Have you ever wondered how we know when the first day of fall is? It’s all about how our planet, Earth, moves around the Sun. Earth orbits the Sun with a slight tilt, and this tilt changes how much sunlight different parts of the world get throughout the year.
Right now, the northern half of the Earth, called the Northern Hemisphere, is finishing summer. During summer, the days are long because we get more sunlight. Meanwhile, the southern half, known as the Southern Hemisphere, is coming out of winter, where the days are shorter with less sunlight.
On September 23rd, something special happens. Earth reaches a point in its orbit where everyone on the planet experiences equal amounts of day and night—12 hours of each. This day is called the Fall Equinox. It’s the start of a season where the nights become longer than the days.
For some, like astronomers and bats, long nights are exciting because they love the dark. But if you prefer longer days, don’t worry! Just wait for half a year, and the days will start getting longer again.
