When Are We Closest to the Sun?

I'm setting this to autopost at 1:00 am (GMT) on Friday 5th January 2012. If you're reading this at round about that time, then the answer is NOW*. Right now.

The thing is, Earth's orbit around the Sun isn't perfectly circular. Its orbit follows a path called an ellipse, which is a sort of squashed circle. This means that we're not always the same distance away from it- we get closer to and further away from the Sun on a cycle which lasts about a year, so our next closest approach (which is called 'perihelion') will be about this time next year, to within a few days.

Another interesting idea is that, due to the way celestial mechanics works, the point at which we're closest to the Sun is also the point at which we're moving fastest in our orbit, and the point at which we're furthest from the Sun (known as 'aphelion', and falling on July 5th this year) is the point at which we're moving at our slowest speed.

Here's one for your brain to chew on: here in the UK, we're at the closest point to the Sun in the middle of winter, yet furthest away from it when we're slinging on the flip-flops and reaching for the sun cream. How does that work, d'ya think?

* Here are the dates and times for the years 2000-2020 inclusive (along with some other info), straight from the NASA's mouth: http://aa.usno.navy.mil/data/docs/EarthSeasons.php


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