Some confusion about light years... Need help!?

Question

They say a light year is the distance travelled by light in 1 year. So now if some star is said to be 10 billion light years away, it means it must take light some 10 billion years to get to us, doesn't that also mean that whatever we are seeing of that star at this time is actually 10 billion year old story & what may exist that far right now might be very different than what we can see???

Analogous to the above concept, theoritically, anything travelling (towards us) faster than light would always be invisible, isn't it? If, at this time, something is headed for earth, travelling faster than light, we will never even see it before we are hit.

Answer 1

yes

Answer 2

Very true..... even if it traveled at light speed we may not see it since even with our vast resource we can only search and keep an eye on about 30%(i think dont quote me) of the space.

But it is a possiblity to travel faster than light. Just because we havent seen/found it doesnt mean it doesnt exist. if something left the sun at 240 times faster then the speed of light we would NEVER see it since it gets to earth in app. 1 second and keeps going.

So yes it is a possibility, but very hard to target billions of light years away. like try hiting a grain of sand 200miles away with a rifle bullet.

Answer 3

Just to shake this up a bit here, if it takes some 10 billion years for light to hit us, or wherever we are, according to this theory, if I am reading it correctly thus this conclusion can be formed:

If the sun burns out, we will still see light for another 10 billion years, provided that we are 10 billion light years away, and that we were already seeing light from the sun.

How is this explained, it doesnt make too much sense to me?

Answer 4

Yes you got it exactly
A star you are looking at a billion light years away, you are looking a billion years into the past.
Intergalactic objects called Quasars only exist at very long distance in light years. Therefore they are unlikely to exist currently and are an example of something that existed at an earlier period in the universe's history. This shows the universe is not steady state but evolves and changes. A light year is about 6 trillion miles

Answer 5

I'm no expert, but when you're looking at a star that is 10 billion light years away, yes, you're seeing light that is 10 billion years old. Like with the sun, the light we see from the sun is eight minutes old.

Answer 6

You were on a roll until you mentioned faster than light travel. As far as our current understanding, nothing can travel faster than the speed of light. In fact, only light can travel exactly at the speed of light. To talk about faster than light travel is speaking science fiction, not fact... at least for now. ;-)

Answer 7

Yeah. The further out you look into space, the further you are looking back into time. For instance, the sun is about 8 light minutes away from the planet Earth, so if there were to be a supernova, we wouldn't see it for 8 minutes.

Answer 8

Yes, that's right. There is no way for us to know what any given area of space really looks like "right now" if it is more light years away than our own ability to send craft there. We can only tell what it looked like however many light years ago.

Someday we may have other ways to "see" but right now, the speed of light is our limit.

Answer 9

if it is in fact 100 bill away odds are the star no longer exists so yes that is very much true. what you see of the sun is approx. 8.3 m away. you never actually see somthing in real time.

Answer 10

You are exactly correct. That is why the Hubble spacescope can see in the past. Very hard to fathom (believe) but true.

Thanks,
Buster

Answer 11

Correct.