The Naked Scientists

The Naked Scientists Forum

Author Topic: How far can we see?  (Read 6946 times)

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
How far can we see?
« on: 06/10/2007 18:11:17 »
What is the most distant object that can be seen with the (average) naked eye? And how far away is it?


 

paul.fr

  • Guest
How far can we see?
« Reply #1 on: 06/10/2007 18:13:22 »
The Andromeda Galaxy. A long way.
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
How far can we see?
« Reply #2 on: 06/10/2007 18:17:56 »
That's not far. Galactically it's our nearest neighbour apart from the Magellanic clouds.
 

another_someone

  • Guest
How far can we see?
« Reply #3 on: 06/10/2007 18:47:36 »
What is the most distant object that can be seen with the (average) naked eye? And how far away is it?

I think one of the questions must be: when, and from where?

Assuming we are talking about earthbound observation (clearly, looking at the stars from the ISS is a whole different matter), then the levels of atmospheric pollution and light pollution are a major constraining factor, and observations made 300 years ago would see far more than that most people can see today (but again, some locations on the Earth still remain freer from light pollution, and to some extent from atmospheric pollution, than others).
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
How far can we see?
« Reply #4 on: 06/10/2007 20:06:57 »
I live in a small village a few miles outside Banbury, near Chipping Norton. The skies here are incredibly clear. There is practically zero light pollution apart from the glow of Banbury on the horizon.

OK, it's not the top of an Andean mountain, but I'm sure you can see a long, long way from here.
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8659
  • Thanked: 42 times
    • View Profile
How far can we see?
« Reply #5 on: 07/10/2007 15:25:47 »
An odd aside to this question is when can you see furthest, and the answer is in the dark.
During daylight the most distant object you can see is the sun. At night, even the closest star you can see is much further than that.
 

another_someone

  • Guest
How far can we see?
« Reply #6 on: 07/10/2007 18:40:59 »
An odd aside to this question is when can you see furthest, and the answer is in the dark.
During daylight the most distant object you can see is the sun. At night, even the closest star you can see is much further than that.

What about Venus?

Yes, I realise that Venus is in an orbit that is closer to us than the Sun is, but at various points in its orbit, it is clear that Venus would be further from us than the Sun - can Venus actually be seen during daylight hours through any part of its orbits where its distance from us is further than the Sun's distance from us?
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
How far can we see?
« Reply #7 on: 07/10/2007 19:02:54 »
An odd aside to this question is when can you see furthest, and the answer is in the dark.
During daylight the most distant object you can see is the sun. At night, even the closest star you can see is much further than that.

Although that is generally the case, there are occasions when comets can be seen that are further away then the sun. Supernovae, also, are sometimes visible in daylight.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
How far can we see?
« Reply #8 on: 07/10/2007 19:45:06 »
What is the most distant object that can be seen with the (average) naked eye? And how far away is it?

On a good night I can see clearly across the street into my neighbors room....with binoculars the view is even clearer...which is nice !!





*note to self : me hopes the membership realise that ewe're just impersonating James Stewart in Hitchcock's Rear Window ! http://en.wikipedia.org/wiki/Rear_window
 

Offline sohail

  • Jr. Member
  • **
  • Posts: 23
    • View Profile
How far can we see?
« Reply #9 on: 07/10/2007 20:02:14 »
An odd aside to this question is when can you see furthest, and the answer is in the dark.
During daylight the most distant object you can see is the sun. At night, even the closest star you can see is much further than that.

What about Venus?

Yes, I realise that Venus is in an orbit that is closer to us than the Sun is, but at various points in its orbit, it is clear that Venus would be further from us than the Sun - can Venus actually be seen during daylight hours through any part of its orbits where its distance from us is further than the Sun's distance from us?

I'd imagine that the only reason we can see Venus is because it is silhouetted against the sun and when it is a further distance away from us is must be behind the 2D face of the sun we see and therefore we can't ever see it when it is further away then the sun.
 

another_someone

  • Guest
How far can we see?
« Reply #10 on: 07/10/2007 20:07:30 »
I'd imagine that the only reason we can see Venus is because it is silhouetted against the sun and when it is a further distance away from us is must be behind the 2D face of the sun we see and therefore we can't ever see it when it is further away then the sun.

If this were the case, then we should see a black Venus, instead of the morning/evening star.  It seems to me to be evident that we are looking at reflected light, rather than a silhouette.  What you say is certainly true of mercury, but I don't think it is normally true of Venus.
 

Offline Ophiolite

  • Hero Member
  • *****
  • Posts: 716
  • Thanked: 6 times
    • View Profile
How far can we see?
« Reply #11 on: 08/10/2007 08:19:41 »
For one of the Inferior planets to be silhouetted against the sun it must be in transit across it. Because the orbits of Venus and Mercury do not lie exactly in the same plane as the Earth's orbit, these are rare events.
"Transits of Venus are among the rarest of predictable astronomical phenomena and currently occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years." [Source: wikipedia]
Transits of Mercury are more common - around a dozen every century. (No prizes are on offer for explaining why the transit of Mercury is important to physics. :))

We see Mercury and Venus 'side on', not in silhouette. Thus Another someone is wholly correct: when we view Venus it is at times further away from us than the sun.
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8659
  • Thanked: 42 times
    • View Profile
How far can we see?
« Reply #12 on: 08/10/2007 20:56:14 »
Let me know when it's as far away as the second nearest star and I will accept that I was wrong about seeing further in the dark.
 

Offline Quantum_Vaccuum

  • Sr. Member
  • ****
  • Posts: 135
  • The Base Of Chemistry
    • View Profile
How far can we see?
« Reply #13 on: 09/10/2007 01:34:53 »
if ur talking about how far we can see, does  it take in acount the sise of the object?
 

another_someone

  • Guest
How far can we see?
« Reply #14 on: 09/10/2007 03:49:36 »
if ur talking about how far we can see, does  it take in acount the sise of the object?

In astronomical terms (for anything outside of our solar system, and even much that is within our solar system) size is very rarely an issue - brightness is the primary issue.
 

The Naked Scientists Forum

How far can we see?
« Reply #14 on: 09/10/2007 03:49:36 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums