November 2021 Stargazing Guide for Lunar Eclipse

[Orbax appears on background of the galaxy.]

Orbax: Greetings junior scientists, scientists, and citizens of this great big weird, wild and wonderful world in which we live. As always I am your humble science communicator, the great Orbax, here for a special edition of our Star Gazing Guide! 

[Fade to white.]

[Orbax reappears with a moon background.]

[Music plays quietly in background throughout.]

Orbax: In the evening of November 18th into the early hours of the morning of the 19th we're going to have the opportunity to see the longest partial lunar eclipse in this century and everybody in North America is going to be able to see it!  

So what exactly is a lunar eclipse? 

[Video animation of a solar eclipse appears in the background, while Orbax describes it.]

Orbax: You're likely familiar with a solar eclipse. Now this occurs when the moon passes between the earth and the sun but what's a lunar eclipse? 

[Video animation of a lunar eclipse appears in the background, while Orbax describes it.]

Orbax: Well a lunar eclipse occurs when the moon actually falls into the earth's shadow. But the moon appears to line up with the earth like this twice a month during new moon and full moon so why don't we have eclipses twice a month then? Well, it's actually a little more complicated than that. The plane of the moon's orbit around the earth is actually tilted with respect to the plane of the earth's orbit around the sun but here's the thing... the moon's orbit stays fixed with respect to the stars meaning that tilt actually changes with respect to the earth and twice a year it actually lines up in such a way that the moon passes through the earth's shadow and that is when we have a lunar eclipse! As the moon passes through the earth's shadow it will still be visible and it might even have a red tinge to it so why is that? 

[Animated diagram of light passing through the earth’s atmosphere appears in the background as Orbax describes it.]

Orbax: As light passes through the earth's atmosphere it's scattered, meaning that shorter wavelengths like blue light are actually diverted away from the moon whereas longer wavelengths like red light are what pass through and illuminate the moon. 

[Cut to an animation from the perspective of someone standing on the moon during the lunar eclipse as Orbax describes it.]

Orbax: As a matter of fact if you happen to be standing on the moon during the lunar eclipse you'd actually be bathed in a red glow and see a red ring emanating from around the earth. 

[Cut back to Orbax on a black background.]

Orbax: Which is all the remains of the light escaping earth's atmosphere of all the sunrises and sunsets that are taking place along  the edge of the earth. November's full moon is 
known as the Beaver Moon [beaver image appears in the background] named from folklore as the beavers urgently prepare for the winter to come. It's also known as the Frosty Moon and the Oak Moon! 

[A diagram of penumbra and umbra appear in the background as Orbax describes it.]

Orbax: But back to our lunar eclipse... the moon will start by passing into the penumbra, the part of the earth's shadow where the sun is only partially covered by the earth. At this point you won't really be able to see any changes to the moon with the naked eye. Around 2am eastern time it will pass into the darkest part of the earth's shadow known as the umbra. This is where the earth completely obscures the sun from the moon. At the moment of greatest eclipse, around 4 a.m eastern time, 99.1 percent of the moon will be entirely within the umbra. 

[Screen fades into a world map indicating there the eclipse will be visible.]

Orbax: This will be visible from all of North America as well as some parts of South America, Polynesia, Eastern Australia and Northeastern Asia. 

[Cuts back to Orbax with a background of the penumbra/umbra chart.]

[Music beat gets a louder.]

Orbax: By 6am the moon will be back to normal viewing. 

[Background changes back to an image of the moon.]

Orbax: This is the longest partial lunar eclipse that will take place this century with a duration of 3 hours 28 minutes and 23 seconds, so if you get the opportunity, I suggest you take the chance and look up.

[Orbax points and looks up.]

Orbax: And don't forget to have a scientastic day! 

[Image of Dr. Glynis Perrett appears on screen.]

Orbax: Special thanks to Royal City Science's own planetary geochemist Dr. Glynis Perrett for her help preparing our stargazing guide.

[Images and video courtesy of NASA, used under creative commons license for education.]

[Guelph Physics logo appears.]