Thinking about our solar system,
let's imagine you could get in a car
and drive to Pluto at highway speeds.
It would take you about 6,000 years
to get there.
When we start to think about other stars
outside of our solar system,
we need to think about
another unit of distance.
This is why astronomers
use the unit light-years.
Light travels at 186,000 miles per second.
One light year is about 6 trillion miles.
The closest star to our Sun
is about four light years away.
Our own Milky Way galaxy is about 100,000
light-years across.
We know from deep field images
of the universe that there are hundreds
of billions,
perhaps a trillion other galaxies.
Using some of the deepest images
yet from JWST,
we've been able to see galaxies
that emitted their light about 13 and a half
billion years ago.
Now, here's a really important thing. Because the universe is expanding,
those most distant galaxies
are actually much further away
than 13 and a half billion light years.
I'm glossing over some math here,
but we can estimate that the observable
universe is about 92 billion
light-years across.
But we're pretty sure that the universe
is even bigger than what we can see.
And here's where things get really weird,
we don't actually know
if the universe is finite or infinite.
As much as we've learned about
the universe, science has no reliable
estimate of the actual size of the entire universe.
We Asked a NASA Scientist.
NASA. A NASA 360 Production.
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