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P07 Barycentric balls Figure A1 Description: A schematic diagram of the Earth-Moon system (not to scale), highlighting the position of the barycentre and the orbits of the Earth and Moon about this point. The barycentre is located around 4 650 km from the centre of the Earth – the radius of the Earth is just under 6 400 km. The barycentre is approximately 80 times further from the centre of the Moon than from the centre of the Earth. Credits: ESA
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P07 Barycentric balls Figure A2 Description: A) Set of equal-mass (empty) tennis balls. B) Set of tennis balls with unequal masses, one of the tennis balls has been filled with ball bearings, lead pellets or coins and is coloured to identify it as the more massive ball. Credits: ESA
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P07 Barycentric balls Figure A3 Description: Left: For the pair of equal-mass tennis balls, the centre of mass or barycentre is located at the centre of the system in the middle of the length of the string, marked by the X. Both tennis balls describe the same orbital path (dashed line). Right: For the pair of unequal-mass tennis balls, the centre of mass or barycentre is located much closer to the more massive, filled ball (coloured red) – marked by the X. This is observed as the more massive ball following a much smaller orbital path/circle whilst the lighter ball follows a much larger orbit/circle. Credits: ESA
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P07 Barycentric balls Figure X1 Description: How to assemble the two sets of tennis balls. Credits: ESA
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P07 Barycentric balls Figure X2 Description: Two objects (mass M and m) in orbit about a common centre of mass or barycentre. The objects are separated by a distance d and the distance between the centre of the most massive object M and the barycentre is B. Credits: ESA |
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P07 Barycentric balls Figure X3 Description: An artist’s impression of ESA’s Gaia spacecraft. Credits: ESA–D. Ducros, 2013
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P07 Barycentric balls Figure X4 Description: The Hipparcos spacecraft produced a positional survey of two million stars. Credits: ESA
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P07 Barycentric balls Figure X5 Description: Hubble Space Telescope (HST) image showing the four small moons orbiting the Pluto-Charon double-dwarf planet system. The orbital paths of the smaller moons are overlaid. Credits: NASA, ESA, and M. Showalter (SETI institute)
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P07 Barycentric balls Figure X6 Description: An artist’s impression of a fast spinning pulsar drawing mass from its companion star. The strong gravity from the dense pulsar (on the right) attracts material from the companion star (on the left). Credits: NASA/Dana Berry |
European Space Agency
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