Larry Long, age 12, of Quincy.. Ill., for His question:

When is the sun closest to the earth?

The orbit of the earth is an ellipse, or oval, with two foci or central points. The sun is at one of these foci, which means that its distance varies as the earth swings around its yearly orbit. The mean or average between us and the sun is 92,900,000 miles  or thereabouts. But the distance varies by same three million miles.

Strange to say, the earth is nearest to the sun when we are in the northern hemisphere mid winter. This is in early january when we are about one and a half million miles closer to the sun than we are in april and october. In July, we are three million miles farther from the sun than we are in chilly January.