What we've found
5,000+confirmed planets around other stars
1995first planet found around a Sun-like star
Billionsof possible Earth-sized planets in our galaxy
0confirmed signs of life beyond Earth
NASA's Kepler and TESS missions found most known exoplanets.
How we search
Transits
A planet dims its star as it passes in front
Atmospheres
Telescopes look for gases life might make
Radio listening
SETI scans the sky for artificial signals
Our solar system
Probes study Mars, Europa and Enceladus
Two famous ideas
The Drake equation (1961)
- Estimates how many talking civilizations might exist
- Multiplies stars, planets and chances of life
- Most of its numbers are still unknown
The Fermi paradox
- If life is common, where is everybody?
- Maybe it's rare, short-lived or far away
- Or we haven't looked long enough
Sources: NASA Exoplanet Archive; SETI Institute
Remember
The galaxy is full of planets; whether any have life is one of the biggest open questions in science.
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Answer key
- About how many planets around other stars have been confirmed?More than 5,000More than 5,000 confirmed exoplanets.
- What is the transit method?Watching a star dim as a planet passesPlanets block a bit of starlight.
- What does the Fermi paradox ask?If life is common, where is everybody?It contrasts likely life with no evidence.
- What does SETI do?Searches for artificial signals from spaceIt listens for signals from other civilizations.
- Has life beyond Earth been confirmed?No, not yetNo confirmed evidence yet.