Why is the Eagle Nebula so "static"?

  • This, of course, is a newbie question, as I am nothing more than a hobbyist. But I was quite surprised to see the recently-released "before and after" pictures of the so-called "Pillars of Creation" in the Eagle Nebula (here and here). For something that looks like such a "nebulous" cloud of gas (pardon the pun), I would have expected at least some visible sign of change in the 25 years between the two photos. But at the pixel resolution which I had available, I could not detect even the slightest difference between them. Of course, I am accustomed to terrestrial clouds which are in constant motion, so I (mistakenly?) expected something analogous at the astronomical level. Can someone provide, in layman's terms, how my understanding of this cosmological feature is deficient? In other words, how might I adjust my instinctive intuition that this object should be more dynamic? Is it just the sheer scale that I am not comprehending? (By the way: what is the distanse between the three spires, as compared to, say, our solar system?)

  • It appears to be static because it's huge beyond your imagination.

    The distance to the nebula is 7,000 light years. Its apparent size is 7 arc minutes. Therefore its linear size is about 14 light years.

    Think about that. The whole nebula is so big, it takes light 14 years to cross it. Any motion therein must necessarily be much, much slower. No wonder you're not seeing much change.

    Data source: wikipedia

    Calculation using Wolfram Alpha

    space.com gives the size of the Eagle Nebula as 70 by 55 light years, the pillars of creation being a smaller region within that. But yeah, still huge any way you slice it.

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Content dated before 7/24/2021 11:53 AM

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