Will Tuesday Be the Darkest Day in 456 Years?

What is the alignment on Winter Solstice: sun, earth, moon? What is earth, moon, sun? A solar eclipse? Is the Summer Solstice the same? How about the Vernal and Autumnal Equinoxes?

ohio county wrote:What is the alignment on Winter Solstice: sun, earth, moon?

No particular alignment. Solstice has to do with the shortest and longest (# of hours of daylight) day of the year in the Earth's 365 day orbit around the Sun. Winter Solstice = shortest day in December, Summer Solstice = longest day in June. And when it is Winter Solstice in the Northern Hemisphere it is Summer Solstice in the Southern Hemisphere, and vice versa.

Here is a neat animation of the Earth's orbit:
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0408/es0408page01.cfm?chapter_no=04

What is earth, moon, sun? A solar eclipse?

Yes, if moon cast shadow on earth, it solar eclipse, click this animated web site:
http://www.f-lohmueller.de/pov_tut/animate/anim112e.htm

Is the Summer Solstice the same?

See above - longest day.

How about the Vernal and Autumnal Equinoxes?

Equinoxes means equal, thus when the night time and day time hours are equal in length, which occurs at a specific day & time in the Spring and Fall.

A 1 page graphic description see: http://www.athropolis.com/sunrise/def-sol2.htm

Ohio, to be specific, the exact times and dates of the Solstices and Equinoxes are determined by the position of the earth in its orbit around the Sun. The earth's orbit is an elipse, not a circle. See below and note that the earth is farther from the Sun during our Summer than it is during our Winter:



Ohio, hopes that answers your questions, ........ if not I got plenty more answers.

Thanks, Sam. That was very helpful. I had always thought the solstices and equinoxes were marked by the alignment of earth, moon, and sun, ergo, why the big deal with a full lunar eclipse on the winter solstice? Once again, I am pleased (despite the lack of acclimation) to note that I was wrong and that I appreciate the correction and opportunity to learn something.

why the big deal with a full lunar eclipse on the winter solstice

Ohio, because it is nigh onto as scarce as hen's teeth when it happens.

To explain why, ya gotta picture the earth spinning on its axis every 24 hours, with its axial plane being 23 degrees off of its orbital (ecliptic) plane around the Sun every 365 days ...... while at the same time the moon is orbiting around the earth every 28 days ....... with its orbital plane being slightly different (5.145°) than the earth's orbital (ecliptic) plane around the Sun. To wit:




So, looking at the above graphics, what you got is, the Moon is rotating every 28 days, around the earth that is rotating every 24 hours, while the earth is revolving around the Sun at a 23° angle every 365 days .

So, looking at the top right, for one to see a full lunar eclipse, the earth/Moon has to rotate on around the Sun until the Lunar Orbital Plane is equal too the Ecliptic Plane and the Moon "M" is cutting exactly across the shadow being cast by the earth.

And to see that happen, one has to be standing in just the right spot on the earth, .... at night time, ..... when the Sun, the earth and the Moon all line up, ...... because the earth doesn't "throw" that big of a shadow and the Full Moon will pass through it fairly quick. And thus you don't have all night to look at it because everything is in motion and it won't happen again for months or years.

Now for one standing somewhere on the earth to see a a full lunar eclipse, ...... it is not that uncommon. But for anyone in the Northern Hemisphere to see a full lunar eclipse on a specific night, December 21st, it is a rare event indeed. Like a 456 year event.

I hope the above makes sense and answers your question. I have this problem where my "typing" can't keep up with my "thinking" and the text is often confusing.