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Stargazing

For my part, I know nothing with any certainty, but the sight of the stars makes me want to dream. – Vincent Van Gogh

August 8 – 13, 2022

MONDAY, AUGUST 8

■ Three doubles at the top of Scorpius. To the right of Antares is the head (or forehead) of Scorpius, a near-vertical row of three stars. The brightest of them is Delta Scorpii, the one in the middle.

The top one is Beta Scorpii: a fine double star for telescopes, separation 13 arcseconds, magnitudes 2.8 and 5.0.

Just 1° lower left of Beta is the very wide naked-eye pair Omega1 and Omega2 Scorpii. They point roughly back to Beta. The two Omegas are 4th magnitude and ¼° apart. Binoculars show their slight color difference; they’re spectral types B9 and G2.

Upper left of Beta by 1.6° is Nu Scorpii, separation 41 arcseconds, magnitudes 3.8 and 6.5. In fact it’s a telescopic triple. High power in good seeing reveals Nu’s brighter component itself to be a close binary, separation 2 arcseconds, magnitudes 4.0 and 5.3, aligned almost north-south.

TUESDAY, AUGUST 9

■ The two brightest stars of summer are Vega, overhead soon after dark, and Arcturus, shining in the west. Vega is a white-hot type A star 25 light-years away. Arcturus is a yellow-orange-hot, type K giant 37 light-years distant. Their color difference is plain to the unaided eye and more obvious in binoculars.

To me, the tints of bright stars stand out a little better in the deep blue of late twilight. How about you? Could this be a color-contrast effect of seeing yellow, orange, or orange-red stars on a deep blue background?

WEDNESDAY, AUGUST 10

■ Whenever Vega crosses nearest your zenith, as it does not long after dark now, you know that the Sagittarius Teapot is at its highest due south.

Two hours later when Deneb crosses closest to the zenith, it’s the turn of little Delphinus, and boat-shaped Capricornus down below it, to stand at their highest due south.

THURSDAY, AUGUST 11

■ Full Moon (exact at 9:36 p.m. EDT). The Moon rises around sunset and shines all night close to Saturn  since both are close to their oppositions.

FRIDAY, AUGUST 12

■ The Perseid meteor shower should be at its peak late tonight, but the light of the Moon, just a day past full, will compromise the view this year. Only the brightest of the meteors will shine through. The shower is most active from 11 or midnight until dawn local time, when your side of Earth faces most directly into the oncoming meteors (i.e., the shower’s radiant is highest).

Layer up warmly even if the day was hot; remember about radiational cooling under a clear, open sky. A sleeping bag makes good mosquito armor, and use DEET on the parts of you that remain exposed. Lie back in a reclining lawn chair facing away from the Moon. Be patient.

The shower’s radiant, in northern Perseus under Cassiopeia, would be the meteors’ perspective point of origin if you could see them coming from far away in space. But the meteors only become visible in their last moments when they hit the upper atmosphere, and this can happen anywhere in your sky.

SATURDAY, AUGUST 13

■ Saturn is at opposition tonight, directly opposite the Sun in our sky. So it’s highest around the middle of the night.

In a telescope, do you notice that Saturn’s rings seem a little brighter than usual compared to Saturn’s globe? This Seeliger effect is caused by the solid ring particles backscattering sunlight to us when the Sun is almost directly behind us (i.e. Saturn at opposition). The dusty surfaces of the Moon and Mars also display this “opposition surge,” but Saturn’s clouds do not. In the case of Saturn the effect is named for Hugo von Seeliger, who studied it in detail and published his findings in 1887.


THIS WEEK’S PLANET ROUNDUP

Mercury in Virgo is very low in the sunset glow. About 20 or 30 minutes after sunset, try scanning for it with binoculars just above the horizon almost due west. Good luck. At least Mercury is fairly bright: roughly magnitude –0.2 all week.

Venus, magnitude –3.9 in Cancer, continues to rise as dawn begins. As dawn brightens, look for it low in the east-northeast. It’s far below Capella.

Mars in Taurus rises around midnight or 1 a.m. and stands high in the east-southeast as dawn begins, shining at an impressive magnitude +0.1 between Aries and Taurus. It’s twice as bright as similarly colored Aldebaran a fist or so to its east.

Mars is still pretty small in a telescope, 9 arcseconds in apparent diameter, but it’s growing  by about half an arcsecond per week now. It’ll reach opposition December 8th, 17 arcseconds wide.

Jupiter in Aries rises due east soon after the end of twilight, shining at a bright magnitude –2.7 at the Pisces-Cetus border. It’s highest in the south (transiting) just before dawn begins. In a telescope Jupiter is now a good 46 arcseconds wide, nearly its maximum. Jupiter comes to opposition September 26th.

Saturn, magnitude +0.4 in western Aquarius, reaches opposition on the night of August 13-14. Spot it very low in the east-southeast in late twilight, higher in the southeast in late evening, and at its highest and best in the south around 1 a.m. Saturn’s rings appear roughly as wide, end to end, as Jupiter’s disk. See “Saturn at Opposition” in the August Sky & Telescope, page 48.

Uranus in Taurus, magnitude 5.7 in Aries, is in the background of Mars this week.

Neptune, magnitude 7.8 at the Pisces border, is high in the south before the first light of dawn, west of Jupiter.

Pluto, is retrograde in Capricorn.


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