Happy Solstice!
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Simulation of Earth during Northern Summer Solstice.
Image Credit: NASA
For those of you in the northern hemisphere, happy summer solstice! For everyone “down under” it’s the winter solstice, but don’t worry.. after today your days will be getting longer and spring will only be a few months away! This years June solstice happens today at 1:16 EDT
What’s a “solstice” you ask? Well, here comes the science!
Earth doesn’t rotate perpendicular to its rotational axis, and is tilted almost 24 degrees. Due to this tilt, during summer in the northern hemisphere, Earth’s northern hemisphere is tilted towards the sun. (the north pole points towards the sun at almost 24 degrees) and thus, the sun shines at its northernmost point of the year. An interesting point is that without our “axial tilt” we wouldn’t really have seasons on Earth!
The June solstice is also known for the longest hours of daylight for those in the northern hemisphere, and the shortest day of the year for those in the southern hemisphere. Two notable extremes of this phenomenon are in the Arctic Circle and the Antarctic Circle, yet near the equator the effect is on length of day is minimal.
North of the Arctic Circle, the sun will be visible through the night, and those in the Antarctic will experience nearly complete darkness. Of course, these situations are reversed in the December solstice, where the northern hemisphere begins “winter” due to being tilted away from the sun, and the southern hemisphere begins summer due to being pointed towards the sun.
If you’d like to know more about Earth’s axial tilt and seasons, visit this NASA page:
http://www-istp.gsfc.nasa.gov/stargaze/Sseason.htm
The four seasons of Earth. Image Credit: Wikimedia Commons
Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer
2012-12-04 08:06:15
Source: http://www.dearastronomer.com/2011/06/21/happy-solstice/
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