The Earth’s solstices come twice a year. For the Northern Hemisphere, the summer (June) solstice occurs around June 20-21, and the winter (December) solstice happens around December 21-22.
At the solstice, the Sun’s path appears farthest north or south, depending on which half of the planet you are on. Seasons change on Earth because the planet is slightly tilted on its axis as it travels around the Sun.
Earth’s axis may be imagined as an imaginary pole going right through the center of our planet from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night.
This image was taken with the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on EUMETSAT’s Meteosat-9 captured this view of Earth from geosynchronous orbit, and shows how sunlight fell on the Earth on December 21, 2010.