What is the farthest distance we have seen and how can we determine the distance?

[Omnis]

To be more specific, what is the farthest distance we've seen into space in light years? Also, how can we determine how far away something is based in light years? Is it all down to size vs. magnification or what?

 

[skip0110]

I believe we have seen pretty close to the beginning of time, so the distance in light years is equal to that time.

Remember, since light takes time to travel, you are looking into the past whenever you look at something. For something close to you it's less than a nanosecond, but in space, that time matters.

We measure the distance by measuring the intensity of the background radiation from the big bang, which dissipates in a well-known manner. By measuring the level of this radiation, we know how long ago the thing we are looking at happened, and thus know how far away from us it is by multiplying that time by the speed of light (actually, the distance in light years is equal to the time because of the way the units are defined).

 

[Jedi2016]

Many millions of light-years, I'm sure. We've seen entire groups of distant galaxies.

 

[niky]

We're still about half-a-billion years or so from seeing all the way to the Big Bang... depending on how long ago it was. I think the furthest scientists have "seen" so far with optical telescopes is about 15 billion years back, give or take. But there's very little you can actually see at these distances. It's like saying you can see Mars with your naked eye, but you can't actually say anything about it, except it's "reddish".

 

[Omnis]

Thanks, skip. That answers my question.

 

[3-Wheel Drive]

The [WIKIPEDIA]Hubble Ultra Deep Field[/WIKIPEDIA] is the furthest we've seen into space, @ 13 billion light years.



YTMND has a pretty cool thing about one of the Deep Fields:
A Tiny Glimpse

 

[Klostrophobic]

All these years I thought we used a big freakin' ruler.

 

[Sureboss]

A rather useless yet interesting fact coming up.

I was watching a programme about the sun the other day (on Discovery Science) and they were saying that it takes the light once created 200,000 years to get from the core of the sun to the 'outer' yet only eight and a half minutes to reach earth.

 

[Touring Mars]

Many millions of light-years, I'm sure. We've seen entire groups of distant galaxies.

Try billions... ~13.7 billion light years is as far as we can 'see', and even with much more powerful telescopes and/or techniques, we could not see beyond that (even in principle) because that distance is the horizon (in time) as far back as the moment of the Big Bang itself.... although it doesn't mean that there are no objects further away than that, it just means we cannot see them... e.g. if we moved to a planet 10 billion light years away from Earth, we would still be able to see 13.7 billion light years in all directions (including our old planet 10 billion light years away) but we'd also be able to see objects between 13.7 and 23.7 billion light years distant to Earth, which we could never actually see from Earth itself...

It also doesn't mean that these objects are actually 13.7 billion light years away from us either... the most distant galaxies that have been seen by the Hubble Space Telescope are moving away from us at such a rate, and, given that it takes time for the light to reach us, they are actually about 46 billion light years away from us now (although we 'see' them at 13.7 billion light years distance)...

 

[Famine]

It takes over 8 and a half minutes for the Sun's light to reach Earth...


We measure distances with redshift. By measuring luminosity and size of a star you can determine the approximate mass. Plug it into the Hertzsprung-Russell diagram and you can find out what colour it's supposed to be. Find out what colour it appears and you can determine how far it has moved towards the red end of the spectrum (Redshift) and you can then say how far away it is.


The largest redshift ever detected equates to 13.7 BILLION light years distance.


You can also measure stellar parallax, by observing the object for a long time in comparison to known objects. The greater the stellar parallax, the closer the object is.

 

[Christhedude]

as i am really into sience like that, its really interesting!
Can somebody please explain to me, what you mean with...looking back at the big bang.
I dont really get it...how can you look back at the big bang, and how can you even look back in time. I know theres something about looking into the past if you travel more then light speed.
chris

 

[UnoMOTO]

I'm trying to think this one through here so give me some help. First we start with a BIG BANG. All types of matter including light start spreading out from a common point. I don't think that the matter that would eventually make up the earth traveled at the speed of light. So...wouldn't the light information about that BANG moment be long gone already? Unless you’re saying that you can see far enough in the opposite direction to "catch up to the light information".

Since light travels faster then matter how can we see the moment of the bang? I hope you understand what I am asking. I wish I could draw a picture to explain my thought.

edit:
treed with the same question

 

[Sureboss]

I've always been early for things.

Also, I don't want to be around when the Sun eventually 'runs out' of 'fuel'. That'll be one weird event, I wonder if we'd have caught Bin Laden by then?