On this iron-dense planet, a year lasts just eight hours, Science News

We do not say what the universe could throw at us. Just when some of us think we know all about it, a new discovery throws all that smugness out of the park.

Scientists have now spotted one of the smallest planets ever discovered outside of our solar system. The planet, referred to as GJ 367b, is a hot world. It’s just a little bigger than Mars and as dense as pure iron.

The planet revolves around its star every eight hours. It is 31 light years from Earth.

Scientists are eager to find exoplanets, as these alien worlds are known, that could harbor life. The newly discovered one, called GJ 367b, certainly couldn’t, as it has fierce surface temperatures and possibly a surface of molten lava on the side facing its star, they said. But other small exoplanets discovered and studied using the same methods could emerge as good candidates for nurturing alien life.

A quarter of a century after the first discoveries of exoplanets, scientists turned to their more precise characterization to better understand their variety, from large Jupiter-like gas giants to smaller, rocky Earth-like planets where life could thrive.

“Gas giants like Jupiter, as we know them, are uninhabitable because they have more extreme temperatures, weather conditions, pressures and a lack of building blocks essential to support life,” said the astronomer Kristine Lam of the Planetary Research Institute of Germany. Aerospace Center (DLR), lead author of the study published in the journal Science. It was quoted by Reuters.

“Unlike gas giants, small terrestrial worlds like Earth are more temperate and consist of important ingredients, such as liquid water and oxygen, to house life forms. Although not all terrestrial exoplanets are not habitable, look for smaller worlds and identify the type of planets they can help us understand how planets were formed, what makes a planet habitable and whether our solar system is unique, ”Lam added.

GJ 367b is the smallest exoplanet to be characterized with such precision. It is about 5,600 miles (9,000 km) in diameter – compared to 7,900 miles (12,700 km) from Earth and 4,200 miles (6,800 km) from Mars. Its mass is 55% that of the Earth and it is denser – close to that of pure iron.

Researchers have calculated that 86% of GJ 367b is made up of iron, with an interior structure resembling Mercury, the planet closest to our sun. They wonder if the planet has lost an outer mantle that once enveloped its core.

“Perhaps like Mercury, GJ 367b might have experienced a giant impact episode that ripped off the mantle, leaving behind a large iron core. Or maybe the exoplanet is a remnant of a gaseous planet from the size of Neptune or super-Earth, where the planet’s atmosphere has completely washed away as the planet is blown away by a large amount of radiation from the star, ”Lam said.

(With contributions from agencies)

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