In today’s class, we’re going to discuss the parts of a shadow.

Tonight at 8:51 PM, Spain time, there will be a slight lunar eclipse. All the information about it is here:

This got me thinking, “What the heck are Earth’s umbra and penumbra?” No fear, Wikipedia to the rescue! The diagrams are very helpful.

umbra - the darkest part of the shadow, where light is completely blocked by the object causing the shadow.

penumbra - the part of the shadow where the light source is only partially blocked.

But wait! There’s one more!

antumbra - the part, darker than the penumbra, where some of the light source is visible around the edges of the blocking object due to the blocking object not being big enough to completely block the light source.

There you go! Now you’ve learned something today.

As you can see from the eclipse map, it will not be at all visible from North America. Too bad for you guys.