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AndromedaWay
2013-Jun-17, 07:11 PM
I have a question for you. What, if you're into astronomy and outer space, fascinates you the most about it? For me it would be the sizes and distances involved. Talking about distances, consider: light travels at or around six trillion miles in a year in the vacuum of space. Yet, even moving 186,000 miles a second, it would take even light thousands, millions, even billions of years to get to all kinds of places in the universe. Those are the kinds of distances you can't even really think about, no matter how hard you try.
Then too there are the enormous sizes of things in the universe: galaxies, nebula, stars, what have you. We think our Earth is huge, and it is - to us. But our Earth fades into obscurity from a few billion miles out. Our solar system is, to us again, huge beyond imagining. And to us puny humans, it is. However it's tiny, tiny, tiny compared to our galaxy. And even our galaxy becomes a pinpoint of light the further in space you get.
I could prattle on and on about this kind of thing; hey, it fascinates me. Now, what fascinates you?

Solfe
2013-Jun-17, 08:17 PM
Endless variety for me. The distances are sort of a downer.

Spacedude
2013-Jun-17, 08:41 PM
All of the above that you listed but, it's the universe's estimated Age of 13.8 billion years that tops it for me. If there is a "God" involved he sure had a lot of time on his hands before thinking about creating the Earth and then us. Not only are we a speck in space, we're a speck in time.

BigDon
2013-Jun-17, 10:01 PM
All of the above that you listed but, it's the universe's estimated Age of 13.8 billion years that tops it for me. If there is a "God" involved he sure had a lot of time on his hands before thinking about creating the Earth and then us. Not only are we a speck in space, we're a speck in time.

And this is just the start.

Deep time studies suggest an outer age of three trillion years or 3000 billion. 13 billion years is still the opening credits.

BigDon
2013-Jun-17, 10:05 PM
Something just hit me. On this time-scale, when does the Universe run out of readily available hydrogen for star formation?

AndromedaWay
2013-Jun-17, 10:26 PM
Something just hit me. On this time-scale, when does the Universe run out of readily available hydrogen for star formation?
A long, long, LONG, LONG, LONG time from now ;)

neilzero
2013-Jun-17, 11:05 PM
I like the idea that we have a trillion more years of seeing naked eye stars. So I will guess that 1% of all the hydrogen everywhere is already in stars, planets, compact stars, brown dwarfs, asteroids comets and moons. On the bad side about 90 percent of the hydrogen is in the portion of the universe that is expanding at an accelerating rate, so it will likely never form stars, but possibly half of it is hydrogen ice, a few atoms per chunk = sub microscopic.
Most of the 1% is already sequestered, but trace amounts are escaping from various bodies steadilly and punctuated, such as red giant stars, solar wind and super nova = some of the hydrogen is being recycled. Likely there will be about half as many naked eye visible stars, just before Andromeda merges, which will possibly produce a ten times increase in naked eye visible stars for about a billion years , followed by a slow dwindling in their number as perhaps half of the hydrogen in our galaxy will be sequestered with the remainder mostly too widely scattered. A few other galaxies will be brightly lit, but possibly none within naked eye distance.
One trillion years from now there will still be lots of class M stars, but very few OBAFGK stars in our galaxy (unless another galaxy merges after Andromeda) as they will be cold compact stars with rare exceptions. Neil

slang
2013-Jun-17, 11:27 PM
Supermassive black holes eating stars. SMBH's small enough that the star gets torn apart outside the event horizon. Such events are called TDE's, Tidal Disruption Events, causing a gamma ray burst, and a lot of study has already gone into it. I won't pretend to understand most of it, but those events fascinate me, as does how information is eeked from GRBs to infer their happening.

That's eating stars. Those humongous gigantic and also very big things like that big yellowish son of a gun that gives us life. Eaten'. Like, zap. Fascinating. :)

edona7
2013-Jun-17, 11:40 PM
I like the fact that astrophysics encompass things as massive as SMBHs and things as small as quarks (when going back to the Big Bang). Kind of covers it all, physics wise. and get the best photos to look at. I can still remember when if first saw images from the Hubble Space Telescope. My favorite are the stellar nurseries. Something I could never have imagined.

