Perseid Meteor Shower Will Peak on August 12
August 8, 2012
The Perseid meteor shower of 2012 is set to
peak on August 12th, when the Earth is expected to encounter the ‘core’ of the
Perseid swarm, where meteoroid concentration is densest.
The Perseids will be easiest to view during this time because the meteors appear to separate from a part of sky near the Double Cluster in Perseus. It’s an illusion of perspective though, since that is the direction toward which the Earth’s orbital motion carries us at this time of the meteor shower.
At the same time, the meteoroids are traveling on parallel paths nearly perpendicular to the Earth’s orbit. The combined speeds of the Earth and the meteoroids cause the Perseids to rush into our atmosphere at average speeds of 37 miles (60 km) per second.”
For a single observer with access to a wide-open view of a clear, dark sky, meteors should appear at an average rate of about one every minute or two. Veteran observers, however, say that the Perseids tend to appear in bunches: several over an interval of minute or two followed by a lull of several more minutes before appearing again.
The meteors you see are actually comet fragments, bits of metal and stone, they are only called meteoroids while they exist in and move through space. But a meteor is not a particle of matter itself. It is merely the short-lived streak of light produced by the meteoroid as it is heated to incandescence by its plunge through the Earth’s atmosphere.
The kinetic energy released per gram of the meteoroid’s weight far exceeds the energy efficiency of the most powerful man-made explosives. Thus, an object the size of a pea or pebble can create a very substantial meteor trail.
A meteoroid swarm is sometimes referred to as a ‘flying gravel bank,’ though it is not a very compact one. The Perseid meteoroids, for example, are anywhere from 60 to 100 miles (96 to 160 kilometers) apart at the densest part of the swarm. Earth enters the outer fringes of the gravel bank around July 25, but does not leave it behind until we see the last stragglers around August 18. All told, the Perseid stream is immense – perhaps as large as 50 million miles in diameter.
This image shows the approximate location in the sky where the meteors will appear to be coming from.