Doing the math: speed of light @~186,000 miles/s *60 = 11,160,000 miles
per minute * 60 = 669,600,000 miles per hour *24 = 16,070,400,000 miles
per day
an AU is 93,000,000 miles then, 400 AU = 37,200,000,000 or a little over
2 light days.
Antennas on two rotating planets. IF the two antennas lined up exactly,
how long would they be able to hear each other given the optimum
rotation so the facing sides are traveling in the same direction.
Granted, at 60 LY the beam width would be pretty broad.
Time for signal acquisition would be pretty short.
73
Roger (K8RI)
On 8/31/2016 Wednesday 10:59 AM, transistor wrote:
The book Earth As a Distant Planet talks about this, too. Two things jumped
out at me.
It states the U.S. Naval Space Surveillance radar (the picket fence radar
located in the Midwest) would be detectable now at 60 light years distance,
with an Arecibo type antenna.
There is also an estimate that the Starfish atomic test from the early '60's
could be detected in X-ray emissions out 400 AU. I haven't done the math but
400 AU is probably not all that far in light years.
Of all the comments on this topic so far, Mr. Haas' have been the best.
Scott
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