Scale of earth, sun, galaxy and universe
Scale of the Galaxy Scale of the Galaxy
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- In the last video I hinted that things were about to get wacky,
- and they are! So if we start where we left off in the last video,
- we started right over here, looking at the distance
- to the nearest star and, just a reminder
- in this drawing right here this depiction right here this circle right here
- this solar system circle, its not the size of the sun, its not the size
- of the orbits of the Earth or Pluto or the Kuiper belt this is close
- to the size of the Oort cloud. The actual orbit of earth is
- about one, well the diameter of the orbit of earth is about one
- fifty thousandth of this so you wouldn't even see it on this. it wouldn't even make
- up a pixel on this screen right here, much less the actual size
- of the sun or something much smaller.
- And just remember that orbit of the earth that was at a huge distance. It takes
- 8 mins for light to get from the sun to the earth. It's a super long distance.
- If you shot a bullet at the sun from earth, it would take you 17 years to get to the sun.
- So this huge distance wouldnt even show up on this picture.
- Now what we saw in the last video is that if you travel at unimaginably fast speeds,
- if you travel at 60,000 km/h, and I picked that speed 'cause that's how fast
- Voyager 1 actually is travelling
- that's one of the fastest, I think one of the fastest objects we have
- out there in space, right here, and is actually kind of leaving the solar system
- as we speak. But even if you were able to get that fast,
- it would still take 80,000 years, 75 or 80,000 years to travel the
- 4.2 light years to the Alpha Centauri cluster of stars. To the nearest star,
- it would take 80,000 years, 80,000 years.
- And that scale of time is already an amount of time I have trouble comprehending
- You can imagine all of modern civilization has occured definitely in the last 10,000 yrs
- but most of recorded history is in the last 4 or 5000 years.
- So this is 80,000 years to travel to the nearest star.
- So its a huge distance.
- Another way to think about it, is that if the sun
- were the size of a basketball and you put that basketball in London,
- if you wanted to do it in scale, the next closest star which is actually a smaller
- basketball right over here, Proxima Centauri, that smaller basketball you'd have to put
- in Kiev, Ukraine. in order to have a similiar scale.
- So these are basketballs, sitting in these cities and you would have
- to travel about 1200 miles
- to place the next basketball. and these basketballs are representing these super huge things
- that we saw in the first video, the Sun. If you actually made the earth
- relative to these basketballs, these would be little grains of sand
- so if there are any little small planets over here they would have to be grains
- of sand in Kiev, Ukraine versus the grain of sand in London.
- So this is a massive, massive distance. Already, at least in my mind, unimaginable. And when it gets
- really whacky is when you start realising that this, even this, is a super
- super small distance relative to the galactic scale.
- So this whole depiction of kind of our neighborhood of stars this thing over here
- is about, give or take, and we're doing rough estimates right here
- its about 30 light years. I'll just do LY for short. So thats abt 30 LY
- Now and once again you cannot actually, you can take pictures of our galaxy
- from our point of view but you actually can't take a picture of the whole galaxy from above it.
- So these are going to be artist depictions, but if this is 30 LY
- This drawing right here of kind of our local neighborhood of the galxy
- this right here is roughly, these are all approximations, this is about
- let me do this in a darker color, this about 1 thousand LY
- and this is the 1000 LY of our suns neighborhood if you can even call it a neighborhood
- even this isn't really a neighborhoood if it takes you 80,000 yrs to get to your nearest neighbor
- but this whole drawing over here it would take forever to get anywhere over here
- it would be 1/30th of this so it would be about that big
- this whole drawing and what's really going to blow your mind is
- this would be roughly a little bit more than a pixel on this drawing right here
- that spans a 1000 LY but then when you start to really put it into
- perspective so new lets zoom out a little bit. So this drawing right here
- this 1000 LY is now this 1000 LY over here. so this is our local vicinity of the sun
- and once again the word local is used in a very liberal way
- at this point
- so this right here is a 1000 ly
- if your sitting here and your looking at an object that is sitting (let me do this in a darker color)
- if we're sitting here on earth and we're looking at an object sitting here
- that's 500 LY away we're looking at it as it was 500 years ago
- becasue the light that is reaching our eyeballs right now or our telescopes
- right now left this guy over here 500 yrs ago. in fact he's not even going to be there anymore
- he'll probably have moved around a little bit. So just even on this scale, we're alredy
- talking abt these unimaginably huge distances and then when we zoom out
- this is kind of like our local part of the galaxy over here. This piece right here
- this is called the Orion Spur and people are still trying to work out
- exactly what the actual details of the actual shape of the milky way galaxy is
- the galaxy that we're in but we're pretty sure we have these spiral arms
- and we have these spurs off of them, but its actually very hard to come up with the actual shape
- especally because you can't see a lot of the galaxy because it's kinda on the other side,
- on the other side of the centre
- but really just to get a sense, I mean at least it blows my mind if you really
