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In the previous video we talked about the phases of the moon
and how that relates to the moon's orbit around the Earth.
It might be helpful to watch that video first.
To put things in perspective
here's the relative size of the Sun, the moon, and the Earth.
The Sun is about 400 times bigger than the moon.
Now let's look at the actual distances between them.
The Sun is also about 400 times further from the Earth than the moon is.
This is why the Sun and Mon appear to be about the same size in the sky.
So, now you know that animations on screen are not always drawn to scale.
The Moon's orbit is actually not a perfect circle,
it's in the shape of an ellipse.
When it's closest to the Earth, we call it Perigee.
When it's farthest away from the Earth, we call it Apogee.
It's only a small difference but it's enough to cause to Moon to grow and shrink as seen from the Earth.
Okay now we get into some rare events with the Moon.
Each time a new Moon happens,
there's a chance that the Moon will block the sunlight
and cause a shadow to appear on a portion of the Earth.
When this happens it's called a 'solar eclipse.'
The reverse can also happen.
Each time we have a full Moon,
there's a chance that the Earth will block the sunlight from reaching the Moon.
We call this a 'lunar eclipse.'
So, now the question is:
...why don't we get a solar eclipse...
...and a lunar eclipse every month?
As the Earth orbits around the Sun
we can map out a 2D plane that referred to as the ecliptic.
The Moon doesn't orbit on the same plane.
It's tilted by about five degrees.
This means that most of the time,
the Moon passes above or below the Sun as seen from the Earth.
We can map out two invisible points in space where the Moon's orbit crosses the ecliptic.
We call these the lunar nodes.
When they line up with the Sun, Earth, and Moon
that's when a solar eclipse or a lunar eclipse will occur.
This is referred to as an eclipse season.
These happen about twice a year.
During an eclipse season, there's no guarantee that you'll be able to see anything.
In the case of a solar eclipse,
the Moon may pass slightly above or below the Sun and give us a partial solar eclipse.
This won't really dim the sunlight enough for us to see it.
When the Moon entirely crosses the Sun
we will be able to see it.
If the Moon is closer to Apogee
then it will appear smaller
and we'll get what's called an Annular Solar Eclipse.
If the Moon is closer to Perigee
then it will appear bigger
and we'll get what's called a Total Solar Eclipse.
Even if you're lucky enough to be on the right spot on the Earth
the longest you'll be able to see a Solar Eclipse is about 7 minutes;
You'll need to be under the Umbra,
which is the darkest part of the Moon's shadow.
For a Lunar Eclipse, the Earth is the one casting the shadow.
We may see a partial Lunar Eclipse,
or a Total Lunar Eclipse.
This can be seen from anywhere on Earth where it's night,
and will last for several hours.
For about an hour the Moon will appear red because of the sunlight bending around the Earth;
this is where the term Blood Moon comes from.
So next time someone says the words Solar Eclipse or Lunar Eclipse,
you could explain it them, or just send them a link to this video.
I'm Jared Owen, thank you for watching.