Earth (or the Earth) is the third planet from the Sun and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System’s four terrestrial planets. It is sometimes referred to as the World, the Blue Planet, or by its Latin name, Terra. Earth is a terrestrial planet, meaning that it is a rocky body, rather than a gas giant like Jupiter. It...
Draco is an extended constellation of the northern hemisphere. Draco (Latin for Dragon) is a far northern constellation that is circumpolar for many northern hemisphere observers. It is one of the 88 modern constellations, and one of the 48 constellations listed by Ptolemy. The star Thuban (Draconis) was the northern pole star around 2700 BC, during the time of the ancient Egyptians. Due to the...
Dark Matter should not to be confused with Dark Energy, Dark Fluid (is an alternative theory to both Dark Matter and Dark Energy and attempts to explain both phenomena in a single framework), or Dark Flow (astrophysical term describing a peculiar velocity of galaxy clusters). In astronomy and cosmology, dark matter is matter that is inferred to exist from gravitational effects on...
DARK ENERGY should not to be confused with Dark Energy or Dark Fluid. In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe. Dark energy is the most accepted hypothesis to explain the observations since the 1990s indicating that the universe is expanding at an...
An impact crater is an approximately circular depression in the surface of a planet, moon or other solid body in the Solar System, formed by the hypervelocity impact of a smaller body with the surface. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain...
Cosmology is study of the Universe in its totality, and by extension, humanity’s place in it. Though the word cosmology is recent (first used in 1730 in Christian Wolff’s Cosmologia Generalis), study of the Universe has a long history involving science, philosophy, esotericism, and religion. In recent times, physics and astrophysics have come to play a central role in shaping the...
A comet is basically a ball of ice and dust that looks like a star with a tail.Some comets do not have tails, looking like hazy, round spots of light. A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail – both primarily from the effects of solar radiation upon the comet’s nucleus, which itself is a...
The celestial spheres, or celestial orbs, were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, adopted by Aristotle and developed by Ptolemy, Copernicus and others. In this celestial model the stars and planets are carried around by being embedded in rotating spheres made of an aetherial transparent fifth element (quintessence), like jewels...
Cassiopeia is a northern constellation which greek mythology considered to represent a vain queen. It is one of the 88 modern constellations, and was also one of the 48 listed by Ptolemy. Cassiopeia contains two stars visible to the naked eye that rank among the most luminous in the galaxy: p Cas and V509 Cas. The star n Cas is a nearby (19.4 ly) binary star comprising of a yellow Sun-like dwarf...
A black hole is a region of spacetime from which gravity prevents anything, including light, from escaping. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called “black” because it...