Earth Hits Aphelion July 3rd. What Does That Mean?
From our friends at the National Weather Service comes the reminder that Aphelion is not a bad thing.
This Thursday, July 3rd, at about 6 P.M. MDT the Earth will reach Aphelion, its farthest point from the Sun in its orbit. This occurs because the orbit of the Earth is not perfectly circular but slightly elliptical, with the Sun not quite in the center but offset slightly. At the time of aphelion the Earth will be about 94.5 million miles distant from the Sun. That is about 3.1 million miles farther away from the Sun than when the Earth was at its closest point (perihelion) of 91.4 million miles back on January 4th. At the time of aphelion the Sun will actually appear to be just a little over 3% smaller than it was at the time of perihelion (Don’t look to see, you won’t really be able to tell the difference, and it could be dangerous).
Despite the Sun being more distant, the northern hemisphere is much warmer than during its winter perihelion time simply because the axial tilt of the Earth causes the Sun’s rays to impact the surface at a much more direct angle, which far overcomes the very small effect due to being farther away.
Because the Earth is farther away from the Sun at this time of year, it moves a little slower in its orbit. That is why the summer season over the northern hemisphere (and winter over the southern hemisphere) is the longest season of the year, longer by a few days as opposed to the other seasons.
Over the next 6 months the Earth will draw gradually closer to the Sun once again, reaching its closest point (perihelion) next January 4th.