Andrew Pontzen
speaker
36 appearances
1 recordings
1 series
first heard Sep 2014
last heard Sep 2014
Andrew Pontzen’s voice in public audio — every appearance, attributed to the second.
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Appearances
And we measure the amount of time that passes between sending out the radio pulse and getting it back.
And because we know how fast radio waves travel, they travel at the speed of light, we can work out from that exactly how far away Mars has to be.
Are you happy, Giles?
The data we have tell us about the way the planets move around in the night sky is really, really accurate.
And these Doppler pulses that we can use are also really, really accurate.
So we think the estimate that we have is very good.
And of course, we've used it to send spacecraft around the solar system as well.
And so it's been put to the test, really.
Although we haven't flown anything into the sun with a tape measure, we've done lots of stuff that would come out quite wrong if we were wrong about the distance to the sun, if it was actually twice as far away or something.
So it is a guess, but we have a lot of confidence in it.
Andrew, I have one final question.
How far away is the sun?
It is 150 million kilometres away.
Wow, that's a very round number.
Well, that's the number that I remember.
I think it's 149,500,000 or something like that.
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