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Toepoke

There is no dark side of the moon

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7 hours ago, mrniaboc said:

I had no idea there was an astronomy thread on the TAMB. Good stuff! 

There's more than one! There are (from memory) ones on lunar eclipses, perseids (or leonids) and the flat earth (under various threads, including one about a 'weegie accent' IIRC).

Edited by exile

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19 hours ago, mrniaboc said:

I had no idea there was an astronomy thread on the TAMB. Good stuff! 

Mr Nybock, i have an astronomy question...

Earlier tonight i was telling my missus about how her parents live in an area of the country with 'dark skies'... i.e. no light pollution, and therefore great for stargazing.

When i was last there, i was able to see the 'band' of the milky way. A long section of the sky that was brighter than the rest of it.

My question is why? Why does the galaxy form in this way?

I've tried reading this, but am none the wiser. https://en.m.wikipedia.org/wiki/Milky_Way

Please explain it to me like i'm 5.

 

Edited by Dave78

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1 hour ago, Dave78 said:

Mr Nybock, i have an astronomy question...

Earlier tonight i was telling my missus about how her parents live in an area of the country with 'dark skies'... i.e. no light pollution, and therefore great for stargazing.

When i was last there, i was able to see the 'band' of the milky way. A long section of the sky that was brighter than the rest of it.

My question is why? Why does the galaxy form in this way?

I've tried reading this, but am none the wiser. https://en.m.wikipedia.org/wiki/Milky_Way

Please explain it to me like i'm 5.

 

Great question Dave! 

In very simple terms spiral galaxies, like our Milky Way, form into flat disks because they are spinning. Just like the planets going round our Sun in the Solar System, the stars in our galaxy are all orbiting round the centre of the galaxy. With everything rotating round in the same direction its easy for the stars and gas to flatten out into a disc. 

In slightly less simple terms the rotation of the gas leads to collisions of the gas molecules and they therefore lose energy. However, the gas doesn't lose its total angular momentum (as this should always be conserved). This combination of losing energy while conserving angular momentum means the gas forms into a flat disc shape. 

I hope that helps a little bit. It's great to get out to a dark sky sight and see that Milky Way band. I miss it living in London. 

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44 minutes ago, mrniaboc said:

Great question Dave! 

In very simple terms spiral galaxies, like our Milky Way, form into flat disks because they are spinning. Just like the planets going round our Sun in the Solar System, the stars in our galaxy are all orbiting round the centre of the galaxy. With everything rotating round in the same direction its easy for the stars and gas to flatten out into a disc. 

In slightly less simple terms the rotation of the gas leads to collisions of the gas molecules and they therefore lose energy. However, the gas doesn't lose its total angular momentum (as this should always be conserved). This combination of losing energy while conserving angular momentum means the gas forms into a flat disc shape. 

I hope that helps a little bit. It's great to get out to a dark sky sight and see that Milky Way band. I miss it living in London. 

Thankyou! That's a much clearer answer for an eejit like me compared to dry wikipedia pages.

And now my followup question...

You say all galaxies are orbiting round the centre of the universe. Why do they do that? I mean, i can understand how planets revolve around the sun, as it's the most massive thing in our solar system. But what's at the centre of the universe to make everything orbit it?

I'm guessing the eagle of the 9th, and an alien mega-structure in the shape of 42.

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On 12/1/2019 at 3:43 AM, Dave78 said:

Thankyou! That's a much clearer answer for an eejit like me compared to dry wikipedia pages.

And now my followup question...

You say all galaxies are orbiting round the centre of the universe. Why do they do that? I mean, i can understand how planets revolve around the sun, as it's the most massive thing in our solar system. But what's at the centre of the universe to make everything orbit it?

I'm guessing the eagle of the 9th, and an alien mega-structure in the shape of 42.

Hahahaha. Actually there's an important distinction here. What I said was that the stars in a galaxy are orbiting around the centre of the galaxy, just like the planets in our solar system orbiting around the Sun. However, galaxies do not orbit around the centre of the Universe. In fact, there is no centre! Our Universe is homogeneous and isotropic, which is really just a fancy way of saying that at large scale it looks the same in all directions regardless of where you are in it. At large scales, galaxies are all actually moving away from each other as space expands. It was observing this expansion of space that led to the Big Bang Theory, which suggests that at one point in the past the Universe was so small that everything in it was basically contained in a tiny point, then it started expanding outwards.

OK, I hope that's not too much.

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Everything is moving away from each other at ever increasing speeds. Some parts of the universe are now too far away to ever catch them with light. Eventually everything will be in complete isolation with everything else. This expanding force isn't well understood at all. It may just be a propery of space and as more space exists (universe expands) so more of this property exists and therefore the universe expansion keeps getting quicker and quicker.

A lot of galaxies have huge masses in their centre, Black-holes basically.

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1 hour ago, phart said:

Everything is moving away from each other at ever increasing speeds. Some parts of the universe are now too far away to ever catch them with light. Eventually everything will be in complete isolation with everything else. This expanding force isn't well understood at all. It may just be a propery of space and as more space exists (universe expands) so more of this property exists and therefore the universe expansion keeps getting quicker and quicker.

A lot of galaxies have huge masses in their centre, Black-holes basically.

Exactly right. The fate of our Universe appears to be a cold, isolated one. Best to focus on the footy instead.

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7 hours ago, Grim Jim said:

Stuff isn't moving apart though is it?   Is it not space that is expanding, or have I got that wrong?

It depends on how you look at it.

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18 hours ago, mrniaboc said:

Exactly right. The fate of our Universe appears to be a cold, isolated one. Best to focus on the footy instead.

