Sky at a Glance | August 1st, 2008

By: Alan MacRobert August 1, 2008 0

Some daily events in the changing sky for August 1 – 9.

Friday, August 1

New Moon, and total eclipse of the Sun for parts of the Arctic, Siberia, and China. The eclipse is partial over most of Europe and Asia. Skywatchers in easternmost Canada also have a partial view right at sunrise. See eclipse prediction map — and afterward, check our homepage for eclipse reports as they come in! Taking pictures? Submit 'em here!

Watch as the thin Moon waxes from day to day as it passes the three twilight planets. (This scene is 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 actual size.)

Sky & Telescope diagram

Saturday, August 2

One day after it was eclipsed, the Moon is a hair-thin crescent very low in the west shortly after sunset, to the left of Venus as shown here. Bring binoculars.

Jupiter's Great Red Spot should cross Jupiter's central meridian (the imaginary line down the center of the planet's disk from pole to pole) around 11:33 p.m. Eastern Daylight Time. Visually, the "red" spot appears very pale orange-tan. It should be visible for at least 50 minutes before and after in a good 4- or 6-inch telescope if the atmospheric seeing is sharp and steady, which it usually isn't. A light blue or green filter helps. The Red Spot transits about every 10 hours 56 minutes; for all its transit times, good worldwide, see our listing or applet online.

Sunday, August 3

From now through August 7th, Neptune (8th magnitude) is just 9 arcminutes southeast or south of the 5th-magnitude star 42 Capricorni. It's even closer to the double star h5291, whose components are a faint magnitude 9.5 and 10.6, separation 25 arcseconds. See finder charts.

Monday, August 4

Two of Jupiter's moons, Io and Callisto, create a double shadow transit on the planet's face visible from the West Coast starting at 2:04 a.m. Tuesday morning PDT. It's still in progress when Jupiter sets an hour or two later.

Earlier in the night, big Ganymede casts its shadow on Jupiter from 10:38 p.m. to 1:55 a.m. EDT (7:38 to 10:55 p.m. PDT). For a complete listing of the events happening among Jupiter's moons all month (good worldwide), see the August Sky & Telescope, page 58.

What's more, Jupiter's Great Red Spot should transit around 1:11 a.m. Tuesday morning EDT (10:11 p.m. Monday evening PDT).

Tuesday, August 5

About 30 minutes after sunset, pick up Venus in binoculars just above the west-northwest horizon, and see if you can detect tiny, twinkly Regulus 1° to its lower left. Regulus is slightly less than 1% as bright!

How good, or bad, is your sky? What's your naked-eye limiting magnitude for stars overhead? Find out using the head-of-Draco map in Fred Schaaf's article in the August Sky & Telescope, page 48.

Wednesday, August 6

Spica is the star shining upper right of the Moon this evening.

The twin globular clusters M10 and M12 in Ophiuchus fit in the same binocular field of view. Know how to find them? See Gary Seronik's "Binocular Highlight" in the August Sky & Telescope, page 50. Locate Ophiuchus itself with the evening constellation map one page previous.

Thursday, August 7

Jupiter's Great Red Spot transits around 10:31 p.m. EDT.

Then a little later Jupiter's moon Io emerges from eclipse out of Jupiter's shadow, around 10:59 p.m. EDT. Watch for it just off Jupiter's eastern limb.

Friday, August 8

First-quarter Moon (exact at 4:20 p.m. EDT).

Interesting coincidence all this month! Every night, bright Jupiter is at its highest due south right when bright Vega passes its highest overhead.

Saturday, August 9

Already you're likely to be seeing occasional Perseid meteors from late evening through the beginning of dawn. The shower should peak on the morning of August 12th, but it runs from many days before then to several days after. Tonight the Moon isn't as much of a problem as it'll become in a few days. Located under the head of Scorpius tonight, the Moon sets around midnight daylight saving time.

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

Mercury is hidden in the glare of the Sun.

Venus (magnitude –3.9) is still deep in the glow of sunset. Look for it just above the west-northwest horizon about 30 minutes after sundown, as shown at the top of this page. Using binoculars, can you spot Regulus close by?

Very slowly, Venus is making its way upward for a grand "Evening Star" showing in late fall and winter.

Mars and Saturn (magnitudes +1.7 and +0.8) are getting farther apart and sinking lower in the evening twilight, as shown at the top of this page.

A diagonal white rift has appeared in Jupiter's dark North Equatorial Belt (below center), as seen in this stacked-video image taken August 5th by Christopher Go in the Philippines. Similar diagonal rifts, tilted the other way, are near the same longitude in the South Equatorial Belt, above center. The System II longitude at the time of the picture was 43°. The Great Red Spot was just around the limb; it's currently near System II longitude 127°. South is up, to match the south-up view in many telescopes.

Christopher Go

Jupiter (magnitude –2.7, in Sagittarius) shines with a steady glare in the southeast to south during evening. It's upper left of the Sagittarius Teapot and just below the bowl of the smaller, dimmer Teaspoon. It's highest around 10 or 11 p.m. daylight saving time.

Uranus and Neptune (magnitudes 5.7 and 7.8, respectively, in Aquarius and Capricornus) are well up in the southeast by 11 or midnight. Neptune this week is near 42 Capricorni and h5291, as described under August 3 above. Use our article and finder charts.

Pluto (magnitude 14.0, in the northwestern corner of Sagittarius) is in the south during the evening. If you've got a big scope and a dark sky, use 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.

To be sure to get the current Sky at a Glance, bookmark this URL:
http://SkyandTelescope.com/observing/ataglance?1=1

If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of this URL to any other character and try again.

About Alan MacRobert

Alan M. MacRobert became an avid Sky & Telescope subscriber in 1966 at age 14, joined the editorial staff in 1982, and is now a senior contributing editor, semi-retired. He played a role in practically every part of the magazine and the company's other products for more than a generation, both on the amateur-observing side and the science-reporting side. In 1994 a book collection of his observing how-tos and telescopic sky tours was published as Star Hopping for Backyard Astronomers. He has produced This Week's Sky at a Glance online every week since 1989.