One more mystery of the mysterious spots on Ceres

The mysterious atmosphere, discovered last year by the Dawn probe over the surface of the mysterious white spots on Ceres, is seasonal in nature, it arises from splashes of solar activity, and not as a result of the convergence of the star and the dwarf planet.

“Something similar, as our observations show, can occur on other airless and water-rich celestial bodies, including the poles of the moon and some other asteroids, and the atmosphere on their surface can also arise at a time when an outbreak of solar activity is taking place,” – says the head of the mission Dawn Christopher Russell (Christopher Russell).

In August 2015, Russell and his colleagues talked about another amazing discovery on this dwarf planet. Watching the mysterious white spots, tools and cameras Dawn found on the surface of Ceres above them an unusual haze, which scientists found traces of a temporary atmosphere consisting of water vapor, ammonia and other gases.

Initially, the scientists believed that this “atmosphere” occurs according to the same scenario as the tail of comets – as a result of the melting of ice and frozen gases as they approach the Sun. But observations in the next few months made Russell and his colleagues question this hypothesis – a haze over white spots then appeared or disappeared, as if “breaking” this rule.

Moreover, during the approach of the Sun and Ceres the atmosphere did not exist on it, which led astronomers, using data from all the scientific instruments of the probe, to comprehensively study what happened to the planet at the appearance and disappearance of its “atmosphere”. The discovery, as it often happens, came from an unexpected source.

Analyzing data from Dawn, scientists noticed that particle detectors fixed the appearance of powerful beams of electrons and other charged particles just before clouds of vapor and gases appeared above the “white spots”. Having studied the strength, direction and other characteristics of these beams, Russell and his colleagues came to the conclusion that their source was the Sun and outbursts of activity on its surface.

How can these outbreaks be related to the atmosphere at Ceres? The fact is that water molecules easily detach from the ice surface if they are bombarded by cosmic rays or electrons with a sufficiently high energy. Flows of such particles, as explained by planetologists, are the reason why Europe and Ganymede, the satellites of Jupiter, have a rarefied atmosphere. This prompted scientists to think that something similar could happen on Ceres.

Now the Sun is in a peculiar period of calm, so the atmosphere on the surface of Ceres arises extremely rarely. A few years ago, when flashes on the Sun occurred much more often, the atmosphere on the surface of a dwarf planet could exist almost constantly, the researchers conclude.