An astronomical event I would like to witness.

Super novas happen on average about once a century per galaxy which means we aren't very likely to witness one in the Milky Way. The nearest star that is on the verge of exploding is betelgeuse and according to what I've read and heard it could explode at any time. Again according to what I've heard it will be a spectacular sight while still not close enough to earth to impact us. While I'm not wishing any possible aliens a very bad day I would like to be around to see the event.
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Bob DeWoody

The last one was in 1604 in our Galaxy. So a supernova is overdue.
Tullio
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Yeah chris but the theories that it could go bang at
any time are based from observations that are 600 years old
(that is what we are seeing now)
If it does go bang in the next couple of years
then it will in fact have happened 600 or so years ago.
It could go tonight. But you wouldn't see it for the
fireworks in Edinburgh.

If it just actualy physically exploded now,we wouldn't know.
We would have to wait 600 years for the light to reach us.

The thought that it could blow at any minute can only be based
on observations from 600 year old light.

Therefore it could have (and probably has) already exploded,
so when we "see" and therefore discover it ,we would be seeing
live and in real time something that happened 600 years ago.

So what i meant by bang tonight was the actual visible discovery.
So instant viewing.

We are saying the same thing in different ways aren't we ?

john3760


Anyway off tho the pub.
(I'm old fashioned i still like to wait till 12 on a sunday)

I prefer Newcastle Brown,but i had one for you anyway.

This actually got me thinking .

What is the actual size of the universe at this moment in time ?

We know it is 13.75 (or so) billion years old,because the most
distant things we can "see" (detect) are 13.75 or so light years away.

Our perception of the actual size of the universe is based on
what we can see.

But that light / radiation has taken 13.75 billion years to get
to us ,so the emitters of this light/radiation can't possibly be in the same place as they were 13.75 billion years ago.They have had that amount of time
to move at whatever speed everything moves apart, so the universe must be at "this moment in time as we see it" billions of times bigger than we
percieve it.

We would have to wait 13.75 billion years to see the size of the universe
as it actually is at this moment in our time.

Just a thought

I'm probably horribly wrong.

john3760

As we look to the sky we see the past. Three supernovas were sighted in historical times, the Crab in 1054 a.D., the Tycho in 1572 and the Kepler in 1604, plus a Lupus in 1006. But they had exploded way before.
Tullio
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The Universe is 54 billion light years across. This is due to inflation and expansion at faster than the speed of light.

I thought it was 30 billion across.
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Proud member of TSWB.

End terrorism by building a school

I googled THE SIZE OF THE UNIVERSE ,and came up with this.

http://www.google.co.uk/url?sa=t&rct=j&q=http%3A%2F%2Fmembers.shaw.ca%2Ftfrisen%2Flee%2520strobel%2Fhow%2520big%2520is%2520our_universe.htm&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fmembers.shaw.ca%2Ftfrisen%2FLee%2520Strobel%2Fhow%2520big%2520is%2520our_universe.htm&ei=wjYBT6KwLoXO8QPIoODWAQ&usg=AFQjCNHp6SSAzxMwZ0XausIxCu88xKav3w&sig2=tnauEHETkahbBDuixrL73g

I'm pleased i didn't try to work it out myself,I'd probably be on a long time.


john3760

According to Stellarium Betelgeuse is 427.47 LY away so if it exploded 427.46 years ago we could be seeing it any time now. Tonight is a very clear and cool evening over central Florida and even to the naked eye Betelgeuse looks very red.
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Bob DeWoody

I thought it was 30 billion across.

Well, I am running Albert@home, which is a Beta Project like Test4Theory@home. Poor Uncle Albert would be surprised by many things, including neutrinos...
Tullio
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Do you know or can you point me in the right direction,
where i can find out the latest data about the speed
of the expansion of the universe.


john 3760

Try here:
Nature
Tullio
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Another thread gone astray.
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Bob DeWoody