Perihelion and Aphelion

Hello!

This is more of an article than a blog but I wanted to talk about it. This website can be whatever I want, right?

You may not see it easily, but over the course of a year, the sun becomes bigger and smaller in a roughly periodic way. With that, we have defined the point where from the Earth's perspective, the sun looks the biggest and smallest. These points are known as perihelion and aphelion respectively.

Perihelion is the point where the Earth is closest to the Sun. The distance from the Earth to Sun at this point is around 147,000,000 km. For this year, perihelion occurred during the date January 2, however the exact time is always changing from year to year.

Interestingly, perihelion happens during winter (in the Northern Hemisphere), which may seem contradictory at first, due to the fact that it is common sense to think that the closer to the Sun, the higher the temperature. However, the changes in distance, in the astronomical scale are not great enough to cause massive changes in temperature. And also, seasons are caused by the tilt of the Earth's axis, not by how far the Earth is from the Sun.

Aphelion is essentially the opposite of perihelion, it is when the Earth is farthest from the Sun. At this point, the sun is around 152,000,000 km away from the Earth. This year, aphelion will occur on July 5th, around the middle of summer in the Northern Hemisphere or the middle of winter in the Southern Hemisphere.

You might be wondering how this phenomenon might happen. Fortunately, the answer is very simple, the reason perihelion and aphelion exist is due to the elliptical orbit of the Earth around the Sun. The ellipse shape of the orbit leads to some parts closer to the Sun and some parts further.

It is certainly interesting to see that the Earth goes closer and farther from the Sun, especially when they don't match with the seasons we expect to be.

Thanks for reading!