I guess depending on their level of technology it might. After all there's a difference between detecting a heat source in far off space and having a clue what it means.

If it was this planet it would take that long just to agree who should prepare. :03:

Well if the other side has achieved the level of telescopes and spectrographs they would be able to spot a spacecraft, determine its its closing or not using its blueshift/redshift, determine if its accelerating (by increase in shift), and determine what its emitting as exhaust (by what appears in the spectrograph).

So late 1800s in equivalent technology they would have the possibility of detection and classification.

Well technically it might be possible but it's a very big sky. What do you think are the odds of such an object being discovered in the late 1800's or even now?

For today check out what Ken Burnside wrote on project rho:

http://www.projectrho.com/public_htm...eat_Signatures

For the past Burnside mentions a drive system of a spaceborne warship at a decent distance would be about an Apparent Magnitude of 12, which would put it just below the Apparent Magnitude of Iapetus (which was discovered in 1671). In the early and mid 1700s they were finding asteroids with apparent magnitudes in that region (ex: 3 Juno, and 5 Astraea).

OMG! That thread has a picture that makes me look silly. My joke about Kirk pointing at the screen apparently really happened in ST3: The Search For Spock, and I forgot about it! :oops: :damn: :rotfl2:

[edit] That whole article is great! :rock:

You take the spectrum of the source. telling what it means is obvious. It's either a star, or a spacecraft.