A habitable world

Distance from its star, not too far, not

too close

Size, not too big, not too small

Atmosphere to keep the planet warm

and water liquid

Water

Habitable Zone

What does life need?

Raw materials: hydrogen, carbon,

oxygen, nitrogen and minerals like iron

and sulfur.

Energy: Sun, volcanoes

A liquid: Water

Jupiter’s moons Io, and Europa—

way beyond the Habitable Zone

Europa: Water ocean, under the ice crust, melted

by internal heat sources— this could be fairly

common

Inferred Ocean

Is Europa telling us to expand our

definition of Habitable Planet?

Recently, we have discoveredthat life without the sun ispossible.

Instead of photosynthesis,organisms have beendiscovered living in a varietyof places via chemosynthesis- the use of chemical energy.

Could this happen on otherworlds?

A deep-sea hydrothermal vent.

Europa

Mars today

How to find a planet?

Problem:

The stars emit light (a lot!) and planets doesn’t, they just

reflect the light from their parent star.

How to solve it?

Cover the star!!!!

Measure the effects of the planets on the stars:

Stars wobble because of the planets

Stars dim when a planet crosses in front of them

Looking for habitable worlds

Kepler:

Look for

terrestrial

planets around

100,000 stars.

Launch on

2006.

Darwin:

Look for terrestrial planets around 1,000.

Launching after 2014.

Looking for habitable worlds

Tau Ceti e is an unconfirmed planet that may be orbiting the

nearby Sun-like star Tau Ceti e at a distance of 11.905 light

years from the Sun.

If we travel in 18 km/s speed, we reach Tau Ceti e at

1.97×1011 years

Conclusion