Clarissa

Swift
2013-Jun-18, 01:23 AM
To elaborate, this section of the forum is for astronomy and space exploration questions with straightforward, generally accepted answers.
As this is almost certainly going to be a broad discussion, and not a question with a simple, straightforward answer, I'm moving this thread from Q&A to Astronomy.

Spacedude
2013-Jun-18, 02:16 PM
Thanks BigDon, after I posted "13.8 billion years" it hit me that I should have said "at the very least 13.8 billion years".

Buttercup
2013-Jun-18, 02:25 PM
Hypocrites.

Especially how blind to self they can be. :surprised:

Yeah, I know this is supposed to be about outer space: My answer is "distance." Mind-boggling.

Cougar
2013-Jun-18, 05:48 PM
What's really fascinating is how much our scientists have figured out in the past 100 years, before which it was unknown if the Milky Way galaxy was the entire universe or not. This is not to say there's not a lot yet to figure out, but come on, our understanding of the universe has really expanded beyond all imagination in the past 100 years.

kzb
2013-Jun-18, 05:51 PM
It's actually the closer to home stuff that I find most interesting. Our own galaxy and the solar neighbourhood. I think that is because I believe have a chance of actually understanding it. Plus, it's real things with a bit of certainty.

Beyond that, I think things are a bit woolly. A lot of current cosmology could well be heavily revised in the next few decades or centuries.

Ilya
2013-Jun-18, 07:15 PM
Brief summary of the future, in years:

If proton is unstable:

Sun becomes red giant: 5*10^9
All stellar activity ceases: 10^14
Galaxies cease to exist (all matter is either flung out or falls into central black hole): 10^22
All baryonic matter decays: 10^30-10^36
Star-size black holes evaporate: 10^66
Galactic black holes evaporate: 10^100

If proton is stable:

Sun becomes red giant: 5*10^9
All stellar activity ceases: 10^14
Galaxies cease to exist (all matter is either flung out or falls into central black hole): 10^22
Star-size black holes evaporate: 10^66
Galactic black holes evaporate: 10^100
All remaining atoms quantum tunnel into iron: 10^1600
Neutron stars quantum tunnel into black holes which then "quickly" evaporate: 10^(10^26)
All remaining iron quantum tunnels into mini-black holes which then evaporate: 10^(10^76)

Arneb
2013-Jun-18, 08:21 PM
All of the above that you listed but, it's the universe's estimated Age of 13.8 billion years that tops it for me. If there is a "God" involved he sure had a lot of time on his hands before thinking about creating the Earth and then us. Not only are we a speck in space, we're a speck in time.
Actually, I dare disagree here.

With distances, you quickly get into "more zeroes than a line of forum text holds on my screen" territory. With time, not so much. Consider that our good old Earth's is actually a whopping third of the age of this entire Universe. I mean a THIRD! And if you compress the estimated age of the Universe into an Earth year, a human lifetime is a bit less 1/5 th of a second - one camera click, with an exposure time which is difficult to hold steady with your hand even if you have an image stabilizer. These ratios to me seem... commensurable, if you like, as I have a good idea what a year is and a good idea what 1/5 th of a second is. It's very different with distances. Try doing that with a light year.I'd say those Solar System to scale parks, where the Sun is a baseball in the centre and Pluto is pinhead a few kilometers away are on a par with the times involved - you can imagine both distances. But that's just one light hour. And THEN the light years start, and the parsecs. an d the kilo-, mega, and gigaparsecs....

I remember someone saying that, compared to most processes on an atomic scale we get "almost as old" as the Universe.

Sounds comforting to me- but as BigDon said, 13.7 billion years are just the opening credits. Or even the cold open.

