This Week's Sky at a Glance

by Alan M. MacRobert

Some daily events in the changing sky for June 6 – 14.

The waxing Moon, in its monthly march away from the Sun, poses first with Mars and then with Saturn and Regulus. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. For clarity, the Moon is shown three times its actual size.)

Sky & Telescope diagram

Friday, June 6

A thin crescent Moon at dusk is lined up far to the lower right of Saturn, Regulus, and Mars, just off the right edge of the picture here. Look farther to the right of the Moon for Pollux and Castor, the heads of the Gemini twins. The twins' feet are already at or below the horizon.

Saturday, June 7

The crescent Moon hangs in the dusk close to Mars, as shown at right. They're only about 2° apart as seen at the time of twilight for North America. Mars looks smaller because it's 780 times farther away (as of tonight). But Mars is actually twice the Moon's diameter.

Sunday, June 8

This evening the waxing Moon shines with Saturn and Regulus, as shown above.

Monday, June 9

Now the thicker waxing Moon is left of Saturn and Regulus, off the edge of the picture.

Saturn's largest moon, Titan, is spottable in a small telescope four ring-lengths to Saturn's east this evening. A guide to identifying all six of Saturn's satellites that are sometimes visible in amateur scopes is in the June Sky & Telescope, page 60.

Tuesday, June 10

First quarter Moon (exact at 11:04 a.m. Eastern Daylight Time).

Wednesday, June 11

On Thursday morning, Jupiter-watchers across North America can watch Ganymede, Jupiter's biggest moon, slowly disappear into eclipse by Jupiter's shadow around 4:45 a.m. EDT; 1:45 a.m. PDT. Then, 25 minutes later, the tiny black shadow of Europa starts crossing Jupiter's face. But by that time, most observers in the Eastern time zone will have lost Jupiter in the growing light of day.

Thursday, June 12

Discovery + Space Station = nice flyovers! The space shuttle Discovery undocked from the International Space Station yesterday morning; tonight you may still have a chance to see the two of them crossing your sky on nearly the same track. Discovery is less bright than the ISS. To find whether you can see them, and if so when and where to look, put your location and time zone into our Satellite Tracker.

After nightfall this evening, the gibbous Moon shines in the south-southwest with Spica glittering to its upper left.

On Friday morning, the tiny black shadow of Jupiter's moon Io crosses the planet's face from 2:44 to 5:00 a.m. EDT, followed by Io itself from 3:21 to 5:38 a.m. EDT. Easterners lose the last parts in twilight or daylight. Westerners (subtract 3 hours to get Pacific time) get to see the whole thing. For all of Jupiter's satellite phenomena this month, good worldwide, see the June Sky & Telescope, page 58.

Friday, June 13

After dark, the gibbous Moon shines in the south with Spica to its upper right. Very high above the Moon (almost overhead as seen from mid-northern latitudes) is brighter Arcturus. The reason Arcturus looks brighter than Spica is it's much nearer: 37 light-years away, compared to Spica's 260 light-years. In reality, hotter Spica is 16 times as luminous as Arcturus.

And oh yes, the Moon is only 1.3 light-seconds away.

Saturday, June 14

Bright Arcturus shines its highest in the south at the end of dusk (almost overhead as seen from mid-northern latitudes). The brightest star high in the east-northeast is Vega, Arcturus's equal; they both shine at magnitude zero. These are the two brightest stars of summer — which officially begins in 6 days.

Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly foldout map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of maps; the standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.

More beginners' tips: "How to Start Right in Astronomy".

This Week's Planet Roundup

Jupiter on May 24th. The North Equatorial Belt, above center, "is getting lighter in color from the deep dark red a few weeks ago," writes photographer Christopher Go. The black dot on it is the shadow of Io. Visible below center are not just one red spot but three; see article. The Great Red Spot remains near System II longitude 121°. North is up (though many telescopes show south up).

Christopher Go

Mercury and Venus are lost in the glare of the Sun. Mercury is on the near side of the Sun (inferior conjunction June 7th), and Venus is on the far side of the Sun (superior conjunction June 9th).

Mars (magnitude +1.6, in Cancer) shines high in the west after dark, to the lower right of the Saturn-and-Regulus couple as shown at the top of this page. Mars is drawing nearer to them every week. They'll have a close get-together in early July.

In a telescope, Mars is a minuscule 4.9 arcseconds wide — a very tiny blob. The Mars Phoenix Lander is near the north polar cap.

Jupiter (magnitude –2.6, in eastern Sagittarius) rises around 10 or 11 p.m. daylight saving time, left of the Sagittarius Teapot. It's highest in the south, and offering the sharpest views, before and during dawn.

In a large amateur scope during excellent seeing, a pair of white storms has been visible in Saturn's South Temperate Zone. This stacked-video image was taken at 11:15 UT on May 1, 2008, when the System II longitude on the central meridian was 70°. North is up.

Christopher Go

Saturn (magnitude +0.7, in Leo) glows in the southwest after dark, about 3° upper left of fainter Regulus (magnitude +1.4), as shown at the top of the page. They're gradually getting wider apart.

Uranus and Neptune (magnitudes 6 and 8, respectively, in Aquarius and Capricornus) are in the southeast before dawn. Use our article and finder charts.

Pluto (magnitude 14.0, in northwestern Sagittarius) is well up in the southeast by 11 or midnight. It comes to opposition on June 20th. If you've got a big scope and ambition to match, here's our article and finder chart.

All descriptions that relate to your horizon or zenith — 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) equals Universal Time (UT, UTC, or GMT) minus 4 hours. ----------------------

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This Week's Sky at a Glance