Sirius in fiction below)—and even if such were eventually discovered, with an estimated age of 230 million years the system is too young to have fostered the development of life or a complex biosphere. Sirius AB is the alpha star of the constellation Canis Major (the great dog, sometimes styled as Orion's hunting dog), whence its cognomen "the dog star". The most commonly used proper name of this star comes through the Latin "Sirius", from the Greek Σείριος ("Seirios", "glowing" or "scorcher"). The ancient Greeks observed that the appearance of Sirius heralded the hot and dry "dog days" of summer, and feared that
Belief with delineating the boundary between justified belief and opinion, and involved generally with a theoretical philosophical study of knowledge. The primary problem in epistemology is to understand exactly what is needed in order for us to have knowledge. In a notion derived from Plato's dialogue "Theaetetus", where the epistemology of Socrates (Platon) most clearly departs from that of the sophists, who at the time of Plato seem to have defined knowledge as what is here expressed as "justified true belief". The tendency to translate from belief (here: doxa – common opinion) to knowledge (here: episteme), which Plato (e.g. Socrates of