It works like this: As Earth tracks its yearlong orbit around the sun, it does so at a jaunty tilt of about 23.5 degrees. This tilt means that Earth’s two polar hemispheres lean into or away from the warmth and light of the sun, depending on the position of Earth in its orbit. In 2016, the winter solstice for us in the Northern Hemisphere is on December 21, when we’re tilted farther away from the sun than we’ll be all year. Meanwhile, the Southern Hemisphere is leaning into the sun and is enjoying its longest day of the year—its summer solstice. But don’t be too jealous—we can take some comfort in knowing that in six months we’ll have traded positions with the Southern Hemisphere and will enjoy long, warm days once again.