Why all the photos from 67p are black and white? I was wondering why every picture we saw on internet about Rosetta's landing on 67p just black and white ? Is there something i should know ?
True fact is that most of the images seen so far are taken from the navigation camera (NAVCAM) of the orbiter, Rosetta, and that takes black&amp;white pictures.

Here is a very interesting article about how these pictures are taken (ironically it is on a NASA blog). They state that they show pretty much what you would see with a human eye from there, even thought the comet is actually all very dark. The white parts are due to the contrast with the very dark surroundings.

I'm not sure about the images received by the lander. They are captured by the CIVA cameras, where CIVA stands for Comet Infrared and Visible Analyser. So I guess they might show some infrared light not visible to the human eye, then processed to be in b&amp;w. Unfortunately, I could not find a precise explanation on ESA's website so far. (here their page for Philae instrumentation).

Anyway, as a general rule you should not expect that all images from spacecraft are in true colors.