There have been a very large number of planets detected to date.
This is a graph where you can see
the planet mass plotted against the year of discovery.
And as you can see an ever
increasing number of exoplanets, but what's more interesting
about this graph is you can see that the planetary mass is decreasing year by year.
In other words, the methods for finding exoplanets are
becoming much more sophisticated and as they become more sophisticated,
we're finding smaller and smaller planets, pushing into the realms
of earth-like planets orbiting distant stars within the habitable zone.
Certainly the most exciting possibility for astrobiologists.
So, what have we learned in this lecture?
Well, hopefully what we've learned is that there is a zoo of
planetary types out there, a whole variety of different planets orbiting other stars.
Most of them are not going to support life.
They're very different to planets that we know in our own solar system.
Some of them are too close to their star.
They're probably too hot to support life. Some of them may be too far out.
Been too cold.
But as methods are improving, we're beginning to find smaller
rocky planets that may be discovered in the habitable zone.
A third of planetary systems, may have rocky planets in the
habitable zone based on the observations that we have so far.
