What is a compound word for when the sun goes down?

What was the name of the first shuttle to be launch? What is different about mars then other planets? What runs at the top of the troposphere? How did the months of the year get their names? What was the name of the polish astronomer who proved that it was the earth that circulates around the sun? Our solar system is located approximately how many light years from the center of the galaxy? Why can see rainbows on rainy days? Too much in the atmosphere can interfere with the successful transmission of infrared rays into space.? How do you measure the distance to the stars with parallax? What is a star called in its earliest stage of life? What is the percentage of the atmosphere made up of oxygen? What does an ash cloud do? What are 3 facts about first quarter moon? What are the phases in the rythmic activity program? How can planets weight something if space is weightless? Is fusion or fission the main energy source for stars? Which planet has a moon named Ariel? How far away is Mars from the Sun in AU? What is the term for the distance light can travel in one year in a vacuum? What is Bernard's star?