Perihelion is a day to celebrate

man and woman walk dog as sun sets over frosty field
Posted by

If someone is sad that holiday season is over, here is something to celebrate.  The earth is the closest it will ever be to the sun for the year! 

We all know the earth revolves around the sun. It takes about 365.25 days to do this, or one year.

However, that revolution (or orbit) is not a perfect circle. Instead, it’s slightly elongated or elliptical, which means the earth is farther from the sun at one time and closer at another.

How close is the earth to the sun? It depends

There is about a 3 million mile change over the year in how close the earth is to the sun.

  • When we are shooting off fireworks on July 4, we will be the farthest from the sun for the year, at 94,509,598 miles.
  • On January 4, 2022, the earth will be 91,406,842 miles from the sun. Perihelion is the term used for when the earth is closest to the sun.

How is this possible?

It seems to be just of opposite of what you would think! But the explanation lies in the fact that the distance between the earth and the sun doesn’t make our seasons. That is caused by sun angle, or how high the sun gets in the sky.

As the earth rotates or spins, the spin is not straight up and down. It’s tilted 23.5 degrees from straight up and down. This changes the height of the noon day sun throughout the year as we move around the sun.  

Right now, our noon sun is not very high, because the northern part of the earth is tilted away from the sun. The lower the sun, the more spread out the sun’s energy is, which in turn decreases how intensely the earth is heated. Six months from now the sun will be much higher in the sky, and we will be sweating our…well we will be sweating.

Having said that, being closer to the sun this time of year does have a small benefit, in that it makes our winters slightly less harsh than they would be if our winter came when the earth is farthest from the sun. Maybe not a large consolation, but one nonetheless.

 

MEET THE AUTHOR
Duane Friend is an energy and environmental stewardship educator with University of Illinois Extension, serving the organization in many roles since 1993. Duane provides information and educational programs to adult and youth audiences in the areas of soil quality, weather and climate, energy conservation, and disaster preparedness. These programs provide practical solutions for families, farms, and communities.  He assists families in creating a household emergency plan, farmers with the implementation of soil management and conservation practices, and local government officials and business owners with energy conservation techniques.

ABOUT THE BLOG
All About Weather is a blog that explores the environment, climate, and weather topics for Illinois. Get in-depth information about things your weather app doesn't cover from summer droughts to shifting weather patterns.