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In the movie Contact, aliens from the Vega system contact humans by retransmitting Hitler's August 1st opening speech of the 1936 Summer Olympics, popularly held to be the first radio transmission to make it into deep space.

Taking a wild guess that the broadcast was at high noon in Berlin, the sky from that city would have looked like this (via the planetarium software C2A):

starfield

I have helpfully highlighted Vega, centered in the cyan crosshairs.

As you can see, it's right on the horizon. For reasons I won't get into, the exact altitude makes a huge difference in whether a radio signal reaching Vega is merely improbable or outright impossible, and the altitude of Vega depends on the rotation of the Earth. Therefore, the following question:

At what time of day did Hitler make his address?

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  • Haven't you forgotten about the 25 or so years it would take the radio signal to reach Vega? – fdb Aug 20 '17 at 22:20
  • @fdb I don't think that matters. It's just about whether Vega was in line-of-sight at time of transmission. Of course, Contact is based on the novel written by Carl Sagan. I'd be surprised if Sagan got it wrong (but then again, I can't remember if the contact actually came from the Vega system in the book). – sempaiscuba♦ Aug 20 '17 at 22:51
  • Not an astronomer, but AFAICT Vega is always above the horizon in Berlin. More problematic for the story is that the signal would have been detectable only ~320 AU (or 0.00506 light years) away—a far cry from Vega's 25.04 light years (especially since the falloff is quadratic). – imallett Aug 20 '17 at 23:15
  • On what basis do you say that Vega had to be in the line-of-sight at the time of transmission? It seems that Vega would have to be in the line-of-sight (assuming radio waves travel over such large distances in a perfect straight line) at the time of reception. It is like trying to hit a moving target with a rifle. You don't fire at where the target is but where it will be when the bullet arrives. – Barry Aug 20 '17 at 23:48
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    @Barry The apparent motion of Vega is due to the rotation of the Earth. The correct analogy here is a stationary target, rotating rifle. – imallett Aug 21 '17 at 0:32
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I found a programme for the 1936 Berlin Olympiad which seems to show that the opening ceremony began at 16:00 (4pm) local time.

Hitler didn't make his speech until late in the proceedings, after the Parade of Nations and a speech by the president of the German Olympic Committee. The Parade of Nations had something over 5,000 athletes from 51 nations marching in alphabetical order (with Greece leading the parade and Germany, as host nation, at the end).

Based on more recent Olympic opening ceremonies, we need to allow a couple of hours for the Parade of Nations and the speech by the president of the German Olympic Committee. So Hitler probably made his speech at about 18:00 (6pm) local time (give-or-take an hour or so).

Germany wasn't using daylight saving in 1936 (they abolished at in 1919 and didn't re-introduce it until 1940), so 18:00 in Berlin would be 19:00 UT.

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  • (Accepting this answer; it shows that Vega would be at least 29°34' in the sky. If anyone can cite a more precise time, I'll accept that answer instead.) – imallett Aug 20 '17 at 22:14
  • In response to edit, for people of the future, 18±1 local (19±1 UT, as UTC didn't exist yet) corresponds to Vega being at an altitude: (18 UT: +55°38') (19 UT: +64°33') (20 UT: +72°19'). – imallett Aug 21 '17 at 0:28

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