When you think of ringed planets,
you probably assume there's
only one of them
in our Solar System.
Saturn.
But what if I told you
that there are three
other planets similar to Saturn?
Yeah, it's true.
Jupiter,
Uranus and Neptune
all have their own sets of rings.
Most people don't know about them
because they're much thinner
and pretty much invisible
from Earth.
We only learned about them
when Voyager 1 and Voyager 2
flew past them in the 1970s and 80s.
Some scientists
even think
that Earth had rings
at some point in its existence.
Four and a half billion years ago,
when a planet
the size of Mars
smashed into our young rock,
it ejected so much debris
that it likely briefly formed
a small ring around Earth.
Despite their unimaginably massive
gravitational pull,
black holes don't go around
sucking in everything in their way.
It just doesn't work like that.
Black holes
are more like sinkholes.
If you were to get too close to one,
you'd get spaghettified
and lost to the blackness
of this monstrosity.
But if you're
far enough away from it,
you'd be safe.
Even if our Sun was replaced
in the middle of our Solar System
by a black hole with similar mass,
all the planets would just orbit
like nothing happened.
Things would get pretty
dark, though.
Now, speaking of darkness,
the Moon doesn't have a dark side.
Our planetary partner
gets hit by the sunlight
all around.
The reason why you don't see
the other side of the Moon
is because
it's always facing away from us.
Yeah,
our Moon rotates on its axis
at the same rate it orbits Earth,
making it what's called
tidally locked to our planet.
If a large asteroid is
on a deadly collision
course with Earth,
the best thing to do is to nuke it.
Oh, sorry, wait.
I've actually got that wrong.
Do not nuke asteroids
that are about to collide with us.
The reason why?
Well, because the nuclear explosion
will shatter the asteroid
into millions of smaller pieces.
Yeah, the pieces
that would still be headed
for impact with us.
Instead of dealing
with just one giant asteroid,
we'd have to deal
with multiple impacts,
and it would make our evacuation
really difficult
or straight-up impossible.
Now, you still can use a nuke
to prevent an asteroid collision,
but you don't even have to strike
the space rock.
We just set off a nuke
near the asteroid.
Emphasis on near.
Then the force from the blast
would nudge it off course.
That would keep our planet safe.
Hopefully.
You know, nuking
the asteroid off course
isn't the only good thing
you can do for our planet.
Sometimes it's
simpler than that, like
making sure our air and water are clean.
Unfortunately,
just the other week,
the Supreme Court cut back
the Environmental Protection
Agency's authority
to regulate water pollution,
and that's bad news.
Over the past 50 years,
the EPA reduced
six of the most common
air pollutants by 78%
and significantly improved air quality.
Their work has saved
countless ecosystems,
and restricting the EPA's
ability to control water
and air pollution
is going to have serious
consequences in the future.
But you know what?
Together,
we can put people ahead
of corporate profits
and protect our environment.
Speak out.
Vote and
make sure your representatives know
how vital the EPA's work is to you.
We only have one chance on this planet.
Standing on Earth at night,
you can see thousands of stars.
But the view from the Moon
is actually quite boring.
Yeah, astronauts
who traveled to the Moon reported
that stars aren't easily visible
from there.
Because our Moon is
super reflective,
it really cranks up the brightness
making it harder
to see out to the stars.
It's kind of like
stargazing in a city
with a lot of light pollution.
Not fun.
You'd need to travel further
into space
to get some better views.
Traveling in space
won't make you taller.
Though, it's true
that astronauts can grow up to
5 cm (2 in) in space.
That's because the Earth's gravity
doesn't weigh them down,
and the vertebrae in their spines
are able to expand a bit.
But this effect is only temporary.
As soon as you return to Earth,
you get back to your regular height.
Yeah, thanks, gravity.
And space travel doesn't
make you age slower, either.
Not really.
Albert Einstein theorized
that time would pass slower
for someone
traveling at high speeds versus
for someone stationary.
This is called time dilation.
And while it's true,
you'd have to travel
incredibly fast
to achieve this de-aging effect.
Like almost speed-of-light fast.
Yeah, with our current space traveling technology,
the difference in
time is so minimal
that it's not even worth calculating.
If you thought crying in space
was impossible.
Well, first, why?
And second, you're wrong.
It's just different.
Without gravity
to pull your tears down,
they don't trickle down your face
like they do here on earth.
The tears just stick to your eyes
and form a sort of watery blob.
They might even cover your eyes
if you cry a lot.
So while you can
totally cry in space, it's
probably best that you don't.
And not great for visibility.
Hey, Martian dust storms
are a real headache.
The dust particles are so fine
that they can get anywhere.
And these dust storms
can last for months,
but they can't physically damage
any equipment that we leave
on the red planet.
The thing is,
is that the Martian atmosphere is
super thin,
just about 1% of the atmosphere
we have on Earth.
So even when these dust particles
zoom around at about 100 km/h (60 mph),
they can't pack a big punch
without the help of air.
But what they can do
is cover our solar panels
and put our rovers
into a power saving hibernation.
Oh, and they wouldn't
inhale this dust either.
Who knows what this fine powder
could do to your lungs long term.
Twinkle, twinkle, little star.
How I wonder what you are.
Up above the world so high,
this song is a big, fat lie.
Yeah, despite the famous
children's song, stars
don't twinkle.
The flickering is just an illusion.
Their light is actually
very steady.
Stars appear to twinkle
due to the gas molecules
that make up our atmosphere.
They deflect
some of the light from stars,
making them appear as
if they're shimmering.
Asteroid belts are
typically depicted
as minefields of floating rocks.
Spaceships have to weave in
and out of the asteroids
in a life-or-death situation.
But in reality,
our asteroid belts are nothing
like what you see in the movies.
Asteroids aren't
that close together.
In fact,
they're extremely far apart.
For example,
in the asteroid belt
between Jupiter and Mars,
each of the asteroids is several
million kilometers
away from their nearest neighbor.
And the chances of a collision
are about one in one billion.
So, while Han, Chewy and Leia
had you on the edge of your seat
in the Empire Strikes Back,
asteroid fields like that
are far from reality.
The Great Wall of China
is known to be
the only man-made object
that's visible from space.
But this is entirely false.
Yeah, sure.
Maybe you could see it
with a camera
and a zoom lens,
but it's almost invisible
to the naked eye.
At 5-10 m (16-32 ft) wide,
the wall is way too
thin to be seen from space.
However, you can still see
plenty of other manmade objects
from space.
Things like dams, bridges
and pyramids.
And at night,
you can see a light show
from the world's big cities.
And that's not all.
We're ready to bust
even more crazy space myths like
the sun being yellow and humans
without a suit exploding in space.
But that's a story
for another WHAT IF.