Arneb
2013-Jun-18, 08:23 PM
Brief summary of the future, in years:

If proton is unstable:

Sun becomes red giant: 5*10^9
All stellar activity ceases: 10^14
Galaxies cease to exist (all matter is either flung out or falls into central black hole): 10^22
All baryonic matter decays: 10^30-10^36
Star-size black holes evaporate: 10^66
Galactic black holes evaporate: 10^100

If proton is stable:

Sun becomes red giant: 5*10^9
All stellar activity ceases: 10^14
Galaxies cease to exist (all matter is either flung out or falls into central black hole): 10^22
Star-size black holes evaporate: 10^66
Galactic black holes evaporate: 10^100
All remaining atoms quantum tunnel into iron: 10^1600
Neutron stars quantum tunnel into black holes which then "quickly" evaporate: 10^(10^26)
All remaining iron quantum tunnels into mini-black holes which then evaporate: 10^(10^76)

That must be why they say, The Future is bright. The Future is Orange.

EDG
2013-Jun-21, 06:17 AM
What fascinates me is the fact that we and everything around us on our tiny, insignificant planet are made of - including our planet itself - was originally manufactured the hearts of dying (and sometimes exploding) stars. A lot of the atoms in my computer and monitor were made in a supernova!

"We are the Universe made manifest, trying to figure itself out.", as Delenn said on Babylon 5 :).

Spacedude
2013-Jun-21, 01:19 PM
With distances, you quickly get into "more zeroes than a line of forum text holds on my screen" territory.

True, but zeros are relative. if you are measuring in miles, light years, parsecs, inches, the number of zeros vary greatly. Same with time as in years, days, seconds, etc.

Romanus
2013-Jun-22, 04:57 AM
Habitable exoplanets, full stop. Think they should be our top priority.

Honorable mention: standard candles and astrometry, protoplanetary disks.

Paul Beardsley
2013-Jun-22, 07:11 AM
With distances, you quickly get into "more zeroes than a line of forum text holds on my screen" territory.

I do like this line!


True, but zeros are relative. if you are measuring in miles, light years, parsecs, inches, the number of zeros vary greatly. Same with time as in years, days, seconds, etc.

No, this isn't right. The point is, if you choose units that we as humans can relate to, you get an overwhelming number of zeroes for distance, but a much more manageable number of zeroes for time.

But this thread has reminded me of just how long the universe might last. The really significant stuff might be immensely far in the future. Maybe in a trillion or two years from now, there will be lifeforms arguing over evidence that suggests there was intelligent life in the universe when it was less than 14 billion years old. "No, that's far too early. There weren't enough second generation stars to produce the stuff of life in sufficient quantities back then."

Cheers to AndromedaWay for raising such a thought-provoking question. Hooray for new members!

caveman1917
2013-Jun-22, 03:15 PM
But this thread has reminded me of just how long the universe might last.

Luckily it was made before that recent manufacturing trend where everything breaks and you have to replace it every couple of years :)

ASTRO BOY
2013-Jun-24, 10:42 PM
I have a question for you. What, if you're into astronomy and outer space, fascinates you the most about it? For me it would be the sizes and distances involved. Talking about distances, consider: light travels at or around six trillion miles in a year in the vacuum of space. Yet, even moving 186,000 miles a second, it would take even light thousands, millions, even billions of years to get to all kinds of places in the universe. Those are the kinds of distances you can't even really think about, no matter how hard you try.
Then too there are the enormous sizes of things in the universe: galaxies, nebula, stars, what have you. We think our Earth is huge, and it is - to us. But our Earth fades into obscurity from a few billion miles out. Our solar system is, to us again, huge beyond imagining. And to us puny humans, it is. However it's tiny, tiny, tiny compared to our galaxy. And even our galaxy becomes a pinpoint of light the further in space you get.
I could prattle on and on about this kind of thing; hey, it fascinates me. Now, what fascinates you?



In a somewhat limited sense, it reminds me of that photo from Voyager when Sagan suggested the cameras be focused on the inner solar system from a position out near Neptune from memory....A Pale Blue Dot floating in a sunbeam was caught in that photo....That was us!

It also conjurs up plenty of speculative and Imaginative ideas of what could lie beyond our observable Universe, as well as within the confines of that comparitive small bubble and how far we have yet to go to even begin to unravel some of the mysteries it all entails.