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since we've been talking how stars formed and the evolution of stars

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i thought it was about time that we looked at some cool pictures of stars

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forming or stars themselves, or evolution of stars.

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so this right here is from the Eagle Nebula,

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Just so you know, the word Nebula is kind of a general word for any interstellar cloud of gas or dust

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so when we're talking about the Eagle nebula, we're actually talking about a huge nebula

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and actually, it's a nebula that expands.

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and so that you have a sense, this is just one of the pillars of the "Pillars of creation"

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This is just a small part of the actual Eagle Nebula

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And just this pillar right over here, just this pillar here

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so that you have a sense of how large it is, just this pillar itself is 7 light years

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it is 7 light years talls

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so this is an enormous amount of distance

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remember, the distance from earth to the nearest star was about 4 light years

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it would take voyager, if it were pointed in the right direction

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moving at 60 thousand kilometers per hour

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it would take Voyager 80 thousand years to go 4 light years

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just this pillar is 7 light years

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but i wanted to show you this because these type of nebulae, the plural of nebula

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are where stars can form.

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so this right here, you actually see, is actually a breeding ground for the birth of new stars

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this gas is condensing, just like we talked about a couple of videos ago. Until it gets to that critical

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temperature, the critical density, where you can actually get

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fusion of hydrogen

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so this is just a huge interstellar cloud of hydrogen gas

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and over here you can see its just this breeding ground for stars

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and we don't even, we think that this structure doesn't even exist anymore

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because remember, this thing is very very far away from us

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in fact is, just so you have the number, this thing is 7000 light years away

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7000 light years away

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which means that what we are seeing now, the photons that are reaching our eyes or telescopes right now

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left this region of space 7000 years ago

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so we're seeing it as it was 7000 years ago

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so a lot of this gas, a lot of this hydrogen, may have already condensed into many many more stars

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so the structure might not be the way it looks right now

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and actually there was another

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super nova that happened that might have blown away a lot of this stuff

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and we won't even be able to see the effects of this super nova

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for another thousand years

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but anyway, this is just a pretty amazing photograph in my opinion

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especially, and its beautiful at any scale

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and it's even more mindblowing when you think that this is 7, this is a structure

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that is 7 light years tall

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and this is really just part of the Eagle Nebula

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one of the pillars of creation

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this right here is a star field, and this is as we're looking towards the center of our galaxy

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the milkyway

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this is the Sagittarius star field

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the neat thing here you see is such a diversity in stars

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this is also kind of mind numbing because every one of these stars, are inside of our galaxy

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this is looking towards the center of our galaxy

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this isn't one of those where we're looking beyond our galaxy or looking at clusters of galaxies

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this is just stars here

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but the thing here is that you see a huge variety, you see some stars that are

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shining red, right over here

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and obviously, the apparent size, you cannot completely tell

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because the different stars are at different distances and at difference intensities

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but the redder stars, these are stars in their red giant phase

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or they're probably at their red giant phase

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i haven't done specific research on these stars

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but that's what we suspect

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those are in their red giant phase

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the ones that are kind of in the yellowish white part of the spectrum

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these are stars that are probably in their main sequence

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probably not too different than own sun

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the ones that are in the yellowish white, closer to orange-yellowish-white part of the spectrum

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and the ones that look a little more bluish, or a little bit more greenish

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these are burning super fast

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let me see if i can find, this one looks a little big bluish to me,

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these are burning super super fast, and so

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the super massive stars, they burn kind of fast and furious and then just die out

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but the smaller stars, the ones with less mass

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they burn slower over a much much longer period of time

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so the ones that are burning fast

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are emitting a lot of energy at the smaller wavelength part of the light spectrum

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that's why they look bluer or greener and these are going to be more massive stars

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the ones that look white or bluer or greener

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while the redder ones

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the redder ones are less massive stars that are kind of in their super giant phase

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and so they are at this point cooler than the main sequence stars

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this right here, this right here is the cat's eye nebula

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and the word nebula, this is actually a planetary nebula

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this one here is a planetary nebula

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and it's called a nebula because it is kind of this gas that's kinda floating out in space

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but it's at a completely different kind of scale than this Eagle nebula

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that we drew over here

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so when people talk about nebulas, they normally talking about something like the eagle nebula

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these huge masses of interstella gas

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when people talk about planetary nebulas; this is actually still a huge radius

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but no where near 7 light years

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but this is the bi-product of a star shedding all of its outer material

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so at the center of this, we see kind of a mature star here

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and it's shed of kind of its outer layers

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and it did that in its red giant phase

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so the core would keep flaring up, having these hot explosions

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and every time you have one of these hot explosions, you had more and more of its outer layers getting

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pushed off, pushed off into space

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forming this planetary nebula

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so this as we see it right now

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its still not yet a white dwarf, it is still an active star

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fusion is still occurring in this star, but it is well on its way onto becoming a a white dwarf

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once all its fuel runs out

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it's past its red giant phase, it's thrown all of this material into space and it's on its way onto becoming

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a white dwarf

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anyway hopefully you enjoyed that

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i actually find all of these images to be pretty captivating

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especially the star field one

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because this just inside of our galaxy

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hopefully it gives more appreciation for how many stars there are

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i mean this is just a small fraction of the 200 to 400 billion stars inside the milky way