August 11, 2010 — The night sky will put on a show in the coming days – and you don't need a telescope to appreciate it, according to University of Virginia astronomer Ed Murphy.
The annual Perseid Meteor Shower, which typically produces 50 to 60 meteors per hour under dark skies, peaks Thursday evening. Meteors will become visible (if skies are clear) around 9 p.m. as the sky darkens. The best time to see the shower will be after 11 p.m. and into Friday morning.
A telescope or binoculars are not needed to view this shower, just clear skies. Simply lie outside on a blanket or in a chair, face northeast and look high up in the sky.
"The typical Perseid meteor is traveling about 30 kilometers per second – 18 miles per second – as it hits the Earth's atmosphere," Murphy said. "The meteoroids are a bit larger than a good-sized grain of sand and the glowing trail is the result of the small meteoroid compressing and heating the air around it as it enters our atmosphere."
The Perseid meteoroids derive from the Comet Swift-Tuttle. The Earth currently is passing through the debris cloud from the tail of that comet.
For more on the Perseid Meteor Shower, click here.
Also during the next few evenings, Murphy notes, the planets Venus, Mars and Saturn will be beautifully grouped together in the western sky just after dark.
To see the triangle-shaped grouping, go outside around 9 p.m. and look west. Roughly just above distant treetop level, about 12 degrees above the horizon, shines Venus. It currently is, by far, the brightest object in the evening sky. And about 4 degrees – the width of two fingers held out at arms length – to the upper right of Venus is Saturn. About 3 degrees to the upper left of Venus is Mars. On Friday night, the thin waxing crescent moon will be about 9 degrees to the left of Venus.
"Venus, like the moon, goes through phases," Murphy said. "This was one of Galileo's most important discoveries, since it was proof that Venus orbited the sun and not the Earth."
When viewed from a small telescope, Venus appears as less than half full; Saturn will show its rings, though less than ideal because it is so low in the sky; and Mars, presently on the far side of the sun, will appear as a small red-orange ball with no visible surface features.
Murphy suggested watching these plants shift position over the next two weeks with respect to one another and the background stars. Saturn will sink lower and lower each evening and will be lost in the evening twilight within a week or two. Venus will slide below and to the left of Mars. By late August, both Mars and Venus will be very low in the sky and difficult to see.
To view a map of the August sky, visit here.
To learn more about the night sky and astronomy, consider joining the Friends of the Leander McCormick Observatory. Members receive a newsletter and are invited to special events each year at U.Va.'s observatories.
The Leander McCormick Observatory, located at U.Va. in Charlottesville, is open free to the general public on the first and third Friday of each month (except holidays) from 9 to 11 p.m. Upcoming dates are Aug. 20, Sept 3 and 17.
The Fan Mountain Observatory (located 13 miles south of Charlottesville) is open to the general public two nights per year, each April and October. The next open night is Oct. 8, from 8 to 11 p.m. Tickets, which are free and required (except for Friends of the Leander McCormick Observatory), can be obtained by sending a self-addressed stamped envelope, along with the number of tickets requested (up to six), to: Fan Mountain Public Night, P.O. Box 400325, Charlottesville, VA 22904-4325. Tickets for the October public night will be available after Sept. 1; do not send requests before this date. The ticket supply usually is exhausted within three weeks.