Sinkholes found on a comet
Sinkholes have been detected on Comet 67P/Churyumov-Gerasimenko halfway between the Earth and Mars.
The European Space Agency's Rosetta orbiter has been collecting data on 67P since it arrived at the comet last August. Comets spew ice, dust and gas into space – and for the first time researchers have been able to link these activities to features on the comet's surface.
Planetary scientist at the Max Planck Institute Jean-Baptiste Vincent and colleagues have published the results in Nature.
Vincent said sinkholes on comets form in the same way they do on Earth. Material under the surface is eaten away, creating a hollow cavity. When the topmost layer can no longer be supported it collapses, revealing a deep circular hole.
Rosetta's images have revealed that 67P is covered in pits which hold "strange things", said Vincent. "We see lots of fractures and features that look like pebbles – some call them dinosaur eggs. They look like the primordial pieces that make up comets to begin with."
The comet will approach the Sun in coming weeks. As it heats up, the jets will become more active. Researchers hope Rosetta's chemical sensing instruments will be able to detect rarer compounds, possibly including amino acids, which have been found on meteorites.