Posts Tagged 'winter solstice'

Solstice Eclipse

by Toby Swaford, K-12 Education Coordinator

The moon on the breast of the new-fallen snow
Gave the luster of mid-day to objects below.

– Clement Clarke Moore

The moon looks red when it's inside Earth's shadow

Stargazers across North America will witness a rare December solstice / lunar eclipse this evening.  The moon will appear to change colors as the Earth’s shadow passes across the lunar surface turning it from gray, to orange, and then, finally, red.

This spectacular display happens when the moon passes behind the earth and enters the earth’s shadow. The earth block’s the sun’s light, which normally shines on the moon and causes it to look white to us, and changing colors of the moon come courtesy of our atmosphere, which will filter the available light.

Diagram of a Lunar Eclipse

Tonight’s eclipse is starting at 11:33 p.m. Mountain Time, December 20th (your start time may vary, depending on the local time zone).  Some aspects of the event will also be visible to viewers in Western Europe and Asia, but North America is best positioned for viewing. Unlike a solar eclipse, tonight’s event can be seen safely with the naked eye requiring no special equipment (blankets, thermos bottles of hot cocoa, and a lawn chair are optional; but what the heck, you’ve probably got most of that stuff just lying around the house).

What makes tonight’s eclipse even more special is that it’s happening on the winter solstice – the shortest day of the year. A total lunar eclipse coinciding with the winter solstice is fairly unique; the last time the two events coincided was 456 years ago.  Luckily, we won’t have to wait that long for another eclipse to come along: the next one is slated for April 15, 2014.  Granted, Tax Day isn’t nearly as festive an event as the solstice, and the visibility won’t be nearly as good here in North America, so get out there and enjoy tonight’s show!

Winter solstice

by Toby Swaford, K-12 Education Coordinator

The Winter Solstice usually occurs on December 21st or 22nd in the Northern Hemisphere. Described as the first day of winter, the solstice is caused by the Earth’s tilted axis (roughly 23.5 degrees) as it orbits around the sun. This is the phenomenon that causes both the change of seasons and the amount of sunlight we receive each day. Speaking of which, the Winter Solstice is often described as the shortest day of the year, although it technically still has 24-hours in it. Granted most of those hours are a little on the dark side (at least for those of us in the Northern Hemisphere), with sunrise occurring around 7:30 AM, and the sun setting just nine hours later at 4:30 PM.

During the late fall and early winter, the sun seems to hang lower on the horizon than at any other time of the year, due to the Northern Hemisphere being tilted away from the sun at its most extreme angle during our year long journey around the solar system. Conversely, the Summer Solstice takes place when the North Pole is angled closer to the sun, giving us the maximum amount of daylight we’ll get all year.

The term solstice is derived from the Latin, translating as the “sun stands still.” If you watch the sun rise and set over the next few days, these events will seem to take place in the same two parts of the sky each day. This stability is short lived and in the next few weeks the daylight will begin to last a bit longer. This occurrence held special meaning for many of the cultures found throughout the Northern Hemisphere and is the basis for the myriad of winter holidays celebrated today.


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