People are saying that The Pillars Of Creation have been destroyed, and will take 400-500 Million light years to reach us. Can someone explain how do we know it when the light hasn’t reached us?
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Looking around the galaxy we can see many examples of the sequence of events as stars form from these sorts of clouds, and have worked out an appropriate timeline for how how long it takes.
When we (well, scientists in the respective fields) apply this knowledge to something like the Pillars of Creation we see the state shown is a temporary condition, with a fairly defined lifespan before it turns from a dust cloud into a star field.
We then compare that length of time against how far away they are we can know that the actual events have already occurred, just the light from those events won’t reach us for a very long time.
Edit: As others have pointed out, the specific demise of the Pillars is an impending supernova. For a star to go supernova it needs to be pretty decently sized, and perhaps counterintuitively, larger stars actually have much shorter lifespans. For very large stars this can be a few million years, vs the billions of years our Sun has left.
As a star matures it starts burning different fuels in its core – first hydrogen, then helium, then carbon, then oxygen, then finally silicon. The duration of each state shortens, dramatically. It can fuse hydrogen for millions of years, helium for tens of thousands, carbon for a few hundred, oxygen for a matter of months, and silicon for about a day.
Once it starts fusing silicon the product (Iron) sucks energy out of the reaction, so the force from the ongoing nuclear explosion in the center can no longer hold back the enormous force of gravity, and the star collapses in on itself, resulting in a supernova.
If we see evidence; or a timeline that suggests, a star 6000 light years away is in the carbon burning stage we know it’s already gone through a supernova and some time in the next ~500 years we’ll see the result.
Well, it will take around 6000 years, not 500 million.
We don’t know, it’s a prediction based on observing other space objects. Based on what we’ve seen before they expect the same to happen
So, first thing first, the pillars of creation is part of a nebula inside our own galaxy 6,500 to 7,000 light years away. That means that the light we can see from it now, has originated 6,500 – 7,000 years ago. As far as I understand, there is believed to be a supernova that we see developing near the pillars, again with light from thousands of years ago.
The supernova would be very energetic and its shockwave would likely scatter the gas, destroying the pillars as they are today. There is a timeline prediction for that supernova saying that it happened ~5000 years ago. But we might not see the supernova and its effects on the nebula for many years. So, in effect the nebula might be gone, we just waiting to see it unfold.
The Pillars of Creation are a star forming region, a dust cloud, about 7000 light years away. That means we see them as they were 7000 years ago. A light year is a measurement of distance, not of time. The length that light travels in one year.
The 400-500 million years number is definitely wrong, that is very roughly a time frame for star formation.
We have observed other, similar star formation regions and have a pretty good understanding what happens there and at what timescale. We also have computer models that represent the pillars quite accurately.
The destruction specifically refers to observations that a shock wave from a supernova (an exploding star) is wiping the dust cloud away so it will no longer be visible. That means we have some hints that this is happening or beginning to happen and that’s how we know it. If that is happening right now, we will only know of it, as in actually seeing it, in 7000 years.
Your mate takes a photo of a strange cloud and sends it to you by mail. When you receive it, you look at the picture, you know the post took two days and clouds don’t last that long.
People don’t seem to understand that light years is a measurement of distance, not time. It won’t take 4-500 million light years to reach us, it will have to travel 4-500 million light years to reach us.
You know the light has reached us when you can see it. The Eagle Nebula is about 7000 light years away, meaning when you look at it, you are seeing it as it appeared 7000 years ago.
Is the structure still there? No way to know other than wait and watch it change over time. But 7000 years is a very short time– so probably
I have a cool photo of a friend of mine jumping to catch a flying trapeze. I caught her mid air, in a perfect “superman” style pose. Despite it being a photo so you can’t literally see her moving, just from her posture and where she is relative to the trapeze, you can immediately tell she didn’t make the jump. We’ve all seen enough people jumping to know what a miss looks like.
The Pillars of Creation are a similar situation. We’ve seen enough other similar things that we know what to look for, and we know that the way they look means they’re going poof.
Eli5: The same way that you can put a banana on a counter and can say, “In a week or two this banana is going to be withered and moldy.”
The arrow of time moves forward, and knowing the natural progression of things based on similar observations allows us to make these predictions.
Well, light *has* reached us, it’s just that it took 6,500 years for that light to get to us. Light travels at 650 million miles per hour, which is really fast. But the universe is so damn big that it still takes 4 years for light to travel to us from our closest star (not including our sun lol)This means that when you look into the night sky and see that star, you are seeing that star as it was 4 years ago.
So the pillars of creation could be gone completely for all we know, but we wouldn’t be able to see any change from our telescopes until 6,500 years *after* they stopped emitting light. So if they died 6,499 years ago, we would be able to see that change next year, because that’s how long it took for the light to reach us through the vast vast vast emptiness of space
Edit: just a cool thing taking it one further. This means that time travel *does* exist already and has for the entirety of human existence. The night sky is a window into the past where we can see thousands and millions and even billions of years into the past. The universe is fokin cule m8
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