New York, Jan 13 : A team of astronomers has discovered a planet closer and younger than any other Earth-sized world yet identified. The planet is known as HD 63433d and it's the third planet found in orbit around a star called HD 63433. HD 63433d is so close to its star, it completes a trip all the way around every 4.2 days. The new planet was described in a new study published in The Astronomical Journal. 'It's a useful planet because it may be like an early Earth,' said Melinda Soares-Furtado, a NASA Hubble Fellow at the University of Wisconsin-Madison. 'Even though it's really close-orbiting, we can use follow-up data to search for evidence of outgassing and atmospheric loss that could be important constraints on how terrestrial worlds evolve,' she added. HD 63433 is roughly the same size and star type as our sun, but (at about 400 million years old) it's not even one-tenth our sun's age. The star is about 73 light years away from our own sun and part of the group of stars moving together that make up the constellation Ursa Major, which includes the Big Dipper. The authors are collaborating on a planet-hunting project called THYME. In 2020, they used data from NASA's Transiting Exoplanet Survey Satellite to identify two mini-Neptune-sized planets orbiting HD 63433. /IANS