This Week’s Sky at a Glance, July 5 – 13

Moon under Leo, July 5-6, 2019

On the weekend after July 4th, the thickening Moon passes under Leo. (The blue 10° scale is about the size of your fist at arm's length.)

Friday, July 5

• As twilight fades, look for Regulus to emerge into view 2° or 3° from the crescent Moon, as shown here (for the middle of North America).

Saturday, July 6

Three doubles at the top of Scorpius. The head of Scorpius — the vertical row of three stars to the right of Jupiter and Antares — is highest in the south after dark this week. The brightest of the three is Delta (δ) Scorpii, the one in the middle.

The top star of the row is Beta (ß) Scorpii, a fine double star for telescopes.

Just 1° below Beta is the very wide naked-eye pair Omega1 and Omega2 Scorpii, not quite vertical. Binoculars show their slight color difference. They're spectral types B9 and G2.

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

Sunday, July 7

• High in the northwest after dark, the Big Dipper hangs down by its handle as it begins its long, slow scoop toward the right.

• Low in the north-northeast, meanwhile, the upright W of Cassiopeia is slowly beginning to tilt and climb.

Monday, July 8

• First-quarter Moon tonight (exactly so at 6:55 a.m. Tuesday morning EDT). As the stars come out, look for Arcturus nearly 30° (about three fists at arm's length) above the Moon, and Spica less than half that far to the Moon's left.

• How old are the craters you see on the Moon with a small scope? Bright, splashy Tycho is young at age 85 million years. The lava-flooded craters in and around the edges of the maria obviously predate the maria, most of which flowed onto the lunar surface between 3 and 3.5 billion years ago. Find the ages of many telescopic favorites with Charles Wood's "How Old Is That Crater?" in the July Sky & Telescope, page 52.

Tuesday, July 9

• Now Spica shines below the Moon during and after dusk.

• Saturn is at opposition, shining upper left of the Sagittarius Teapot late these evenings at magnitude +0.1. This week it's highest in the south for best telescopic viewing from about midnight to 2 a.m. daylight-saving time.

Wednesday, July 10

• After nightfall, Altair shines in the east-southeast. It's the second-brightest star on the eastern side of the sky, after Vega high to its upper left. (Jupiter and Saturn don't count.)

Above Altair by a finger-width at arm's length is little orange Tarazed. A bit more than a fist-width to Altair's lower left is little Delphinus, the Dolphin, leaping leftward.

Thursday, July 11

• 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).

Moon, Jupiter, Saturn, July 12-16, 2019

As the gibbous Moon waxes to full this month it steps above Scorpius and Sagittarius, pairing with Jupiter and Saturn along the way.

Friday, July 12

• The Moon this evening forms a triangle with Jupiter to its lower left and Antares under it, as shown above.

Saturday, July 13

• The Moon and Jupiter cross the sky together tonight, as shown above. Jupiter is 1,700 farther than the Moon at this month's pairup of the two. In fact the Moon is roughly the size of Jupiter's own four Galilean moons, mere pinpoints as seen in good, steadily braced binoculars or a small scope. This evening for North America, all four appear on Jupiter's celestial west side relatively close to the planet.

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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.

Jumbo Pocket Sky Atlas cover

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown above is the Jumbo Edition for easier reading in the night. 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, are the even larger Interstellarum atlas (stars to magnitude 9.5) and 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

Mercury and Mars disappear into the sunset.

Venus (magnitude –4.0) remains very low in bright dawn. You can search for it barely above a flat east-northeast horizon about 20 minutes before sunrise. Bring binoculars. Good luck.

Jupiter with Red Spot on July 2, 2019

Jupiter's Great Red Spot looks pretty normal visually, but look closer at this high-res image taken July 2nd by Christopher Go. South here is up. Note the small extensions on the spot's preceding [left] and south following [upper right] sides, as Go remarks. And, "Note the flake activity on the following side of the GRS."

Jupiter (magnitude –2.6, in southern Ophiuchus) is the white point glaring in the south-southeast as the stars come out. Orange Antares, fainter at magnitude +1.0, twinkles 7° or 8° to its lower right. Jupiter is at its highest in the south soon after dark.

Jupiter and Antares form a wide, flat, almost isosceles triangle with Delta Scorpii (Dschubba) to their right. Delta, a long-term eruptive variable of the Gamma Cassiopeiae type, has been not much fainter than Antares for most of the last 19 years — after, without warning, brightening by half in July 2000.

In a telescope Jupiter is 45 arcseconds wide. See Bob King's observing guide to Jupiter.

Saturn (magnitude +0.1, in Sagittarius) comes to opposition on July 9th. It's the steady, pale yellowish "star" low in the southeast after dark, about 30° east (lower left) of Jupiter. Look to Saturn's lower right for the Sagittarius Teapot.

With a telescope you'll want to observe Saturn when it's highest — from about midnight to 2 a.m. daylight-saving time — since it's still far south this year (declination –22° now) and thus never very high for us northerners. Saturn's rings are tilted a wide 23° to our line of sight, nearly as open as they've been for the last few years.

Uranus (magnitude 5.8, in Aries) is in the east just before the first sign of dawn.

Neptune (magnitude 7.9, in Aquarius) is high in the south-southeast at that time. Finder charts for Uranus and Neptune.

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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, GMT, or Z time) minus 4 hours.

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Audio sky tour. Out under the evening sky with your earbuds in place, listen to Kelly Beatty's monthly podcast tour of the heavens above. It's free.

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“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

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