VOA慢速英语--大行星可能提供有关遥远星球大气的线索（在线收听）

Scientists have found a rocky, Earth-like planet that may offer a chance to study other atmospheres. This kind of research could help the hunt for life outside of Earth.

The researchers said recently that the planet, called Gliese 486 b, is not itself likely to have life. Orbiting a star relatively near our solar system, Gliese 486 b is hot and dry like Venus, with possible rivers of lava flowing on its surface.

But its nearness to Earth and its physical qualities make it well- suited for a study of its atmosphere. Such research will use the next generation of telescopes, including the James Webb Space Telescope that the American space agency NASA plans to launch in October.

These telescopes could give scientists data to study the atmospheres of other exoplanets - planets beyond our solar system - including ones that may have life.

José Caballero of the Centro de Astrobiología in Spain was the co-writer of the research that appeared in the journal Science.

Caballero called the new research possibility, "the Rosetta Stone of exoplanetology." He was comparing it to the ancient piece of stone that helped experts understand ancient Egyptian writing.

Scientists have discovered more than 4,300 exoplanets. Some have been large gas planets similar to Jupiter.

Others have been smaller, rocky Earth-like worlds. These are considered candidates for having life. But current scientific instruments tell us little about their atmospheres.

Trifon Trifonov of the Max Planck Institute for Astronomy in Germany was the lead writer of the research. Trifonov said an exoplanet needs to have certain qualities to work well for atmospheric study.

Gliese 486 b is located about 26.3 light years - the distance light travels in a year - from Earth, or about 9.5 trillion kilometers. It is among the closest exoplanets. It orbits a star that is smaller, cooler and less bright than our sun. Gliese 486 b's mass is 2.8 times greater than Earth's.

The planet orbits very close to its home star. Its surface temperature is about 430 degrees Celsius and its surface gravity may be 70 percent stronger than Earth's.

"Gliese 486 b cannot be habitable, at least not the way we know it here on Earth," Trifonov said.

Still, Gliese 486 b could prove useful for studying the atmosphere of an Earth-like planet using the James Webb Space Telescope and the future Extremely Large Telescope, which is now being built in Chile.

The chemical mixture of an atmosphere can tell a lot about a planet and its ability to have life.

Cabellero said that what we learn from Gliese 486 b and other Earth-like planets could help scientists better understand atmospheres of other exoplanets that may have life.

Words in This Story

lava – n. melted rock from a volcano

journal -- n. a magazine that reports on things of special interest to a particular group of people

habitable – adj. suitable or fit to live in