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
Right, well, bear with me because it is a bit indirect.
What we do is we start with the distance to a planet.
So let's say Mars.
And that's what's going to help us work out what the distance to the sun is.
Then we use what we know about the way that planets orbit around the sun.
This was written down for the first time by Johannes Kepler and linked to gravity by Isaac Newton.
So we now understand it very, very well.
And it turns out that the amount of time it takes for a planet to go around the sun rises as the distance that that planet is from the sun also rises.
And that link...
means that if we time how long it takes, say, Mars to go round the Sun and how long it takes us to go round the Sun, which is about two years for Mars and exactly one year for us, then we can use this link to work out, relatively speaking, how big is the orbit of Earth round the Sun and Mars round the Sun.
Then you add in what you know about how far it is from Earth to Mars and this gives you all the information you need to solve this problem automatically.
and work out the distance to the Sun.
Yeah, I thought you might ask me that.
Today, the best estimate that we have is from something called radar ranging.
And the way this works is you may have heard of radar.
It's used to track planes, for example.
And it's just a massive version of that, the thing that you would see at the airport.
We send big radio pulse towards Mars.
That bounces off Mars and comes back to us.
And then we receive it again here on Earth.
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