New Studies Dismiss Signs of Life on Distant Planet

Science|New Studies Dismiss Signs of Life on Distant Planet

In April, a team of astronomers announced that they might — just might — have found signs of life on a planet over 120 light-years from Earth. The mere possibility of extraterrestrial life was enough to attract attention worldwide. It also attracted intense scrutiny from other astronomers.

Over the past month, researchers have independently analyzed the data, which suggested that the planet, called K2-18b, has a molecule in its atmosphere that could have been created by living organisms. Three different analyses have all reached the same conclusion: They see no compelling evidence for life on K2-18b.

“The claim just absolutely vanishes,” said Luis Welbanks, an astronomer at Arizona State University and an author of one of the studies.

The debate has less to do with the existence of alien life than with the challenge of observing distant planets. We can see a nearby planet like Jupiter because it reflects enough sunlight to become visible to the naked eye. But a planet like K2-18b is so far away that it becomes invisible not just to the naked eye but to conventional telescopes.

Astronomers have devised a series of increasingly sophisticated tricks to glean information about distant planets. They can measure the wobble of stars and the gravity of planets orbiting them. In 2010, researchers caught a glimpse of GJ 1214b, a planet 48 light-years away, as it passed in front of the star it orbits. When the star’s light shined through the planet’s atmosphere, certain wavelengths were absorbed indicating that GJ 1214b might have an atmosphere rich in water vapor.

In 2022, astronomers began using a powerful new tool to peer at distant planets this way. They pointed the James Webb Space Telescope at faraway solar systems and began detecting exquisitely faint patterns in starlight, clues to the complexity of exoplanet atmospheres.