What is the difference between a '' and a ''? The atmosphere is the mass of air that surrounds a planet. 19. What is the difference between a. and a. It takes the earth 365.25 days to make one complete revolution around the sun. 20. What is the difference between a'smart' and a'smart'? Earth’s axis is tilted 23.5 degrees. 21. What is the difference between a'smart' and a'smart'? The distance from the earth to the sun is 1 astronomical unit. 22. What is the difference between a'smart' and a'smart'? When it is summer in the northern hemisphere, it is winter in the southern hemisphere. 23. What is the difference between a'smart' and a'smart'? If the Northern Hemisphere is tilted toward the sun, it is experiencing summer. 24. What is the difference between a'smart' and a'smart'? Hemispheres experience opposite seasons at any given point in the year. 25. What is the difference between a'smart' and a'smart'? Gravity is a force that exists throughout the universe. 26. What is the difference between a '' and a ''? It takes the earth 24 Hours to rotate on its axis one time. 27. What is the difference between a '' and a