A planet that orbits a star outside our own solar system.
The universe is a huge, mostly empty, and lonely place. This week it became a little bit less lonely. On August 25th, a team of astronomers from the ESO (European Organization for Astronomical Research in the Southern Hemisphere) published evidence of an Earth-like planet orbiting the closest star to Earth. Our new neighbor, Proxima Centauri b (Proxima b for short), orbits the star Proxima Centauri, so named due to its proximity to our own solar system. It is only four light years away from Earth. This exoplanet has a minimum mass of 1.3 times the mass of Earth and races around its star, orbiting once every 11.2 days. This orbital radius puts Proxima b solidly in the ‘habitable zone’ around Proxima Centauri; the habitable zone is the region around a star where liquid water may exist on the surface of a planet.
The announcement of this exoplanet follows the confirmation of thousands of other exoplanets, many of which have been described as 'Earth-like' in the news. What’s so special about this one after we’ve been inundated with news of Earth-like exoplanets for years? It's all about the location. Most of the confirmed exoplanets are tens of light years away. These distances are unattainably far for any sort of light-speed communication. Proxima b is close enough to send and receive a radio signal in eight years! In the greater metropolitan area of the Milky Way galaxy, we live in the galactic suburbs, which makes Proxima b the neighbor we pop in on to borrow a cup of sugar. So as astronomers continue to learn more about our new neighbor, perhaps it's time to start considering how we might drop by and introduce ourselves.