this video is really cool. they're showing how astronomers are looking for Earth like planets around the galaxy.
As these planets cannot be viewed due to their distance from Earth and the light from their host sun, they measure the motion of the star and can model their solar systems through seeing how the "sun" wobbles, which is due to gravitational tug of the planets that orbit them.
With this gravity recorded, a model of the planets that orbit the star are built, and from that the characteristics, based on their size and distance from the sun they orbit, of the planets can be modeled.
Pretty neat stuff
Interesting to think what, if anything, might be looking back.