The Atmosphere. The earth is surrounded by layers of gases, our atmosphere. They are kept near the earth’s surface by gravity. Our atmosphere filters the sunlight and keeps dangerous rays from reaching our planet. Without such a filter it would get too hot during the daytime.At night it prevents heat from escaping so it does not get too cold.he Atmosphere. The earth is surrounded by layers of gases, our atmosphere. They are kept near the earth’s surface by gravity. Our atmosphere filters the sunlight and keeps dangerous rays from reaching our planet. Without such a filter it would get too hot during the daytime.