Physics Photo of the Week
winter solstice is the date around Dec. 21 or 22 every year year when
the Sun is the furthest south relative to the celestial equator.
As a result the northern hemisphere receives the least light due to the
low altitude of the Sun as well as the least amount of daylight.
The above photo shows the Sun rising on the solstice on December 21, 2009. Note it's position
rising over the crest of the Swannanoa Mountains across the Valley from
WWC campus. The animated photo at right shows the
positions of the rising Sun throughout November, 2009 to Feb 2010 last
winter. A graphical calendar was also added so you can observe
that the Sun is furthest to the right (south) on the solstice. On
the date of the solstice, the position of the Sun appears to stand
still, hence the word "solstice" for "stationary Sun".
A much more subtle effect near the December solstice is the time of
latest sunrise. In spite of the fact that there are the fewest
hours of daylight on the solstice, the latest sunrise doesn't occur
until about 2 weeks later in our latitudes. Notice that the image
with the latest sunrise doesn't occur until January 4. Likewise
the earliest sunset occurs early in December - about 2 weeks before the
solstice (see the PPOW
11, 2009). The offset of the latest sunrise and
earliest sunset is due to the elliptical orbit of the Earth (also
explained in the December
PPOW). This effect is much more pronounced in the
December solstice than the June solstice because the Earth is
significantly closer to the Sun in the northern hemisphere winter.
Total Lunar Eclipse. On
December 21, 2010 (next Tuesday) - between 1:00 am and dawn - there is
also a total eclipse of
the Moon visible from all of North America. Hope for clear skies
for this coincidence between the solstice and the lunar eclipse!
Most important: You
get up way before dawn on December 21 to see the eclipse!
Totality begins 2:41 AM Eastern Standard Time and totality ends at 5:53
This is the last Physics Photo of the Week for 2010 due to the
Christmas Holidays. The next Physics Photo is not scheduled to be
posted until January 21, 2011. Have a Merry Christmas and a Happy
Photo of the
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 firstname.lastname@example.org.
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.
the Physics Photo
the Week Archive.
Observers are invited to submit
digital photos to: