The Rosetta spacecraft orbiting the comet 67P/Churyumov-Gerasimenko has found that even comets have weather. Scientists said the European Space Agency spacecraft has discovered a proof of a daily water-ice cycle on the comet's surface, linked to its rotation, exposing regions of the comet to frequently alternating sunlight and shadow.

They explained that the cycle drives a small weather system, wherein the ice sublimates into vapor at the time of the comet's 'sunrise'.

The researchers said with each rotation, a square-kilometer field of solid ice in the 'neck' area of the dumbbell-shaped comet appears and then fades away.

In a report published in the journal Nature, researchers said the discovery was made using Rosetta's Visible, InfraRed and Thermal Imaging Spectrometer, or Virtis.

Planetary scientist Maria Cristina De Sanctis from the Institute for Space Astrophysics and Planetology in Rome said, "We observed this cycle for several comet rotations. We were surprised to see so clearly the appearance and disappearance of the ice due to temperature and illumination conditions".

She said the heat from sunlight kicks off the sublimation, and the ice directly converts from its frozen state to a vapor without changing into a liquid stage. The scientist added that most of the vapors escape into space instead of settling back onto the surface as ice, when the area of the comet rotates back into darkness.