The upcoming Perseid meteor shower this week is one of the very best of the year, and this time around there won’t be any moonlight to wash the meteors out.
Of course, city and suburban light also can do a real number on your Perseid pleasures, although a few of the brighter shooting stars will still manage to shine.
If at all possible get out into the countryside and take in the Perseid show under a canopy of dark, starry heavens. With a sharp eye you may see well over 60 meteors an hour.
The Perseid meteor shower peaks Thursday night and early Friday morning, although the viewing should be pretty good most of the week. The best time is anytime from midnight until the start of morning twilight, about 4:30 a.m.
Meteor showers occur when Earth, in its orbit around the sun, crosses a debris trail of dust and pebbles left behind by a comet that’s passed by.
The “parent” comet for the Perseids is Comet Swift Tuttle, which last passed by this part of the solar system in the early 1990s.
The best way to describe a comet is to compare it with a dirty snowball. As comets get close to the sun, some of the icy nucleus melts and frees dust and pebbles that trail behind.
These billions of meteoroids all become potential ammunition for meteor showers. After Swift Tuttle passed by in the early ’90s, the Perseid showers were really great.
The meteors streak into Earth’s atmosphere at speeds anywhere from 30 to more than 40 miles per second. Air friction incinerates the dust and pebbles at altitudes of 30 to 60 miles high, but the streak of light you see is much more than just these tiny meteoroids getting toasted.
Most of the light to see from meteors is caused by ionization. Even though most are tiny, the meteroids temporarily excite the atoms and molecules in the column of air causing an extremely vivid collective glow.
Even after you see the initial streak there’s often a luminous trail that can go on for a few seconds.
Meteors can have some color to them: blues, greens, reds and yellows, depending on the nature of the material, their speed and angle, and the height at which they become visible.
Meteor showers are referred to by the constellation where their radiant is. The radiant is the point in the general direction that the meteors seem to be coming from. In the case of the Perseids the radiant is the constellation Perseus.
Right now, Perseus resides in the east-northeast sky in the post-midnight hours. Meteors will be all over the sky, but their tails will seem to point back in the general direction of Perseus.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch,” available at bookstores. Check his website, www.lynchandthestars.com.
The Everett Astronomical Society: www.everettastro.org/.
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