Saturn (at proper) and Jupiter (left) dominate the morning sky this month. The ringed planet gives particularly good viewing because it reaches opposition. Credit score: Alan Dyer
The fuel giants reign as spectacular objects in a single day; their moons additionally appeal to consideration. Our night sky has a quickly diminishing view of Mercury, with Mars troublesome to identify. Morning carries Uranus and Neptune, simply seen in binoculars. And within the second half of August, Venus returns as a superb object within the predawn sky.
Mars is difficult at magnitude 1.8 within the twilight sky, however you would possibly get a glimpse on Aug. 18, when it stands 11/4° south of a waxing crescent Moon within the west after sundown. The pair units simply over an hour after the Solar and Mars turns into more and more tougher to identify as its altitude declines. Discover the Moon first, then seek for Mars.
On Aug. 1, Mercury stands 6° excessive within the western sky half-hour after sundown, shining at magnitude 0.1. The planet dims to magnitude 0.4 by Aug. 10 and is now 5° excessive half an hour after sundown. It’s almost 5° decrease than Mars, however the Purple Planet is way fainter and fewer seen.
One day earlier, on the ninth, Mercury reaches biggest jap elongation, when it stands 27° east of the Solar. Nonetheless, the low angle of the ecliptic renders the planet troublesome to see; it’s extra favorable for Southern Hemisphere observers. On the 18th, whilst you’re trying to find Mars close to the Moon, Mercury sits some 6° under our satellite. It’s very near the horizon, too low to be simply seen.
Saturn reaches opposition Aug. 27 and the ringed planet is seen from nightfall to daybreak. On Aug. 1, Saturn rises by 9:30 p.m. native daylight time and is effectively positioned 25° above the southeastern horizon by midnight. It’s situated in Aquarius the Water-bearer. The planet reaches its opposition magnitude of 0.4 by Aug. 16.
The evening of Aug. 2/3, Saturn stands inside 4° of a shiny, almost Full Moon. The Moon returns to Aquarius Aug. 30, when the 2 stand 6° aside a couple of hours after rising. Additionally close to Saturn is the intense 1st-magnitude star Fomalhaut, situated 20° southeast of the planet in Piscis Austrinus.
Telescopic views reveal the sunlit northern aspect of the rings, that are tilted earthward by 8° in early August. Their angle will increase to 9° by the thirty first. In just some years, the rings will seem edge-on with solely a small annual fluctuation. The disk of Saturn spans 19″ at opposition — fairly spectacular when viewing it from a distance of 820 million miles. Saturn’s rings span 43″, greater than double the disk’s width.
Skilled observers will search for the Seeliger impact, a brightening of the rings at opposition when the shadows of ring fragments are hidden from view because the illuminating Solar stands straight behind us. Observe the rings over a couple of nights across the twenty seventh to see whether or not you discover the impact. You may additionally report Saturn photographically to create a everlasting report.
Three separate rings are seen in small telescopes. The outer A hoop is dusky. Below glorious circumstances, its Encke Hole may be seen. A broader darkish hole, the Cassini Division, is well seen on the interior fringe of the A hoop. Inside to that’s the brightest ring, the B ring. Darker and extra ethereal than the A hoop is the innermost C ring, additionally known as the Crepe Ring for its diaphanous nature.
Orbiting Saturn in the identical aircraft because the ring system is a group of moons, many seen in small telescopes. Most evident is Titan, which shines at magnitude 8.5. This moon’s environment provides it a barely yellowish hue. It stands north of the planet Aug. 7 and 23, and south Aug. 15 and 31.
Fainter moons orbit nearer to the rings. At opposition, they’re at their brightest for the 12 months. Rhea is brightest round magnitude 9.7, then Tethys round 10.3 and Dione at 10.5. Magnitude 11.9 Enceladus, which orbits each 33 hours, is difficult to see because of Saturn’s brilliance. This icy moon sports activities lively geysers close to its southern pole.
Because of their orbital tilt, the moons now endure transits and occultations with Saturn. Such occasions are tougher to look at than their jovian counterparts because of the bigger distinction between Saturn and its moons. For a problem, see in the event you can spot Dione because it’s occulted by Saturn on the morning of Aug. 7, when it skims the northern limb of the planet between roughly 3:15 a.m. and 4:45 a.m. EDT.
Exceedingly troublesome is the reappearance of Twelfth-magnitude Enceladus from behind Saturn the identical morning at 4:41 a.m. EDT, reappearing off the planet’s northeastern limb. In the meantime, a 3rd occasion is going on south of the rings. Tethys and its shadow start a transit, beginning with the shadow simply earlier than 4:40 a.m. EDT. The moon follows six minutes later. Many related occasions will happen fairly recurrently now, given these moons’ brief orbital durations.