- think about what it saying these unbeleivable distances show up as a lil dot here
- this whole drawing shows up as a dot here. now when we zoom out over here
- that dot would no longer even show up
- it wouldn't even register a pixel on this drawing right over here
- and then this drawing this whole thing right over here
- this whole pic is this grid is this grid right over here it is this right over here
- so hopefully that gives you a sense of how small even our local neighborhood
- is relative to THE galaxy as a whole
- the galaxy as a whole just to give you a sense has 200,
- 200-400 billion stars
- or maybe i should say solar systems just to give you a sense that you know
- when we saw the solar system its not just the sun
- its all this neat dynamic stuff in there, planets and asteroids
- and solar winds and so there's 200 to 400 billion stars
- and for the most part 200 to 400 billion solar systems so its and
- unimaginably complex or huge place
- and just to make it clear you know even when we zoom into this pic right here
- and i think its obvious based on this that these lil white pockets right here
- these aren't this isn't one star this isn't two stars these are thousands of stars
- here so when you go over here
- each little blotch of white that you see that's not a star that's not a thousand stars
- we're starting to talk in the millions of stars when you look at certain blotches here and there
- i mean it maybe one star that closer to you or it might be a million
- stars that are far apart and that are just relatively close
- together and eveything has to be used in kind of
- loose terms here. And we'll talk more about other galaxies
- but even this isn't the upper bound of galaxies
- people believe the Andromeda Galaxy has a trillion stars in it
- a trillion sources and we're talking about these huge
- huge immense distances and so just to give you a sense
- of where we fit in the picture this is a rough location of our sun
- and remember that lil dot i drew just now
- is including millions of stars, millions of solar systems
- already unimaginable distances but if you really wanna get the sense
- relative to the whole galaxy, this is an artist's depiction
- once again we could never obviously get this perspective on the galaxy
- it would take forever to travel this far
- so that you could see the galaxy from above but this is our best guess
- looking at things from our vantage point we actually could never even see
- we actually can't even see this whole area over here
- 'cause it's on the other side of the centre of the galaxy which is super super
- dense and super bright and so its very hard to see things on the other side
- we think or actually there's a super massive black hole at the centre of the galaxy
- and we think that they're at the centre of all or most galaxies
- but you know the whole pint of this video or actually this whole series of videos
- is just to put you in awe a lil bit of just how huge this is
- 'cause when you think about the scales it's just, i dunno no, words can reallly describe it
- but just to give you sense we're about 25000LY from the centre of
- the galaxy so even when we look at things at the centre of the galaxy that's how they
- were 25000 yrs ago
- it took 25000 yrs for that light to get to us, I mean when that light left the centre
- of the galaxy I won't even guess to think what
- humanity was like at that point in time
- so its these huge distances and the whole galaxy of here
- and like solar systems its hard to say the edge of the galaxy
- 'cause there's always gonna be a few more stars and other things orbiting
- around the galaxy as you go further and further out but the main
- density the main disc is about 100,000LY
- is the diameter roughly of the main part of the galaxy and it's about a 1000 LY thick
- so you kind of imagine it as a disc its fairly flat
- but its a 1000 LY thick! It's a 1000 LY thick you would have to do this distance
- 250 times just to go from the top part of the galaxy to the bottom part
- much less going across the galxy
- so it might sem relatively flat but it's still immensely
- immensely thick. and just as another way to visualise it
- if this thing right over here that includes the Oort cloud
- roughly a LY in diameter it is a grain of sand
- a mm in diameter grain of sand
- then the universe as a whole is gonna be the diameter of a football field
- and those are two tractable things, i can imagine a grain of sand
- a mm wide grain of sand in a football field. but remember that's a grain sand
- that grain of sand is still 50 or 60, 000 times the diameter of the Earth's orbit
- and it would still take a bullet or something travelling as fast as a jet plane
- 15 hrs to just go half of that or sorry 15 yrs or 17 yrs I forgot
- the exact number but you knpw 15, 16 , 17 yrs to even cover half of that distance
- 30 yrs to cover an entire diamtere, so 30 yrs to cover the entire diameter
- of earths orbit tahts one 60,000th of our lil grain of sand in the football field
- and just to kind of really i dunno have an appreciation for how amaz- i dunno how mind blowing this
- really is , this is a picture of the milky way galaxy, our galaxy
- from our vantage point as you can see we're in the galaxy so we're
- seeing and this is looking towards the centre and
- even this picture you start to appreciate the complexity of what a 100
- billion stars are but what i really wanna point out is that even in this pic
- when yu're looking at some of these things that are like stars
- those arent stars! those are thousands of stars or millions of stars
- maybe it could be one star closer up but when we're startin
- to approach the centre of the galaxy these are thousands
- and thousands and millions of stars or solar systems
- that we're actually looking at so its really, it starts to
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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