A planet twice the size of Earth has been discovered in the Goldilocks habitable zone. The planet in question is located some 3,000 light years from Earth in a binary star system. The new planet, dubbed OGLE-2013-BLG-0341LBb (astronomers seriously need to work on their planet names), orbits its star at nearly the same distance as the Earth orbits the Sun.
Great news, right? It’s a cool discovery, but OGLE’s star isn’t cooperating. That star is a lot dimmer than the sun, leading OGLE to look more like Hoth than Earth.
What’s cool about the discovery? The same type of planet orbiting a star similar to our sun would be in the habitable zone.
“This greatly expands the potential locations to discover habitable planets in the future,” Scott Gaud, a professor at Ohio State University and the study’s co-author, said in a statement. “Half the stars in the galaxy are in binary systems. We had no idea if Earth-like planets in Earth-like orbits could even form in these systems.”
How did astronomers spot a planet so far away? They used a technique known as gravitational microlensing. Astronomers use the gravity of a star to focus the light from a more distant star like a massive galactic lens. Then, astronomers look for small blips within the light signal.
That’s how OGLE was spotted. A small blip was formed as the host star and its system passed in from of a star 20,000 light years away.
“Now we know that with gravitational microlensing, it’s actually possible to infer the existence of a planet—and to know its mass, and its distance from a star—without directly detecting the dimming due to the planet,” Gaudi said. “We thought we could do that in principle, but now that we have empirical evidence, we can use this method to find planets in the future.”
Computer analysis of the data led to details about the planet’s mass and how far it sits from its star. Rough estimates by astronomers put the planet’s orbit at 90 million miles from its star and a surface temp of a chilly -352 degrees Fahrenheit.
This discovery will expand astronomers’ hunt for Earth-like planets. Two-star systems such as this one are the most common type of star-system in our galaxy. Stars that shine a bit brighter could very well have habitable planets near them.