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Astronomycast episode 633 weirdly habitable worlds. Welcome to Astronomycast for weekly

facts based journey through the cosmos where we help you understand not only what we know,

but how we know what we know. I'm Fr. Cain publisher of Universe today with me as

always is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the

Director of Cosmic Quest. Hey Pamela, how are you doing? I am coming to the conclusion

that we should no longer ask that question and I think I mentioned this in the last

show. Well you did, you did. Ask, are you okay and the answer is yeah I think I'm okay.

Are you okay? Yeah, I'm okay. Yeah, yeah. So then if I say like because I can't not

ask how you're doing, but you can say I'm okay. I'm okay. I can say that it's true.

Yeah, exactly. All right, well we've always assumed that habitable planets would need

to be like Earth. A terrestrial planet orbiting a sunlight star, but now astronomers have

been discovering planets in the habitable zone around very much non-sun-like stars.

That strange place could be habitable. All right, so give us like the textbook definition

of a habitable planet. The textbook definition is a planet that exists in the region orbiting

a star where it gets enough energy that you would expect water at its surface to be liquid

if there is sufficient gravity and pressure. Right. So earth Venus Mars all have the potential

to be habitable to a degree. Mars didn't stay that way Venus overshot and this brings us

to the Goldilocks phenomena of our own planet Earth. And so like if Venus had a better atmosphere

and maybe plate tectonics, it could be, it would have liquid water on its surface. If Mars

had a thicker atmosphere, maybe a protective magnetosphere, it would be maybe five times

the mass. It could have liquid water on its surface. And so obviously there's lots of

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