Astrological Overview December 21st: The Sun enters Capricorn The Sun enters Capricorn at 10:59am ET on December 21st marking the Winter Solstice and shortest day of the year in the Northern Hemisphere. Capricorn is a cardinal, earth sign and all four cardinal signs mark the beginning of a new season. The cardinal signs initiate, catalyze and lead. Capricorn represents career, business, your life purpose, reputation and public life, government, structure and foundation, takin