Summer solstice - First day of summer
Jun 21, 2019
Summer Solstice! First day of summer in the United States. The sun's arc is at its farthest point north, overhead at the Tropic of Cancer, which runs off the tip of Florida.
Seasons change because Earth's axis tilts 23 1/2 degrees to the plane of its orbit. As Earth orbits the sun, its axis points in the same direction. Earth is closest to the sun in early January and fartherest from the sun in early July. The difference is about 3 million miles.
It is hotter in July and August than on the first day of summer because it takes time for the Northern Hemisphere to heat up. Conversely, it is colder after the first day of winter because it takes time for the Northern Hemisphere to cool off.
The sun is above the horizon 24 hours north of the Arctic Circle and below the horizon 24 hours south of the Anarctic Circle.
Earth averages 93 million miles from the sun.
Earth orbits the sun 67,000 miles an hour.
Earth's orbit around the sun is 585 million miles.
The 5 major circles of latitude are the Arctic Circle, Tropic of Cancer, Equator, Tropic of Capricorn, Anarctic Circle.