Exoplanet Duo Orbits A Nearby Ancient Kapteyn's Star

Alien worlds are exoplanets that circle stars beyond our Sun. For a generation now, planet-hunting astronomers have been spotting these very remote worlds, and have found that while some bear an almost eerie resemblance to the eight familiar major planets that dwell in our own Solar System, others are so bizarre that they are unlike anything astronomers ever dreamed of seeing.

In June 2014, an international team of astronomers reported their discovery of a delightful duo of planets circling a nearby and very ancient star known as Kapteyn's Star. One of these newly discovered planets circles within its parent star's habitable zone, which is that "just right" Goldilocks distance for water to exist on its surface in its life-sustaining liquid state. Where there is liquid water, the possibility--though not the promise--of life exists as well. The study has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.

Named for the Dutch astronomer Jacobus Kapteyn, who discovered it towards the close of the 19th century, Kapteyn's Star is very speedy. In fact, it is the second fastest-moving star in the sky, and is a denizen of the our Milky Way's galactic halo, which is an extended cloud of stars that circle our Galaxy in extremely elliptical orbits. Kapteyn's Star is a red dwarf sporting only one-third the mass of our Sun, and it can be observed in the southern constellation of Pictor with only an amateur 'scope.

Kepler 10c Earthlike Planet Enormous Rocky Alien World

The first discovery of an alien world circling a Sun-like star beyond our own Solar System occurred back in 1995, and it was an amazing find--a massive gas-giant, Jupiter-like planet hugging its parent star in a fast, close, roasting orbit. Prior to this historic discovery, astronomers did not think that such immense gaseous worlds could exist so close to the searing-heat of their glaring, seething, roiling parent-stars--and that all gas-giant planets must dwell in the colder, outer regions of their planetary systems, just like Jupiter does in our Sun's own family.

 After two decades of one surprising exoplanet discovery after another, planet hunting astronomers have learned that when it comes to the discovery of alien worlds, they should definitely expect the unexpected. In June 2014, a team of astronomers announced their amazing discovery of a rocky world weighing-in at 17 times more than our Earth--and this hefty planet is also twice Earth's diameter.

The planet, dubbed Kepler-10c, has presented quite a challenge to planet formation theorists in their attempts to explain how such a weighty, rocky world could have formed.