13. Description of the core message of your event and key topics to be covered (c.100 words):
Unravelling the nature of Dark Matter and Dark Energy is one of the major challenges of today's science. While such is pursued, the gathering of empirical evidence for/against Dark Matter (DM) in individual real-life galaxies is a related interesting exercise. The fundamental problem in the quantification of dark matter in these systems is that direct observational evidence of DM remains elusive, and this owes to the definition that DM neither emits light of its own nor does it allow for any incident light to be reflected off itself. Consequently, we cannot invoke the more easily available astronomical images but are left to make predictions about the DM content of individual galaxies using information obtained from measurable manifestations of the gravitational field of the galaxy. Indeed, such measurements are difficult, noisy and few! This results in the learning of the DM content becoming sensitive to the choice of the mathematical model adopted to describe the available data.
The Cassini mission detected in 2004 a magnificent plume of a few hundred kilometres height,
topped the South pole of Enceladus, the sixth largest moon of Saturn. Further investigations shown that it was formed by vapour and icy grains, shot from cracks in icy shell of the satellite. We made a mathematical model of the phenomena and have predicted, that deeply beneath the moon surface, an ocean of liquid water must exist. Moreover, latter observations demonstrated that the liquid ocean is salty, which implies its global nature and contact with the rocky core of the planet. The existence
of liquid water put Enceladus to the list of places where exo-terrestrial life may be possible.