the south earlier than daybreak. Jupiter dominates at magnitude –2.6. Saturn, 20° to Jupiter’s west (proper), is a extra modest +0.4. They’ll attain their oppositions in August.

Before daybreak, look 20° under or decrease left Jupiter for Fomalhaut. It types a pretty good isosceles proper triangle with Jupiter and Saturn. Jupiter is at the (nearly) proper angle.

Two darkish red barges had been close to Jupiter’s central meridian when Christopher Go took this picture on June fifteenth (when the System II longitude of the central meridian was 79°). The remainder of the North Equatorial Belt has pale tremendously, apart from a very darkish red line alongside its southern edge. (South is up.) Meanwhile, the usually vibrant Equatorial Zone largely stays a pale, nearly belt-like tan colour.

Uranus (magnitude 5.8, in Aries) is low within the east earlier than daybreak begins.

Neptune (magnitude 7.9, in Aquarius 21° east of Jupiter) is properly up within the southeast earlier than daybreak.

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 upon 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. To grow to be extra skilled about time programs than 99% of the individuals you will ever meet, see our compact article Time and the Amateur Astronomer.

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

This is an outside nature pastime. For an easy-to-use constellation information protecting the entire night sky, use the massive month-to-month map within the heart of every subject 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 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 tons of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in arduous 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; practically 3 times 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 remember to learn how to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, reminiscent of 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 learners, I do not suppose, and never on mounts and tripods which can 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 along 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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