What is a Meteor Shower?
Meteor Shower is an occurrence in which a number of meteors seem to radiate from a point in the sky with a bright, fiery trail. This happens when the Earth during its course around the sun, encounters debris left behind by a cosmic body say, comet. During a typical meteor shower, one can see up to 100 meteors per hour. When the meteor showers get intense with more than 1000 meteors per hour, they are called Meteor Storms.
Mechanism of Meteor showers
As the Earth approaches, Cosmic debris called meteoroids shoot into the atmosphere at extremely high speeds. When they enter Earth’s atmosphere, they become meteors. High speed & air resistance cause the meteors to heat up, creating a bright, fiery trail. Most meteors disintegrate before reaching the ground. The few that do strike the Earth’s surface are called meteorites. Meteors are also referred to as Shooting Stars because they seem to shoot from one point with a bright trail that stays for a short time before the meteor disintegrates.
Comet Disintegration – How is Comet debris formed?
Whenever a comet approaches the sun, it gets unstable. The volatile components begin to sublime creating empty pockets in the body of the comet. It loses mass. They shred hundreds of tons of material per second. This weakens the structural integrity. Any external force like the powerful solar winds, massive gravitational pull of planets like Jupiter & Saturn can act as a blow, disintegrating parts of the comet. In case the comet is mostly made up of volatile compounds, it will disintegrate completely. These disintegrated parts float in space as cosmic debris.
Instances of comet disintegration in the past
i. Shoemaker-Levy9 could not withstand the gravitational pull of Jupiter
ii. Schwassmann–Wachmann 3 underwent massive disintegration when it approached perihelion in 2011
According to some theories, the estimated life span of Halley’s comet is 10000 years. Like any other comet, it will keep losing material en route its journey around the sun & there will come one day when the massive Halley’s will be reduced to dust.
Meteor Showers from Halley’s Comet debris
Halley’s comet, like all other comets, revolves round the sun in an elliptical orbit. As the icy comet makes its way around the sun, it leaves behind a trail of comet debris. At certain times of the year, Earth crosses paths with the debris en route its revolution around the sun. These debris shoot into the Earth’s atmosphere causing a meteor shower. This phenomenon happens twice a year:
1. During October
The meteor showers during this part of the year are called Orionid Showers.
2. During May
The second set of showers is called Eta Aquarids.
These tiny left-over comet fragments are usually smaller, some as small as a grain of sand. The Orionids are named after the direction from which they appear to radiate or originate, which is near the constellation Orion (The Hunter). Sometimes the shower peaks at 80 meteors an hour; at others it is closer to 20 or 30. Orionid meteors are visible from anywhere on Earth & can be seen anywhere across the sky
Eta Aquarids are named after constellation Aquarius in which they seem to radiate. Point of origin lies close to the brightest star in the constellation, Eta Aquarii. These showers are visible between April to May every year.
Other spectacular meteor showers
When Earth comes in contact with the debris left behind by comet Tempel-Tuttle, we witness Leonid showers. They seem to radiate in constellation Leo near the start Gamma Leonis & typically occur in the month of November.
These occur during August every year. Most years, Perseids are the most prominent showers.
Best ways to view meteorite showers
1. Go away from city lights & pollution
Light & pollution can hinder a clear view of the sky. One may want to get away from the city to somewhere calm & dark.
2. Go out around mid-night
The best time to view the show is around 1.30 AM. Although it is subject to conditions.
3. Have patience. Sit back & Relax.
One needs to have real patience to spot the shooting meteorites. Also, some meteorites have shorter trails & hence are hard to spot.
4. Spot with naked eye. No binoculars & telescopes.
Additional tools won’t help as these are designed to see more stationary objects in the sky.
Meteoroid: Particle broken off from an asteroid or comet on its way around the sun is called a Meteoroid.
Meteor: A meteoroid that enters the Earth’s atmosphere & burns up is called a Meteor.
Meteorite: A meteor that doesn’t burn up completely & reaches the earths surface is called a Meteorite.
Comet & Asteroid: Material left over from the formation of planets
Disclaimer: The images used may not be real. Images courtesy Pixabay.com