This Week’s Sky at a Glance, July 9 – 17 – Sky & Telescope

Nova Cas continues wobbly. It’s been almost four months since Nova Cassiopeiae 2021 erupted to magnitude 7.7. It has stayed roughly that vibrant ever since, making it formally a “slow nova,” apart from swelling to five.Three for a week in May. Recently it has been wavering. As of July 10th it was about 7.8, having dropped out of the blue from a mini-peak of 6.6 the week earlier than.The nova is pretty effectively up within the north-northeast after darkish, relying in your latitude. It climbs excessive later within the night time. See Bob King’s replace: Noctilucent Cloud Show, a Mercurial Nova, and More, with charts and comparability stars.


■ Venus continues to shine low within the west-northwest throughout twilight. Mars, just one/200 as vibrant, is 2° to its higher left this night; binoculars assist. They set earlier than twilight’s finish. Watch the 2 planets shut in and attain their conjunction about ½° aside on July 12th and 13th.

■ When twilight ends, you may discover the 2 brightest stars of summer time, Vega and Arcturus, about equally close to the zenith: Vega towards the east, Arcturus towards the southwest (relying in your location).

About a third of the best way from Arcturus to Vega is the faint semicircle of Corona Borealis, the Northern Crown, with its modestly vibrant crown jewel, Alphecca or Gemma, on its entrance.Nearly two thirds of the best way from Arcturus to Vega is the Keystone of Hercules.For extra see Fred Schaaf’s “The Path from Arcturus to Vega” within the July Sky & Telescope, web page 45.

■ New Moon (actual at 9:17 p.m. EDT).


■ If you’ve got a darkish sufficient sky on these previous few nights earlier than moonlight comes again, search for the Milky Way forming a magnificent arch excessive throughout the entire japanese sky. It runs all the best way from beneath Cassiopeia within the north-northeast, up and throughout Cygnus and the underside of the Summer Triangle within the east, and down previous the spout of the Sagittarius Teapot within the south.


■ The skinny, two-day previous crescent Moon hangs eerily a few levels to the best of Venus (and faint little Mars) low within the west throughout twilight, as proven beneath.If you’ll be able to see Mars (convey binoculars), you’ll be able to undoubtedly see brighter Regulus twinkling 12° to Venus’s higher left.

The new crescent Moon steps up low in twilight simply as Venus and Mars undergo conjunction. (The Moon is drawn about thrice its precise obvious measurement.)MONDAY, JULY 12

■ Big, macho Venus, Goddess of Love, and wimpy little Mars, God of War, are at their closest collectively now, about ½° aside, low within the west-northwest in twilight. This night the crescent Moon shines higher left of them, as proven above.Look for Regulus a little much less far to the Moon’s left or decrease left.


■ Mars is now ½° below Venus. The Moon has thickened and moved farther to their higher left. Regulus is about halfway between the Moon and Venus, as proven above.


■ The ever-waxing Moon is now decrease left of Denebola, Leo’s 2nd-magnitude tail tip. They’re lower than a fist at arm’s size aside.The brighter star method off three fists left of the Moon is 1st-magnitude Spica.


■ With the advance of summer time, the Sagittarius Teapot, within the south-southeast decrease left of Scorpius after darkish, is beginning to tilt and pour from its spout to the best. The Teapot will tilt farther and farther for the remainder of the summer time — or for a lot of the night time should you keep out late.


■ In late twilight, Spica shines three or 4 finger-widths decrease left of the primary-quarter Moon (it is precisely first-quarter at 6:11 a.m. EDT Saturday the 17th). High above them is brighter Arcturus, tinted with a decrease colour temperature: yellow-orange.

Now Mars strikes away decrease proper of Venus, whereas brighter Regulus houses in from the higher left. Regulus will move 1° from Venus on the night of the 21st.■ The tail of Scorpius is low due south proper after darkish, to the decrease proper of the Sagittarius Teapot. How low will depend on how far north or south you reside: the farther south, the upper.

