Extraterrestrial Life

I am giving a talk on the habitability of exomoons so I thought it would be cool to inform everyone on what I’ve learned these past couple of weeks. And this way I can distill my knowledge, and nobody else will have to read scientific papers.

I recently went to a AAS (American Astronomical Society) conference and the most popular and well-attended talks were those given by the Kepler team of astronomers. Right now in astronomy, searching for exoplanets is the “sexy” topic. Everyone wants to know how many planets they’ve found and how many of those may be habitable. I believe this is because we as a species are obsessed with finding life somewhere out there.

Because after all, it would be incredibly depressing to be all alone in this universe.

So the Kepler mission is uniquely tuned to look for Earth-sized planets orbitting other stars in the “habitable zone”.

What is the habitable zone?

The habitable zone is determined by the type of star the planet orbits. For instance, Earth orbits a normal star, so it can exist in its orbit without becoming so hot that the oceans boil off or so cold that they all freeze. But for colder stars, the habitable zone for planets exists closer to the star because the star is much colder, so the planet must be closer to stay warm.

This is all well and good for planets, but some astronomers have had the idea to extend this search to habitable moons of these planets. After all, look at our own solar system. Saturn and Jupiter have a plethora of moons, and its been theorized that some of these moons, such as Titan (Saturn) or Europa (Jupiter) may be habitable.

Here’s the distinction for moons:

Their habitable zone is determined not only by their distance from the star, but by their distance from the planet.

Tidal heating from the planet as well as a protective magnetic field and reflection of light and thermal emission from the planet can aid the moon in maintaining a stable climate.

But detecting these tiny (relatively small) moons is incredibly difficult – scientists have theorized that Kepler will only be able to detect exomoons that are 0.2 times Earth’s mass. This is a big moon! The largest moon in our solar system is Ganymede (Jupiter) and it is only 2% of the mass of Earth. So we would be looking for a class of moons that we haven’t even experienced in our own solar system!

Whatever the challenges, I firmly believe that with the next generation of precision ground-based and space-based missions, we may be able to detect the ever-elusive habitable exomoon (or exoplanet). Besides, wouldn’t it be cool if Star Wars’ Endor or Pandora or all those places in Star Trek were a reality? After all, astronomy is a lot like science fiction.