#astronomy This Week’s Sky at a Look, July 9 – 17 – Sky & Telescope

July 10, 2021 - Comment

Nova Cas continues wobbly. It has been almost four months since Nova Cassiopeiae 2021 erupted to magnitude 7.7. It has stayed roughly that vivid ever since, making it formally a “gradual nova,” apart from swelling to five.three for per week in Could. Just lately it has been wavering. As of July 10th it was about

Nova Cas continues wobbly. It has been almost four months since Nova Cassiopeiae 2021 erupted to magnitude 7.7. It has stayed roughly that vivid ever since, making it formally a “gradual nova,” apart from swelling to five.three for per week in Could. Just lately it has been wavering. As of July 10th it was about 7.eight, having dropped immediately from a mini-peak of 6.6 the week earlier than.

The nova is pretty properly up within the north-northeast after darkish, relying in your latitude. It climbs excessive later within the evening. See Bob King’s replace: Noctilucent Cloud Present, a Mercurial Nova, and Extra, with charts and comparability stars.


■ Venus continues to shine low within the west-northwest throughout twilight. Mars, only one/200 as vivid, 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 will 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).

A couple of third of the way in which from Arcturus to Vega is the faint semicircle of Corona Borealis, the Northern Crown, with its modestly vivid crown jewel, Alphecca or Gemma, on its entrance.

Practically two thirds of the way in which 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 (precise at 9:17 p.m. EDT).


■ In case you have a darkish sufficient sky on these previous few nights earlier than moonlight comes again, search for the Milky Means forming an impressive arch excessive throughout the entire japanese sky. It runs all the way in which from under Cassiopeia within the north-northeast, up and throughout Cygnus and the underside of the Summer time 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 couple of levels to the appropriate of Venus (and faint little Mars) low within the west throughout twilight, as proven under.

In the event you can see Mars (carry binoculars), you possibly can positively see brighter Regulus twinkling 12° to Venus’s higher left.

The brand new crescent Moon steps up low in twilight simply as Venus and Mars undergo conjunction. (The Moon is drawn about 3 times its precise obvious measurement.)


■ Massive, macho Venus, Goddess of Love, and wimpy little Mars, God of Struggle, 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.

Search for Regulus rather less far to the Moon’s left or decrease left.


■ Mars is now ½° underneath 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 manner 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 appropriate. The Teapot will tilt farther and farther for the remainder of the summer time — or for a lot of the evening if you happen to keep out late.


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

Now Mars strikes away decrease proper of Venus, whereas brighter Regulus properties in from the higher left. Regulus will go 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 depends upon how far north or south you reside: the farther south, the upper.

Search for the 2 stars particularly shut collectively within the tail. These are Lambda and fainter Upsilon Scorpii, often known as the Cat’s Eyes. They’re canted at an angle; the cat is tilting his head somewhat to the appropriate and winking (Upsilon is fainter than Lambda; they’re magnitudes 1.6 and a pair of.6). Each are blue-white supergiants, 700 and 500 mild years away, respectively. Sure, 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 often known as the Little Cat’s Eyes. They’re oriented virtually precisely the identical manner as Lambda and Upsilon, and like these, they don’t seem to be a real binary: they’re 500 and 800 light-years from us. Are you able to resolve the Mu pair with out binoculars?


■ The Moon remains to be basically first-quarter this night (on the night occasions for the Americas). Spot Spica a fist to the Moon’s decrease proper, and Arcturus 3 times as far to the Moon’s higher proper.

■ Cassiopeia is now properly previous its bottoming-out for the yr at the same time as seen quickly after darkish. Search for its tilted W sample lowish within the north-northeast. The farther north you reside, the upper it will likely be.



This Week’s Planet Roundup

Mercury glimmers very low within the east-northeast as daybreak grows vivid. It sinks somewhat decrease this week however doubles in brightness, from magnitude zero.zero to –zero.7. Binoculars assist.

Do not confuse Mercury with Aldebaran more and more far to its higher proper, or Capella even farther higher left.

Venus (magnitude –three.9) continues to shine low within the west throughout twilight. Proper close to it’s tiny Mars, 200 occasions fainter at magnitude +1.eight. They seem closest, about ½° aside, at conjunction on July 12th and 13th. By the 16th Mars is 2° to Venus’s decrease proper. Each planets proceed to set earlier than twilight ends.

Farther higher left of Venus you will discover Regulus, transferring nearer to Venus every single day. It is a half magnitude brighter than Mars.

Saturn (magnitude +zero.three, in Capricornus) and brighter Jupiter (magnitude –2.7, in Aquarius) rise within the east-southeast somewhat 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 finest, round three a.m. daylight saving time. See “Motion at Jupiter” within the July Sky & Telescope, web page 50, and “Saturnian Challenges” beginning on web page 52.

Each will attain opposition in August.

Earlier than daybreak, look 20° decrease left of Jupiter for Fomalhaut. It now varieties an virtually good isosceles proper triangle with Jupiter and Saturn. Jupiter is on the proper angle.

Two darkish pink 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 pale significantly, apart from a really darkish pink line alongside its southern edge. (South is up.) In the meantime, the usually white Equatorial Zone largely stays a pale, virtually belt-like tan shade.

Uranus (magnitude 5.eight, in Aries) is properly up within the east simply earlier than daybreak begins.

Neptune (magnitude 7.9, in Aquarius 21° east of Jupiter) is increased 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 depend upon longitude (primarily Moon positions) are for North America.

Japanese Daylight Time, EDT, is Common Time minus four hours. Common Time is also referred to as UT, UTC, GMT, or Z time. To grow to be extra professional about time programs than 99% of the individuals you will ever meet, see our compact article Time and the Beginner Astronomer.

Need to grow to be a greater astronomer? Study your manner across the constellations. They’re the important thing to finding every thing fainter and deeper to hunt with binoculars or a telescope.

That is an out of doors nature passion. For an easy-to-use constellation information protecting the entire night sky, use the massive month-to-month map within the heart of every difficulty 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-scale sky atlas (set of charts). The essential customary 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 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 open air by pink flashlight. Pattern charts. Extra in regards to the present editions.

Subsequent up is the bigger and deeper Sky Atlas 2000.zero, plotting stars to magnitude eight.5; almost 3 times as many. The subsequent up, as soon as your manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And be sure you learn how one can use sky charts with a telescope.

You will additionally desire a good deep-sky guidebook, comparable to Sky Atlas 2000.zero Companion by Sturdy and Sinnott, or the larger (and illustrated) Night time Sky Observer’s Information by Kepple and Sanner.

Can a computerized telescope change charts? Not for freshmen, I do not assume, and never on mounts and tripods which are 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 creating the abilities 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 along 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 considering clearly are a lot better now than ever earlier than. It isn’t that there is one thing new in our mind-set, it is that credulous and confused considering might be rather more deadly in methods it was by no means earlier than.”
            — Carl Sagan, 1996

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


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