accretion: (in astronomy) The growth of any celestial object due to bringing in new building materials, such as gas, plasma, dust and other particles. The object’s gravitational tug brings in these new materials, eventually causing them to coalesce. (v. accrete)
accretion disk: A plane-like disk made from gas, dust and more that grows and orbits around some astronomical object. That gravitational tug of that object, known as the accretor, causes material in the disk to loses energy and angular momentum. This causes the disk to slowly spirals inward. Accretion disks likely play a role in the development of stars and planets and in the powerful spectral emissions that come from quasars, radio galaxies and some supernovas.
atmosphere: The envelope of gases surrounding Earth, another planet or a moon.
atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
black hole: A region of space having a gravitational field so intense that no matter or radiation (including light) can escape.
cavity: (in dentistry) a tiny hole in a tooth that develops over time. Dental cavities are more likely to happen when a person eats a lot of sugar or does not brush and floss regularly. Dentists refer to these as caries.
cosmic: An adjective that refers to the cosmos — the universe and everything within it.
cosmos: (adj. cosmic) A term that refers to the universe and everything within it.
density: The measure of how condensed some object is, found by dividing its mass by its volume.
disk: A round, flat and usually fairly thin object. (in astronomy) A rotating cloudlike collection of gases, dust or both from which planets may form. Or the structure of certain large rotating bodies in the cosmos, including spiral galaxies.
electromagnetic: An adjective referring to light radiation, to magnetism or to both.
electromagnetic radiation:…
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