Solar System: Things to Know This Week
Not to be—ahem—eclipsed, the Perseids meteor shower peaks annually in mid-August and is considered the most popular meteor shower of the year.
This week, 10 things you need to know about this beautiful nighttime show and how to catch a front-row seat.
1. Light in August
In this 30 second exposure, a meteor streaks across the sky during the annual Perseid meteor shower Friday, Aug. 12, 2016 in Spruce Knob, West Virginia. The Perseids show up every year in August when Earth ventures through trails of debris left behind by an ancient comet. Image Credit: NASA/Bill Ingalls
With very fast and bright meteors, Perseids (pronounced PURR-see-ids) frequently leave long “wakes” of light and color behind them as they streak through Earth’s atmosphere. Perseids are one of the most plentiful showers, with between 50-100 meteors seen each hour, and occur with warm summer nighttime weather, allowing sky watchers to easily view them.
2. Show Schedule
You can see the Perseids this year between now and Aug. 24, 2017, but mark your calendars for peak dates Aug. 12 and 13. This year, the waning gibbous moon rises about midnight local time, which will cut the expected rates in half this year (25 to 50 per hour at the peak from a very dark sky). But the Perseids are so bright and numerous that it should still be a good show.
3. Night Owls Welcome
The Perseids (and every meteor shower) are best viewed in the Northern Hemisphere between 11 p.m. - 3 a.m. Come prepared with a sleeping bag, blanket or lawn chair.
4. Look Up
Find an area well away from city or street lights and set up where you’re shadowed from the moon’s glare. Face whatever direction you like, ideally the one unobstructed by trees, buildings or moonlight. Look up, taking in as much of the sky as possible. If you have a group, each person should look in different parts of the sky. After about 30 minutes in the dark, your eyes will adapt, and you’ll begin to see fainter objects, including meteors. Be patient; the show will last until dawn, so you have plenty of time to catch a glimpse.
5. Functional Fashion
Pack a baseball cap and wear it sideways to cover any glare from the moon. The waning gibbous moon will block out many of the fainter meteors this year, but the Perseids are so bright and numerous that it should still be a good show.
6. Meteor Matters
Where do meteors come from? Some originate from leftover comet particles and bits of broken asteroids. When comets come around the sun, they leave a dusty trail behind them. Every year, Earth passes through these debris trails, which allows the bits to collide with our atmosphere and disintegrate to create fiery and colorful streaks in the sky. But the vast majority of meteors don’t come from meteor showers—instead, they randomly fall all of the time.
The pieces of space debris that interact with our atmosphere to create the Perseids originate from Comet 109P/Swift-Tuttle. Swift-Tuttle takes 133 years to orbit the sun once, and Comet Swift-Tuttle last visited the inner solar system in 1992. Swift-Tuttle is a large comet: its nucleus is 16 miles (26 kilometers) across. This is almost twice the size of the object hypothesized to have wiped out the dinosaurs.
Comet Swift-Tuttle was discovered in 1862 by Lewis Swift and Horace Tuttle. In 1865, Giovanni Schiaparelli realized that this comet was the source of the Perseids.
9. Great Balls of Fire
The Perseids are known for fireballs, which are large explosions of light and color that last longer than an average meteor streak. Why? They originate from bigger particles of cometary material.
10. Sky Map
The point in the sky from which the Perseids appear to come from—also known as their radiant—is the constellation Perseus. But don’t get confused: The constellation name only helps viewers figure out which shower they’re viewing on a given night; it’s not the source of the meteors (see #6 for that answer!).
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