If weather satellites suddenly detect a smile-shaped weather pattern covering a large portion of the planet, it could be because Earth just found out it has an older and bigger brother living just a stone’s throw away – cosmically speaking – and it may have a temperature and atmosphere that could sustain life.
Astronomers using data from the HIRES spectrometer at the Keck Observatory in Hawaii, the Planet Finding Spectrometer at the Magellan/Las Campanas Observatory and the European Southern Observatory’s La Silla facility, both in Chile, discovered two exoplanets orbiting Kapteyn’s Star, an M1 red dwarf just 13 light years away. It’s a halo star, the closest one to our solar system, that once belonged to an ancient elliptical galaxy that was absorbed and destroyed by the Milky Way.
The planets were found using radial velocity measurements which identify tiny periodic changes in the motion of a star that are caused by the gravitational pull of planets. The big brother, Kapetyn b, is at least five times larger than the Earth, orbits its star every 48 days and is warm enough for liquid water to exist on its surface. Kapteyn c is even larger, has a year lasting 121 days and appears to be too cold for liquid water.
Not much else is known about the planets and any attempts to find out will have to take place soon – cosmically speaking. Kapteyn’s Star is a high-velocity, low-luminosity halo star that is moving away from our solar system at 142 miles-per-second. Astronomically speaking, in 3500 years it will leave the constellation Pictor and enter Dorado.
According to the report in the journal Monthly Notices of the Royal Astronomical Society Letters, the planets may be 11.5 billion years old – over twice as old as Earth and 2 billion years younger than the universe. If there’s life on Kapteyn b, it could be much older than us.
If that’s the case, maybe we can entice them to visit by wrapping the equator with handrails