Every year in early January, Earth reaches the closest point in its orbit to the Sun, a moment astronomers call perihelion.

Here's how the astronomical phenomenon influences our planet—from the length of our seasons to the way Earth moves through ...

Earth's orbit is an ellipse, not a perfect circle. Earth's distance from the Sun varies by about 3 million miles throughout the year. Earth's orbit's semimajor axis is approximately 93 million miles.

Why does the Earth’s tilt create our season? The Earth orbits the Sun, but with a tilt. That tilt is important to those of us on the planet because it creates our seasons. How does that work? What ...