Should we leave them alone? Yesterday a new spacecraft set out to visit one of Jupiter’s moons. Some scientists are hoping that it will find proof of life.
Blast off for alien-hunter spaceship
Lift off: A European mission set off to Europa last year, but the Nasa clipper will arrive first (in the year 2030) by using a cosmic piggyback. Glossary
Jupiter - The largest planet in our solar system. It is a gas giant.
Telescope - A device which makes things look nearer than they are.
Venus - In mythology, the Roman goddess of love, beauty, desire and fertility. Venus is also the closest planet to Earth.
Climate change - Long-term shifts in temperatures and weather patterns. Human action is a major cause of climate change.