article: Whatever caused small space rocks to lump together billions of years ago, magnetism is unlikely to be the reason. Scientists announced today that measurements made by the European space probe Philae, which landed on comet 67P in November, show the comet's core isn't magnetised. Some astrophysicists have suggested that magnetism might have been responsible for aligning and then binding together rocks into larger boulders during the early stages of planet formation. A composite of 18 images showing off the comet 67P/Churyumov-Gerasimenko activity from different angles as seen between 31 January (top left) and 25 March (bottom right), when the spacecraft was at distances of about 30 to 100 km from the comet . But in a paper published online by the journal Science, the team led by Hans-Ulrich Auster at the Technical University of Braunschweig, Germany, said their data — which benefited from three unexpected bounces that allowed Philae to collect more results than planned — don't support this theory. 'If the surface was magnetised, we would have expected to see a clear increase in the magnetic field readings as we got closer and closer to the surface,' said Auster. 'If comet 67P/Churyumov-Gerasimenko is representative of all cometary nuclei, then we suggest that magnetic forces are unlikely to have played a role in the accumulation of planetary building blocks greater than one meter (3 feet) in size.' Allan H. Treiman, a senior scientist at the Lunar and Planetary Institute in Houston, Texas, who wasn't involved in the study, said the results credibly suggest other forces were responsible. Magnetic  data before (top) and after (bottom) the cliff collision at between the first and second touchdowns. Height above the surface is plotted on the x-axis and magnetic field strength on the y-axis. The measurements (crosses) are compared with a hypothetical model (solid line) assuming a slightly magnetised surface . data collected by the Rosetta Plasma Consortium fluxgate magnetometer on board the orbiter (top) and the Rosetta Lander Magnetometer and Plasma Monitor on board the lander (bottom) have been used to investigate the magnetic properties of Comet 67P/Churyumov-Gerasimenko . Studying the properties of a comet can provide clues to the role that magnetic fields played in the formation of Solar System bodies almost 4.6 billion years ago. The infant Solar System was once nothing more than a swirling disc of gas and dust but, within a few million years, the Sun burst into life in the centre of this turbulent disc, with the leftover material going into forming the asteroids, comets, moons and planets. The dust contained an appreciable fraction of iron, some of it in the form of magnetite. Indeed, millimetre-sized grains of magnetic materials have been found in meteorites, indicating their presence in the early Solar System. This leads scientists to believe that magnetic fields threading through the proto-planetary disc could have played an important role in moving material around as it started to clump together to form larger bodies. 'Auster did not find any magnetic field, with a very sensitive instrument, so it seems unlikely that magnetism in the solar nebula was significant for the collection of meter-sized objects,' Treiman said in an email. 'At that scale, it seems likely that electrostatic or gravitational attraction would be stronger.' The findings are part of a series of scientific results obtained by scientists analyzing data collected by the Philae lander and its mothership Rosetta, which is flying alongside the comet on its elliptical orbit around the sun. Magnetic data providing an estimate of the final landing region. Initially, Philae was seen to rotate slowly during the descent to Agilkia. It landed and then bounced, rotating significantly faster as the momentum of the internal flywheel was transferred to the lander . Some astrophysicists have suggested that magnetism might have been responsible for aligning and then binding together rocks into larger boulders during the early stages of planet formation. Sorry we are not currently accepting comments on this article.
highlights: Was thought magnetism was responsible for aligning and binding rocks .
  This could have led to  early stages of planet formation, scientists said .
  Rosetta results do not support theory as 67P's core is not magnetised .
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