Sky at a Glance | August 14th, 2009

Some daily events in the changing sky for August 14 – 22.

Friday, August 14

  • Jupiter is at opposition, big and bright. It's opposite the Sun in the sky: rising around sunset, shining highest in the middle of the night, and setting around sunrise.

    Facing east at dawn
    Early risers can watch the waning crescent Moon pass Mars and then Venus in the dawn. (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. In the Far East, move it halfway.)
    Saturday, August 15

  • At dawn Sunday morning the waning crescent Moon hangs with Mars, as shown at right.

    Sunday, August 16

  • If you're up before dawn Monday morning, look east for the Moon over Venus as shown at right. They form a quadrilateral with Pollux and Castor.

  • Venus is only 3/4° from 3.5-magnitude Delta Geminorum on Monday morning.

    Monday, August 17

  • Shortly after sunset, Saturn is 3° upper right of Mercury very low in the west; bring binoculars. See the diagram under "This Week's Planet Roundup" below.

  • Neptune is at opposition, three days after Jupiter was. By no coincidence, Jupiter is shining 3° to Neptune's west.

  • On Tuesday morning, look for the thin crescent Moon lower left of Venus.

  • Just before the first trace of dawn on Tuesday and Wednesday mornings, Venus is less than 1° from the little 8th-magnitude Eskimo Nebula, NGC 2392.

    Tuesday, August 18

  • The head of Scorpius is still fairly high in the south-southwest right after dark. So remember the prediction that the recurrent nova U Scorpii is likely to blow this year (reaching about 8th magnitude). See our article and the AAVSO's.

    Wednesday, August 19

  • The Eagle Nebula (or Star Queen Nebula) in Serpens Cauda became an astronomical icon with the Hubble image of its "Pillars of Creation," released in 1995. The nebula and its associated star cluster look quite different in an amateur scope. Many lesser clusters and nebulae also swarm in the vicinity. Explore them with Sue French's "Deep-Sky Wonders" column and sky chart in the August Sky & Telescope, page 59.

    Thursday, August 20

  • New Moon (exact at 6:02 a.m. EDT).

    Friday, August 21

  • Bright Vega crosses the zenith soon after dark this week as seen from mid-northern latitudes (exactly so from latitude 39°). When Vega is highest overhead, you know that the Teapot of Sagittarius, rich with telescopic wonders, is at its highest in the south.

    Saturday, August 22

  • With summer growing late, bright golden Arcturus is shining ever lower in the west after dark. And the Big Dipper is swinging lower in the northwest.


    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 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).

    Pocket Sky Atlas
    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope
    Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts; 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 more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.

    Can a computerized telescope take their place? I don't think so — not for beginners, anyway, and especially not on mounts that are less than top-quality mechanically. 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 and a curious mind." Without these, "the sky never becomes a friendly place."

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


    This Week's Planet Roundup

    This week, use binoculars in bright twilight to scan above the western horizon for these two departing planets.
    Mercury and Saturn (magnitudes 0.1 and 1.1, respectively) appear near each other in bright twilight just above the horizon due west. Use binoculars to look for them about 30 minutes after sunset. At the beginning of the week Saturn is above Mercury; later it's to Mercury's upper right, as shown here.

    Venus (magnitude –4.0, in Gemini) blazes in the eastern sky before and during dawn, as shown at the top ofg this page.

    Mars (magnitude +1.0, passing between the horntips of Taurus) is high to the upper right of Venus before dawn. To its own upper right is similar-looking Aldebaran. To its lower right is similarly colored Betelgeuse.

    Jupiter (magnitude –2.9, in Capricornus) is at opposition on August 14th. It comes into view low in the southeast early in twilight — the first "star" to appear after sunset. It's higher in better telescopic view by 11 or midnight.

    Jupiter impact on August 19, 2009
    Over the past month, the impact scar on Jupiter has spread out sideways, faded, and broken up into pale, feathery bits. Yellow ticks mark its approximate ends in these images by Christopher Go of Cebu, Philippines. He took them 75 minutes apart on August 17, 2009. Click on the image for a larger view.
    Christopher Go
    The impact on Jupiter. A black dust marking, like those made by the Comet Shoemaker-Levy 9 impacts in 1994, appeared suddenly in Jupiter's south polar region around July 18th. Backyard observers tracked it as it spread and elongated. By August 17th it had broken up and faded nearly to invisibility, as shown at right. See our article.

    Uranus (magnitude 5.8, just below the Circlet of Pisces) is well up in the southeast by 11 p.m.

    Neptune (magnitude 7.8, in Capricornus) appears 3° or 4° from Jupiter but 20,000 times fainter. See our finder charts for Uranus and Neptune.

    Pluto (14th magnitude, in northwestern Sagittarius) is highest in the south just after dark. See the finder chart in the June Sky & Telescope diagram" target="new_window">Sky & Telescope, page 53.

    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 (also known as UT, UTC, or GMT) minus 4 hours.

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