The Expanding Universe
The scientifically accepted explanation for the origin of the universe
Big Bang Theory
Our solar system resides within this spiral galaxy
Milky Way
The inner four planets—Mercury, Venus, Earth, and Mars—are known as this type of dense, rocky planet
Terrestrial
This natural phenomena causes light or sound waves to be compressed or expanded based on an object's motion
Doppler Effect
Launched by the Soviets on October 4, 1957, this was the first satellite put into space
Sputnik 1
This astronomer discovered that distant galaxies appeared red-tinted, proving the universe was expanding
Edwin Hubble
Scientists classify this variety of galaxy as having an oval-like shape with a smooth profile
Elliptical
Claudius Ptolemy's ancient interpretation that believed the Sun, Moon, and stars all orbited the Earth
Geocentric Model
This category of the electromagnetic spectrum, which includes microwaves and infrared, contains the lowest energy light
Radio Waves
On April 12, 1961, this Soviet individual became the first man sent to space
Yuri Gregarin
This matter cannot be seen but accounts for most of the matter in the universe
Dark Matter
Small stars collapse and turn into this kind of stellar remnant when they die
White Dwarf
The oval-like path, or ellipse, in which planets revolve around their host
Orbit
An object moving away from an observer appears slightly this color because its light waves are longer
Red
This American mission in July 1969 achieved the first human walk on the Moon
Apollo 11
A remnant of light created by the Big Bang that is now found in the microwave band
CBR (or Cosmic Background Radiation)
The process inside a star where hydrogen and helium atoms collide to create energy and new elements
Nuclear Fusion
During an eclipse, this term refers to the fully shaded inner region of a shadow
Umbra
The study using charts or graphs of light intensity to determine what elements an object is composed of
Spectroscopy
She became the first American woman in space, riding on the Challenger Shuttle in 1983
Sally Ride
The Big Bang was (and continues to be) this, rather than an explosion
Expansion
This massive explosion marks the end of life for massive stars
Supernova
This is a product of Earth’s rotation that causes moving objects (like wind) to seem to be deflected
Coriolis Effect
Besides element, temperature, and density, astronomers can determine this property of a star from analyzing its spectral line
Magnetic Field
This new NASA initiative seeks to return to the Moon, establish a permanent lunar presence, and then travel to Mars
Artemis Program