How is it we can see galaxies light years away?

[Specter]

Let's say we look through the hubble telescope back in 1990, wouldn't it take a light year to actually see anything that far? So where are imageslike this coming from?

 

[toast1985]

I was thinking about this while watching "Alien Planets" on National Geographic a few days back .

 

[Kobekobe]

photoshopped.

 

[stonedface]

you're not looking at the present, but at the past

 

[raptors29]

Isn't a light year a measure of length, not time?

 

[recycledpaper]

i just had this discussion with some guy on here... i had a similar thought that by looking at the stars right now, we are technically looking into the past ofthe star. he corrected me by saying that is not how it works. it had to with relativity, i forgot what he said though.

 

[maddenfan04]

Originally Posted by raptors29

Isn't a light year a measure of length, not time?

/thread

 

[recycledpaper]

looking at all those galaxies.. you KNOW there's a place like pandora out there

the only problem is getting there... any NT'ers up to date on space travel technology? any advances that are currently being tested? damn we need to enterthe space age!

 

[spsfinest212]

that looks like some shiny stuff on a piece of black foam...

 

[stonedface]

Originally Posted by MaddenFan04

Originally Posted by raptors29

Isn't a light year a measure of length, not time?

/thread

a lightyear is the distance light travels in one year.. so yea its a measure of length. Space and time are relevant I just dont completely understand how orwhy.

 

[doosta45]

Originally Posted by StonedFace

you're not looking at the present, but at the past

this

whenever you see a star twinkle, its a galaxy/star that exploded some thousand, million, billion years ago thats finally reaching us

 

[Specter]

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 minutes to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn'tmake sense to me.

 

[doosta45]

^ i swear it was if the sun exploded, it would hit us in like 8minutes or something like that. not no 7 years

 

[recycledpaper]

Originally Posted by Dips3tRydah

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 years to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn't make sense to me.

i don't know who is dumber, you or the person who told you that.

 

[Specter]

Originally Posted by recycledpaper

Originally Posted by Dips3tRydah

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 years to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn't make sense to me.

i don't know who is dumber, you or the person who told you that.

I meant minutes my bad.

 

[stonedface]

Originally Posted by recycledpaper

looking at all those galaxies.. you KNOW there's a place like pandora out there

the only problem is getting there... any NT'ers up to date on space travel technology? any advances that are currently being tested? damn we need to enter the space age!

Whats the point even if space travel technology is getting more advanced, the government will never tell the truth about what they discover out inspace, just because they believe society and religion isn't ready to accept extra terrestrial life-forms.

The world as we know it, is the world as we know it, and nothing else, maybe someday we will understand the truth to our existence but not in any of ourlifetimes

 

[dirtylicious]

the light has been travelling to earth for a lot longer than we could detect and see it

 

[much respected]

Simply put.. when you look @ something it's not like a telephone call where the light only starts illuminating when you're looking. It's constantso when you're looking you're looking at light that has traveled across the universe for sometimes billions of years.

 

[recycledpaper]

Originally Posted by Dips3tRydah

Originally Posted by recycledpaper

Originally Posted by Dips3tRydah

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 years to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn't make sense to me.

i don't know who is dumber, you or the person who told you that.

I meant minutes my bad.

o ok, carry on then

 

[lieutenant kif]

Originally Posted by Dips3tRydah

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 minutes to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn't make sense to me.

huh?

This is how it works. The closest star to earth is about 4 light-years away, this means that if you look at it tonight, you are actually seeing the light ofthat star from 4 years ago. If you look at it 4 years from now, you will be seeing the light it emitted today.

For stars that are 20 light years away, in 20 years you will see the light that it emitted today.

 

[dirtylicious]

8.3 minutes

 

[1c3m4m]

Originally Posted by doosta45

Originally Posted by StonedFace

you're not looking at the present, but at the past

this

whenever you see a star twinkle, its a galaxy/star that exploded some thousand, million, billion years ago thats finally reaching us

Wow, I nvr knew that

 

[recycledpaper]

Originally Posted by Lieutenant Kif

Originally Posted by Dips3tRydah

Originally Posted by StonedFace

you're not looking at the present, but at the past

I get that, just like how the suns light takes 7 minutes to hit earth, but how is it in only 20 years we can see galaxies 40+ light years away? Doesn't make sense to me.

huh?

This is how it works. The closest star to earth is about 4 light-years away, this means that if you look at it tonight, you are actually seeing the light of that star from 4 years ago. If you look at it 4 years from now, you will be seeing the light it emitted today.

For stars that are 20 light years away, in 20 years you will see the light that it emitted today.

yep that's how it is.

now i'm gonna ask a question i asked some other dude, please correct me and explain again.

say one of the stars you're looking at isn't even there anymore and you are just looking at the light that's still traveling. if you looked at saidstar with a telescope, would you be viewing the past of that star? is that how it works?

 

[nktran001]

I love these kind of topics.

 

[lieutenant kif]

^ well the telescope doesn't really make a difference, since the telescope and your eye are at the same place.

But yes, you are looking at the image of how it existed in the past. How far in the past depends on how many light years away it is.

If a star that is 20 light years away exploded today, and tomorrow wasn't there at all, then 20 years from now you would see all the light from thatexplosion. 20 years and 1 day from now you would see empty space where the star used to be. But during those 20 years, when the light was in transit, thatspace would have been empty, we just wouldn't have known it in those 20 years.