The Rosetta mission of the European Space Agency spent two years at comet 67P/Churyumov-Gerasimenko. The mission ended in 2016 when the spacecraft collided with the comet. In the time spent at 67P, a huge number of images were captured. These images are now freely available at Rosetta website. An astrophotographer from Spain, Jacint Roger noticed something interesting in the images, an ice chunk traveling with 67P. He created a gif from the images which focused on the icy companion.
The images obtained were from two months after perihelion in the month of August 2015. 67P was basking in full sunlight at that time. The comet was inside dust as the heat of the Sun released comet gases in space which also carried dust with it. Along with dust, the ice chunk was also released from the comet in this time. The ice chunk is visible as the images focus on the nucleus of the comet. Less than 4 meters in diameter it is called Churymoon, a term coined by Julia Marín-Yaseli de la Parra, Ph.D. and ESA Researcher on Rosetta mission.
The images used by Jacint Roger are from OSIRIS instrument of Rosetta. It had a wide-angle camera for mapping the gas and dust near the comet and a Narrow-Angle Camera for mapping the nucleus of the comet in a high-resolution scale. Rosetta was at a distance of 400 kilometers from the center of the comet when the images were captured by the NAC. After leaving the comet, Churymoon spent the first 12 hours at a distance between 2.4km and 3.9km from the center of the comet in an orbital path. Then it went through the coma whose brightness made it hard to view it. It was again visible after emerging from the coma and its path was confirmed until 23rd October 2015.
Rosetta’s mission also included a study of the debris which was ejected from the planet. Churymoon is possibly the largest debris detected which will be further studied by researchers. It also had to watch the comet moving through perihelion. It took ten years for traveling to 67P/G-C. Earlier comets were only considered as dirty ice chunks moving through space. But Rosetta revealed the complexity of the comet in a detailed way. 67P is all possibility might be the result of a comet collision.
Eberhard Grün, a scientist working on Rosetta said that comets such as 67P/G-C are geographically complex worlds where several processes are involved in creating the comet’s surface and activity.