I last sat in a physics classroom 15 years ago, i wish "exactly right" was my legacy from those days but unfortunately it was more "I can see where you're coming from but you need to work a bit harder"

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9 hours ago, Grim Jim said:

Stuff isn't moving apart though is it?   Is it not space that is expanding, or have I got that wrong?

Both. The galazies are moving in space while space itself is expanding as well. Like particles of air moving in a balloon but you blow it up as well so the volume increases as the particles move about inside it. 

The actual mechanics are probably different just as a conceptual model.

Since we're on this i was reading yesterday that a few experiments have given credence to quantum biology

"It has been an exciting week for quantum biology enthusiasts, with two separate studies suggesting new ways to leverage quantum principles in life sciences applications.

Researchers from the Quantum Nanophysics Group at the University of Vienna found a “quantum interference in molecules of gramicidin, a natural antibiotic made up of 15 amino acids,” potentially opening a door to a “new era for quantum biology,” according to MIT Technology Review.

A separate paper published in Nature this week also suggested that “the theory of quantum open systems can successfully push forward our theoretical understanding of complex biological systems working close to the quantum/classical boundary.”

https://karmaimpact.com/new-era-for-quantum-biology-is-upon-us/

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10 hours ago, Grim Jim said:

Stuff isn't moving apart though is it?   Is it not space that is expanding, or have I got that wrong?

It's basically like space is being created between the galaxies. On a smaller scale however gravity is stronger, and some galaxies are moving towards each other. In a few billions years we will crash into our neighbour galaxy Andromeda.

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41 minutes ago, phart said:

I last sat in a physics classroom 15 years ago, i wish "exactly right" was my legacy from those days but unfortunately it was more "I can see where you're coming from but you need to work a bit harder"

Hahaha I remember those days. Your explanations are spot on though mate!

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42 minutes ago, mrniaboc said:

 In a few billions years we will crash into our neighbour galaxy Andromeda.

And the UK will still be in Brexit negotiations.

"Fucking Andromedans... coming over here, stealing our jobs!!"

 

 

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this one is probably for mrniaboc ??

Watched a clip on TV (think it was Neil Tyson ?) i'm sure he said there are more stars (suns) in our Universe than there are grains of sand on every beach on planet earth - I'm no use at Maths but surely that can't be correct, that number would be incalculable ??

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On 12/3/2019 at 3:08 PM, mrniaboc said:

Exactly right. The fate of our Universe appears to be a cold, isolated one. Best to focus on the footy instead.

Being a scotland fan could be described as cold and isolated too

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46 minutes ago, glasgow jock said:

this one is probably for mrniaboc ??

Watched a clip on TV (think it was Neil Tyson ?) i'm sure he said there are more stars (suns) in our Universe than there are grains of sand on every beach on planet earth - I'm no use at Maths but surely that can't be correct, that number would be incalculable ??

Easily more. Aye the universe is so huge it's mind bobbling. That's just visible stars as well. Plus it's ten times more and not just beaches but deserts as well.

 

A random copy paste

" More stars 'than grains of sand' There are 10 times more stars in the night sky than grains of sand in the world's deserts and beaches, scientists say. Astronomers have worked out that there are 70 thousand million million million - or seven followed by 22 zeros - stars visible from the Earth through telescopes. "

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3 hours ago, glasgow jock said:

this one is probably for mrniaboc ??

Watched a clip on TV (think it was Neil Tyson ?) i'm sure he said there are more stars (suns) in our Universe than there are grains of sand on every beach on planet earth - I'm no use at Maths but surely that can't be correct, that number would be incalculable ??

Here is one explanation. Be warned though, it's not a short answer.

http://cosmologyscience.com/cosblog/comparing-total-number-of-stars-with-grains-of-beach-sand/

 

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4 hours ago, glasgow jock said:

this one is probably for mrniaboc ??

Watched a clip on TV (think it was Neil Tyson ?) i'm sure he said there are more stars (suns) in our Universe than there are grains of sand on every beach on planet earth - I'm no use at Maths but surely that can't be correct, that number would be incalculable ??

Well, as phart posted, there are around 10000000000000000000000 stars in our observable Universe. You can get this number by multiplying the average number of stars in a galaxy (about 100 billion) by the number of galaxies in our Universe (about 100 billion).

However, I have no idea how to estimate the number of grains of sand on Earth hahaha.

The amazing thing is that we're starting to see that most of these stars have planets around them!

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18 hours ago, mrniaboc said:

Well, as phart posted, there are around 10000000000000000000000 stars in our observable Universe. You can get this number by multiplying the average number of stars in a galaxy (about 100 billion) by the number of galaxies in our Universe (about 100 billion).

However, I have no idea how to estimate the number of grains of sand on Earth hahaha.

The amazing thing is that we're starting to see that most of these stars have planets around them!

Just think then - if that is true, then even if complex and intelligent life only evolves once in every million star systems, the Universe should be teaming with life - right ? (as stated above i'm shite at the Maths ha ha)

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11 minutes ago, glasgow jock said:

Just think then - if that is true, then even if complex and intelligent life only evolves once in every million star systems, the Universe should be teaming with life - right ? (as stated above i'm shite at the Maths ha ha)

That's exactly right. Obviously we haven't observed any yet, but the numbers mean that there are an unbelievable amount of chances for life to form. It would be mathematically surprising (to say the least) if Earth was the only place it happened. 

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19 hours ago, Orraloon said:

Here is one explanation. Be warned though, it's not a short answer.

http://cosmologyscience.com/cosblog/comparing-total-number-of-stars-with-grains-of-beach-sand/

 

Cheers Orraloon - my Brain has just melted 😂

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