1. An astronaut has to wear a spacesuit it may be very cold in space. A. so B. but C. because D. because of 2. The UFO landed on a area. A. grass B. grassy C. grassed D. grassing 3. Scientists have been trying to find of aliens. A. amounts B. records C. traces D. sights 4. There have been many UFO reported. A. sights B. signs C. signals D. sightings 5. Mars is called the Red Planet due to its surface. A. red B. redder C. reddest D. reddish 6. In the mid-19th century, scientists discovered that Mars had some similarities Earth. A. to B. with C. of D. from 7. Neptune is bright blue it is named after the Roman God of the sea. A. because B. but C. so D. or 8. There is a lot of interest in doing experiments in the conditions. A. weigh B. weighing C. weight D. weightless 9. Titan, one of Saturn’s , has a thick atmosphere. A. satellite B. spaceships C. moons D. comets 10. Scientists believe that Mars also seasons just as the Earth does. A. spends B. experiences C. experiments D. takes