#astronomy This Week’s Sky at a Look, July 30 – August 7 – Sky & Telescope

July 30, 2021 - Comment

Nova Cas takes one other brightness bump! Nova Cassiopeiae 2021 erupted to magnitude 7.7 final March. It has stayed principally about that vivid ever since — making it a “sluggish nova” — however with a brightness spike to five.5 in early Could and smaller bumps since then. For some time it appeared completed for, however

Nova Cas takes one other brightness bump! Nova Cassiopeiae 2021 erupted to magnitude 7.7 final March. It has stayed principally about that vivid ever since — making it a “sluggish nova” — however with a brightness spike to five.5 in early Could and smaller bumps since then. For some time it appeared completed for, however as of July 27th UT it had climbed again as much as 6.zero. Then by the 30th it had dropped to about 7.2. Charts and comparability stars.


■ As summer season progresses, Arcturus strikes down the western facet of the night sky. Arcturus varieties the underside level of the Kite of Bootes. The Kite, quite slim, extends higher proper from Arcturus by 23°, about two fists at arm’s size. The decrease proper facet of the kite is dented inward, as if some celestial intruder as soon as banged into it.


■ On this Saturn-day, Saturn is at some point earlier than opposition. Do you discover that Saturn’s rings are distinctly brighter, in comparison with Saturn’s globe, than they often are? This Seeliger impact is attributable to the stable ring particles backscattering daylight to us when the Solar is nearly straight behind us. The dusty surfaces of the Moon and Mars do that too, however Saturn’s clouds don’t. Within the case of Saturn the impact is called for Hugo von Seeliger, who studied it intimately and revealed his findings in 1887.

■ Final-quarter Moon (actual at 9:16 a.m. EDT). By the point the Moon rises late tonight, round midnight or 1 a.m. native daylight saving time, its terminator shall be not precisely straight however very barely concave. Look about 15° above the Moon for the brightest stars of Aries, 2nd and Third magnitude.

By the very first trace of daybreak Sunday morning the Moon shall be fairly excessive. Spot the Pleiades to its left, Aldebaran an analogous distance beneath the Pleiades, and the a lot looser Hyades simply above and proper of Aldebaran.


Saturn is at opposition, reverse the Solar as seen from Earth. This 12 months Saturn’s rings are tilted 18° to our line of sight — so much lower than their most tilt of 26°, which they displayed from 2016 by means of 2018, however nowhere close to the edge-on facet they’ll current in 2025. However their present middling tilt appears (to me anyway) to make Saturn look essentially the most characteristically Saturnlike. (See the pic close to the underside of this web page.)

At present is Lammas Day or Lughnasadh, one of many 4 conventional “cross-quarter” days halfway between the solstices and the equinoxes. Form of. Within the many centuries after this custom took maintain in Europe the calendar drifted with respect to the seasons, till our present Gregorian calendar was instituted a couple of centuries in the past to cease such issues. So in 2021, the midpoint between the June solstice and the September equinox really falls on August sixth, at 5:02 p.m. Japanese Daylight Time (21:02 UT).

That minute is the precise center-balance of astronomical summer season: the very high of the circle of the 12 months (as outlined by the astronomical seasons, for the Northern Hemisphere.)


■ With the advance of summer season the Sagittarius Teapot, within the south after darkish now, is tilting and pouring from its spout to the best. The Teapot will tilt farther and farther for the remainder of the summer season — or for a lot of the evening when you keep out late.

■ Tonight, telescope customers can watch Jupiter’s moon Europa slowly disappear into eclipse by Jupiter’s shadow round 12:29 a.m. EDT. Following behind is Io, which is able to likewise disappear into Jupiter’s shadow round 2:19 a.m. EDT. (Subtract 1 hour from these to get CDT, and so forth.)

Earlier within the evening, Jupiter’s Nice Purple Spot ought to cross Jupiter’s central meridian round 10:24 p.m. EDT. The spot must be seen virtually as simply for about an hour earlier than and after, in a very good Four-inch telescope if the atmospheric seeing is sharp and regular. A light-weight blue or inexperienced filter helps a bit.

The Purple Spot transits about each 9 hours 56 minutes. However not fairly like clockwork! It drifts east or west in Jupiter’s ambiance considerably irregularly. A change usually turns into detectable to visible transit timers over a span of some months. Our transit-time predictions are primarily based on pretty current observations, however do not be shocked if the Purple Spot has taken it into its head to maneuver a couple of minutes off schedule.


Looking Hebe. The asteroid 6 Hebe is a little bit previous opposition, a pinpoint of about magnitude eight.Four north of the Sagittarius Teaspoon. A pair of 10×50 or bigger binoculars, used with care and precision below a darkish sky, could also be sufficient so that you can decide it out utilizing the finder chart within the July Sky & Telescope, web page 50. (The chart there reveals Hebe’s place for zero:00 UT on the dates indicated, which falls on the night of the earlier date for North America.)


■ In case you use a telescope a lot you are in all probability accustomed to Lyra overhead, harboring Vega, the Double-Double, and the Ring Nebula amongst different sights. And close by is Albireo, the beak of Cygnus and one of many sky’s best gold-and-blue double stars.

