Science- An animation showcases how the seasons change with Earth's orbit around the sun.
- Earth's angle causes very specific weather patterns and daylight during the course of a year.
Astronomers believe that billions of years ago, a Mars-sized object smashed into Earth, knocking our planet over and leaving it tilted at an angle.
That ancient bump is what caused the Earth's seasons — times of the year that have very specific weather patterns and hours of daylight that vary depending on the latitude.
Most places experience four noticeable seasons: spring, summer, autumn, and winter. Below, view how the seasons change with Earth's orbit around the Sun:
Eleanor Lutz, who is currently a graphics editor at The New York Times, made the animation in 2019 using open data from NASA, USGS, and Natural Earth.
"I've always been very interested in designs that combine science and art. When I learned to code as part of my Biology PhD, I wanted to apply coding to my design work as well," Lutz told Insider. "I decided to create a series of astronomy maps, because there is a lot of wonderful open-source data in the astronomy community."
The graphic showcases how seasonal changes in precipitation and temperature affect Earth's ice, vegetation, cloud cover, and sunlight.
Earth's tilt relative to the sun causes the seasons
Earth is currently tilted 23.4 degrees relative to the plane where most objects in the solar system orbit the sun, NASA explains. That means that as our planet travels in a nearly circular orbit around the sun, different parts of the globe receive different amounts of sunlight throughout the course of a year.
Earth is divided into a northern and southern hemisphere by an imaginary ring called the equator. When the northern hemisphere is leaning toward the sun in June, it experiences summer. That's when the sun's rays hit that part of Earth more directly, heating Earth's surface. When it's summer in the northern hemisphere, it's winter in the southern hemisphere.
Six months later, in December, the situation is reversed: the northern hemisphere is tilted away from the sun, and it experiences winter weather.
The tilt of the Earth's axis also defines the length of daylight hours, which are shortest in each hemisphere's winter. This is most dramatic at the planet's poles, above the Arctic Circle.
In Utqiaġvik, Alaska, the northernmost town in the US, the darkness lasts from mid-November until mid-January.
Near the equator, the seasons are less pronounced, because each day the sun strikes at about the same angle. There, the duration of daytime remains almost 12 hours throughout all of the seasons.
The angle of the Earth's tilt is relatively stable, but there are some slight shifts over large time scales (tens of thousands of years). According to NASA, the angle is slowly decreasing.