DIANNA COWERN: This episode is brought to you
by CuriosityStream.
Hi, everyone.
I'm Dianna.
You're watching Physics Girl.
And there is an imminent total solar eclipse.
I know we all know about it already.
We also know that I'm going to be the one that
doesn't get to see it because--
it's my fault--
I agreed to go to Charleston.
I'll be looking to start a post cloud cover support
group for any of you out there.
Anyway, this got me wondering, do eclipses
happen in other parts of the solar system?
Like, does the Curiosity Rover get
to see a total solar eclipse on Mars?
Short answer, no.
Mars' moons, Phobos and Deimos, are too tiny to block out
the sun completely.
But you do get a funky partial solar eclipse, seen here,
filmed by Curiosity itself.
On Mars' surface, Phobos looks about a third the size
of the moon, and the sun looks about 2/3 as wide
compared to how it looks on Earth.
So you get that partial eclipse.
Can we take a second to recognize how amazing it
is that we have a video of what a solar eclipse looks
like from the surface of another planet?
Anywho, no Mars TSE, but Jupiter has 69 moons.
Now we just need those moons to be big enough and close enough
to Jupiter.
It does help that Jupiter is way further away from the sun,
so the sun looks a lot smaller in the sky, which
means Jupiter has multiple moons with the right conditions.
In fact, Jupiter can have multiple eclipses
happening at the same time.
In 2004, the Hubble telescope took this photo three
of Jupiter's largest moons--
Io, Callisto, and Ganymede-- are simultaneously casting shadows
on Jupiter, which means three total solar eclipses at three
different locations on Jupiter.
That so many giant coverups.
It's a conspiracy!
Sorry.
Saturn.
Saturn gets some unique eclipses because of its rings.
Technically, Saturn's rings aren't moons,
they're belts of orbiting dust, ice, and rock.
But they end up making these gorgeous shadows.
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Saturn sometimes casts a shadow on its rings,
kind of like what happens with a lunar eclipse here on Earth.
Here's some interesting stuff about Saturn.
Saturn has seasons-- cool--
because its axis is tilted, just like Earth's axis.
But it takes 30 years for Saturn to go around the sun,
so each season lasts over seven years.
And depending on the season, Saturn casts a different shadow
on its rings, and its rings cast a different shadow on Saturn.
Now, the object with the coolest eclipses, in my opinion,
is Pluto.
Yeah, Yeah, Yeah.
Pluto is a dwarf planet and not a real planet, but whatever.
Picture yourself on Pluto, where the sky is also blue
and the sun is a tiny pinprick in the sky.
Because the sun appears about 40 times smaller
in the sky on Pluto and 1,000 times dimmer than on Earth,
Pluto's moon, Charon, looks super big,
because it's half the size of Pluto
and it's 20 times closer to Pluto
than the moon is to Earth.
So yeah, it blocks out the sun.
As far as eclipses go, it's overkill.
In fact, there was a period of time between 1985 and 1990
when Charon eclipsed the sun every day.
Pluto eclipses.
That being said, our eclipse here on Earth
is pretty perfect.
It's kind of an amazing coincidence
that total eclipses has happened here on Earth at all,
because it's totally random that the moon would
be exactly the right size and exactly
the right distance from Earth.
But it won't always be that way, because the moon is moving away
from Earth at four centimeters per year.
So in 600 million years, we won't get total solar eclipses.
Because this is how an eclipse happens on Earth.
The moon orbits the earth at a slight tilt of five degrees.
Then, every once in a new moon--
that's when the moon is between the Earth and the sun
and the dark side is facing the Earth--
the moon is just aligned that it casts a shadow on Earth.
If you were near the moon, it would look like this.
This happens about two times every three years
on a small sliver of Earth.
This time around the Eclipse will
be visible across a thin strip of the United States mainland.
And basically, every other part of the mainland,
including where I live in San Diego,
you'll be able to see a partial eclipse.
So I'm super pumped for the 30% chance I have of no cloud cover
and being able to see the total solar eclipse.
It's been almost 40 years since the last TSE was visible
in North America, so wish me luck.
Thanks for watching, and happy physicsing.
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