That would depend on what object we are talking about.
Venus is the planet with the closest orbit to that of Earth.
Mars and Venus orbit closest to the earth in the order sunward to rimward: Venus, Earth, Mars.
At periapsis, that is, when it is closest to Earth in its orbit.
At the point when it is closest to the sun.
Venus
Venus' is. Mars' is next.
There is one single point in the Earth's orbit where it is closest to the sun. That point is called the "perihelion".
Perihelion is when the Earth is closest to the sun.
During the summer, which is the hottest therefore it's the closest to the sun.
That would depend on what object we are talking about.
tonight, 9/20/2010
Earth passes through the point in its orbit that is closest to the sun, which is known as its perihelion, during the first half of January.