The earth moves around the sun in June and fastest in January.When is the earth farthest from the sun?

Question

about Kepler's law of planetary motion

Answer 1

I think the question should refer to earth's motion being <slowest> in June and fastest in January. Since the total (potential + kinetic) energy of an orbit is constant, the greatest potential energy (distance from the sun) occurs when kinetic energy (speed) is least. Thus, given the conditions cited in the question, earth is farthest from the sun in June. Actually for 2008 this occurred July 4 (ref.). January and July makes more sense than January and June, since perihelion and aphelion are at opposite points of the orbit, with 6 months separation.

Answer 2

Ok. Let's get some terminology down first. If a body (like the Earth) is orbiting around the Sun, we say it is closest to the Sun at perihelion and farthest from the Sun at aphelion. If a body (like the Moon) is orbiting around the Earth, its closest point to the Earth is perigee and its farthest point from the Earth is apogee. In 2000, perihelion for the Earth was on January 3, 2000, and aphelion was on July 4, 2000. The Earth was 91,405,436 miles from Sun at perihelion and 94,511,989 miles from Sun at aphelion. For the year 2001, perihelion will occur on January 3, 2001 and aphelion will occur on July 4, 2001. The actual date for perihelion and aphelion will differ from year to year. But, you can see that the Earth is closest to the Sun in January and farthest from the Sun in July!