astraburning62 wrote: ↑Wed Aug 04, 2021 5:38 am
I get really tired of descriptions of intergalactic objects such as Centaurus A (which is 13.05million light years away) as being 'nearby'. 13 million lights is not in any human sense of the word, 'nearby'. Sure, in a galactic relativistic sense its closer than most but use of this kind of relativistic language is far from helpful in communicating just how vast interstellar distances actually are. It still stuns me that highly educated intelligent people still have a warped understanding of how truly vast the universe - to me its the flat earth mentality of the era we inhabit. We need to start communicating better the cosmic realities and not cushion people from them. Having said that, very interesting picture, thanks for posting APOD Robot.
Think of it like this. In space almost nothing is nearby, apart from the Moon. That is why people have visited the Moon and come back from it alive.
13 million light-years is actually quite nearby for another galaxy. And Centauri A is the most nearby galaxy that has an actively accreting supermassive central black hole with a jet. So yes, in view of what Centaurus A is, it is nearby.
An aside here: I once created a simple more or less to scale model of the inner Solar system, using a 2 meter in diameter table cloth for the Sun, a 0.02 meter in diameter cotton ball for the Earth, and a yellow pea for the Moon. I also created Mercury (a pea), Venus (a cotton ball) and Mars (another cotton ball), and then I found a long enough straight stretch of walking path in a park, and had other people help me place the objects at the roughly correct distances from each other. It completely boggled my mind to see how far away the planets were from each other and from the Sun. And that was only the inner
(But the Moon was ridiculously close to the Earth.)
So I completely agree with you that space is... vast, for the lack of a better word. Space is humongous, to use another puny word for what space really is. I realize that as a human, I can't even begin to picture the "true" distance to Alpha Centauri in my mind. I can (at least in theory) make a model of the nearest stars and place them at more or less correct distances from each other, and I can certainly look at other people's models or drawings of the 3-D relationships between the nearest stars and get a good idea of the relative distances involved, but I absolutely can't picture the true kilometer by kilometer distance to Alpha Centauri in my mind. And I'd say that no one can, because no human brain is equipped to deal with such vastness.
For all of that, Centaurus A is nearby, in view of what sort of object it is.