a blood moon lunar eclipse wasn't always
something to look forward to when the
moon turned red thousands of years ago
the ancient Mayans and Mesopotamians
feared that something monstrous and evil
was eating the moon they would shout at
the night sky to try and fend off the
ravenous beasts and since the average
lunar eclipse lasts around 100 minutes
and the moon returns to normal afterward
they were probably convinced that
they're wooing and howling actually
worked we know now that the moon doesn't
need our protection but why does it turn
red in the first place
whenever you look up at a full moon
you're seeing sunlight that's reflected
off the lunar surface so if something
were to block that sunlight say the
earth then in theory the moon should
disappear from view but during a total
lunar eclipse when the moon passes
through the Earth's shadow we get a red
moon not a vanishing one so what's going
on to figure it out let's take a quick
trip to the lunar surface this is a NASA
simulation of what the earth looks like
during a total lunar eclipse notice the
red ring around our planet everywhere
you see that ring is either a sunrise or
a sunset and while it's true that no
direct sunlight is reaching the lunar
surface at this moment Earth's
atmosphere is bending the red
wavelengths of light around the planet
so that redness you see during a Blood
Moon Eclipse is a combination of light
from every sunrise and sunset on earth
all happening at once so the moon
appears red for the same reason that
sunrises and sunsets on earth are red
because of a phenomenon called Rayleigh
scattering named after the British
physicist John Williams Strutt also
known as Lord Rayleigh who discovered it
in the late 19th century it describes
how different colors of sunlight
interact with the Earth's atmosphere
look at the sky during daytime for
example it appears blue because air
molecules in Earth's atmosphere scatter
blue light more easily than red but
during sunrise and sunset the light
travels through more of Earth's
atmosphere before reaching your eye
which has two consequences first it
means more overall sunlight is scattered
making the Sun appear dimmer that's why
you can easily gaze upon the Sun at
sunset compared to it high noon and
secondly more scattering means more blue
light scattered away leaving the redder
wavelengths behind
similarly the ring around earth during a
total lunar eclipse is red because the
sunlight travels through a long stretch
of Earth's atmosphere from one end of
the planet to the other so rather than
fear a Blood Moon
like the ancient Mayans and
Mesopotamians why not think of it as a
romantic moment after all it's the only
time when you can see the sunrise and
sunset simultaneously