Rosetta's first glimpse of Comet 67P/Churyumov-Gerasimenko, March 2011
This animation comprises a series of images that include Comet 67-P/Churyumov-Gerasimenko acquired by the European Southern Observatory (ESO; first image only) and by Rosetta's OSIRIS imaging system (all subsequent images) on 25/26 March 2011, when Rosetta was at a distance of 163 million km from the Earth. The images show a progressively narrower field of view, 'zooming in' on the comet, which initially is invisible against the background star field.
The first image was acquired at the ESO's Paranal, Chile, site and shows the centre of our Milky Way galaxy and constellation Scorpius. In March, by coincidence, Churyumov-Gerasimenko happened to be located in this direction in front of the Galactic Centre, which is many, many times further behind it. The comet is invisible.
The next image shows the area of the previous inset box, and includes the bright star Antares and the Rho Ophiuchi nebula region, at the end of the so-called 'Dark River' dust bands (seen at upper left).
The third image zooms into a narrower field of view, and shows a group of stars embedded in the IC 4601 Nebula, a cloud of interstellar dust and gas.
The fourth image zooms in even closer and includes a small red circle in which the comet is located (but still invisible to the naked eye).
Extensive processing was able to reveal the comet as a faint point of light in the fifth image, which is actually a composite of many images taken over a period of 13 hours. The background stars blurred since the comet moved during this time.
Although the comet can be seen only as a very faint point of light, this imaging activity was an important milestone in the mission showing that the cameras are performing very well before the long cruise through deep space. At the time this was acquired the comet was 5.1 AU (astronomical units) from the Sun, while Rosetta was 4.14 AU from the Sun.
This image was originally published on the ESA Portal.