astronomer: A scientist who works in the field of research that deals with celestial objects, space and the physical universe.
average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
black hole: A region of space having a gravitational field so intense that no matter or radiation (including light) can escape.
cosmic: An adjective that refers to the cosmos — the universe and everything within it.
data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.
entity: A person or thing that exists and can be defined or characterized on its own (meaning separate and apart from some general group).
galaxy: A group of stars — and usually invisible, mysterious dark matter — all held together by gravity. Giant galaxies, such as the Milky Way, often have more than 100 billion stars. The dimmest galaxies may have just a few thousand. Some galaxies also have gas and dust from which they make new stars.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
neutron star: The very dense corpse of what had once been a massive star. As the star died in a supernova explosion, its outer layers shot out into space. Its core then collapsed under its intense gravity, causing protons and electrons in its atoms to fuse into neutrons (hence the star’s name). A single teaspoonful of a neutron star, on Earth, would weigh more than a billion tons.
observatory: (in astronomy) The building or structure (such as a satellite) that houses one or more telescopes. Or it can be a system of structures that make up a telescope complex.
pulsar: The name for a spinning, ultra-dense neutron star. A single teaspoonful, on Earth, would weigh a billion tons. It represents the end of life for stars that had started out having four to eight times the mass of our sun. As the star died in a supernova explosion, its outer layers shot out into space. Its core then collapsed under its intense gravity, causing protons and electrons in the atoms that had made it up to fuse into neutrons (hence the star’s name). When these stars rotate, they emit short, regular pulses of radio waves or X-rays (and occasionally both at alternate intervals).
radio: Referring to radio waves, or the device that receives these transmissions. Radio waves are a part of the electromagnetic spectrum that people often use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals. They also are used in radar. Many astronomical objects also radiate some of their energy as radio waves.
star: The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become hot enough, stars will emit light and sometimes other forms of electromagnetic radiation. The sun is our closest star.
sun: The star at the center of Earth’s solar system. It is about 27,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.
telescope: Usually a light-collecting instrument that makes distant objects appear nearer through the use of lenses or a combination of curved mirrors and lenses. Some, however, collect radio emissions (energy from a different portion of the electromagnetic spectrum) through a network of antennas.