This animation shows ESA's Planck observatory scanning the sky and completing its first all-sky survey.

From its orbit around the second Lagrange point (L2) of the Sun-Earth system, Planck performs a continuous scan of the sky. The spacecraft spins at 1 rpm causing the telescope's field-of-view, which is inclined at 85° to the spin axis, to trace out approximate great circles on the celestial sphere. Planck's spin axis is periodically shifted by a few arcminutes per hour in ecliptic longitude (adding up to ~1° per day), to maintain an anti-Sun pointing throughout the year. As a result, the annular region observed with the telescope slowly drifts across the sky, resulting in a complete sky survey.

Version from July 2008.

©ESA - European Space Agency