From UPSC perspective, the following things are important :
Prelims level : Meteor terminology
Mains level : Not Much
The Perseids meteor shower is going to be active from August 17-26.
Try this question from CSP 2014:
Q.What is a coma, in the content of astronomy?
(a) Bright half of material on the comet
(b) Long tail of dust
(c) Two asteroids orbiting each other
(d) Two planets orbiting each other
What is the Perseids meteor shower?
- The Perseids meteor shower peaks every year in mid-August. It was first observed over 2,000 years ago.
- The Perseids occur as the Earth runs into pieces of cosmic debris left behind by the comet Swift-Tuttle.
- The cloud of debris is about 27 km wide, and at the peak of the display, between 160 and 200 meteors streak through the Earth’s atmosphere every hour as the pieces of debris.
- They travel at the speed of some 2.14 lakh km per hour; burn up a little less than 100 km above the Earth’s surface.
What are Meteor Showers?
- Meteors are bits of rock and ice that are ejected from comets as they manoeuvre around their orbits around the sun.
- As meteors fall towards the Earth, the resistance makes the space rocks extremely hot and, as meteorites pass through the atmosphere, they leave behind streaks of glowing gas that are visible to the observers and not the rock itself.
- Meteor showers, on the other hand, are witnessed when Earth passes through the trail of debris left behind by a comet or an asteroid.
- When a meteor reaches the Earth, it is called a meteorite and a series of meteorites, when encountered at once, is termed as a meteor shower.
- According to NASA, over 30 meteor showers occur annually and are observable from the Earth.
Where do the Perseids come from?
- The comet Swift-Tuttle, which was discovered in 1862 by Lewis Swift and Horace Tuttle, takes 133 years to complete one rotation around the sun.
- The last time it reached its closest approach to the sun was in 1992 and will do so again in 2125.
- Every time comets come close to the sun, they leave behind dust that is essentially the debris trail, which the Earth passes through every year as it orbits around the Sun.