Are space ships visable, mano a mano?

[bartman]

In all SciFi movie/series spacecraft are always visible from an outside perspective, no matter how far away from any given star. I know this is scifi but.......
Hypothetically.......
lets just say I'm approaching Pluto in my starship ( lets say Voyager from StarTrek). Could I see another object - lets say Enterprise - visually?
Would the light from the Star be enough to illuminate Enterprise for me to look out of the mess hall on Voyager and see Enterprise clearly? ( given that the ships are in close proximity and the angle of the dangle is so that the star is illuminating the most part of Enterprise)
And then half way to Proxima Centauri, we meet up with an other starship.
Would we be able to see each other visually? ( no sensors etc involved)

This has been bugging me ever since space battles in movies and tv shows include noise .........
heheheheh:D
Cheers
Bartman

[sheeny]

If there's enough light to see pluto, then there should be enough light to see the space ship - depending on distance and orientation to the sun.

If the space ship is near the sun (in the sky) you would be looking at the dark side - very hard to see before collision. The further away it is, the harder it is to see as well... apparent magnitude and all that.;)

Al.

[cfranks]

Of course, with the Enterprise's Anti Collision lights flashing as usual, you should see it for miles! :)

Charles

[bartman]

Thanks Al.....,
True what you say....
What I would like to know is that if two ships were in orbit around Pluto, would both ships be able to see each other ...visually .....and at 2 light years away as well?
Think Star Wars, Star Trek etc etc

[bartman]

Hehheehehhe those strobes would be blinding ........
BTW what do you mean by the term "miles"? :rofl:
:P
Bartman

[RobF]

Don't worry Bart, if you don't see the Enterprise coming, you'll at least hear it :P

Arthur C Clarke still one of the few that insisted on silence except for the sounds of breathing/lifesupport/comms. So ahead of his time.

[bartman]

Bit like submarines.........?
Ping.....ping....
Sorry Rob.....
:thumbsup:

[bartman]

Here is a snap shot of me on Voyager traversing between Sol and Proxima Centauri.
The shot was taken by me mate Data on Enterprise from the port bow.
So my question is.... is this Photoshopped or COULD it be real......

Beside my silly posts .... I am still looking for a real answer....:shrug:

[MrB]

I'm only guessing but:
Relatively close to a star, like Jupiter or Saturn orbit, probably.
Internal reflections on the windows would likely be problematic, kinda like trying to look out a plane window flying at night. The cabin lights make it pretty hard. But from a pitch black room I reckon it'd be visible.
Pluto orbit, probably not. Dark room and dark adapted, maybe :shrug:
Interstellar, not likely.

I have nothing to base this on, just guessing as I said.

EDIT:
Actually, I may have just changed my mind..... starlight can be pretty damn bright once dark adapted on a moonless night... but I wonder how much of this is contributed by atmospheric skyglow(airglow) and light scattered by interplanetary dust?

[Shiggy]

:thumbsup: Exactly. In space, no-one can hear you scream (Alien - Which ironically did have space sounds!).

I love the eerie silence in 2001, only broken by the internal suit/pod sounds.

[bartman]

Thanks MrB...... I'm thinking on the same lines....on a full moon night you can see a lot on the ground......and thats reflected light......

+1 on the eeeeeerieeee silence in 2001!

[venerium]

Alright, so making a few assumptions I think we can at least work a maximum distance out at which we'd be able to detect reflected light from the sun.



<BEGIN BORING CALCULATIONS>
Firstly: eye sensitivity (according to this: http://www.lifeslittlemysteries.com/2426-human-eye.html and wikipedia). The least amount of light detectable by our eyes is at around 140 photos at a frequency of 587.8THz. From E=hf (Planck's relation) we have each photon carrying 3.9*10^-19 Joules of energy, hence a bundle of 140 of them would carry 5.46*10^-17 Joules. The "response rate" of the eye is about 1/10 seconds (http://en.wikipedia.org/wiki/Frame_rate#Background), so we would need this bundle of photons to hit our eyes once every 0.1s for us to detect anything at all. IE we would need 5.46*10^-16 J hitting the area of our pupil per second. Now a fully dark-adapted pupil is around 9mm in diameter, which is an area of 6.36*10^-5 m^2.
Soooo to get a detectable amount of light hitting our eyes, we would need at least 8.58*10^-12 Joules per second per m^2 hitting the surface of whatever planet or spaceship we happen to be on.

