This Week’s Sky at a Glance, July 7 – 15

 

Moon, Saturn, Antares July 7, 2017

The nearly full Moon lines up with Saturn and Antares on the evening of the 7th.

Venus and Aldebaran at dawn, July 8, 2017

Venus starts the week above Aldebaran . . .

Venus and Aldebaran, July 14, 2017

. . . and ends the week closer to Aldebaran's upper left.

Friday, July 7

• The nearly full Moon shines over the Sagittarius Teapot after dark tonight. Look carefully for the Teapot's stars through the moonlight. The Teapot is about the size of your fist at arm's length, with its handle to the left and its spout to the right. Binoculars may help.

Saturday, July 8

• The full Moon is low in the southeast as the stars come out. Look far to the Moon's upper left for Altair, and far to the Moon's upper right for Saturn.

Sunday, July 9

• The Big Dipper, still high in the northwest after dark, is turning around to "scoop up water" through the evenings of summer and early fall.

Monday, July 10

• In very early dawn Tuesday morning, you'll find Venus lined up with the Pleiades above it and Aldebaran below it.

Tuesday, July 11

Double stars in the top of Scorpius. The two brightest points due south after twilight ends are Saturn and, right or lower right of it, Antares. To the right and upper right of Antares is the nearly vertical row of three stars marking the head of Scorpius. The top star of the row is Beta Scorpii or Graffias, a fine double star for telescopes.

Just 1° lower left of Beta Sco is the fainter, very wide naked-eye pair Omega1 and Omega2 Scorpii, oriented diagonally. Binoculars may show their slight color difference.

Upper left of Beta by 1.6° is Nu Scorpii, another fine telescopic double. High power in good seeing reveals that Nu's brighter component is itself a close binary, separation 2 arcseconds.

Wednesday, July 12

Europa: now you see it, now you don't.  Telescope users in western North America can watch an unusual event on Jupiter's eastern limb this evening. At 9:18 p.m. PDT, Europa emerges out of occultation from behind the planet, seeming to bud off from Jupiter's edge. And then just three minutes later it fades away again into eclipse by Jupiter's shadow.

The events are gradual. Use high power to see Europa so close to the planet's glare.

Thursday, July 13

• Venus is passing 3° north (upper left) of Aldebaran in the dawn this morning and Friday morning. See the illustration above.

Mercury in twilight, mid-July 2017

Binoculars will help with finding Mercury and its fainter neighbors. Their visibility in bright twilight is exaggerated here.

Friday, July 14

• Mercury is having a poor apparition low in evening twilight this month. But it's bright enough (magnitude –0.2 this evening) that you can pick it up anyway if the air is good and clear. Your best chance is probably about a half hour after sunset, as shown at right.

• One hour after sunset, as twilight is fading deeper and the stars are coming out, you'll find the two brightest stars of summer, Vega and Arcturus, high overhead equally far from the zenith: Vega toward the east, and Arcturus toward the southwest (depending on your location).

Saturday, July 15

• The tail of Scorpius is low in the south after darkness is complete. How low depends on how far north or south you live: the farther south, the higher. Look for the two stars especially close together in the tail. These are Lambda and fainter Upsilon Scorpii, known as the Cat's Eyes, as shown at the top of this page. They're canted at an angle; the cat is tilting his head and winking.

The Cat's Eyes point west (right) by nearly a fist-width toward Mu Scorpii, a much tighter pair known as the Little Cat's Eyes. Can you resolve Mu without using binoculars? It's hard!

________________________

Want to become a better astronomer? Learn your way around the constellations! They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy.

Pocket Sky Atlas, jumbo edition

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae. Shown above is the Jumbo Edition for easier reading in the night. Larger view. Sample chart.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, is the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide by Kepple and Sanner.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


This Week's Planet Roundup

Saturn on June 11, 2017

This could be the sharpest image of Saturn ever taken from the ground. Damian Peach and six colleagues acquired it on June 11th using the 1-meter Pic Du Midi reflector high in the French Pyrenees. "Rarely seen details are observed, such as small ringlets within Ring C, including the Maxwell and Colombo divisions," writes Peach. "The Encke division is easily observed around the entire [outer] A ring." South is up.

Extremely high quality image of Jupiter by Damian Peach et al., June 11, 2017

And is this the best image of Jupiter ever taken from the ground? The same team at Pic du Midi took it the same night (June 11, 2017) — "months after opposition," notes Peach (as indicated by the slightly sideways illumination causing the shading on the left). North is up.

Mercury (roughly magnitude –0.5) is very low in west to west-northwest about a half hour after sunset.

Venus (magnitude –4.2) shines brightly in the east before and during dawn. Aldebaran, much fainter at magnitude +0.9, is about 5° below Venus at the beginning of this week, then lower right of it, then directly right of it around week's end.

Mars is lost behind the glare of the Sun.

Jupiter (magnitude –2.0, in Virgo) shines showily in the southwest to west during evening. Spica (magnitude +1.0) glitters 10° left of it. In a telescope, Jupiter has shrunk to 37 or 36 arcseconds wide.

NASA's Juno spacecraft flies over Jupiter's Great Red Spot on July 10th at a distance of only 9,000 kilometers. The flyby ought to provide the most detailed imagery of the Red Spot ever, once the data are processed and images are released. Here's some recent infrared imagery of Jupiter in support of the mission. Here's more.

Saturn (magnitude +0.1, in southern Ophiuchus) glows steadily in the south during and after dusk. Fiery Antares, less bright, twinkles 14° to Saturn's right or lower right. Delta Scorpii, the third brightest object in the area, catches the eye half as far to the upper right of Antares.

Uranus (magnitude 5.8, in Pisces) and Neptune (magnitude 7.9, in Aquarius) await high in the southeastern side of the sky before the beginning of dawn. Finder charts.

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All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time (UT, UTC, or GMT) minus 4 hours.

__________________________

"This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours."
— Neil deGrasse Tyson, 2014


"Objective reality exists. Facts are often determinable. Vaccines stop diseases. Carbon dioxide warms the globe. Bacteria evolve in response to antibiotics. Science and reason are no political conspiracy. They are how we discover reality. Civilization's survival depends on our ability, and willingness, to do so."
— Alan MacRobert, your Sky at a Glance editor


"Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passions, they cannot alter the state of facts and evidence."
— John Adams, 1770


 

5 thoughts on “This Week’s Sky at a Glance, July 7 – 15

  1. Johnberridge10

    I was watching the Constellation Scorpio on 7/11 and to the right and north a bright light burst out and disappeared just as fast as it appeared. Any ideas on the occurance or where can I go to find out?

  2. mary bethmary beth

    Since no expert answered your question yet, I’ll give it a try. Think a very early Perseids meteor? Bet it was a beautiful sight. From what city did you see?

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