How many years from 1986 to 2018?

Why is the sun useful to Earth? How many stars are on gams cape? What happens to city lights within earth atmosphere that makes stargazing difficult? What is the point in the moon elliptical orbit where it is farthest from the earth? What happened to Robert falcon Scott? Why is it colder on the top of a mountain than the bottom? Does it get darker faster in the winter compared to other seasons? What are the four most abundant components of the atmosphere? Are tornadoes weather related? Why does the moon exhibit a much stronger tidal effect on Earth than does Jupiter? Which country has most solar radiation? What are the factors the determine a planets albedo? What is polycromatic colour? Why does a star's gravity increase when it gets smaller? What is length of 2nd pendulum on moon? What dies the word urian mean? What day of the week was September 3 1968? Are there any planned space trips to the in the future? In terms of solar mass which of the stars evolves most rapidly? What was the space race?