The Planck satellite was launched in May 2009 and is a modern version of the WMAP satellite with the aim to very precisely measure light from a particular phase in the development of the universe called the cosmic background radiation (CMB). The light being measured is microwaves, yes the same kind of microwaves which you use to make popcorn or reheat last nights dinner.
The theory tells us that some 300,000 years after the inflation period called the Big Bang, the temperature in the universe had dropped enough that the hydrogen-, helium- and lithium plasma it consisted of could form electrically neutral atoms and so the light was no longer trapped. This is called photon decoupling and the these photons have ever since travelled the universe and as the universe expands the wavelength of the photons increases too.
The light is nearly uniform in all directions but there are small, small variations which is interpreted to be the seeds of the first stars ultimately forming the first galaxies, the first supernovas and the first black holes.
Beside this maesurment of the cosmic backround radiation the Planck satellite also has the following aims:High resolution detections of both the total intensity and polarization of the primordial CMB anisotropies Creation of a catalogue of galaxy clusters through the Sunyaev-Zel'dovich effect Observations of the gravitational lensing of the CMB, as well as the integrated Sachs–Wolfe effect Observations of bright extragalactic radio (active galactic nuclei) and infrared (dusty galaxy) sources Observations of the Milky Way, including the interstellar medium, distributed synchrotron emission and measurements of the Galactic magnetic field. Studies of the Solar System, including planets, asteroids, comets and the zodiacal light.
Here is a link to a small picture of the cosmic background radiation according to Planck: spaceinimages.esa.int