New consideration doubles the theoretical number of habitable worlds in Milky Way

A hypothetical water world with the red dwarf Gleise581 glowering on the horizon.

A hypothetical water world with the red dwarf Gleise 581 glowering on the horizon.

Look at a big spiral galaxy like the Milky Way and its blazing with the blue-white light of hot, young stars. But the vast majority of stars in our galaxy are the smaller, redder types. Of the estimated 400 billion suns in our galaxy, astronomers believe at least half of them are red dwarfs. One problem with red dwarfs is they tend to be active, they can flare and dim dramatically over short periods of time compared to our reliable, stable yellow sun. Because they are so much dimmer, planets in the Goldilocks zone where water might exist as a liquid on the surface would need to huddle much closer to the red stars. Not only would those planets would be pummeled by stellar outburst, they’d become tidally locked, always the same side facing the sun, similar to the way our moon always presents the same face to earth. All things being equal, a planet that takes a few weeks to rotate instead of a day would have a less powerful magnetic field to ward off the solar wind. Both Mars and Venus have mostly lost whatever primeval magnetic field they once had and that probably played a role in vaporizing whatever oceans they may have started out with.

But there’s a newer consideration, one which could help protect the planets of red dwarfs, now being modeled and tested. This increases the number of potentially habitable exo-planets to 60 billion! How? Think of a cold Venus: [Read more…]

Kepler spies a new solar system that looks familiar

We’ve found a lot of strange exo-planets in the last two decades, hot Jupiter’s spiraling into their star like giant comets and super earths that could be covered in exotic oceans and ices hundreds of miles deep. Before it’s all over, Kepler may end up being the most famous name in all the Milky Way galaxy! Now the plucky telescope by the same name has found an alien system that looks a little more familiar in one key respect: [Read more…]

Kepler bags a twin earth candidate 600 light-years away!

This diagram compares our solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by the Kepler mission. (NASA/Ames/JPL-Caltech)

It may be the first of many, but it will always be the first. It was inevitable, inasmuch as we all thought it would happen sooner or later, but a chill still ran down my spine when I read what the Kepler planet finder discovered. [Read more…]