Planet: Barnard’s Star b
Discovered by: Ignasi Ribas, et al
Date: Nov. 14, 2018
Key Facts: Barnard's Star b is the second-closest known exoplanet to Earth. The data indicate that the planet could be a super Earth, with a mass at least 3.2 times that of the Earth, which orbits its host star in roughly 233 days. Barnard’s Star, the planet’s host star, is a red dwarf, a cool, low-mass star, which only dimly illuminates this newly-discovered world. Light from Barnard’s Star provides its planet with only 2% of the energy the Earth receives from the Sun.
What’s new: Data from a world-wide array of telescopes, including the European Southern Observatory’s planet-hunting HARPS instrument, revealed Barnard’s Star b, a frozen, dimly lit world. The newly discovered planet is the second-closest known exoplanet to the Earth.
Barnard’s Star is the fastest moving star in the night sky. To zero in on the planet, astronomers used multiple telescopes to measure its star’s “wobble” – how much the star is tugged this way, then that, by the planet in orbit around it. They made such precise measurements that they could account for a shift in the star’s motion at roughly human walking speed, about 2 miles per hour (3.5 kilometers). They also had to account for two other kinds of motion: Barnard’s Star’s apparent motion across the sky, and the fact that the star is also moving toward us. The star has the fastest known apparent motion of any observed so far: about 310,000 mph (500,000 kilometers) per hour in relation to our Sun, or the width of the Moon every 180 years.
Learn more at ESO's official announcement.