James Webb telescope finds its first exoplanet, raising hopes it will discover life elsewhere in universe

Rocky planet is similar in size to Earth and may have an atmosphere, but is likely to be as hot as Venus

The James Webb Space Telescope has detected its first exoplanet, giving hope that it will be able to discover life elsewhere in the universe.

LHS 475 b is a rocky planet almost exactly the same size as our own at 99 per cent of Earth’s diameter. It is orbiting around a red dwarf star at a relatively close 41 light years away in the constellation of Octans.

The Webb telescope was launched on Christmas Day 2021 as the most sensitive and powerful telescope ever built. It is currently in space at a distance 1.5 million kilometres from Earth where it can observe the universe above the planet’s atmosphere.

Its main goal will be to detect and examine the atmospheres of exoplanets – planets orbiting around stars like our own sun to test for the telltale signs of life such as carbon dioxide and water vapour.


Preliminary research suggests LHS 475 b is probably several hundred degrees hotter than the surface of the Earth so more likely to be similar to Venus than to our own planet.

The team at Johns Hopkins University in the United States believe the early results show the exciting potential of the James Webb telescope.

“These first observational results from an Earth-sized, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb,” said Nasa’s astrophysics division director Mark Clampin.

“Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside the solar system, and the mission is only just getting started.”

Among all operating telescopes, only Webb is capable of characterising the atmospheres of Earth-sized exoplanets. The team attempted to assess what is in the planet’s atmosphere by analysing its transmission spectrum.

Although the data show that this is an Earth-sized terrestrial planet, they do not yet know if it has an atmosphere.

“The observatory’s data are beautiful,” said Erin May of the Johns Hopkins University Applied Physics Laboratory. “The telescope is so sensitive that it can easily detect a range of molecules, but we can’t yet draw any definitive conclusions about the planet’s atmosphere.”

Johns Hopkins researcher Jacob Lustig-Yaeger said they have “barely begun scratching the surface of what their [exoplanet] atmospheres might be like”.

The researchers are scheduled to obtain additional spectra with further observations this summer.

The researchers also confirmed that the planet completes an orbit in just two days, information that was almost instantaneously revealed by Webb’s precise light curve. Although LHS 475 b is closer to its star than any planet in the solar system, its red dwarf star is less than half the temperature of the sun, so the researchers project it still could support an atmosphere.

The team’s results were presented at a press conference of the American Astronomical Society on Wednesday.

Ronan McGreevy

Ronan McGreevy

Ronan McGreevy is a news reporter with The Irish Times