Quasi-starA quasi-star (also called black hole star) is a hypothetical type of extremely massive and luminous star that may have existed early in the history of the Universe. Unlike modern stars, which are powered by nuclear fusion in their cores, a quasi-star's energy would come from material falling into a black hole at its core. A quasi-star would have resulted from the core of a large protostar collapsing into a black hole, where the outer layers of the protostar are massive enough to absorb the resulting burst of energy without being blown away or falling into the black hole, as occurs with modern supernova.
Digital single-lens reflex cameraA digital single-lens reflex camera (digital SLR or DSLR) is a digital camera that combines the optics and the mechanisms of a single-lens reflex camera with a solid-state and digitally records the images from the sensor. The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens and then to a mirror that alternates to send the image to either a prism, which shows the image in the optical viewfinder, or the image sensor when the shutter release button is pressed.
Cosmic distance ladderThe cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances.
Circumstellar discA circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the reservoirs of material out of which planets may form. Around mature stars, they indicate that planetesimal formation has taken place, and around white dwarfs, they indicate that planetary material survived the whole of stellar evolution. Such a disc can manifest itself in various ways.
Nebular hypothesisThe nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbiting the Sun which clumped up together to form the planets. The theory was developed by Immanuel Kant and published in his Universal Natural History and Theory of the Heavens (1755) and then modified in 1796 by Pierre Laplace.
Solar SystemThe Solar System is the gravitationally bound system of the Sun and the objects that orbit it. The largest of such objects are the eight planets, in order from the Sun: four terrestrial planets named Mercury, Venus, Earth and Mars, two gas giants named Jupiter and Saturn, and two ice giants named Uranus and Neptune. The terrestrial planets have a definite surface and are mostly made of rock and metal. The gas giants are mostly made of hydrogen and helium, while the ice giants are mostly made of 'volatile' substances such as water, ammonia, and methane.
Konica Minoltais a Japanese multinational technology company headquartered in Marunouchi, Chiyoda, Tokyo, with offices in 49 countries worldwide. The company manufactures business and industrial imaging products, including copiers, laser printers, multi-functional peripherals (MFPs) and digital print systems for the production printing market. Konica Minolta's Managed Print Service (MPS) is called Optimised Print Services.
Astronomical naming conventionsIn ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the most interesting objects, and where relevant, features of those objects.
RadionuclideA radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay.
History of EarthThe history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geological change and biological evolution. The geological time scale (GTS), as defined by international convention, depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history.
