When was the last time the lunar eclipse and winter solstice coincided?

• The U.S. Naval Observatory says 1638;
  

• Starhawk, a prominent Wiccan, puts it at 1544.
  

Whatever the answer, it is a rarity! My daughter saw it go "copper coloured" when she was in work (Much to the annoyance of her mum); in case you missed it, here is a time lapse video shot by William Castleman in Gainesville, Florida.

Winter Solstice Lunar Eclipse from William Castleman on Vimeo.

How do you calculate that 1 year has passed on Earth?

Simple answer?

No it isn't. The problem - our planet does not return to its starting point once it was gone all the way around the sun! So how do you know when a year starts and when it ends?

This clip can also be watched at http://www.youtube.com/watch?v=IhqzW97_47w.

As Chemistry is one of those subjects that really can flourish with the addition of multimedia elements, practitioners should check out the Chemistry Educational Digital Library.

The Chemistry Educational Digital Library is a great place to find video and/or other multimedia elements to use in the classroom, as well as find interactive online applications like...

• a java-based three-dimensional molecule diagramming program;
• an interactive periodic table; and
• a host of other collections to...

WorldClock is an online clock that shows real time statistical data about the world. The data includes...

• world population,
• birth,
• death,
• divorce,
• abortion,
• HIV,
• cancer incidence… etc.

Users can view real time statistics for one...

• year,
• month,
• week and
• day.

The stats presented on the site are averages of the data gathered from sources like...

• World Health Organization,
• CIA Factbook
• US Census and others.