STARGAZER #535 for July 10, 2010

Evening Planetary Show

For the past several months, Saturn, Mars, and Venus have been gracing our evening sky, although they have been widely spaced. But now, as they are closing in on one another, they're in the early stages of an evening sky show you won't want to miss.

Venus, the dazzling "evening star" in the west, is hard to miss, but Mars and Saturn can easily be confused with stars -- so let's see how to figure out what's what.

First, we'll identify some other nearby objects that are part of the show. Two bright 1st magnitude stars in the area are Leo's Regulus and Virgo's Spica. Planet Mercury makes an appearance near the horizon, and the crescent Moon glides by over several nights. Making it easier to find and sort out all the objects is the fact that they are generally aligned diagonally with Venus and Regulus at the lower right and Spica at the upper left with all the rest between them except Mercury.

Venus, of course, is the star of the show, becoming visible soon after sunset well before any of the other players. Tonight as the sky darkens, watch as Regulus becomes visible just two moonwidths below Venus. Regulus is a bright star, yet much dimmer than Venus. Then each night thereafter Venus will gradually move toward the upper left, pulling further away from the star.

To find Mars, make a fist with your left hand and hold it at arm's length. Mars is nearly two fist-widths to Venus' upper left looking slightly reddish and about as bright as Regulus.

Now go one more fist-width to the upper left and you'll Saturn, looking like a creamy-colored star a bit brighter than Mars. Finally, another two and a half fist-widths to the upper left is Spica, a white star about the brightness of Saturn.

While those are the main characters, they're not the entire cast as the crescent Moon makes a cameo appearance. Early Tuesday evening look for a very thin crescent near the western horizon a fist-width below Venus and Regulus. Then over the next several evenings, as its crescent thickens, it passes by the others.

Wednesday evening it is to Venus's lower left, making for a beautiful pairing. Then Thursday evening it forms a triangle with Mars (upper right) and Saturn (above). Friday evening, it is a fist-width to the left of Saturn and Mars. And July 17, nearly at its 1st quarter phase, the Moon is half a fist-width below Spica.

The shy and elusive little Mercury is easy to miss. Orbiting near the Sun, it is never seen far from our star's glare. When in the morning sky, Mercury appears low in the east a little before sunrise, and when in the evening sky, as it is now, it is low in the west for a short while after the Sun goes below the horizon.

About 15 minutes after sunset, start looking for a surprisingly bright star-like object just above the west northwestern horizon three fist-widths to Venus' lower left. It creeps slightly higher each evening over the next couple of weeks, edging closer to Regulus which it finally catches July 27.

As you watch Venus, Mars, and Saturn over the next couple of weeks note that they are closing in on one another, preparing for some dramatic pairings which we'll talk about next time.

Next Two Weeks. Avg. sunrise: 6:35 a.m.; avg. sunset: 8:33 p.m. (exact for Waco, TX).
* Tomorrow's new Moon passing between Earth and Sun produces a total eclipse of the Sun that won't be visible from the northern hemisphere.
* The Moon is at 1st quarter July 18.

Naked-eye Planets. Evening: see above. Morning: Bright Jupiter, rising after midnight, is in the southeast.

Astro Milestone. July 20, 1969, U.S. astronauts Neil Armstrong and Buzz Aldrin were the first humans to land and walk on the moon. (Bet you remember where you were.)

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Stargazer appears every other week in the Waco Tribune-Herald and other newspapers.  Paul Derrick is an amateur astronomer who lives in Waco.  Write him at 918 N. 30th St., Waco, TX 76707, call or fax at (254) 753-6920, or e-mail at paulderrickwaco@aol.com. 

Copyright 2010 by Paul Derrick.  Permission is granted for free electronic distribution as long as these paragraphs are included.  Please obtain permission from the author for publication in any other form.  To be added to (or removed from) the free e-mail distribution list, send your e-mail address (and name) to paulderrickwaco@aol.com.

* * See the Stargazer Web site at http://www.stargazerpaul.com. * *

Astronomers Without Borders is dedicated to fostering understanding and goodwill across national and cultural boundaries by creating relationships through the universal appeal of astronomy.

Astronomers Without Borders projects promote sharing. Sharing resources. Sharing knowledge. Sharing inspiration. All through a common interest in something basic and universal. Sharing the sky.

Wally Pacholka's gallery of starry night sky photography of National Parks.

Highly recommended: Deep-space webcast with Astronomer Ido from his Bareket Observatory in Israel and narration by Astronomer Mark at Adler Planetarium in Chicago of U.S. Musical interpretation of cosmic images! Click: V.O.D. movie.

Also view: Comet Lulin movie.

 3 observatory sites together inventory near-earth objects (NEOs), or more specifically, the potentially hazardous asteroids (PHAs) that pose an impact risk to Earth. Given the catastrophic consequences of a collision with a large object, it would be irresponsible not to carry out an inventory now. Impacts by minor planets play an important role in the evolution of life. (Also see PanSTARRS.)

Sign up for an account and learn how to identify and classify different types of galaxies.  Then, do it!  You're helping the astronomical community process this valuable data.

"Where the Sun Never Rises"

Global telescope network for astrophotography and research in both hemispheres within dark skies.

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Mission: To preserve and protect the nighttime environment and our heritage of dark skies. Make a difference and apply for the IDA Student Award!

Very Cool! 3D orbit visualization JPL Small-Body Data Browser tracks the orbits of asteroids and other small bodies.