- A constellation formed in the late 16th century by the Dutch cartographer and astronomer Petrus Plancius, who took some stars that Ptolemy in his Almagest had catalogued as lying outside Canis Major. These unformed stars can be seen, for example, on the southern half of Albrecht Dürer’s star chart of 1515 as two little groups, one group of six to the south of Lepus, from which the dove was formed, and another group of five between the hind legs of Canis Major which Plancius visualized as an olive branch.
- Geometry (Wikipedia)
Geometry (from Ancient Greek γεωμετρία (geōmetría) ’land measurement’; from γῆ (gê) ’earth, land’, and μέτρον (métron) ‘a measure’) is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures. Geometry is, along with arithmetic, one of the oldest branches of mathematics. A mathematician who works in the field of geometry is called a geometer. Until the 19th century, geometry was almost exclusively devoted to Euclidean geometry, which includes the notions of point, line, plane, distance, angle, surface, and curve, as fundamental concepts.