Now that it's getting closer to winter, have you been noticing that it's getting dark earlier when you are outside playing or looking out from a window?
Well, if you're as curious as we are, you've probably thought about why it gets dark earlier during the winter months than at other times of the year. Let’s check in with our friends at Reference.com to learn a bit about this!
A Tilted Axis
When looking at Earth from outer space, it is a big sphere. However, it is not a straight sphere, but one that is tilted on its axis (at about 23.5 degrees). Because of this tilt, the axis the Earth revolves around is not perpendicular to the sun. This means that, as the Earth orbits, a portion of it will be tilted toward the sun and a portion of it will be tilted away from the sun.
Due to this axial tilt, the Earth receives different amounts of sunlight in different seasons. During Earth’s orbit in the summer months, the top of the Earth (the Northern Hemisphere) is tilted toward the sun, giving us longer days. In winter, the Northern Hemisphere points away from the sun, resulting in fewer hours of sunshine and shorter days. The temperature also gets lower in winter due to less solar radiation reaching the ground.
Is it Like This All Over the World?
While this applies to the Earth’s Northern Hemisphere, it is not true all over the Earth. It works the opposite way in the Southern Hemisphere and, on the equator, the days and nights are always equal.
To make it even more interesting, while most areas experience longer nights during the winter, some areas near the poles can actually experience polar night – nighttime that lasts for more than 24 hours! This occurs in those locations because they are tilted so far away from the sun that the Earth blocks all light for an extended period of time.
Can you imagine living in those areas? What do you think it is like during a polar night?
Looking for more Never Stop Asking "Why?" questions? Catch up on all of the past "Why's" on the blog!