FRIDAY, JULY 10
■ In early dawn tomorrow the 11th, look east-northeast for the waning crescent Moon forming a diagonal line with Mars and Aldebaran under it, as shown below.
The thin waning Moon lines up with Mars and Aldebaran low in the dawn on Saturday morning, July 11th.
On Sunday morning the 12th, bring binoculars to catch the thinner, lower Moon now near Beta Tauri, magnitude 1.6. (The Moon here is always shown about three times its actual apparent size.)
SATURDAY, JULY 11
■ The Big Dipper, high in the northwest as evening advances, is beginning to turn around to "scoop up water" through the hours and months to come.
■ And low in the north-northeast after dark, the upright W of Cassiopeia is slowly beginning to tilt and climb.
SUNDAY, JULY 12
■ Check the sky low in the northwest or north at the end of these long summer twilights. Would you recognize shiny, ripply noctilucent clouds if you saw them? They're the most astronomical of all cloud types, what with their extreme altitude and, sometimes, their formation on meteoric dust particles. They used to be rare, but they've become more common in recent years as Earth's atmosphere changes.
MONDAY, JULY 13
■ You may already know about the Large Sagittarius Star Cloud, that rich puff of Milky Way just off the spout of the Sagittarius Teapot. It's our very partial view of the dense swarm of stars near the center of our galaxy some 25,000 light-years distant. (The Milky Way's exact center is hidden by dark dust clouds in the foreground.) It's not only the brightest, but the farthest part of the Milky Way that's visible to the naked eye.
And did you know about the little globular star cluster NGC 6522 embedded within it? This dense, tiny cluster is just 0.6° northwest of 3rd-magnitude Gamma Sagittarii, the tip of the Teapot's spout. Both fit within the low-power view of most amateur telescopes. NCG 6522 is magnitude 8.5, but switch to higher power once you think you've found it because it's tiny and dense.
And if you find NGC 6522, try for the smaller, fainter globular NGC 6528 to its east by 0.4°, and north-northwest of Gamma Sagittarii by just 0.3°.
TUESDAY, JULY 14
■ One hour after sunset, as twilight is fading and the stars are coming out, you'll find the two brightest stars of summer, Vega and Arcturus, equally near the zenith: Vega toward the east, Arcturus toward the southwest (depending on your location).
■ New Moon (exact at 5:44 a.m. on this date EDT).
WEDNESDAY, JULY 15
■ Soon after nightfall, look due south for orange Antares on the meridian. Around and upper right of Antares are the other, whiter stars forming the distinctive pattern of upper Scorpius. The rest of the Scorpion runs down from Antares toward the horizon, then left.
Three doubles at the top of Scorpius. The head of Scorpius — a near-vertical row of three stars — stands upper right of Antares. The top star of the row is Beta (ß) Scorpii or Graffias: a fine double star for telescopes, separation 13 arcseconds, magnitudes 2.8 and 5.0. (They're unresolved in the photo below.)
In the neighborhood of Antares, a triangle of three nice double stars await telescope users. Akira Fujii
Just 1° below Beta is the very wide naked-eye pair Omega1 and Omega2 Scorpii. They're 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.
THURSDAY, JULY 16
■ In twilight this evening, low in the west, catch the returning crescent Moon less than a fist to the lower right of Venus, as shown below. Hardly more than 1° from the Moon (depending on your location), look for vastly fainter Regulus.
The Moon, Venus, and a shy third. Note: The Moon here is always drawn three times its actual apparent size, and it's placed for skywatchers near latitude 40° N, longitude 90° W (in Indiana, near the population average of North America.)
FRIDAY, JULY 17
■ Now the crescent Moon shines less than a fist left of Venus at dusk, as shown above.
Although the Moon is a crescent, a telescope reveals Venus to be gibbous. Even though they stand in the same part of the sky. Why? The Moon is closer to us than the Sun is, so we see more of the Moon's night side. Venus is on the far side of the Sun from us, so we see more of its daylit side.
