summer

Why does the Southern Hemisphere get the best view of the Milky Way?! | The Galactic Seasons

as an astronomer that lives in the

northern hemisphere it bugs me to no end

that I cannot see the center of the

Milky Way from where I live all those

amazing images you see of the Milky Way

with that really dense region of stars

and dust I ever taken from the southern

hemisphere where it rises to be directly

above your head or in the summer months

from very low down near the equator in

the northern hemisphere and it just

rises above the horizon where I am in

the UK the center of the Milky Way that

most spectacular region in the

constellation of Sagittarius it never

rises high enough above the horizon you

know like more than 10 degrees for me to

actually be able to get a good look at

it it's too low down and in the summer

months when it's visible like the Sun is

not that far below that horizon so it

gets so washed out you really can't

appreciate it at all and even further

Northup like on the pole itself it never

Rises there and you can't see it at all

any time of the year so why is that the

case the Milky Way is kind of like a

fried egg shape right it's a flat disc

with a big bulge yoke in the middle

where there's lots and lots of stars a

supermassive black hole at the center

and if the Sun is just one star in the

Milky Way that orbits around the edge

and we the earth go around the Sun then

how come is it from the southern

hemisphere they're the only ones able to

see the center of the Milky Way well

there's lots going on and in the

northern hemisphere we look out towards

the edge of the Milky Way you know when

you picture the earth bare on the Sun

and the Sun going around the Milky Way

you picture them sort of all going

around in a line but that's not true you

know if it were then the path of the

planet on the moon everything that's in

the plane of our solar system in the sky

would trace the same path as the Milky

Way does across the sky but that's not

the case if we think about like how we

navigate around this day we picture the

earth and the sky is sort of a an

extension of the surface of the earth

there's another sphere that surrounds us

obviously it's in three dimensions but

really how our eyes perceive it is if

it's on the edge of this celestial

sphere it was

the North Pole of the earth in the South

Pole of the earth as well and so we can

imagine there's a North Pole of the

celestial sphere and there's a South

Pole of the celestial sphere and

similarly the equator of the earth can

be expanded outwards to give you the

celestial equator and it just so

happened that the north west your pole

points directly at the star Polaris the

North Star whereas the South celestial

pole isn't actually near to any star

that the human eye can actually see and

the Earth spins on its axis that joins

the North Pole and the South Pole now

the thing is that we know that that axis

is tilted with respect to how we orbit

around the Sun it's what causes our

seasons in the southern hemispheres

summer the South Pole is pointing

towards the Sun and the North Pole is

pointing away making it winter in the

northern hemisphere six months later the

North Pole is pointing towards the Sun

the South Pole is pointing away from the

Sun and it's Northern Hemisphere summer

and southern hemisphere winter between

the two you have the equinoxes equal day

at equal night for both northern and

southern hemispheres and so you have

sort of autumn and spring switched

around between the two hemispheres what

that means is that you've got another

way of navigating around the sky instead

of taking the equator of the earth and

expanding that outwards to your

celestial sphere you can take the orbit

of the earth around the Sun expand that

outwards and then you'll have a new

circle around your celestial sphere

which we call the ecliptic which is at

the same angle as the Earth's tilted

axis with respect to the celestial

equator and that is the path that the

Sun and all the planets in the solar

system take through the sky because they

all all bit on that same plane around

the Sun and so along with the Earth's

orbit around the Sun in one plane you've

also got the sun's orbit around the

galaxy now it's going around what we

call the Galactic plane that plane of

the Milky Way disk but just like how the

Earth's axis is tilted with respect to

the plane it goes around the Sun the

sun's axis is tilted with respect to how

it goes around the galaxy and it means

that the entire plane of the solar

system is a

angle of about 60 degrees with respect

to the galaxy now you might think that's

really weird that the plane of the solar

system doesn't line up with the plane of

the galaxy but the two were formed

independently the galaxy is much older

than the solar system itself and so it

all just depends on what random

direction the gas that made them was

swirling out to the gas that made your

galaxy form and the gas that your son

and your planets formed from happen to

have some rotational energy that we call

angular momentum that happened to be

going in some direction and so that's

why it ends up forming around whatever

direction that gas was going in so for

the Sun it was tilted at slightly about

60 degrees from the rest of the galaxy

and interestingly although those planets

are going around the Sun in one

direction altogether because they all

form from that same cloud of gas that

had the angular momentum the Sun orbits

the Milky Way in the opposite direction

that the Earth orbits the Sun and again

it's all down to the angular momentum of

the thing that it was formed from so

because the player of a solar system is

tilted with respect to the galaxy all

hope is not lost for me the northern

hemisphere astronomer because just like

how the earth axis is tilted and it

means that it causes our seasons so that

once a year the southern hemisphere

points towards the Sun and once a year

the northern hemisphere points towards

the Sun so as the Sun orbits around the

Milky Way

currently the South Pole of the Soudan

points towards the galactic center but

as it moves around as it's on the

opposite side it means the north pole of

the Sun will point towards the galactic

center and because the tilt of the earth

means the north pole of the earth is

only about 23 degrees out from that the

northern hemisphere will point towards

the galactic center so I guess how you

can think of it is that we're currently

in the sun's Southern Hemisphere

galactic summer and then eventually

we'll be in the sun's northern

hemisphere galactic summer the key word

though there is eventually because it

takes the Sun 200 to 250 million years

to make one lap around the

keyway ie it's the lactic year is about

250 million earth years so we're gonna

have to wait at least a hundred to

125,000 years to make it into the Suns

northern hemisphere galactic summer so I

went on to stellarium which is this

amazing app that you can get pew

computer to see you know what the sky

looks like at any time of the year at

any time of day from anywhere in the

world and I wondered how far in the

future couldn't actually show me

unfortunately Stellarium only goes up to

a hundred thousand years in the future

no matter how many times I clicked it to

try to make it go above that hundred

thousand years in the future though

Sagittarius is still not visible from

the North Pole and lasts because the Sun

is only like point zero four percent of

the way around its galactic orbit that

takes 250 million years or so it will

only be when the Sun is 25% around its

galactic orbit that Sagittarius will

start to rise above the horizon at the

North Pole in 60 million years time but

all the time the Sun keeps orbiting

around the center of the Milky Way

Sagittarius will rise higher and higher

latitudes similar to where I am in the

UK so that'll eventually by the year a

hundred thousand it will rise above like

20 degrees in the sky in springtime of

each year so that I am actually able to

appreciate it in all its glory

so all I need to do is live another

ninety seven thousand nine hundred and

eighty-one years and I will get my wish

of being able to see the center of the

Milky Way from where I live in the

northern hemisphere brown skin your skin

just like me oh I need a holiday you

know when you think about the earth

around the Sun the Sun going around the

central Milky Way you often think about

them as being blind so all I've got to

do is live another 918 319 - 100

thousand hundred thousand is between 99

9

9 no 9 8 9 7 what should we do with it

I'm concerned what should we do with

drunkenness drama what should we do with

the drunken about morning