The Big Bang
This is a point in which matter is infinitely dense, as in the center of a black hole or the universe at the very beginning of time
What is a singularity?
These stars are located in the bulge and halo and contain only trace amounts of heavy elements
What are Population II stars?
This is the galaxy in which the Earth resides.
What is the Milky Way?
These tiny particles - like protons, electrons, and neutrons - are small than atoms.
What are subatomic particles?
This is the true shape of the Earth.
What is an Oblate Spheroid?
According to your textbook, this type of universe would result if the amount of matter in the the universe is great enough to force the universe to stop expanding.
What is a closed universe?
These stars have pulsation periods ranging from 1.5 hours to 1 day, generally having the same luminosity, regardless of pulsation period length
What are RR Lyrae Variable stars?
A grouping of an enormous number of galaxies.
What is a supercluster?
This invisible material is thought to be made up of a form of subatomic particle that interacts only weakly with other matter
What is Dark Matter?
The rotation of the Earth upon its axis causes this phenomenon.
What are day and night?
Based on mathematical calculations, scientists estimate the Universe is approximately this old.
What is 13 - 14 billion years old?
This is the astronomical explosion that happens at the end of a massive star's life.
What is a supernova?
This is a very bright, often giant, elliptical galaxy that emits as much or more energy in the form of radio wavelengths as it does wavelengths of visible light
What is a radio galaxy?
This is the theoretical density of the universe that would create a flat universe.
What is the critical density?
The tilt of the Earth on its axis is the main reason the Earth has these.
What are seasons?
This value is used to calculate the rate at which the universe is expanding
What is the Hubble constant?
These stars have pulsation periods between 1 and 100 days and the luminosity as much as doubles from dimmest to brightness
What are Cepheid Variable Stars?
This term refers to the core of an active galaxy where highly energetic objects or activities are located
What is the Active Galactic Nucleus?
This are spiral regions of alternating density which rotate as rigid patterns
What are Spiral Density Waves?
This is the electromagnetic radiation left over from the Big Bang. We can sometimes see it as static on our televisions (especially before the days of cable.)
What is cosmic background radiation?
This is the idea that suggests once the universe stops expanding it will retract and collapse back into a singularity.
What is the Big Crunch?
These stars in the giant branch of the Hertzsprung-Russell diagram that pulsate in brightness due to the outer layers of the stars expanding and contracting
What are Variable Stars?
These are massive and extremely remote celestial object, emitting exceptionally large amounts of energy. It has been suggested that these may represent a stage in the evolution of some galaxies.
What are Quasars?
The larger the mass of an object in space, the greater this force is.
What is gravity?
Georges Lemaître was the scientist responsible for the discovery of the Big Bang and the models of the expanding universe. This was his occupation.
What is a Catholic Priest?