NOAA: Why We Have Seasons
Earth has seasons because sometime early in its long history, something very big hit the young Earth to knock it off-kilter. So instead of rotating with its axis perpendicular to its orbital plane, it is tilted 23.45 degrees from the perpendicular.
Incidentally, that big something that hit Earth also knocked a chunk of it out that became our Moon. At least that is generally accepted theory.
So, here we are, orbiting the Sun, but tilted a bit and always with the axis pointed in the same direction. So different parts of Earth get the Sun’s direct rays as we travel through the year.
The winter solstice marks the shortest day and longest night of the year. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa. The summer solstice marks the longest day and night of the year. It is directly over the Tropic of Cancer, located at 23.5° north of the equator. This year, the Northern Hemisphere summer solstice will occur at 12:24 am EDT on June 21st. The winter solstice will occur at 11:28 am EST on December 21st. For a complete listing of the dates of the winter and summer solstice's and spring and fall equinox's through 2020, check out this site from the U.S. Naval Observatory.
WDRB Meteorologist Jeremy Kappell
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