ASP Astrophysics Fundamentals

Question 1

What is Wien's displacement law?

Accepted Answer

It states that the peak wavelength of blackbody radiation is inversely proportional to temperature

Answer

It describes how stars move through the galaxy

Answer

It defines the relationship between stellar mass and luminosity

Answer

It describes how gas clouds collapse under gravity

Question 2

What is the Stefan-Boltzmann law?

Accepted Answer

A law stating that a blackbody radiates power proportional to the fourth power of its temperature

Answer

A law relating orbital period to orbital distance

Answer

A law describing the relationship between magnetic field strength and stellar rotation

Answer

A law governing the rate of nuclear fusion in stellar cores

Question 3

What is Kepler's third law of planetary motion?

Accepted Answer

The square of a planet's orbital period is proportional to the cube of its semi-major axis

Answer

Planets move in elliptical orbits with the Sun at one focus

Answer

A planet moves faster when closer to the Sun

Answer

Each planet orbits the Sun at a constant average speed

Question 4

What is the Doppler effect and how is it used in astronomy?

Accepted Answer

The change in observed frequency of waves from a moving source; used to measure radial velocities of celestial objects

Answer

The bending of light by gravity; used to measure black hole masses

Answer

The focusing of light by a gravitational lens; used to find exoplanets

Answer

The reddening of light by dust; used to map interstellar medium

Question 5

What is the inverse square law of light?

Accepted Answer

The apparent brightness of a source decreases with the square of the distance from the observer

Answer

Light speed decreases with the square of distance traveled

Answer

A star's luminosity is inversely proportional to its mass squared

Answer

The wavelength of light is inversely proportional to photon energy squared

Question 6

What is the virial theorem in astrophysics?

Accepted Answer

A theorem stating that the average kinetic energy of a gravitationally bound system equals half the magnitude of its average gravitational potential energy

Answer

A theorem relating the kinetic energy of a gas to its expansion rate

Answer

A theorem describing the orbital resonances of moons

Answer

A theorem governing the rotation curves of spiral galaxies