Kind: captions
Language: en
the Milky Way
galaxy 100,000 Lighty years across 100
billion stars our home but how do we
know what it really looks
like the Milky Way is uh very difficult
to actually understand because we're
inside of it we can look at other
galaxies uh you can see beautiful spiral
patterns and other some other
galaxies uh we think the Milky Way looks
like some of these other spiral galaxies
but we don't know because all we see is
a band of stars across the sky um if you
can get away from the city
lights when you see pictures of the
Milky Way they are usually just artistic
renderings what we actually know about
the Milky Way is somewhat analogous to a
17th century European map of the new
world there are similarities but a
modern map is much more accurate so how
do we make a better map and so one way
you could think of trying to figure it
out would be to measure distances to
large numbers of stars all the way
across the Milky Way and then you could
make a plot or a map or a plan view of
what the Milky Way looked like because
you'd know that some stars are very far
away in this direction and some are
closer what I do is using radio light we
can actually measure very very small
shifts in angle as the earth goes around
the Sun and we see a star from a
different
angle and from that we can calculate the
distance to the star when we look at a
star to measure its distance from the
earth we first note other even more
distant background stars in our line of
sight if we look at the star again 6
months later our line of sight will have
changed from our perspective even though
the star has basically remained
stationary it will seem to us as if the
star has shifted a tiny distance
relative to the background Stars
from this incredibly small perceived
shift astronomers can then measure a
very very tiny angle exaggerated here
for effect since we know the distance
from the Earth to the sun we can then
form an imaginary right triangle and
with trigonometry we can calculate the
distance to the star and so we just pick
the most massive young stars in the
Milky Way they're perhaps 500 or so that
we can do in the Milky Way and we're
just measuring the distance to everyone
the nice thing about them is that they
do Trace they're very bright and they
sort of line up like little beads on a
string and Trace out the spiral arms in
the Milky
Way and that's how you map the Milky Way
galaxy
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