The annual Leonids Meteor Shower, a prominent astronomical event, has started and is expected to remain active from the 6th to the 30th of November. The most intense activity of this meteor shower is anticipated on November 17th. In this article, we will delve into some key points about meteors and meteor showers, deciphering what they are, where they come from, and the specifics of the Leonids Shower.
The Phenomenon of Meteors
A meteor, also known as a shooting star, isn’t a star at all. It is essentially a space rock or meteoroid that encounters the Earth’s atmosphere. Meteoroids are objects in outer space that vary drastically in size – from minuscule dust grains to small asteroids. These celestial bodies predominantly originate from comets, asteroids, planets, and the moon.
When a meteoroid enters the Earth’s atmosphere, or that of another planet such as Mars, it does so at high velocity which causes it to burn up. This process creates a spectacular phenomenon popularly known as a ‘shooting star’ or meteor. Some meteors result in larger, brighter explosions of light and color, these are referred to as fireballs. The longevity and luminosity of fireballs can be attributed to their origination from larger particles of cometary material.
If a meteoroid withstands its transit through the atmosphere and successfully impacts the ground, it then attains the classification of a meteorite.
Understanding Meteor Showers
A situation wherein the Earth comes across numerous meteoroids all at once is called a meteor shower. Comets, similar to Earth and other planets, revolve around the sun. However, unlike the nearly circular orbits of the planets, the orbits of comets are highly eccentric. As a comet approaches the sun, it loses some of its icy surface due to evaporation, thereby releasing several particles of dust and rock which are referred to as meteoroids. This comet debris strews along the comet’s trajectory, particularly in the inner solar system inhabited by planets Mercury, Venus, Earth, and Mars.
Every year, as the Earth orbits around the sun, it crosses paths with the orbit of comets, leading to Earth encountering considerable comet debris. The resultant meteor showers are named after the constellation from where the meteors appear to be originating. An example is the Orionids Meteor Shower that happens each year in October and seems to originate near the ‘Orion the Hunter’ constellation.
The Leonids Meteor Shower
The Leonids meteor shower derives its debris from a small comet called 55P/Tempel-Tuttle located in the Leo constellation, which takes 33 years to circumnavigate the sun. Known as a significant meteor shower, the Leonids feature exceptionally fast meteors, often reaching speeds of up to 71 kilometers per second. However, the rates can sometimes be as low as 15 meteors per hour.
These meteors, known as Leonids, can also be referred to as fireballs and earthgrazer meteors. They achieve the fireball moniker due to their vibrant colors, and the term earthgrazer owing to their tendency to streak close to the horizon.
Intriguingly, a Leonid shower morphs into a meteor storm every 33 years, during which hundreds to thousands of meteors can be spotted each hour. The last recorded Leonid meteor storm took place in 2002. For a meteor shower to become a storm, it should display at least 1,000 meteors per hour.
