How far can I (one) see?

[Dibble]

I've just let the idiot dog out in the garden for a whizz.

It's a clear night and I can "see" many constellations - Orion's Belt is the one that is most obviously visible. So can I actually "see" billions of miles? If I can't actually see these billions of miles, how come I can see so many stars/constellations?

[RobinBanks]

The light is very bright so it's getting to you rather than you seeing that far as such!

[Moonhawk]

The Andromeda galaxy is visible to the naked eye - it is 2.5 million light years away.

As the poster above states however - human vision is limited simply by having a light source bright enough to be detectable by the photoreceptors in your eye. In that case - human vision is, in theory, infinite given a sufficiently bright source of light.

Edited by Moonhawk on Monday 1st December 00:30

[MLH]

Moonhawk said:

The Andromeda galaxy is visible to the naked eye - it is 2.5 million light years away.

Ive just had to google that in terms of miles...

14,696,249,525,000,000,000 miles!

What provides the light source for this galaxy?

Either way my mind is puddled! It always is when it comes to space!

[longshot]

MLH said:

Moonhawk said:

The Andromeda galaxy is visible to the naked eye - it is 2.5 million light years away.

Ive just had to google that in terms of miles...

14,696,249,525,000,000,000 miles!

What provides the light source for this galaxy?

Either way my mind is puddled! It always is when it comes to space!

A st load of stars or suns if you like.

[Monkeylegend]

You are looking back in time.

[SLCZ3]

You are actually only seeing to the photo receptors in your eyes, the light impinging on it , so you see the image that has crossed/travelled that distance over a period of time.
So clear as mud eh.

[mcflurry]

Dibble said:

I've just let the idiot dog out in the garden for a whizz.

It's a clear night and I can "see" many constellations - Orion's Belt is the one that is most obviously visible. So can I actually "see" billions of miles? If I can't actually see these billions of miles, how come I can see so many stars/constellations?

I can't see the stars without my glasses, therefore your eye sight is a billion times better than mine lol

[Silverbullet767]

MLH said:

Moonhawk said:

The Andromeda galaxy is visible to the naked eye - it is 2.5 million light years away.

Ive just had to google that in terms of miles...

14,696,249,525,000,000,000 miles!

What provides the light source for this galaxy?

Either way my mind is puddled! It always is when it comes to space!

What you're looking at happened 2.5 million years ago.

Mind blown.

[Simpo Two]

You're not seeing distance, just light.

[Eric Mc]

MLH said:

What provides the light source for this galaxy?

200 billion stars give or take the odd billion - plus glowing dust lanes.

[Simpo Two]

In other words, nuclear fusion.

[annodomini2]

Eric Mc said:

MLH said:

What provides the light source for this galaxy?

200 billion stars give or take the odd billion - plus glowing dust lanes.

1 Trillion according to Wikipedia, Andromeda is bigger than the Milky way.

[TwigtheWonderkid]

Simpo Two said:

You're not seeing distance, just light.

You could say that about looking at anything.

[Eric Mc]

annodomini2 said:

1 Trillion according to Wikipedia, Andromeda is bigger than the Milky way.

And it's heading our way.

[blueg33]

Seeing, is just emitted or reflected light entering you eyes. Light mostly travels in straight lines, so if there is a straight line between you and the source of the light, with no obstacles then there is no limit to how far you can see

[Simpo Two]

TwigtheWonderkid said:

Simpo Two said:

You're not seeing distance, just light.

You could say that about looking at anything.

Yep. All your eyes do is send the image back to the brain. It makes no difference to them whether the light has travelled 1,000 light years or an inch. Photons is photons.

Resolution and sensitivity/attenuation would be the main factors in whether you can see a distant star.

[TwigtheWonderkid]

Simpo Two said:

TwigtheWonderkid said:

Simpo Two said:

You're not seeing distance, just light.

You could say that about looking at anything.

Yep. All your eyes do is send the image back to the brain. It makes no difference to them whether the light has travelled 1,000 light years or an inch. Photons is photons.

Resolution and sensitivity/attenuation would be the main factors in whether you can see a distant star.

Agreed. So to make the OP's question a bit clear and to get to what I suspect he means, what's the most distant object that gives off light bright enough to see with the naked eye. (or gave off light as it may not exist anymore although we can still see it.)

[Eric Mc]

It's pretty certain that the Andromeda Galaxy is still there.

[SpudLink]

So, a star that suddenly appeared very bright in Andromeda might have gone supernova 2.5 million years ago, and you would be seeing 2.5 million light years (whatever that is in miles).
A supernova in a galaxy much much further away could mean you are seeing billions of light years, although what you are seeing happened before multi-celled life started on earth.
Is that right (in simple terms for my simple brain).