There are not many days like Tuesday, Dec. 21, 2010. Take it from people who know - astronomers. There was maybe one day like this Tuesday in the past 2,000 years. On Tuesday morning, astronomers say, there will be - or depending on when this is read, was - a total eclipse of the moon. And on the very same day, the winter solstice arrives.
The last time the two celestial events occurred within the same calendar day was long before any of our lifetimes. The year, according to Geoff Chester, public affairs officer at the U.S. Naval Observatory, was 1638. Although the solstice does not always occur on the same date each year, the date in 1638 was the same as Tuesday's - Dec. 21.
Chester said he looked it up, because as the time of the two events drew nearer, people began to make inquiries of him. He said his research took him back to the year A.D. 1.
That seemed to be reasonably far back. He consulted "a number of well-respected sources." And his finding, essentially was this: "It's a comparatively rare event." Although it does not appear to have any cosmic significance.
Few alive today are likely to see a recurrence. The next time the winter solstice and a total lunar eclipse will occur on the same calendar day will be Dec. 21, 2094.
A total lunar eclipse occurs when the Earth blocks the sun's rays from the face of the moon. The moon is then fully in the shadow cast in space by the Earth.
The absolute midpoint of the eclipse will be at 3:17 EST Tuesday morning, Chester said.
The moon then continues moving through the Earth's shadow, emerging completely shortly after 5 a.m.
A slight effect known as the penumbral phase may be seen for as much as an hour longer. But it is generally considered too subtle for most people to notice.
The winter solstice, which occurs afterward, is the time when the sun reaches its lowest point in the northern sky. That is the moment that many people consider to be the start of the winter season. Lunar Eclipse December 2010.
