I'm perpetually in a state where I'm
talking about objects which are
unimaginably far away it's pretty much
impossible to imagine how huge some of
our universe is our brains can
comprehend the distances around us sort
of especially when we've got a pile of
tools to help we can measure our height
with a tape measure or the distance
along the ground using an odometer when
you get a feel for how far away a
hundred kilometers is because we can
drive it pretty short period of time but
space is really big and for most of us
our brains can't comprehend the full
awesomeness of the cosmos let alone
measure it so how do astronomers figure
out how far away everything is how do
they know how far away planets stars
galaxies and even the edge of the
observable universe is assuming it's all
trickery your bang on astronomers have a
bag of remarkably clever tricks and
techniques to measure distance in the
universe and for them different
distances require different
methodologies up close these
trigonometry using differences in angles
to puzzle out distances and they also
use a variety of standard candles these
are bright objects that generate a
consistent amount of light so you can
tell how far away they are at the
furthest distances astronomers use
expansion of space itself to detect
distances fortunately each of these
methods overlap so you can use
trigonometry to test out the closest
standard candles they can use the most
distant standard candles to verify the
biggest tools now around our solar
system and in our neighborhood of the
galaxies astronomers use trigonometry to
discover the distance to objects they
measure the location of a star in the
sky at one point of the year and then
measure again six months later when the
earth is on the opposite side of the
solar system the star will have moved a
tiny amount in the sky this is known as
parallax because we know the distance
from one side of yours orbit to the
there we can calculate the angles and
compute the distance to the star now I'm
sure you can spot the flaw this method
falls apart when the distance is so
great that the star doesn't appear to
move at all so fortunately astronomers
shift to a different method observing a
standard candle it was a seafood
variable the C fields are special stars
that dim and brighten in a known pattern
you can measure how quickly a C fiood
pulses you can calculate its true
luminosity and therefore its distance C
fields let you measure distances to
nearby galaxies but out beyond a few
dozen mark mega parsecs
you need another tool supernova in a
very special type of binary star system
one star dies and becomes a white dwarf
while the other star lives on the white
dwarf begins to feed material off the
partner star until it hits exactly one
point four times the mass of the Sun at
this point it detonates as a type 1a
supernova generating an explosion that
can be seen halfway across the universe
because these stars always explode with
exactly the same amount of material we
can detect how far away they are and
therefore their absolute brightness of
the greatest scales astronomers use the
Hubble constant this is the discovery
but Edwin Hubble that the universe is
expanding in all directions
the further you look the faster galaxies
are speeding away from us and by
measuring the redshift of light from a
galaxy you can tell how fast it's moving
away from us and thus its approximate
distance
at the very end of the scale is the
cosmic microwave background radiation
the edge of the observable universe and
the limit of how far we can see
astronomers are always looking for new
types of standard candles and have
discovered all kinds of clever ways to
measure distance they measure the
clustering of galaxies beams of
microwave radiation from stars and the
surface of red giant stars all in the
hopes of verifying the cosmic distance
ladder measuring distance has been one
of the toughest problems for astronomers
to crack and their solutions have been
absolutely ingenious thanks to them we
can have a sense of scale for the cosmos
around us so what concept in astronomy
do you have the hardest time holding in
your brain tell us in the comments below
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measuring distance oh I want to come
back yeah measuring distance