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Why Do We Have Different Seasons? | California Academy of Sciences

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It's all about Earth's tilt!

Many people believe that Earth is closer to the Sun in the summer and that is why it is hotter. And, likewise, they think Earth is farthest from the Sun in the winter.

Although this idea makes sense, it is incorrect.

It is true that Earth's orbit is not a perfect circle. It is a bit lop-sided. During part of the year, Earth is closer to the Sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the Sun and summer when it is farthest away! Compared with how far away the Sun is, this change in Earth's distance throughout the year does not make much difference to our weather.

There is a different reason for Earth's seasons.

Earth's axis is an imaginary pole going right through the center of Earth from "top" to "bottom." Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth's surface gets some of each.

Earth has seasons because its axis doesn't stand up straight.

But what caused Earth to tilt?

Long, long ago, when Earth was young, it is thought that something big hit Earth and knocked it off-kilter. So instead of rotating with its axis straight up and down, it leans over a bit.

By the way, that big thing that hit Earth is called Theia. It also blasted a big hole in the surface. That big hit sent a huge amount of dust and rubble into orbit. Most scientists think that that rubble, in time, became our Moon.

As Earth orbits the Sun, its tilted axis always points in the same direction. So, throughout the year, different parts of Earth get the Sun's direct rays.

Sometimes it is the North Pole tilting toward the Sun (around June) and sometimes it is the South Pole tilting toward the Sun (around December).

It is summer in June in the Northern Hemisphere because the Sun's rays hit that part of Earth more directly than at any other time of the year. It is winter in December in the Northern Hemisphere, because that is when it is the South Pole's turn to be tilted toward the Sun.

Earth's lopsided orbit

Earth's perihelion (point closest to Sun) = 91,400,000 miles from Sun

Earth's aphelion (point farthest from Sun) = 94,500,000 miles from Sun

While that is a difference of over 3 million miles, relative to the entire distance, it isn't much.

And, believe it or not, aphelion (when Earth is farthest from the Sun) occurs in July, and perihelion (when we are closest) occurs in January. For those of us who live in the Northern Hemisphere where it's summer in July and winter in January, that seems backwards, doesn't it? That just goes to prove that Earth's distance from the Sun is not the cause of the seasons.

Related Resources for Educators

Seasons (Educator Guide to go with Seasons Spotlite video)
Seasons (Nearpod Lesson to go with Seasons Spotlite video)
Our World: Sun's Position
Sun's Position (Educator Guide to go with Sun's Position Spotlite video)
Sun's Position (Nearpod Lesson to go with Sun's Position Spotlite video)

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Yes because they both go in the same sephere

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Yes because they are both mean that the Earth is spinning.

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Both are movement

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No because one means that it is rotating on its axis and one means that it is revolving around the sun

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Yes because they are all rotations

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They are the same because it is a sign of movement.

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One is rotating on its axis and one is revolving around the sun

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Yes because they are both about the earth Moving

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No, because rotation is Earth spinning around its axis, which takes 24 hours and is a day, meanwhile revolution is Earth orbiting around the sun, which takes 365 days and is a year, it also causes us to have our 4 seasons, winter, summer, autumn, and spring.

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Earth’s revolution is Earth revolving around the sun, the reason we have seasons is because of Earth’s axis not being straight, and instead being tilted about 23 degrees. This is believed to have been caused by a giant asteroid hitting Earth millions of years ago.

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Whats similar about earth's revolution and rotation is that they both involve the movement of earth.

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The earth rmovment is in a Circular and the other in A pulling movment

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One is around the sun and one is spinning.

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As the earth spins on its axis, producing night and day, it also moves about the sun in an elliptical (elongated circle) orbit that requires about 365 1/4 days to complete. The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons.

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yes they are both similar because they both move in a circular pattern

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The reason why we have different seasons is because the earth is tilted.

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No because one is rotating on its axis and one is is revolving on the sun

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no because earth orbits the sun and at the same time it rotates

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The differences between earth rotation and revolution is that earth revolution involves revolving around the sun but earth rotation doesn't .

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No because when earth is orbiting the sun it goes around it and when earth spins on its axciss it makes day and night

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The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons.

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The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons.

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The only reason the Earth has seasons is because it rotates around its axis and also it's tilted about 23 degrees by a astroid that hit earth many years ago.

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No because when earth is orbiting the sun it goes around it and when earth spins on its axciss it makes day and

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we have different seasons because earth is tilted on it axis so the northern hemisphere is tilted to the sun they have summer and the southern hemisphere would have winter

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The earth is tilted on it axis so every day it move on its axis and when it move on it’s orbit it give us seasons and and both give us seasons in the northern hemisphere and the southern hemisphere.

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We have seasons because of Earths slight tilt with its axis. So, if its summer in the Northern Hemisphere, its winter in the southern hemisphere. Earths revolution is basically just Earth orbiting around the sun.

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yes the earth goes around the sun

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We have seasons because it rotates around its axicss and when it’s orbiting the sun

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no the sun dost move from earth it dos stay

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the earth is moveing from the sun

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the earth is is moveing to the man