You Are Here (Part 1: Space)

where exactly is the earth what the

Milky Way cool now where's that exactly

let's get to it

okay so we know our planet Earth 70%

water comfortable temperature great

music and culture 10 out of 10 would

visit again but where exactly is the

earth the earth is here in the inner

solar system orbiting a star called very

imaginatively by humans the Sun or soul

to give it its Latin better name the Sun

is a rather mediocre but stable

main-sequence star that is about halfway

through its lifecycle in about four

billion years it was swell and

completely obliterate all traces of a

long dead civilization but we haven't

gotten to that bit yet it is currently

powered by fusion of hydrogen into

helium and energy and where's 9.8 nah

million kilograms which is such a

massive number that our primitive simian

brains can't even visualize that massive

amount especially the ones that still

use Imperial the Earth orbits 149

million kilometres or one astronomical

unit away in the inner solar system

while Jupiter is five times further out

Neptune is at 30 au and the edge of the

solar system and Voyager are between 80

and 100 thousand au away which is very

specific but where's the solar system

right his work gets interesting and I

can start filling this video with more

facts and less spite our nearest star

Proxima gets what that's called in Latin

and Alpha Centauri which are 4.4

light-years away as well as Barnard Star

Wolf 359 and quite a lot of others is

quite hard to visualize our position in

3d space but I'm going to try my best or

will try my best as I haven't edited

this video yet this is made especially

hard as all of these surrounding stars

are travelling in random different

directions compared to us our local

neighborhood of Stars is inside an

interstellar gas cloud called the local

cloud in fact the Sun will enter a

separate cloud called the G cloud in the

next 20 millennia or so both of these

clouds are flowing out from a dense area

and star forming gas called the Scorpius

centrist Association which sounds like

an accounting business but for our human

purposes we can just ignore most

movement as it really where matter on

the timescales we're talking in the

cloud there aren't as many stars as

elsewhere in the galaxy but the whole

thing is 1.5 million astronomical units


30 light-years across which is pretty

small compared to what's to come

zoom out further when we see our local

interstellar cloud is pretty much

exactly halfway down the Orion Arm of

the Milky Way which is about ten

thousand light-years long but despite

this figure it is only a very minor arm

as the offshoots from the massively

large Perseus arm which is about three

and a half times larger yeah and this

leads us to the Milky Way you may have

heard of it it's our galaxy and for once

it's kind of big compared to its

neighbors but not the biggest we'll get

to that later

it's a barred spiral galaxy called that

because of the bar shape in the center

it is over 150,000 light-years across

around 2,000 light-years thick with a

bulge in the middle way is an amazing

0.5 Treader Cillian kilograms which is

over 400 billion times what the Sun

weighs and looks also something like

this yeah this or a version of this is

literally the only photograph we have

because this solar system is the only

perspective we have and we are inside

the thing we are trying to photograph

which makes it a bit difficult yeah it's

not like we can step back and look at it

from the side because not only will it

take a million years for even light to

get that far but there is no side in

space it's all relative so how do we

know what it would look like well we can

calculate how far away they are due to

how far they appear to have moved in a

six-month span in reality we're the ones

that have moved but judging from how far

that star has moved relative to distant

galaxies called its parallax we can

determine through simple geometry how

far away they are also we see other

galaxies from the side or top or

whatever and work out generally how

galaxies are structured we can't see

most of the stars on the other side of

the core due to the intense light and

mass there but applying our general

rules of galaxies to the distance stars

we can see we get a map something like

this hooray usually in films also you

hear about the Alpha Quadrant of a

galaxy the quadrants are a thing for

real galaxies as well except they're

numbered and

technically we're in - yeah because the

zero degree line the equivalent of the

Greenwich Meridian for the galaxy is

always drawn so the intersects with the

Sun which is a very self-centered thing

to do but we don't exactly have much

else to base it off of but like a Sun

the Milky Way has its own local cluster

of galaxies and that's what it's called

the local cluster most are tiny compared

to ours and some even orbit the Milky

Way like planets to a star the Milky Way

is one of the biggest in the local

cluster and second only to the Andromeda

galaxy it is - a widely known fact that

these two galaxies are destined to

collide and the black holes at the

center of each will merge and form the

initially chaotic milk dromeda galaxies

hopefully in the 3.5 billion years until

then we can come up with a better name

than milk dromeda I mean come on that's

worse than calling a Galaxy Eric who's

cooler Eric instead of milk dromeda is

probably better but for now that's our

local cluster zoom out further when we

see the Virgo supercluster

a cluster of clusters including the

local cluster and the Virgo cluster

which gives the cluster its name

have I said cluster enough for cluster

to lose its meaning of cluster cluster

cluster cluster cluster cluster cluster

cluster cluster cluster cluster anyway

is approximately a hundred million

light-years across

and in it there are a hundred clusters

with their own stars and their own

worlds yeah these stars are too far away

to use the Stars parallax to measure

their distance so we're going to have to

use the very light itself using the

Doppler effect okay quick subtle ninja

edit here I completely messed up the

definition of the Doppler effects I'm

going to try to explain it to you

without a script array this isn't going

to go wrong whatsoever the Doppler

effect occurs when the thing that's

emitting this slight or sound is

traveling at a different speed to you

that has the effect of squashing or

stretching the sound or light waves now

with light this can manifest itself as a

higher or lower colour on the spectrum

with sound it's a higher or lower pitch

that's why when sirens go past it seems

higher and then as it goes past and is

moving away from you it seems lower this

has the effect in space of because

of the expansion of the universe the

further things are moving faster away

and therefore the more stretched out the

light is as a result it looks more red

and the universe slowly turns red as you

go away from us this is called redshift

and this is technically how we find out

how far away things are yeah I didn't

mess that whatsoever so we must be

getting close to the size of the

universe right nope as we zoom out to

the Laniakea super cluster which is a

cluster of clusters of clusters hmm yeah

this weirdly named group has over 300 to

500 super clusters and a hundred

thousand galaxies each with billions of

stars and all of them are out there

right now yeah also in the Laniakea

super cluster is the rather ominously

named Great Attractor

which is kind of ominous in real life as

well it's this thing that we can't see

that has a mass tens of thousands of

times more than our own galaxy but in

theory with all that mass we should be

upset right well we probably could if it

weren't for the Milky Way's core being

in the way so we can't see it thanks a

lot Milky Way I know we owe our

existence to you but you do get annoying

sometimes okay so here we go zooming

further out and we've stopped why have

we stopped becoming here already

oh it seems we've reached the edge of

the observable universe and we can't see

any further it's kind of in the name the

light coming from there was emitted 13.8

billion years ago and that light we are

seeing now but in that time that object

has moved away from us to the point

where it's 47 billion light years away

now so that's how we get the radius of

everything we can see known as the

observable universe we can't see any

further as those objects that emit light

have been around long enough for the

distance from further away to reach us

so in a system in a cloud in an arm of a

galaxy in the cluster and a cluster in a

cluster in the universe we are here I'll

also talk about the start of everything

what came before that and the depressing

but inevitable end to the universe so

see you then

try not have an existential crisis in

the meantime