SATURDAY, JULY 18
■ Starry Scorpius is sometimes called "the Orion of Summer" — for its brightness, its blue-white giant stars, and its prominent red supergiant (Antares in the case of Scorpius, Betelgeuse for Orion). But Scorpius passes a lot lower across the southern sky than Orion does, for those of us at mid-northern latitudes. That means it has only one really good evening month: July.
The rich area around the tail of Scorpius is now at its best low in the south soon after night is fully dark, as shown below. Find it about a fist and a half at arm's length lower left of Antares. Or, about a fist or less lower right of the spout of the Sagittarius Teapot. How high or low this whole scene will appear depends on how far north or south you live: the farther south, the higher.
Shaula and Lesath in the tail of Scorpius are the Cat's Eyes. Halfway between them and the Teapot's spout is the big bright open cluster M7, one of the finest in the sky — if you can see this low to the south! Nearly 4° upper right of M7 is smaller, much more modest M6. And the Cat's Eyes point west (right) to Mu Scorpii, a much closer pair known as the Little Cat's Eyes.
SUNDAY, JULY 19
■ The eyes in the tail. Spot the two stars especially close together in Scorpius's tail, shown above. These are Shaula and Lesath, Lambda and Upsilon Scorpii, also known as the Cat's Eyes. They're unequal and canted at an angle; the cat has a bleary eye and is tilting his head to our right. They're magnitudes 1.6 and 2.6. Both are blue-white supergiants, 700 and 500 light years away, respectively. The fainter one, Lesath, is the nearer one.
Between the Cat's Eyes and the Teapot's spout are the open star clusters M7 and M6, speckle-splashes in binoculars. M7 is the bigger and brighter one; M6 is much less of a standout.
Also: A line through the Cat's Eyes points side-eye to the right (west) by nearly a fist toward Mu Scorpii, a much tighter pair known as the Little Cat's Eyes. They're oriented almost exactly the same way as Lambda and Upsilon, but they're only 0.1° apart, so they appear as a single dot on the chart above; bring binoculars. They too are not a true binary. They're 800 and 500 light-years away, and again the fainter one is nearer.
This Week's Planet Roundup
Mercury is buried in the glow of sunrise.
Venus shines brightly (magnitude –4.2) as the "Evening Star" low in the west in twilight. It's getting a little lower every week. It now sets around the end of twilight.
As twilight deepens, look for Regulus to Venus's lower right. It's only 1/180 as bright at magnitude +1.4, so bring those binoculars. On Friday July 10th they're still just 1.6° apart. But the gap between them widens fast, to 9° by Friday the 17th.
In a telescope, Venus is a brilliant little gibbous disk 63% sunlit and 18 arcseconds from pole to pole. Catch it as soon in the late afternoon or early dusk as you can, before it sinks low into worse atmospheric seeing.
Venus will remain in twilight view until the end of the summer, ever lower, enlarging while waning in phase.
Mars, magnitude +1.3 in Taurus, glows in the east in early dawn. Aldebaran, its near-twin in brightness and color, twinkles 6° to its lower right or right.
Mars is still on the far side of its orbit from us, so in a telescope it's only a tiny, fuzzy blob 4½° arcseconds wide.
Jupiter is buried deep in the sunset.
Saturn (magnitude +0.7, at the Pisces-Cetus border) rises in the east around midnight. Once it's up, find it below the Great Square of Pegasus. It's well placed for telescopic viewing high in the southeast before dawn. Saturn is the brightest thing in its dim area. (Don't confuse it with Fomalhaut, its near-twin in brightness, twinkling four fists down to Saturn's lower right.)
Late last fall Saturn's rings turned nearly edged-on to Earth and almost disappeared. Now the rings' inclination has widened back up to 9°.
Saturn on July 3rd. North is up.That's the thin black hairline barely inside the rings' outer edge, much thinner than the prominent black Cassini Division closer in. It's most visible at the rings' ansae, their narrow ends. The planet casts its shadow lower right onto the rings.
Uranus (magnitude 5.8, in Taurus) hides in the distance 5° west of Mars.
Neptune (magnitude 7.9, at the Pisces/Cetus border) hides even more distantly 10° west of Saturn. You'll need detailed finder charts to distinguish Uranus and Neptune from background stars of similar brightness.
"Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence."
— John Adams, 1770