David Kipping

But for now, the entire solar system is one pixel, certainly with the transit method and most other telescopes.

And so all you can do is see where that one pixel, which contains potentially dozens of planets and the star, maybe even multiple stars, dims for a short amount of time.

It dims just a little bit, and from that you can infer something.

Yeah, I mean, it's like being a detective in the scene, right?

It's indirect clues of the existence of the planet.

Yeah.

I mean, it depends on the type of star we're talking about.

If it is a star truly like the Sun, the dip that causes is 84 parts per million.

I mean, it's like a firefly flying in front of a giant floodlight at a stadium or something.

That's kind of the brightness contrast that you're trying to compare to.

So it's extremely difficult detection.

And in the very, very best cases, we can get down to that.

But as I said, we don't really have any true Earth analogues that have been in the exoplanet candidate yet.

Unless you relax that definition, you say it doesn't have to be a star just like the Sun.

It could be a star that's smaller than the Sun.

It could be these orange dwarfs or even the red dwarf stars.

And the fact those stars are smaller means that for the same size planet passing in front of it, more light is blocked out.

A very exciting system, for example, is TRAPPIST-1, which has seven planets which are smaller than the Earth.

Those are quite easily detectable, not with a space-based telescope, but even from the ground.

That's just because the star is so much smaller that the relative increase or decrease in brightness is enhanced significantly because of that smaller size.