Universe Formation

Midterm

What is the Big Bang Theory?

The theory that the universe began as an extremely hot, dense point and has been expanding ever since.

What is a singularity?

A point of infinite density and temperature where space and time begin.

What does expansion of the universe mean?

Galaxies are moving away from each other as space itself stretches.

What are the possible outcomes of the universe?

Open: expands forever; Closed: collapses; Flat: expansion slows but never stops

What is the composition of the universe?

75% dark energy, 21% dark matter, 4% luminous matter.

What is a solar system?

A star and all objects that orbit it.

What is a galaxy?

A massive system of stars, gas, dust, and dark matter held together by gravity.

What is the universe?

Everything that exists including all matter, energy, space, and time.

What is a spiral galaxy?

A galaxy with a flat disk, spiral arms, and a central bulge.

What is an elliptical galaxy?

A round or oval galaxy with mostly older stars and little gas or dust.

What is an irregular galaxy?

A galaxy with no defined shape.

What evidence supports the Big Bang Theory?

Expansion of the universe, cosmic background radiation, and redshift.

What is cosmic background radiation?

Weak microwave radiation left over from the early universe.

What is Einstein’s Theory of Relativity?

Space and time are linked, and gravity is caused by the bending of spacetime.

What is the Doppler effect?

The change in wavelength or frequency of a wave due to motion.

What are the main properties of waves?

Frequency, wavelength, and amplitude.

What is frequency?

The number of waves that pass a point per second.

What is wavelength?

The distance between wave crests.

What is amplitude?

The height of a wave related to energy and brightness.

What is the relationship between wavelength and frequency?

They are inversely related; as one increases, the other decreases.

What is redshift?

Light shifts to longer wavelengths when an object moves away.

What is blueshift?

Light shifts to shorter wavelengths when an object moves closer.

Which color has the longest wavelength in visible light?

Red

Which color has the shortest wavelength in visible light?

Violet

What is the electromagnetic spectrum?

The full range of electromagnetic radiation from radio waves to gamma rays.

How do electromagnetic waves travel?

At the speed of light through space while transferring energy.

Why is light important in astronomy?

Light released or reflected by distant objects allows scientists to study the universe.

What is spectroscopy?

The study of light spectra to determine an object’s composition, temperature, and motion