However between Albireo and Lyra, what concerning the much-overlooked globular cluster M56? At magnitude eight.three you may even have the ability to detect it with massive binoculars in a darkish sky. To pinpoint the spot, hone in with Matt Wedel’s “Misplaced in Area,” his Binocular Spotlight column and chart for this lesser-known discover within the August Sky & Telescope, web page 43.

■ It could be the peak of summer season, however wintry Gemini is arisen within the east by the point daybreak begins. The waning crescent Moon crosses it on Thursday and Friday mornings, August fifth and sixth, as proven beneath.

Many of the stars of Gemini have light into the rising mild of day by the point dawn is barely 45 minutes away. You will do higher to look earlier when the constellation is decrease. In case you do get outside on the late facet, binoculars will assist, and the waning Moon gives a reference. (The Moon positions listed below are, as at all times, actual for an observer in the course of North America.)


■ The Large Dipper hangs diagonally within the northwest after darkish. From its midpoint, look to the best to seek out Polaris (not very vivid) glimmering due north as at all times.

Polaris is the tip of the Little Dipper’s deal with. The one different Little Dipper stars which are even reasonably vivid are the 2 forming the outer finish of its bowl: 2nd-magnitude Kochab and Third-magnitude Pherkad. On August evenings you may discover them to Polaris’s higher left (by a few fist and a half). They’re known as the Guardians of the Pole, since they ceaselessly circle round Polaris by means of the evening and thru the 12 months.


■ Shiny Vega passes closest to overhead round 10 or 11 p.m. now, relying on how far east or west you’re in your time zone.

How intently it misses your zenith is dependent upon how far north or south you’re. It passes proper by means of your zenith when you’re at latitude 39° north (Washington DC, Cincinnati, Kansas Metropolis, Lake Tahoe). How intently are you able to choose this simply by trying?

Deneb crosses closest to the zenith two hours after Vega. However to see Deneb precisely straight up that you must be farther north, at latitude 45°: Portland, Minneapolis, Montreal, southern France, northern Italy.


■ Have you ever been seeing any Perseids meteors but? For now you may solely see the very occasional Perseid throughout your observing periods, however their numbers are steadily rising. The bathe is because of peak late subsequent Wednesday evening, August 11, however occasional forerunners start exhibiting up as a lot as two or three weeks beforehand. Already the sky is moonlessly darkish. For extra on this 12 months’s Perseids see the August Sky & Telescope, web page 48.

It is virtually definitely a Perseid round this time of 12 months if, once you hint its path backward far sufficient throughout the you discover that this line intersects the northern a part of Perseus.



This Week’s Planet Roundup

Mercury is hidden along side the Solar.

Venus (vivid at magnitude –three.9) shines low due west throughout twilight. It units round twilight’s finish.

Mars is hidden deep within the sundown.

Jupiter (magnitude –2.eight, in Aquarius) and Saturn (magnitude +zero.2, in Capricornus) shine within the east-southeast after darkish. Jupiter begins the evening lowest, however it’s by far the brighter of the 2. Saturn glows yellowly 19° (about two fists at arm’s size) to Jupiter’s higher proper. The pair ranges out round midnight, relying in your date and placement. By then they’re practically at their highest within the south, at their telescopic greatest.

Saturn reaches opposition on August 1st, Jupiter on August 19th, so that they’re already basically as shut and massive as they’re going to get this 12 months. See “Saturnian Challenges” beginning on web page 52 of the July Sky & Telescope, additionally “Motion at Jupiter” within the August situation, web page 50, and “Canine Days with the Fuel Giants” on web page 49 of August.

Jupiter on July 12, 2021Jupiter on July 12th, imaged by Christopher Go. South is up. The South and North Equatorial Belts have principally diminished to slim darkish traces. Purple barges and spots proceed simply north of the NEB. A lot of the Equatorial Zone continues pale yellow-tan. The Nice Purple Spot is on the opposite facet of Jupiter, however notice the row of white ovals within the south temperate space.

Saturn on July 25, 2021Saturn on July 25. North is up. This beautiful stacked-video picture reveals element within the broad A Ring, in addition to the skinny Encke Hole simply contained in the outer fringe of the outer B Ring. Agapios Elia of Nicosia, Cyprus, took video throughout 45 minutes on July 25, 2021, utilizing a 9.25-inch Schmidt-Cassegrain scope. He de-rotated the globe in processing and stacking massive numbers of the of greatest frames.

Uranus (magnitude 5.7, in Aries) is excessive within the east-southeast earlier than daybreak begins.

Neptune (magnitude 7.eight, on the Aquarius-Pisces border 23° east of Jupiter) crosses excessive within the south within the early-morning hours.

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 Common Time minus Four hours. Common Time is also referred to as UT, UTC, GMT, or Z time. To turn into extra professional about time methods than 99% of the individuals you may ever meet, see our compact article Time and the Novice Astronomer.

Need to turn into a greater astronomer? Be taught your method across the constellations. They’re the important thing to finding the whole lot fainter and deeper to hunt with binoculars or a telescope.

That is an out of doors nature interest. For an easy-to-use constellation information masking the entire night sky, use the massive 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 may 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 lots of 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 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 subsequent up, as soon as you already know your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And you’ll want to learn learn how to use sky charts with a telescope.

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

Can a computerized telescope exchange charts? Not for novices, I do not assume, and never on mounts and tripods which are lower than top-quality mechanically, that 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’t come with out creating 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 will 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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