James Webb Space Telescope discovered an Earth sized exoplanet

NASA's new James Webb Space Telescope has confirmed the existence of a rocky planet, dubbed LHS 475 b, of about the same size as Earth

The exoplanet was discovered using the transit method

Credit: Illustration: NASA, ESA, CSA, L. Hustak (STScI); Science: K. Stevenson, J. Lustig-Yaeger, E. May (Johns Hopkins University Applied Physics Laboratory), G. Fu (Johns Hopkins University), and S. Moran (University of Arizona)

Researchers at Johns Hopkins University in Maryland announced the discovery of LHS 475 b after analyzing data from the JWST. The planet owes its discovery to passing between its host star and Earth leading to Webb witnessing dips in the star's light.This method of exoplanet detection is known as the transit method.

Atmospheric measurements

Apart from the fact that it is extremely impressive to be able to detect an exoplanet that is as small as Earth, the James Webb Telescope is also unique in its ability to take measurements of an exoplanet's atmosphere. 

More detailed measurements show that, aside from its size, LHS 475 b is a very different place than Earth. It is several hundred degrees Celcius warmer on its surface, and although it is not yet certain whether it has its own atmosphere, a number of scenarios can be ruled out. For example, it cannot have a thick methane-like atmosphere akin to what we know from Titan, a moon of Saturn in our own solar system.

The team adds that, although it's possible the exoplanet has no atmosphere, other atmospheric compositions, such as an atmosphere made entirely of carbon dioxide, haven't been ruled out. Contrary to popular belief, a 100% carbon dioxide atmosphere is much more difficult to detect. 

Transmission spectrum - LHS 475 b. A flat line in a transmission spectrum, like this one, can be exciting, but futher observations are needed.

Credit: Illustration: NASA, ESA, CSA, L. Hustak (STScI); Science: K. Stevenson, J. Lustig-Yaeger, E. May (Johns Hopkins University Applied Physics Laboratory), G. Fu (Johns Hopkins University), and S. Moran (University of Arizona)

LHS 475 b is a few hundred degrees warmer than Earth, according to the findings, so if clouds are found it may be a world more similar to Venus, which has a carbon dioxide atmosphere and is constantly covered in heavy clouds. 

According to Lustig-Yaeger, one of the researchers, we are only at the beginning of studying small exoplanets. "We have barely begun scratching the surface of what their atmospheres might be like."

For the researchers to discriminate between a pure carbon dioxide environment and no atmosphere at all, much more exact measurements are needed. Future observations are expected to yield more spectra so we will keep you posted.

Sources and further reading:

• Transit method of exoplanet discovery (NASA exoplanet exploration)

• Near Infrared Spectrograph (JWST)

• LHS 475 b discovery - (NASA)

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