Earth isn't the only planet with seasons, but they can look wildly different on other worlds

A bluish-green planet in space with a star nearby. distant stars and colorful clouds of gas surround the planet and fill the background. a bright star is nearby.

Spring, summer, fall and winter – the seasons on Earth change every few months, around the same time every year. It's easy to take this cycle for granted here on Earth, but not every planet has a regular change in seasons. So why does Earth have regular seasons when other planets don't?

I'm an astrophysicist who studies the movement of planets and the causes of seasons. Throughout my research, I've found that Earth's regular pattern of seasons is unique. The rotational axis that Earth spins on, along the North and South poles, isn't quite aligned with the vertical axis perpendicular to Earth's orbit around the sun.