Researchers using NASA's James Webb Space Telescope have confirmed the existence of the first exoplanet, or planet that orbits another star. The planet, formally known as LHS 475 b, is almost exactly the same size as our own, with a diameter that is 99% that of the Earth. The team's leaders are Jacob Lustig-Yaeger and Kevin Stevenson, both of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

The team chose to use Webb to look at this target after carefully analysing targets of interest from NASA's Transiting Exoplanet Survey Satellite (TESS), which pointed to the planet's existence. Webb's Near-Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with just two transit observations. 'There is no disputing the planet's existence. According to Lustig-Yaeger, the specific data provided by Webb validates it. Its modest size and rocky composition have impressed the observatory, Stevenson continued.

The first observational data from an Earth-sized, rocky planet, according to Mark Clampin, director of the Astrophysics Division at NASA Headquarters in Washington, 'open the door to several future chances for researching rocky planet atmospheres with Webb.' Webb is assisting us in learning more about Earth-like locations outside of our solar system, despite the fact that the mission is in its early stages.

It can tell us a lot about the planet through this flat line in the transmission spectrum, which makes it fascinating. On August 31, 2022, researchers used the Near-Infrared Spectrograph (NIRSpec) on NASA's James Webb Space Telescope to study planetary LHS 475 b. This spectrum shows that Webb did not discover any detectable concentrations of any element or chemical. The results (white dots) are in accordance with a spectrum devoid of characteristics that would be present on a planet without an atmosphere (yellow line). The purple line, which represents a pure carbon dioxide atmosphere, cannot be distinguished from a flat line at the current level of accuracy. Because methane would be expected to block more sunlight at 3.3 microns if it were present, the pure methane atmosphere shown by the green line is not chosen.

Out of all the operational telescopes, only Webb can characterise the atmospheres of exoplanets the size of Earth. Scientists tried to ascertain what is contained in the planet's atmosphere by looking at its transmission spectrum. Even though the data suggests that this planet is a terrestrial globe the size of Earth, they do not yet know if it has an atmosphere. According to Erin May of the Johns Hopkins University Applied Physics Laboratory, the observatory's findings are astounding. Despite how sensitive the telescope is, it is still too early to make any conclusive statements regarding the planet's atmosphere.

The team is unable to identify what is present, but they can confidently state what is not. There are some terrestrial-type atmospheres that we can rule out, according to Lustig-Yaeger. Titan on Saturn's moon cannot have an atmosphere that is primarily dominated by methane.

The team continues by saying that various atmospheric compositions, including an atmosphere comprised entirely of carbon dioxide, haven't been ruled out, even if it's probable the planet has no atmosphere. According to Lustig-Yaeger, a 100% carbon dioxide environment is far more compact and difficult to detect. More precise measurements are required in order for the researchers to distinguish between an environment with only carbon dioxide and one with no atmosphere at all. Future observations this summer should provide the researchers with more spectra.

According to Webb, the planet is a few hundred degrees warmer than Earth; therefore, if clouds are discovered, researchers may conclude that the planet is more like Venus, which has a carbon dioxide atmosphere and is perpetually shrouded in thick clouds. We're at the forefront of exploring tiny, rocky exoplanets, claims Lustig-Yaeger. 'We are just beginning to understand what their environments might be like.'

The two-day orbital period of the planet was almost instantly visible in the precise light curve of Webb, which the researchers also confirmed. LHS 475 b may still have an atmosphere despite being the closest planet to its red dwarf star in our solar system because it is just about half as hot as the Sun.

How can astronomers find a distant planet? by monitoring the changes in light as it orbits its star? The brightness of the LHS 475 star system fluctuated over time as the planet passed in front of it on August 31, 2022, according to a light curve produced by the Near-Infrared Spectrograph (NIRSpec) on NASA's James Webb Space Telescope. At a distance of roughly 41 light-years, the rocky exoplanet LHS 475 b orbits a red dwarf star in the constellation Octans. It is the size of Earth. The planet, which orbits its star in barely two days on Earth, is extremely close to it. The planet's existence was confirmed thanks to Webb's discoveries.

The researchers' discovery has opened up new possibilities for finding Earth-sized planets circling smaller red dwarf stars. According to Stevenson, the discovery of a rocky planet emphasises how precise the mission's equipment was. And the discoveries it will make after this are just the beginning. According to Lustig-Yaeger. The new frontier with this telescope is rocky exoplanets.

LHS 475 b, in the constellation Octans, is only 41 light-years away, making it a nearby object.

On January 11, 2023, the team's results were made public during a news conference hosted by the American Astronomical Society (AAS).

The James Webb Space Telescope is the world's top space observatory for science. Webb will explore the mysterious structure, beginnings, and purpose of the cosmos, as well as distant worlds orbiting other stars beyond our solar system. An international project called Webb is coordinated by NASA, the Canadian Space Agency, and the European Space Agency (Canadian Space Agency).