Scattered Disc

Scattered disc is a distant circumstellar disc in the Solar System that is sparsely populated by icy small solar system bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical … Continue reading Scattered Disc

Seyfert Galaxy

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable. Seyfert galaxies were first detected in … Continue reading Seyfert Galaxy

Space Probe

Space probe, or simply probe, is a robotic spacecraft that doesn't orbit the Earth, but instead explores farther into outer space. A space probe may approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or enter interstellar space. Once a probe has left the vicinity of Earth, … Continue reading Space Probe

Nuclear Star Cluster

Nuclear star cluster (NSC) or compact stellar nucleus is a star cluster with high density and high luminosity near the center of mass of most galaxies. NSCs are the central massive objects of fainter, low-mass galaxies where supermassive black holes (SMBHs) are not present or are of negligible mass. In the most massive galaxies, NSCs are entirely absent. Some galaxies, including the Milky Way, are known to contain … Continue reading Nuclear Star Cluster

Transit

Transit is a phenomenon when a celestial body passes directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of the larger body, covering a small portion of it. However, the probability of seeing a transiting planet is low because it … Continue reading Transit

Stellar collision

Stellar collision is the coming together of two stars caused by stellar dynamics within a star cluster, or by the orbital decay of a binary star due to stellar mass loss or gravitational radiation, or by other mechanisms not yet well understood. Astronomers predict that events of this type occur in the globular clusters of … Continue reading Stellar collision

Black Hole Information Paradox

Black hole information paradox is a puzzle resulting from the combination of quantum mechanics and general relativity. The combination of the two means that information must always be preserved. Calculations suggest that physical information could permanently disappear in a black hole, allowing many physical states to devolve into the same state. This is controversial because … Continue reading Black Hole Information Paradox

Primordial Black Holes

Primordial black holes are a hypothetical type of black hole that formed soon after the Big Bang. In the early universe, high densities and heterogeneous conditions could have led sufficiently dense regions to undergo gravitational collapse, forming black holes. Yakov Borisovich Zel'dovich and Igor Dmitriyevich Novikov in 1966 first proposed the existence of such black … Continue reading Primordial Black Holes

Interacting Galaxies

Interacting galaxies are galaxies whose gravitational fields result in a disturbance of one another. An example of minor interaction is a giant galaxy interacting with its satellites, which is common. A satellite's gravity could attract one of the primary's spiral arms, or the secondary satellite's path could coincide with the position of the primary satellite's … Continue reading Interacting Galaxies