What is Earth's orbital eccentricity?

Earth’s orbital eccentricity is how round or stretched out Earth’s path around the Sun is.

Imagine you're drawing a circle with a piece of chalk, that's like Earth’s orbit when it's perfectly round. But if you stretch the circle into an oval, that’s what happens when Earth’s orbit becomes more stretched out, or eccentric.

Think of Earth as a kid on a swing. When the swing moves in a perfect arc, like drawing a circle, it's smooth and even. But sometimes, the swing goes higher on one side than the other, making an oval shape instead of a circle. That’s what happens with Earth’s orbit.

When Earth's eccentricity is high, its path around the Sun looks more like an oval. When it’s low, it’s almost circular. This change affects how close or far Earth gets from the Sun during the year, kind of like how a kid on a swing feels when they go higher or lower.

Sometimes Earth’s orbit is more stretched out, and sometimes it's more round, just like a swing can be smooth or wobbly!