kosmos: Observational history of comets

Evidence: 100 • authority: 72

Comets have been observed by humanity for thousands of years, but only in the past few centuries have they been studied as astronomical phenomena. Before modern times, great comets caused worldwide fear, considered bad omens foreboding disaster and turmoil; for example, the 1066 passage of Halley's Comet depicted as heralding the Norman conquest of England. As the science of astronomy developed planetary theories, understanding the nature and composition of comets became a challenging mystery and a large area of study. Halley's Comet, reappearing every 75–76 years, was pivotal to the study of comets and their orbits. Thinkers such as Immanuel Kant in the eighteenth century hypothesized abou…

Evidence: 70 • authority: 72

Evidence: 51 • authority: 72

Evidence: 51 • authority: 72

The Kreutz sungrazers ( KROYTS) are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. At the far extreme of their orbits, aphelion, Kreutz sungrazers can be a hundred times farther from the Sun than the Earth is, while their distance of closest approach can be less than twice the Sun's radius. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. These sungrazers make their way from the distant outer Solar System to the inner Solar System, to their perihelion point near the Sun, and then leave the in…

Evidence: 51 • authority: 72

The Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system (not part of a larger star system) within the Milky Way Galaxy. The system formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, creating the Sun and a protoplanetary disc from which the orbiting bodies assembled. The Sun accounts for 99.86% of the Solar System's total mass. Inside the Sun's core, hydrogen is fused into helium, releasing energy that is emitted through the Sun's photosphere. This creates the heliosphere and a decreasing temperature…

Evidence: 51 • authority: 72

Evidence: 38 • authority: 80

Evidence: 38 • authority: 80

COMETS WHOSE RETURN HAS BEEN OBSERVED

Evidence: 38 • authority: 88

Evidence: 38 • authority: 80

Evidence: 38 • authority: 72