A black hole is a region of spacetime exhibiting gravitational acceleration so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
Saturn is the smaller of the two gas-giant planets, twirling around our Sun, in the outer regions of our Solar System--far from the delightful warmth of our lovely incandescent roiling gas-ball of a Star. Jupiter is the larger of the duo of gas-giants dwelling in our Solar System, as well as the largest planet in our Sun's bewitching family, which is composed of eight major planets, an assortment of moons and moonlets, and a rich menagerie of smaller objects. Saturn is the second-largest planet in our Solar System--and probably the most beautiful.
"Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth," commented Dr. Linda Spilker in the April 13, 2017 NASA Press Release. Dr. Spilker is Cassini project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
The discovery of a moon can lead to a treasure chest filled with valuable information about the dwarf-planet system. This is because, by measuring the moon's orbit, astronomers can then go on to calculate a mass for the system and gain an important insight into its evolution.