Re: What would a laser-powered sail starship look like from space?

Anders Sandberg (
19 Oct 1999 11:15:53 +0200

Larry Klaes <> writes:

> If a starship composed of a 1,000 kilometer-wide sail being pushed
> at nearly the speed of light by a very powerful laser beam in the
> terrawatt range was headed towards Earth - and was, say, less than
> 1/2 a light year away - how would it appear from our planet in
> various spectrums and wavelengths, especially optical?

I don't think the ship would be visible, the angular diameter would be around 10^-14 degrees. But since the laser would be rather spread out, it would be visible as laser light coming from the departure star. It might be hidden by the starlight, but would likely show up as a strange peak in the emission curve.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y