Astronomy Question?

Question

Is it just a chance that we are living in an age in which the December solstice and June solstice coincide with Perihelion and Aphelion respectively? Will the solstice points drift with time, due to precession of the earth, along its orbit about the sun?

Answer 1

I think it is just chance. The perihelion of Earth's orbit does precess, as does the tilt of Earth's axis. They precess at different rates, and the combined cycle lasts about 100,000 years. However, the Earth's orbit is not very eccentric, so the seasons are by far the dominant factor in climate. Compare to Mars, which has an orbit five times as eccentric as Earth's. On Mars, the southern hemisphere has more extreme seasons than the north; this is theoretically the case with Earth, but the phenomenon is not observed in practice. Since the Earth's ecosystem has been stable for periods in the past that have lasted much longer than 100,000, these cycles are not a significant factor affecting life on Earth.

Answer 2

It is not quite true. It is a fortnight or so out. Perihelion is January 4th and Aphelion is July 4th this year, whereas the solstice dates are June 21 and December 21,

Mind you if we were still following the Julian Calendar i.e. if September 2nd 1752 had not have been followed immediately by September 14th with a net loss of eleven days (which might be thirteen days by now with 1800 and 1900 not being Leap Years in the Gregorian calendar) there would be a much better correlation between solstice dates and perihelion and aphelion!

Answer 3

Yes, I think it is just a chance that we are living in an age where both the December solstice and the June solstice are coinciding with both Perihelion and Aphelion respectively.

Answer 4

Actually, the solstices do not coincide with perihelion and aphelion.