On January 4th, the earth will be closet to the sun than at any other time of the year -- but not any warmer! Here's why.
Before the 17th century, it was thought that planets and other objects had circular orbits around the sun. Then Johannes Kepler (a German mathematician, astronomer and astrologer who was a key figure in the 17th century scientific revolution and discovered orbits were actually elliptical which means there are points along the orbit that are closest and furthest from the sun.)
Comet ISON for example, had an elongated elliptical orbit and passed extremely close to the sun. That’s why it fried. However, the Earth is the only planet with an almost circular orbit.
Even though on January 4 we'll be 147 million kilometres from the sun, it’s not close enough to warm our world. The average distance to the sun throughout the year is 149 million kilometres. It’s ironic that we’re furthest from the Sun on July 4 at 152 million kiometres.