Look for the 2 stars particularly shut collectively within the tail. These are Lambda and fainter Upsilon Scorpii, generally known as the Cat’s Eyes. They’re canted at an angle; the cat is tilting his head a little to the best and winking (Upsilon is fainter than Lambda; they’re magnitudes 1.6 and a pair of.6). Both are blue-white supergiants, 700 and 500 gentle years away, respectively. Yes, the nearer of the 2 is the fainter one.

Between the Cat’s Eyes and the Teapot’s spout are the open star clusters M6 and particularly M7, showy in binoculars.

A line by means of the Cat’s Eyes factors west (proper) by almost a fist-width towards Mu Scorpii, a a lot tighter pair generally known as the Little Cat’s Eyes. They’re oriented virtually precisely the identical method as Lambda and Upsilon, and like these, they don’t seem to be a true binary: they’re 500 and 800 gentle-years from us. Can you resolve the Mu pair with out binoculars?


■ The Moon continues to be basically first-quarter this night (at the night occasions for the Americas). Spot Spica a fist to the Moon’s decrease proper, and Arcturus thrice as far to the Moon’s higher proper.

■ Cassiopeia is now effectively previous its bottoming-out for the yr whilst seen quickly after darkish. Look for its tilted W sample lowish within the north-northeast. The farther north you reside, the upper will probably be.



This Week’s Planet Roundup

Mercury glimmers very low within the east-northeast as daybreak grows vibrant. It sinks a little decrease this week however doubles in brightness, from magnitude 0.Zero to –0.7. Binoculars assist.Don’t confuse Mercury with Aldebaran more and more far to its higher proper, or Capella even farther higher left.

Venus (magnitude –3.9) continues to shine low within the west throughout twilight. Right close to it’s tiny Mars, 200 occasions fainter at magnitude +1.8. They seem closest, about ½° aside, at conjunction on July 12th and 13th. By the 16th Mars is 2° to Venus’s decrease proper. Both planets proceed to set earlier than twilight ends.Farther higher left of Venus you may discover Regulus, transferring nearer to Venus daily. It’s a half magnitude brighter than Mars.

Saturn (magnitude +0.3, in Capricornus) and brighter Jupiter (magnitude –2.7, in Aquarius) rise within the east-southeast a little later: Saturn across the finish of twilight, Jupiter an hour later to Saturn’s decrease left. They’re highest within the south, at their telescopic greatest, round 3 a.m. daylight saving time. See “Action at Jupiter” within the July Sky & Telescope, web page 50, and “Saturnian Challenges” beginning on web page 52. Both will attain opposition in August.Before daybreak, look 20° decrease left of Jupiter for Fomalhaut. It now varieties an virtually good isosceles proper triangle with Jupiter and Saturn. Jupiter is at the best angle.

Two darkish crimson barges have been close to Jupiter’s central meridian when Christopher Go took this picture on June 15th (at 19:03 UT, when the System II longitude of the central meridian was 79°). The remainder of the North Equatorial Belt has light drastically, apart from a very darkish crimson line alongside its southern edge. (South is up.) Meanwhile, the usually white Equatorial Zone principally stays a pale, virtually belt-like tan colour.Uranus (magnitude 5.8, in Aries) is effectively up within the east simply earlier than daybreak begins.

Neptune (magnitude 7.9, in Aquarius 21° east of Jupiter) is greater within the south-southeast simply earlier than daybreak begins.

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

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

This is an outside nature pastime. For a straightforward-to-use constellation information protecting the entire night sky, use the massive month-to-month map within the heart of every concern of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you may want a detailed, massive-scale sky atlas (set of charts). The fundamental normal is the Pocket Sky Atlas (in both the unique or Jumbo Edition), which reveals stars to magnitude 7.6.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and lots of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in onerous covers and enlarged for simpler studying open air by crimson flashlight. Sample charts. More concerning the present editions.Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; almost thrice as many. The subsequent up, as soon as 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 use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, resembling 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 change charts? Not for learners, I do not assume, and never on mounts and tripods which might be lower than high-high 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 with yourearbuds in place, take heed to Kelly Beatty’s monthlypodcast 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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