NASA scientists to test James Webb Space Telescope on planet with lava-spewing clouds

Imagine a planet where a year lasts just 18 hours. This weird characteristic signifies that the planet is orbiting extremely close to its star and is tidally locked as a result. When a planet is tidally locked, one of its sides always faces the sun which makes the dayside unimaginably hot while the opposite is in endless darkness. NASA says that on such planets, extreme temperatures cause the oceans to boil away, rocks begin to melt, and the clouds rain lava.

With the James Webb Space Telescope, scientists are planning to study the surface and atmosphere of such planets. According to NASA, researchers have locked their sight on two exoplanets- the lava-covered 55 Cancri e and the airless LHS 3844 b. The James Webb Telescope will be used to study the geology of these rocky worlds that reside approximately 50 light-years away. 

The strange world of 55 Cancri e

(Illustration of rocky exoplanets LHS 3844 b and 55 Cancri e as compared to Earth and Neptune; Image: NASA)

This planet circles its stars at a distance of less than 2.4 million kilometers away, which is just one twenty-fifth of the distance between Mercury and the Sun. Owing to such a tight orbit, one year on this planet lasts only 18 hours and the dayside of the planet is thought to be covered in oceans of lava. However, observations from the Spitzer space telescope have revealed a strange characteristic of this planet. 

Scientists have known that a planet orbiting its star this close is usually tidally locked which results in the hottest spot being on the dayside. Besides, the amount of heat emitted from the dayside does not change much over time, however, this is not the case with Cancri e. Surprisingly, the hottest region of this planet shifts occasionally and the total amount of heat detected from the dayside varies. 

Following this discovery, experts have suggested that this planet might not be tidally locked and just like Mercury, it is rotating three times for every two orbits. Alexis Brandeker, a researcher from Stockholm University and leader of the team studying this planet said in a NASA statement, "That could explain why the hottest part of the planet is shifted. Just like on Earth, it would take time for the surface to heat up. The hottest time of the day would be in the afternoon, not right at noon". This scenario has raised the possibility that the surface vapourises during the day, turns into lava droplets, and rains during the evening. 

Webb's second target

The second target of the Webb telescope is the planet LHS 3884B, which completes one year in just 11 hours but it is not hot enough for the surface to be molten due to a relatively small and cooler star. Astronomers will study this rocky world as well, however, Spitzer's data has revealed that a substantial atmosphere is highly unlikely on the planet. Explaining the importance of these exoplanets, Laura Kreidberg at the Max Planck Institute for Astronomy said, "They will give us fantastic new perspectives on Earth-like planets in general, helping us learn what the early Earth might have been like when it was hot like these planets are today".