The Planets

In Our Time: Science

BBC

History

4.5 • 1.4K Ratings

🗓️ 27 May 2004

⏱️ 28 minutes

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Summary

Melvyn Bragg and guests discuss our knowledge of the planets in both our and other solar systems. Tucked away in the outer Western Spiral arm of the Milky Way is a middle aged star, with nine, or possibly ten orbiting planets of hugely varying sizes. Roughly ninety-two million miles and third in line from that central star is our own planet Earth, in thrall to our Sun, just one of the several thousand million stars that make up the Galaxy.Ever since Galileo and Copernicus gave us a scientific model of our own solar system, we have assumed that somewhere amongst the myriad stars there must be other orbiting planets, but it took until 1995 to find one. ‘51 Pegasus A’ was discovered in the Pegasus constellation and was far bigger and far closer to its sun than any of our existing theories could have predicted. Since then 121 new planets have been found. And now it is thought there may be more planets in the skies than there are stars.What causes a planet to form? How do you track one down? And how likely is there to be another one out there with properties like the Earth’s?With Paul Murdin, Senior Fellow at the Institute of Astronomy in Cambridge; Hugh Jones, planet hunter and Reader in Astrophysics at Liverpool John Moores University; Carolin Crawford, Royal Society Research Fellow at the Institute of Astronomy in Cambridge.

Transcript

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0:00.0	Thanks for down learning the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.uk.
0:09.0	I hope you enjoy the program.
0:11.0	Hello tucked away in the outer western spiral arm of the Milky Way
0:16.2	is a middle-aged star with nine or possibly ten orbiting planets of hugely varying sizes.
0:21.8	Roughly 92 million miles and third in line from that central star is our own planet Earth,
0:27.4	enthrall to our Sun, just one of the several thousand million stars that make up the galaxy.
0:33.5	Ever since Galileo and Copernicus gave us a scientific model of our own solar system,
0:38.5	we've assumed that somewhere amongst the myriad stars there must be other orbiting planets, but it took until
0:43.7	1995 to find one. 51 Pegasus A was discovered in the Pegasus constellation
0:49.4	and was far bigger and far closer to its Sun than any of our existing theories could have
0:54.2	predicted. Since then a hundred and twenty new planets have been found and now it
0:58.8	thought there may be more planets in the skies than there are stars. What causes a planet to form? How do you
1:05.0	track one down and how likely is there to be another one out there with properties
1:09.7	like the Earth's? With me to discuss an area of research that's at the forefront of
1:13.5	modern astronomy is Paul Murdoch, Senior Fellow at the Institute of Astronomy in
1:17.6	Cambridge, Carolyn Crawford Royal Society Research Fellow at the
1:21.6	Institute of Astronomy in Cambridge, and Hugh Jones
1:24.2	a planet hunter and reader in astrophysics at Liverpool, John Moore's University.
1:29.2	Paul Murdoch, let's start with an own solar system.
1:32.3	Can you give us a brief outline of its topography
1:35.1	how many planets, how many moons, how many asteroids?
1:38.6	Well let's start with the main body in the solar system, which is the sun. It's not a planet, it's a star like all
	...

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