Physics Photo of the Week

March 21, 2014

Equinox



It's hard to believe that the spring equinox was just yesterday!  The weather hasn't shown much springlike behavior.  However, the astronomical seasons progress regardless of the weather.  Yesterday marked the vernal equinox, when the nights are equal in length to the days.  The photo on the left is sunrise at 7:49 am EDT.  The photo on the left is taken almost 12 hours later at 7:39 pm EDT, at sunset looking back east where the sun rose.  If you look carefully on the right-hand photo, sunlight is still shining on the distant mountain range.  The reason these photos miss the 12 hour interval by about 10 minutes is attributed to the morning sunrise coming a little later due to the uneven horizon (mountains) that the Sun must overcome and the evening sunset is a bit earlier for the same reason.   From the spring equinox until the summer solstice, the days will become longer and the nights shorter.  At North Carolina's latitude, there will be about 15 hours between sunrise and sunset at the June solstice.

Happy springtime, everybody!


Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to dcollins@warren-wilson.edu.

All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion.  These photos and discussions may be used for private individual use or educational use.  Any commercial use without written permission of the photoprovider is forbidden.

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