Iapetus lies removed from Saturn, orbiting each 79 days. It reaches jap elongation Aug. 1, standing 9′ east of the planet. It’s magnitude 11.9, with its darker hemisphere dealing with Earth. Iapetus brightens by way of the month; observe it because it reaches inferior conjunction Aug. 20 at midnight EDT, simply 25″ northwest of Saturn and shining close to eleventh magnitude. The next evening, it’s already skipped almost a full arcminute away, brightening because it goes. Iapetus reaches western elongation subsequent month at magnitude 10.2.
Neptune rises simply after 10 p.m. native daylight time on Aug. 1 and earlier than 8:30 p.m. on Aug. 31. This brings it into the night sky not removed from the Circlet of Pisces. At magnitude 7.7, the planet is straightforward to confuse with the background stars, however its location simply northwest of a line of three stars — Sixth-magnitude 20 and 24 Piscium, and Fifth-magnitude 27 Psc — aids with identification. You will discover this trio of stars 5.6° southeast of Lambda (λ) Psc, the southeasternmost star within the Circlet. Can you see Neptune’s tiny, bluish 2″-wide disk by way of a telescope? It is going to rely on seeing circumstances.
As August opens, Neptune types an equilateral triangle with 20 and 24 Psc. From evening to nighttime, the planet tracks southwest towards 20 Psc, ending the month 19′ from the star. Get aware of this star — throughout subsequent month’s opposition, Neptune will get a lot nearer!
Jupiter rises shortly after midnight on Aug. 1 and is greatest positioned for observing within the hours earlier than daybreak, when it stands greater than 40° above the jap horizon. It’s in Aries the Ram and shines vividly at magnitude –2.4 in early August. On the morning of Aug. 8, Jupiter is lower than 2.5° from a Final Quarter Moon. Notice the Pleiades (M45) in Taurus, some 16° to Jupiter’s northeast.
Swing binoculars towards the gas giant and maintain very regular — you’ll seemingly spot a couple of shiny moons. Step as much as a telescope to actually reveal the jovian system of 4 Galilean moons and a planet replete with gentle and darkish cloud bands. Notice the evident pair of belts straddling the equator. Extra refined belts reside at northerly and southerly latitudes. Jupiter’s quick rotation — slightly below 10 hours — carries cloud options, together with the Nice Purple Spot, throughout the disk. Their motion is noticeable to an attentive observer inside 10 to fifteen minutes.
The Galilean moons orbit roughly each two to 17 days. Their altering relative positions are fascinating to look at, as are transits and occultations.
The morning of Aug. 3, Io’s shadow falls on the jovian cloud tops at 4:45 a.m. EDT, adopted by the moon itself at 5:07 a.m. CDT (proper round dawn on the East Coast). Europa follows swimsuit midmonth. Its shadow begins a transit at 3:23 a.m. EDT on Aug. 14, adopted by the moon at 5:12 a.m. CDT. Discover the longer hole between the transits of shadow and moon for Europa in contrast with Io — the latter has a smaller orbit.
Ganymede performs hide-and-seek for 77 minutes close to Jupiter’s north pole Aug. 13. The shallow angle of the limb slowly hides the moon round 5:33 a.m. EDT — you’ll discover Ganymede dimming a couple of minutes earlier than this. The massive moon could seem to mix with the limb of Jupiter fairly a bit earlier, relying in your seeing circumstances. Ganymede reappears by 5:51 a.m. CDT, however be looking out earlier, once more as a result of it might reappear sooner.
Ganymede transits the south polar areas for an hour the morning of Aug. 31, from 3:26 a.m. to 4:27 a.m. EDT.
Notice that the Fifth-magnitude star Sigma (σ) Arietis lies near Jupiter the final two weeks of the month, coming inside an arcminute or two of the planet Aug. 21 and 22. Don’t confuse the star with the moons — they’re of comparable brilliance.
Uranus stands between 7.5° and 9° northeast of Jupiter throughout August. It additionally lies in Aries and is a binocular object at magnitude 5.8. Uranus is greatest seen within the hour earlier than daybreak, when it’s 60° excessive within the southeast and roughly stage with the Pleiades. Few different stars are close by — the brightest are 4th-magnitude Delta (δ) and Fifth-magnitude Zeta (ζ) Arietis, which stand 1.5° aside to Uranus’ northwest. East of them is 63 Ari, a bit brighter than Uranus, which lies 2.6° south of this star. Uranus wanders slowly east and slows to a cease late on Aug. 28, then begins its retrograde movement. A telescope will present a 4″-wide disk with a greenish hue.
Venus passes inferior conjunction Aug. 13 and rapidly springs into the morning sky as a shiny object almost 4° excessive half-hour earlier than dawn on Aug. 21. By the top of August, Venus is 26.5° west of the Solar and virtually 10° excessive among the many dim stars of Most cancers about an hour earlier than dawn. A telescope will present a gorgeous 11-percent-lit crescent spanning 50″.
