Planets take center stage in July
One of the comforting things about the night sky is that it remains constant over the average human lifetime. While different constellations are visible from one season to the next, the overall shape of the constellations remains the same year after year.
However, the fact that Earth resides
in a constantly moving solar system means that occasionally the sky puts on a show worthy of more than just casual observance. July 2010 is one of those times.
Over the course of the month observers will be able to see four of the five naked-eye planets and possibly a comet, all visible in the sunset sky.
The stage for the July sky show is set early in the month with Venus, Mars and Saturn being visible in the late evening sky. These three planets will be spread between the Stars Regulus in Leo and Spica in Virgo. Venus will be the most obvious, being clearly visible even before the sky is completely dark. Mars will be 23 degrees above and to the left of Venus with Saturn just 15 degrees beyond.
By July 10 Mercury will have joined the scene, but it will be fairly low on the horizon and may be lost in the glare of the setting sun. Binoculars will help locate the tiny inner planet.
Even if you can’t spot Mercury, do not despair. Also on the evening of the 10th Venus is just 1 degree from the star Regulus in Leo. In addition, Venus will have moved to within 18 degrees of Mars, and Mars will be just 10 degrees from Saturn.
On the evening of the 13th a slim crescent moon appears on the stage just 15 degrees from Mercury. This may make finding Mercury a little easier even though it is still fairly low on the horizon.
Now the show really takes off. The moon will be just 7 degrees from Venus on the evening of the 14th, 6 degrees from Mars and on the evening of the 16th and 10 degrees from Saturn on the 15th. After the evening of the 17th the moon slowly slides off stage and away from the planetary show.
On the evening of July 27th we find Mercury less than 1 degree from the star Regulus in Leo. Yet the best part of the show is on the evening of the 28th when Venus, Mars and Saturn form a neat little triangle in the constellation Virgo. Venus will be below and to the right of the two fainter planets. Venus will be less than 8 degrees from Mars, but the closest conjunction occurs between Mars and Saturn. The two planets will be less than 2 degrees from each other. Mars will appear red-orange and closer to the horizon, while Saturn will appear yellow or cream colored.
As impressive as this show sounds, it has the potential to gets even better. While the planets and the moon are doing their orbital dance, a rare object from the outer reaches of the solar system makes a brief cameo appearance early in the month. Comet McNaught (C/2009R1) will be present in the evening sky from the 1st through the 12th. Whether the comet will be visible is somewhat unpredictable. The “tail” of a comet is ionized gas streaming back from the comet as the solar wind turns the frozen material into gas. Hopefully comet McNaught will develop a long, clearly visible tail that can be seen with the naked eye. Comet McNaught will be just 3 degrees from Mercury on July 9.
In ancient times planetary conjunctions were seen as omens from the sky. The close gathering of the “wandering stars” was special enough to warrant special consideration. Today fewer people believe in the implications of such close conjunctions, yet the fact that they occur so rarely means that the event itself deserves our attention.
Whether you observe with just your eyes or a wide field telescope, take advantage of the July 2010 conjunction of planets before the players are ushered off stage.
SOURCE: http://trib.com/news/state-and-regional/article_ba8f4369-af77-5da4-90a4-6108f8f2e0c3.html