European and U.S. astronomers discovered traces of water on Ceres, a dwarf planet and the biggest and most spherical asteroid in our solar system.
The water was detected in the form of water vapor columns ejected into space possibly from volcanic geysers.
It is the first unambiguous detection of water on Ceres and, more generally, on a large asteroid belt between Mars and Jupiter. The discovery also raises the question of whether the Ceres could one day be home to microbial life, although it is still too early to make assessments.
The researchers led by Michael Küppers of the European Space Agency (ESA), who used the Space Infrared Telescope “Herschel“, made a related publication in the journal “Nature”.
For nearly 30 years, the scientists have suspected that there was a significant amount of water on Ceres and the first – unconfirmed – proof was found in 1991.
The researchers estimate that the planet-asteroid produces about six pounds of water vapor per second from the surface. One possible cause is that under the surface there is liquid water, which is ejected into space by cold volcanoes in the form of water vapor instead of hot lava (something similar to what was detected on Saturn’s moon Enceladus).
Another possibility is the mass sublimation of surface ice in the periodic influence of solar radiation, i.e. the direct conversion of ice from solid-state to gas, something similar to what happens in an icy comet. When the orbit of the Ceres moves away from the Sun, the ice does not sublimate and thus no water vapor is ejected into space.
NASA’s spacecraft “Dawn“, which is expected to enter into orbit around the icy Ceres in the spring of 2015, will shed more light on the issue.
The spacecraft recently visited another large asteroid, the Estia, a very different “hot” world that is covered by continuous volcanic eruptions. A key question is why the Ceres and the Estia differ so much in terms of heat.
The discovery of water on Ceres reinforces the scenario that asteroids are responsible – at least partly – for water gained by the oceans of our planet in the distant past.
Dwarf planets are now considered by the International Astronomical Union bodies larger than asteroids and smaller than planets. With this in mind, Ceres was upgraded from an asteroid to a dwarf planet in 2006, while Pluto was demoted from a planet to a dwarf.
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