Rising Moon: Younger and outdated collectively
Tycho and Clavius are two longtime favorites of selenophiles. The duo stands out within the Moon’s southern half in a powerful play of sunshine and shadow when the Solar rises over them on the twenty fourth. Below a low Solar angle, Tycho’s usually good ray system is essentially hidden from view. (It’s greatest seen a couple of nights from now.) However there are sufficient hints pointing again to it. A unique giveaway to its identification are the indicators of its youth: a distinguished deep bowl, sharp rim, and well-defined central peak. The overwhelming majority of objects within the crater-crowded southern highlands are something however younger.
Clavius is the large function nearer to the limb. Its debris-filled ground and softer rim are the telltale consequence of age-old battering by smaller impacts on the finish of the solar system’s interval of heavy bombardment. Take a more in-depth look contained in the shallow bowl to see a neat curving chain of impression options. Over the course of an hour, observe the shadows’ retreat and spy the looks of even smaller craters.
Within the following nights, Tycho’s rays turn out to be more and more apparent. Additionally word the darker ring round its raised rim. The warmth from the blast that shaped it induced the encircling floor to partially soften and lose its lighter shade. Whereas Clavius by no means will get misplaced as a result of it’s so huge and distinct, average-sized craters close by that had been apparent on the twenty fourth are actually virtually unidentifiable amongst dozens of divots.
The area will be seen beneath reverse lighting at 5 a.m. on the seventh and Eighth, when the Moon is excessive within the south.
Meteor Watch: Perseid prospects
The Perseid meteor bathe, one of many 12 months’s greatest, peaks Aug. 13 with anticipated charges exceeding one per minute within the hour earlier than daybreak, at the same time as a slender 8-percent-lit crescent Moon hangs in Gemini. This 12 months is among the extra favorable occasions for North American observers, with the expected peak beginning round 3 a.m. EDT.
The most effective place to search for Perseids is often at 45° altitude some 40° to 70° away from the radiant. A favourite constellation to look at throughout the Perseids is Cygnus, as many bathe members run its size.
The bathe is lively from July 17 by way of Aug. 24. Round these dates the charges are very low, rising to a peak within the second week of August. The anticipated zenithal hourly charge on Aug. 13 is 100 meteors per hour. Within the hour earlier than daybreak, Perseus is about 60° excessive, so anticipate a charge nearer to 50 or 60 per hour at peak for North American observers (because the altitude of the radiant strongly impacts the observable charge).
Comet Search: Location, location, timing
Lastly! An prolonged interval of respectable comets begins, and we even have decisions. Don’t dally if you wish to catch C/2021 T4 (Lemmon). Monitoring northward into Libra, this Eighth-magnitude fuzzball from the Oort Cloud is fading after its closest strategy to the Solar July 31. Evaluate it with globular clusters such because the concentrated NGC 6144 close to Antares, then diffuse NGC 5897. As a result of Lemmon is already setting within the southwest because it will get darkish, be prepared initially of your observing session.
Higher fitted to late arrivals on the darkish web site is short-period (6.5 years) 103P/Hartley 2. Glowing a modest magnitude 10, Hartley slides from head to toe in Andromeda because it rises greater with every hour of the evening. By midmonth, the comet is a second Ghost of Mirach, passing by Beta (β) Andromedae not removed from the galaxy NGC 404. This object can catch imagers unawares, posing as an inside lens reflection of the intense star. The inexperienced glow of diatomic carbon across the comet’s coma ought to make for a pleasant distinction with the grey smudge of the galaxy.
Regardless of the almost Full Moon, catch Hartley 2 on the thirty first when it’s lower than a level from M34, a pleasant star cluster in Perseus.
Finding Asteroids: A well-known place
In the event you don’t know the place M22 is, discover out and return 12 months after 12 months. Positioned about 2.5° northeast of the tip of Sagittarius’ Teapot (within the south for many readers), this large globular cluster is a straightforward discover in binoculars from a rural sky. M22 is our anchor level for an all-month stakeout of main-belt asteroid 15 Eunomia.
Because of the various darkish dust lanes crossing the entrance of our Milky Way’s core, magnitude 9 Eunomia received’t be misplaced amongst throngs of extra distant stars. Then again, its obvious movement is on the gradual aspect, so we’ll wish to make a sketch of a star subject and are available again an evening or two later to see which dot has moved. The first to the 2nd and particularly the Sixth by way of the Eighth are the very best alternatives. Over the last third of August, Eunomia is nearly the brightest dot in its area.
Found in 1851 by Annibale de Gasparis, the potato-shaped boulder spans a decent 220 miles finish to finish and 130 miles throughout the center, placing it among the many prime 10 largest our bodies in the primary belt. It seems to be the father or mother of an related asteroid household shaped by a collision way back. Named for the mythological Greek personification of regulation and order, Eunomia was among the many proof used to demote asteroids to their very own group from their authentic standing as planets.
