![]() ![]() Jeremy Perez captured 101 Perseids and 22 sporadic meteors in this composite of 3,700 images taken overnight on August 11–12, 2020. Cooke believes that’s because the parent comet has a larger than normal nucleus (about 26 kilometers) and is capable of producing the larger meteroid fragments that create brilliant flares. Bill Cooke of NASA’s Meteoroid Environment Office calls the Perseids the “fireball champion” of annual meteor showers. Not only are Perseids swift, they're famous for their fireballs, which are meteors of magnitude –3 or brighter. It's comprised of glowing, ionized air, and metal and silicate vapor from the meteoroid itself. The average width of a meteor track is about a meter, while the length spans tens of kilometers. Both the glowing, hot bits of comet dust and trails of ionized air are responsible for the familiar meteor streaks. When the molecules relax back to their previous unexcited state, they radiate light. At the same time, the grain's passage excites (ionizes) the air molecules along its path. This in turn heats the meteoroid white-hot and burns it to soot. Perseids are swift with velocities around 60 kilometers per second and produce more fireballs than any other annual meteor shower.Īs each grain slams into the atmosphere at around 60 kilometers per second, it creates a supersonic shock wave that compresses and heats the air in front of it. Every August, the Earth intersects the comet's orbit and plows through the debris from a previous pass.Ī colorful Perseid fireball blazes during the 2016 shower. Each visit it lays down a spreading trail of dust resembling a jet contrail called a filament. It last reached perihelion in 1992 and will again in 2125. Perseids are the wayward children of their parent Comet 109P/Swift-Tuttle, a periodic comet that returns to Earth's vicinity every 133 years. Visualization: Ian Webster / Data: NASA / CAMS / Peter Jenniskens (SETI Institute) As the planet slams into dust and rock fragments they flare in the atmosphere as meteors. Earth passes through the orbital debris stream left by Comet Swift-Tuttle every mid-August. After midnight, the Earth also rotates into the direction of the meteor stream, which increases the relative velocity at which meteoroids strike the atmosphere, pumping up their brightness, visibility, and number. That's when the radiant climbs highest, and the fewest meteors are cut off by the horizon. But the later you stay up the more you'll see: The hours between 2–4:30 a.m. local daylight-saving time, when the radiant reaches 20° altitude in the northeastern sky. Earth scoops up meteoroids on the dawn side of the planet and outruns them on the dusk side.Ī modest number of Perseids will be visible starting around 10 p.m. The rate of meteor activity is usually greatest in the early hours of the morning because the Earth's orbital motion is in the direction of the dawn terminator.
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