Earth’s tilted axis causes the seasons. As the earth slowly rotates around the Sun, portions of the Earth receive the Sun’s  direct sun rays. When the North Pole tilts toward the Sun, it’s summer in the Northern Hemisphere. Later in the year, when the South Pole tilts toward the Sun, it’s winter in the Northern Hemisphere.

TEXT: nasa.gov https://spaceplace.nasa.gov/seasons/en/ ~ IMAGE-1: By cmglee, NASA - http://visibleearth.nasa.gov/view.php?id=73580, Public Domain, https://commons.wikimedia.org/w/index.php?curid=41309095 ~ IMAGE-2: By I, Dennis Nilsson, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3262268