How much do you know about our
Solar System?
I. Look at the pictures and write the proper vocabulary.
II. Choose the right option.
Our planet, Earth, is the planet from the sun. Earth orbits the once every year, or days.
Earth has one . It is about 385,000 km from Earth. It orbits the Earth days. Our closest neighbors are the planets .
III. Choose the proper form of the verbs.
For hundreds of years, people , "Is Mars 
like our planet? life on Mars? Or life in the past?
Life on Earth water to exist. 
So, scientists asking, water on Mars?
In 2004, NASA two robot explorers 
or rovers to Mars. Their mission? To find signs of water.
The rovers seven months to fly to Mars.
Since 2004, the rovers back a lot of information.
Who what the next rovers ?
Scientists that Mars was warmer many years ago.
There to be rivers and seas on Mars.
A hundred years from now, maybe humans living 
on Mars oxygen equipment to breath.
IV. Correct the verb tenses in yellow.
1. Right now, a team of astronauts live 350 km above Earth in a spacecraft called International Space Station.
2. Astronauts used to eat mashed food from tubes, but scientsists discovered better ways to cook in space.
3. Every day, ISS Astronauts have worked very hard. They do science experiments, build the space station or exercise.
4. When Bill Shepherd have free time, he liked to e-mail people at home and watch movies.
5. In the future, it cost the united States and other countries billions of dollars to participate in the ISS.
6. Muscles and bones becomes weak in space. Some scientists believe that humans live in space some day, so astronauts is studying other changes that happen to the human body during long periods in low gravity.
