{"id":6359,"date":"2014-02-05T15:19:08","date_gmt":"2014-02-05T15:19:08","guid":{"rendered":"http:\/\/hobbyspace.com\/Blog\/?p=6359"},"modified":"2014-02-05T18:19:18","modified_gmt":"2014-02-05T18:19:18","slug":"eso-asteroid-internal-structure-revealed","status":"publish","type":"post","link":"https:\/\/hobbyspace.com\/Blog\/?p=6359","title":{"rendered":"ESO: Asteroid internal structure revealed"},"content":{"rendered":"

An announcement from the ESO<\/a> (European Southern Observatory):<\/p>\n

The Anatomy of an Asteroid<\/a><\/strong><\/p>\n

ESO\u2019s New Technology Telescope (NTT) has been used to find the first evidence that asteroids can have a highly varied internal structure. By making exquisitely precise measurements astronomers have found that different parts of the asteroid Itokawa have different densities. As well as revealing secrets about the asteroid\u2019s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form.<\/p>\n

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Click to Enlarge<\/a><\/em><\/div>\n

Using very precise ground-based observations, Stephen Lowry (University of Kent, UK) and colleagues have measured the speed at which the near-Earth asteroid\u00a0(25143) Itokawa<\/a>\u00a0spins and how that spin rate is changing over time. They have combined these delicate observations with new theoretical work on how asteroids radiate heat.<\/p>\n

This small asteroid is an intriguing subject as it has a strange peanut shape, as revealed by the Japanese spacecraft\u00a0Hayabusa<\/a>in 2005. To probe its internal structure, Lowry\u2019s team used images gathered from 2001 to 2013, by ESO\u2019s\u00a0New Technology Telescope (NTT)\u00a0<\/a>at the La Silla Observatory in Chile among others\u00a0[1]<\/a>, to measure its brightness variation as it rotates. This timing data was then used to deduce the asteroid\u2019s spin period very accurately and determine how it is changing over time. When combined with knowledge of the asteroid\u2019s shape this allowed them to explore its interior \u2014 revealing the complexity within its core for the first time\u00a0[2]<\/a>.<\/p>\n

\u201cThis is the first time we have ever been able to to determine what it is like inside an asteroid<\/em>,\u201d explains Lowry. \u201cWe can see that Itokawa has a highly varied structure \u2014 this finding is a significant step forward in our understanding of rocky bodies in the Solar System<\/em>.\u201d<\/p>\n

The spin of an asteroid and other small bodies in space can be affected by sunlight. This phenomenon, known as the\u00a0Yarkovsky-O\u2019Keefe-Radzievskii-Paddack (YORP) effect<\/a>, occurs when absorbed light from the Sun is re-emitted from the surface of the object in the form of heat. When the shape of the asteroid is very irregular the heat is not radiated evenly and this creates a tiny, but continuous, torque on the body and changes its spin rate\u00a0[3]<\/a>,\u00a0[4]<\/a>.<\/p>\n

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