KNOXVILLE, Tenn. (WVLT) -- This week's Ask Heather explains why we have seasons, and what the terms Equinox and Solstice mean.
John Rorrer posted his question on Heather's Facebook page. He wanted to know more about the differences between equinox and solstice.
These are terms for the Astronomical Seasons: Vernal Equinox, Summer Solstice, Autumnal Equinox, Winter Solstice.
Something very important to know is that the Earth is tilted 23.5 degrees on its axis.
Two times a year the Earth's axis is tilted neither toward nor away from the sun, so there's equal amount of day and night. The Vernal (Spring) Equinox occurs near March 21, and the Autumnal (Fall) Equinox is around September 21. At the equator, the sun is directly overhead at Noon.
The summer solstice is when the earth's tilt toward the sun is at a maximum. The sun is directly over the Tropic of Cancer, which is located at the latitude 23.5 degrees North of the equator.
The winter solstice marks the shortest day and longest night of the year in the Northern Hemisphere. The sun is directly over the Tropic of Capricorn, which is located at 23.5 degrees South of the equator.
Seasons are caused by the Earth's tilt on its axis by 23.5 degrees.