Some daily events in the changing sky for July 31 – August 8.
Friday, July 31
Saturday, August 1
Sunday, August 2
Monday, August 3
Tuesday, August 4
Wednesday, August 5
Thursday, August 6
Friday, August 7
Saturday, August 8
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 diagram" target="new_window">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 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
Mercury (about magnitude –0.4) is having a poor apparition deep in the glow of sunset. Look for it very low in the west-northwest in bright twilight, as shown at the top of this page. Binoculars help.
Venus (magnitude –4.0, in the feet of Gemini) blazes in the eastern sky before and during dawn.
As recently happened with Jupiter, an amateur planetary imager has found a newly-appeared marking on Venus! Frank Melillo of Holtsville, New York, discovered that Venus had unexpectedly grown a "Great White Spot" in ultraviolet light when he imaged it on the morning of July 19th, as shown here. Other amateur ultraviolet imagers soon confirmed it. The European Space Agency's Venus Express probe, currently orbiting Venus, has imaged the spot in detail. See New Scientist article for more.
Mars (magnitude +1.1, in the horns of Taurus) is well to the upper right of Venus before dawn. Not far to Mars's right or upper right is Aldebaran, a close match for it in both brightness and color. The two are 7° apart on August 1st, 10° apart by the 8th.
Jupiter (magnitude –2.8, in Capricornus) shines low in the east-southeast during twilight. It's higher in better telescopic view in the southeast by midnight.
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. Since then it has been elongating. Backyard observers have been spotting it in 4-inch scopes during moments of steady atmospheric seeing. See our article.
Saturn (magnitude +1.1, in Leo) is getting very low in the west after sunset. Look early!
Saturn's rings may have vanished by the time you read this. They turn edge-on to the Sun and go black on August 9–10, visible only in silhouette against the planet's globe as a black hairline (if you get lucky with good atmospheric seeing). The rings turn edge-on to Earth on September 4th, but by then Saturn will be lost in the sunset.
Uranus (magnitude 5.8, just below the Circlet of Pisces), is high in the south before dawn.
Neptune (magnitude 7.8, in Capricornus) appears about 2° from Jupiter, but it's 17,000 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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