What does observing invole?

What is a gigantic cloud of gas and dust in space? Who discovered elliptical orbits? What are the factors that determine the amount of sunshine a place receives? Can life continue in the aquarium indefinitely as long as the sun shines regularly on it? How long can an astronaut walk on the moon? How many light years is mercury from the sun? What are the names of the Six Flags on the moon? 1969 spacecraft that landed on the moon? What planets are similar to each other in size density and internal? What is a brith stone? Summary of the creation story from luzon? Do Moon have the air or the stars? Why did the Doctor erase Donna's memory? Are there 3 heavens? Why is it less expensive to send robots into space than man? What fuses during the red giant phase? Which could cause a satellite to descend low enough that it burns up in Earths atmosphere centripetal force air resistance gravitational force? Was landed duty paid ever an incoterm? Which man stayed spacecraft when Apollo 11 reached Moon? How does red shift change how you read a graph of the galaxy?