We have seasons because Earth’s axis is tilted , not because Earth gets closer or farther from the Sun.

Why Do We Have Seasons? (PBS-style Quick Scoop)

The big idea

  • Earth’s axis is tilted about 23.5 degrees relative to its path around the Sun.
  • Because of this tilt, different parts of Earth receive more direct sunlight at different times of the year.
  • When your hemisphere is tilted toward the Sun, you get summer; when it’s tilted away, you get winter.

If Earth’s axis were straight up and down, we’d still orbit the Sun, but we would not have the familiar pattern of spring, summer, fall, and winter.

How the tilt creates the seasons

Imagine a spinning top going around a lamp:

  1. The top (Earth) is always leaning in the same direction as it circles the lamp (Sun).
  1. When the top’s northern side leans toward the lamp, the north gets more direct light and longer days → northern summer, southern winter.
  1. Half an orbit later, the northern side leans away → northern winter, southern summer.
  1. Midway between those extremes, neither hemisphere leans toward or away → equinoxes, when day and night are close to equal length.

At equinoxes (around March and September), Earth’s axis is tilted sideways relative to the Sun, so both hemispheres share sunlight more evenly.

Important details people often get wrong

  • It is not mainly about distance from the Sun: Earth is actually slightly closer to the Sun during northern winter than during northern summer.
  • Seasons are stronger (hotter summers, colder winters) at higher latitudes, because the change in Sun angle and day length is more extreme there.
  • Near the equator, the Sun’s rays stay fairly direct all year, so seasons are weaker and often described more by “wet” and “dry” than by “summer” and “winter.”

PBS classroom resources and NASA-style interactives often show diagrams where a tilted Earth orbits the Sun and you can compare sunlight and temperatures for cities at different latitudes.

Astronomical vs. meteorological seasons

You’ll sometimes see two slightly different season systems:

  • Astronomical seasons
    • Start and end at solstices and equinoxes (based on Earth’s position in its orbit).
* Example: The September equinox marks the start of fall in the northern hemisphere.
  • Meteorological seasons
    • Use calendar months and average temperatures (March–May spring, June–August summer, etc.).
* Designed so climate scientists and weather services can compare years more easily.

PBS programs about spring and other seasons often tie these definitions to real-world changes in plants, animals, and climate patterns.

A quick story-style example

Think of a year in one place in the northern United States:

  • In winter , your part of Earth leans away from the Sun, the Sun stays low in the sky, and days are short and cold.
  • As you move toward spring , Earth’s orbit brings you nearer to the point where neither hemisphere leans much, so days get longer, snow melts, plants bud, and animals respond to changing light and temperature.
  • In summer , your hemisphere leans toward the Sun, giving you higher midday Sun, more direct rays, long days, and warmer temperatures.
  • By fall , you’re again near an equinox; days shorten, temperatures drop, and ecosystems shift—something PBS nature specials often highlight with migrating birds, changing leaves, and shifting food webs.

All of this comes from one simple fact: Earth is a tilted sphere traveling around the Sun.

Mini FAQ

  • Q: Does every planet have seasons?
    A: Any planet with a tilted axis has seasons, but they can be very different from Earth’s. Venus, with almost no tilt, barely has seasons at all.
  • Q: Why are seasons opposite in the northern and southern hemispheres?
    A: When one hemisphere is tilted toward the Sun (summer), the other is tilted away (winter).
  • Q: What do PBS resources add?
    A: PBS LearningMedia and nature programs pair this science with animations, classroom interactives, and live nature events that track how plants and animals respond to the changing seasons.

TL;DR: We have seasons because Earth’s axis is tilted as it orbits the Sun, changing how direct the sunlight is and how long days last in each hemisphere throughout the year.

Information gathered from public forums or data available on the internet and portrayed here.