Imagine taking the distance that light move around in an entire yr . Now turn that distance into a block , each side one light - year across . How much “ stuff ” would be in there ? And how empty would it be ? It all depends on where you put your monolithic cube .
Top range of a function : Messier 15 , an ancientglobular cluster .
Even though the name is a little perplexing , you probably already know that a clean year is the distance that unclouded travels in a full year . At speed of almost 300,000 kilometers per second , that gets you reasonably far from home .
So take that distance and rick it into a cube , each side one light year in length . Imagine that gargantuan volume of space ; it ’s a lilliputian challenging for some of us to get our heads around . How much “ stuff ” would be in there , and not just “ stuff ” … how much nothing is in there ? There is an answer , but it all depends on the placement of the gargantuan cube .
Measure it at the core of the galaxy , and there are stars buzzing around all over the place . Perhaps in the heart of a orbicular cluster ? In a star form nebula ? Or maybe out in the suburbs of the Milky Way ? There ’s also great voids that live between galax , where there ’s almost nothing .
The space between the galaxy is actually quite empty . Credit : ESO .
There ’s no acquiring around the mathematics in this one . First , let ’s picture out an average compactness for the Milky Way and then go from there . Its about 100,000 lite - twelvemonth across and 1000 light - years thick . According to my buddy Phil Plait , the total loudness of the Milky Way is about 8 trillion cubic light - years . And the full mass of the Milky Way is 6 x 10 to the power of 42 kilograms .
separate those together and you get 8 x 10 to the power of 29 kilograms per light twelvemonth . That ’s an 8 follow by 29 zero . Is that a deal ? It vocalise like a lot .
Millions of glow genius from the bright part of the Milky Way — a region so dumb with hotshot that barely any disconsolate sky is envision across the picture . Credit : ESO .
Actually , that ’s about 40 % of the mass of the Sun . In other Book , on mean , across the Milky Way , there ’s about 40 % the mass of the Sun in every cubic illumination year . But in an average three-dimensional meter , there ’s only about 950 attograms . Almost a femtogram ; a quadrillionth of a gram of thing . Which is pretty faithful to nothing . Seriously , gentle wind has more than a kilo of mass per three-dimensional meter .
In the densest region of the Milky Way , like inside spherical bunch , you’re able to get density of stars with 100 , or even 1000 multiplication greater than our neighborhood of the galaxy . Stars can get as close together as the spoke of the Solar System .
But out in the immense interstellar gulfs between stars , the density drops importantly . There are only a few hundred item-by-item mote per three-dimensional meter in interstellar space . And in the intergalactic voids ; the gulfs between galaxies , there are just a handful of mote per meter .
How much stuff is there in a clean year ? It all calculate on where you look , but if you fan out all the matter around by shaking the Universe up like a snow ball , the answer is very penny-pinching to nothing .
This articleoriginally appearedat Universe Today .
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