Earth's Movement around the Sun


The planets revolve around the sun not in neat circles, but in ellipses, with the sun at one focus of their ellipse. For Earth this ellipse is nearly a circle - earth's distance from the sun varies by less than 2%.

According to Kepler's second law of planetary motion, the line from the sun to the earth sweeps out equal areas in equal times.


This means that if area A is equal to area B; then tA = tB ( see figure on the right).

Since the distance covered during tA is longer than the distance covered during tB, it follows that Earth must move faster during tA than during tB.
Therefore when the earth is closer to the sun it travels faster and if it is further away from the sun it travels slower. Earth is closest to the sun in January - about 147.5 million km and furthest from the sun in June at about 152.6 million km.

 The Solar System Earth's Rotation around its Axis 
  Sundial Home Page © Helga Nordhoff (2001-2008)