Today’s Wonder of the Day was inspired by Daniel. Daniel Wonders, “Why do seasons change?” Thanks for WONDERing with us, Daniel!
It's been a long, cold winter in Wonderopolis, and we've had lots of fun in the snow. But we're looking forward to trading our hats and gloves for shorts and tank tops when the weather gets warmer.
But how do we know warmer weather is really on the way? Is there a chance it will stay cold and keep snowing all year?
Luckily, the answer to that question is "no." After winter is over, we know spring will come with warmer temperatures and lots of flowers. Then the weather will get hot in the summer before cooling off again in the fall. Cold weather will return as fall turns into winter, and the cycle will start all over again.
You may know you'll see lots of different kinds of weather over the course of the year, but have you ever wondered why the seasons change? The answers can be found in the way the Earth moves in relation to the Sun.
The Earth's axis is an imaginary line running between the north and south poles. Each day, the Earth makes one full rotation on its axis. This rotation takes 24 hours, which we call one day.
While the Earth is busy turning daily circles, it is also traveling along a giant oval path around the Sun. This path is called Earth's orbit. It takes our planet 365 days to make one complete trip around the Sun. In fact, that trip around the Sun is how we define one year.
As the Earth orbits the Sun, it is slightly tilted on its axis. The tilt means that, on any given day, the Earth is slightly pointed toward or away from the Sun.
Depending on where you're standing on Earth, there are times your half of the world (called a hemisphere) is pointed toward the Sun. At other times, your hemisphere is pointed away from the Sun. As the Earth travels around the Sun over the course of a year and the tilt of its axis points your hemisphere toward or away from the Sun, you experience the changing of the seasons.
Have you ever noticed that the sun doesn't set until close to bedtime in the summer? By the time winter rolls around, however, you're probably eating dinner when it's already dark outside. The amount of daylight your hemisphere receives also varies because of the Earth's tilted axis.
When the North Pole is tipped toward the Sun, the northern hemisphere receives more sunlight and experiences longer days. This period of longer days, warmer weather and more sunlight is commonly referred to as summer. But just because you're enjoying a nice, hot summer doesn't mean everyone on the planet is, too.
When the northern hemisphere is tipped toward the Sun, the southern hemisphere is tipped away. Although residents of the northern hemisphere may be headed to the pool, the southern hemisphere is experiencing shorter days with less sunlight. When it is summer in the northern hemisphere, it is winter in the southern hemisphere.
Imagine you live in Topeka, Kansas, and you have a friend who lives in Buenos Aires, Argentina. If you want to plan a visit to see your friend in July, you might not want to pack your flip flops and shorts. When it's summer in Kansas, it's winter in Argentina.
Locations near the equator tend to have warm weather year-round. This is because the tilt of the Earth affects them less dramatically. Regardless of whether the Earth is tipped toward or away from the sun, equatorial locations continue to receive more constant light and heat than locations with latitudes closer to the poles.
This is why it can be 12° F in Minnesota on a January day, while it's 70° F in Florida. Don't be fooled, though. Just because a location may not experience dramatic seasonal changes doesn't mean they don't have seasons, too.