Science

What are exoplanets?

This artist rendering released by NASA shows a planet outside the solar system that was detected by NASA’s Kepler spacecraft.  

NASA is holding a news conference on Wednesday at 11.30 p.m. IST on new findings on exoplanets. Prominent NASA scientists, astronomers and a professor of planetary science and physics at Massachusetts Institute of Technology will participate at the briefing. Details of these findings will also be published in the journal Nature on the same day NASA hosts the briefing.

Here’s a primer on the history of exoplanet discoveries:

What are exoplanets?

Planets outside our solar system are called exoplanets. Most of these are part of star systems. There are some “rogue” exoplanets, which are not attached to any star system.

When was the first exoplanet discovered?

The first exoplanet, 51 Pegasi b, was discovered in 1995 by Michael Mayor and Didier Queloz.

How many exoplanets have been identified till now?

According to NASA there are 3449 confirmed exoplanets from among 4,669 candidates in 2,577 solar systems (as of February 21, 2017). Among the confirmed ones there are 1,264 Ice Giants (a giant planet composed mainly of elements such as oxygen, carbon, nitrogen, and sulfur), 1,043 Gas Giants (planets mostly composed of gases such as hydrogen and helium), 781 Super-earths (planets larger than Earth, but smaller than Uranus or Neptune), 348 terrestrial exoplanets (aka rocky planets, they are composed of silicate rocks or metals) and 13 are yet to be classified.

Which is the latest entrant into the exoplanet league?

In May last year, scientists found three planets passing in front of TRAPPIST-1, the dwarf star. Based on further monitoring of the star from the ground and space, scientists have found four more exoplanets orbiting TRAPPIST-1.

Do these exoplanets support life?

The search for exoplanets is also the search for alien life and habitable spaces beyond our star system. NASA’s Kepler and K2 missions have identified several such candidates.  One of the factors that must be satisfied in order to be considered habitable is that exoplanets must orbit within a distance of their stars in which liquid water can exist on the planet’s surface, receiving about as much sunlight as Earth. This distance is called the “Goldilocks” zone because it is neither too far or too close to the star that life becomes impossible.  

Sources: NASA, Wikipedia

This article is closed for comments.
Please Email the Editor

Printable version | Mar 4, 2021 5:15:47 AM | https://www.thehindu.com/sci-tech/science/what-are-exoplanets/article17347465.ece

Next Story