The Earth's annual orbit around the Sun will carry it to its
furthest point from the Sun – its aphelion – at a distance of 1.02 AU.
The Earth's distance from the Sun varies over the course of the year because
its orbit is slightly oval-shaped, following a path called an ellipse. On
5 July, the Earth reaches the point along this ellipse
that is furthest from the Sun.
As a result, this moment marks the point in the year when the Sun appears
smallest in the sky, and when the Earth receives the least radiation from it.
In practice, however, the effect is incredibly small.
The Earth's orbit is almost exactly circular and its distance from the Sun
varies by only about 3% over the course of the year, and so other phenomena,
such the reflection of solar radiation by clouds, have a much more significant
effect in determining our weather.
The annual changes in weather between the summer and winter months are caused
entirely by the tilt of the Earth's axis of rotation, rather than by any
change in its distance from the Sun.
The detailed circumstances of this event are:
The coordinates above are given in J2000.0.
The sky on Fri, 05 July 2013
The circumstances of this event were computed from the DE405 ephemeris published by the Jet Propulsion Laboratory (JPL).
© NASA/Apollo 17