1
$\begingroup$

I found that Earth's perihelion occurs roughly two weeks after winter solstice similar thing happens for summer solstice and aphelion. I understand what those terms mean but I don't understand the reason for the two-week gap. I actually thought they occur on the same day.

What am I not understanding here? Can anyone explain the reason for the two weeks?

My understanding is that the earth's aphelion and perihelion occur on the major axis of earth's elliptical orbit. Why are they not the extremities of analemma which correspond to solstices? Where is my thinking wrong?

$\endgroup$
  • 1
    $\begingroup$ This is a good question! It turns out that the "two weeks" needs no reason or explanation, it could be anything. It would be great if you could add to your answer an explanation why you "...actually thought they occur on the same day." What is it exactly that led you to think that? If you can track that down and realize that they are not connected, you may be able to post an answer to your own question! Hint: What would an analemma look like if the Earth's axis perpendicular to its orbital plane instead of being tilted by 23 degrees? $\endgroup$ – uhoh Jul 16 at 6:07
  • 1
    $\begingroup$ The solstices are caused by Earth's axial tilt. If there was no tilt, there would be no solstice. The apparent closeness in timing of the solstices and the apsides is mere coincidence. $\endgroup$ – Chappo Says Reinstate Monica Jul 16 at 6:12
4
$\begingroup$

There is no connection between the date of the solstice and the perihelion. It is merely a minor coincidence that perihelion occurs close to the solstice.

The relationship isn't fixed. Precession in the Earth's orbit (caused by gravitational perturbations of Jupiter and other planets) will change the relative time of perihelion and solstice over a period of thousands of years.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.