Hey Vsauce I'm Jake and if Star Wars were to have happened in our universe and truly
occurred a long time ago in a galaxy far, far away ... light from the actions in Star Wars
could be hitting Earth right now, or will some day. So if we pointed a telescope at
the right far away galaxy .... could we see Star Wars? Even if we choose the nearest spiral
galaxy to us, Andromeda, the requirements and results for resolving individual planets,
people or ewoks turns out ... to be almost as disappointing as the Phantom Menace.
To make out the flag on our moon from earth we would need a telescope that's 260meters.
If we wanted a clearer picture, one that would show us the stripes, if they were still
there, we would have to bump the size up to 6,850.
The biggest optical telescopes on Earth have mirrors around 10meters and the largest one
planned, the aptly named European Extremely Large Telescope, will be completed in 2022
and have a 39 meter mirror. Still a good deal smaller than you would need to see the flag
on the moon.
When you try and see small objects that are good distances away, especially when they
have less light, it becomes much more difficult to resolve. For example, here is the best
photo we have of Pluto, and this is a celestial body in our own solar system and relatively
close at 4.2 billion km.
So the reason we can take an amazing image of Andromeda, 2.5million light years away,
is because we are looking at an object that is an estimated 260,000 light years across
and contains a trillion stars. It has to do with the relative size to distance where Andromeda
would be .1 or 200,000 times greater than Pluto's.
If we wanted to be able to see a planet or satellite in a completely different galaxy
like Andromeda, you would need a pretty substantial telescope. To be able to get a glimpse at
the forest moon of Endor, more than double the size of Pluto we would only need a telescope
that was 6...wait for it... million 500 thousand kilometers in diameter. About the size of
4.5 of our suns.
But we want to actually see what is happening on the planet. I mean, I want to look at an
Ewok with my own eye because they are adorable. To produce a fairly detailed image we would
need something gigantic, something 1.7 light years large. This telescope would surpasse
Voyager 1's current 18 billion km distance and would be larger than our solar system.
But here is when we run into a slight problem. Bad Astronomy has a great piece about pointing
Hubble at Earth and trying to get a photo. The resulting image would be blurry because
of how quickly it is orbiting. He likens it to "trying to take a picture from a moving
car: nearby objects will streak by, but far away objects appear to be moving slowly."
So even though Andromeda is spatially far away, it is magnified to such a degree that
we'd probably get a very blurry Ewok. The incredibly long exposure time the telescope
would need to collect enough photons to form an image wouldn't help either and whatever
image we were able to produce would have a blue hue since Andromeda is moving so quickly
towards Earth, at a rate of 300km a second, that the light is blueshifted.
Even light coming from people near you has to travel a distance. Since lightspeed is
finite, at arms length you're actually seeing a person 3 nanoseconds younger than they really
are. There is a constant flow of new, old light being spread out across the Universe
so who knows what we might be able to see next, maybe a galaxy far, far away.
And as always, thanks for watching.