Herschel intercepts asteroid Apophis

ESA's Herschel space observatory made new observations of asteroid Apophis as it approached Earth this weekend. The data shows the asteroid to be bigger than first estimated, and less reflective.

These first thermal infrared observations of Apophis at different wavelengths, which together with optical measurements helped refine estimates of the asteroid's properties. Previous estimates bracketed the asteroid's average diameter at 270 ± 60 m; the new Herschel observations returned a more precise diameter of 325 ± 15 m.

Herschel's three-colour view of asteroid Apophis - Copyright ESA/Herschel/PACS/MACH-11/MPE/B.Altieri (ESAC) and C. Kiss (Konkoly Observatory)

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