Why do we have seasons?
Because Earth’s axis is tilted about 23.5 degrees, not because of distance from the Sun. Earth is actually closest to the Sun in early January, in the middle of Northern Hemisphere winter.
Quick Answer
We have seasons because Earth’s axis is tilted about 23.5 degrees relative to its orbit around the Sun. As Earth travels around the Sun, the tilt keeps pointing the same way, so for part of the year the Northern Hemisphere leans toward the Sun and gets more direct sunlight and longer days, and for part of the year it leans away. When the North Pole tilts toward the Sun, it’s summer in the north and winter in the south, and six months later it’s reversed. Distance isn’t the cause. Earth is closest to the Sun in early January, about 91.4 million miles away on January 3, 2026, and farthest in early July, when it’s roughly 3% farther. The December solstice, the start of astronomical winter in the Northern Hemisphere and the day with the least daylight, falls on Monday, December 21, in 2026.
By the Numbers
Key Facts
- The cause
- Earth’s axis is tilted about 23.5 degrees
- Not the cause
- Distance from the Sun
- Closest to the Sun
- Early January: about 91.4 million miles on Jan. 3, 2026
- Winter solstice 2026
- Monday, December 21, in the Northern Hemisphere
How the tilt makes seasons
- The tilt stays put
Earth’s axis keeps pointing the same direction as it orbits the Sun.
- Leaning toward the Sun
That hemisphere gets more direct sunlight and longer days: summer.
- Leaning away
The sunlight is weaker and the days are shorter: winter.
- Opposite seasons
When it’s summer in the Northern Hemisphere, it’s winter in the Southern.
Tilt, not distance
The Sun’s light hits one hemisphere more directly when it’s tipped toward the Sun, and it spreads over a larger area when it’s tipped away. That difference, along with the longer or shorter days, makes the hemisphere warmer or colder. NASA, NOAA and the National Weather Service all explain seasons this way.
Closest in winter
Earth’s orbit is slightly oval, and in early January we’re about 3% closer to the Sun than we are in early July. NASA notes that the change in distance doesn’t make much difference to our weather, and the Northern Hemisphere has winter when Earth is closest to the Sun.
Solstices and equinoxes
At a solstice, one pole is tilted as far toward the Sun as it gets. The December solstice, on December 21 in 2026, is the shortest day in the Northern Hemisphere and the longest in the Southern. At the equinoxes in spring and fall, day and night are close to equal.
Myth vs. Fact
MythSeasons happen because Earth gets closer to and farther from the Sun.
FactEarth is closest to the Sun in January, during Northern Hemisphere winter. The tilt causes the seasons.
MythEveryone on Earth has winter at the same time.
FactThe hemispheres have opposite seasons. When it’s winter in the north, it’s summer in the south.
The Bottom Line
We have seasons because Earth’s axis is tilted about 23.5 degrees, not because of distance from the Sun. Earth is closest to the Sun in January, in the middle of Northern Hemisphere winter.