Below are three different animations showing how Planck scans the sky. The top-left movie shows the ring Planck is scanning superimposed on the first Planck all-sky image. The top-right image shows the same, but with the colours changing each time Planck observes a region of the sky. The bottom-centre image simply shows the number of observations of the sky made by Planck.
Other animations
Below are additional movies available for Planck’s scanning of the sky, shown with the WMAP . For each projection, the animation is shown in both Ecliptic and Galactic coordinates. Ecliptic coordinates are aligned with the Earth’s orbit around the Sun, while Galactic coordinates are aligned with the plane of our Galaxy. In Ecliptic coordinates, the observed ring moves roughly right-to-left, with some small up-and-down wobble. In Galactic coordinates, it moves at an angle, as the Solar System (and therefore the Earth’s orbit) is tilted with respect to our Galaxy. All movies start on 14th August 2009 and run for 1 year.
Mollweide Projection
This projection maps the entire sky into a single oval, much like some maps of the world in atlases. The size and area of each point is preserved, but shapes are distorted, particularly around the edge.
Orthographic projection
This projection shows the sky in two halves. It is as if the map of the sky is shrunk down onto the surface of the Earth, and then viewed from the a long way off.
Cartesian projection
This projection shows the entire sky in a single rectangle, but stretches the top and bottom out sideways to fill the corners.
Cartesian Projection, with planets
This is the cartesian projection again, but this time shows the locations of the planets as symbols inside white circles (not to scale!). There is also a grid plotted on top in Galactic coordinates. The key is: plus(+)=Mars, cross(X)=Jupiter, traingle=Saturn, square=Uranus, star=Neptune.
Image credits
All images should be credited to C. North/Cardiff University/Planck (for the animation and pointing information) and the NASA/WMAP Science Team ( for the sky data). Planet positions are from the JPL Horizons system.