Now we need to calculate the light falling on Pluto from the sun. According to Wikipedia, the average flux of light from the sun at the distance of Earth is 1360 J/s/m^2. From this, we can derive the flux from the sun at pluto (the ratio of the squares of the distances to earth/pluto times the flux at earth): 1.23 J/s/m^2!

This is way more than our supposed limiting flux of 8.58*10^-12 J/s/m^2! So at Pluto we'd almost certainly be able to see things around us.

Now for 2 light years away, the same applies. 2ly = 126 482 AU, therefore flux at 2ly from sun = (1/126482)^2 * 1360 J/s/m^2 = 8.50*10^-8 J/s/m^2. Again over our limit, but only by a factor of 4 now. It might start getting a bit tough to make out anything meaningful, but theoretically it is possible.
<END BORING CALCULATIONS>



So if my assumptions are correct, at both Pluto and in interstellar space 2 light years away from the sun we would still be able to detect a spaceship reflecting sunlight visually. In fact, we would need to be nearly 200 light years away from the sun for our eyes to not detect a single trace of light originating from it!

Inside the galaxy (and definitely closer to the crowded centre) it wouldn't be unlikely to have at least one bright star within 200ly of you, so perhaps while travelling within the Milky Way you'd be able to see (very vaguely) any big reflective objects around you just by starlight. But once you get out into intergalactic space ... good luck seeing anything at all. :P




Disclaimer: this is assuming nothing exists in the universe but you, the sun, and a spaceship that reflects 100% of the light hitting it back towards you.
In reality I'm sure we would need a lot more light than just 140 photons to meaningfully decipher anything we see, like a spaceship.

Disclaimer 2: I do not guarantee the validity of my calculations in any way. Please excuse any glaring errors.

[bartman]

Thank You Vi!
I like those thoughts and calculations ( and I understand the disclaimers too! :) )
I can sleep easy now, knowing I can see another ship whilst travveling the galactic highway!
Cheers!
I appreciate your time:D
Bartman

[Barrykgerdes]

This problem can be answered from basic physics.

How do you see? - Because the eye responds to electro-magnetic radiation in the visible range to give us the sensation of sight

Where does this electro magnetic radiation come from? - From radiations from the object or reflection from an external radiation source.

For our direct eye vision the object will need to be illuminated from an outside source eg the Sun or have some external lighting of its own. Its radiations in other parts of the spectrum will not be visible to the eye.

However , if you are travelling in space and another object is there, your ship will undoubtedly have sensors that respond to all sorts of electro-magnetic radiations. These radiations will be displayed as visible images in your “spaceship” on a screen. So in the comfort of your space ship you will have images of all your surroundings.

Barry

[Keltik]

I think it's actually dependent on how big the other ship is. Have a look at an example of two spacecraft approching ech other in space:http://www.youtube.com/watch?v=MhISvjoc6Gk
In this case, Eagle, the LEM of Apollo 11, is returning from the surface of the Moon to the command module Columbia. I assume that Columbia is no more than 5km or so above the surface. At 48 seconds into the video, the LEM is invisible.
Assuming some putative starship like Enterprise is about 10 city blocks long, I would expect it would be a faint dot barely visible to the eye if it were more than 100km away. Of course, if it were a Klingon warship, with cloaking or even just black housepaint on the outside, you'd be getting a photon torpedo up your keester before you even knew it was there.

[avandonk]

I would imagine that for all these movies we have to suspend reality and disbelief so we can see what is going on in the plot and narrative. It is only make believe folks!

It is no different to Billy Bang Bang in western movies who had unlimited bullets in his six shooter.

Bert