Astrophysics Exam 1

What is Kepler’s first law?

Each planet orbits around the Sun in an ellipse with the Sun at one focus

What is Kepler’s third law?

The ratio of the cube of a planet’s average distance from the Sun (a) to the square of its orbital period (p) is the same for each planet

What mechanism produces bright spectral lines?

Bright spectral lines are produced from hot diffuse gas when electrons go from high to low orbits as they release energy in the form of light.

What mechanism produces dark spectral lines?

Dark spectral lines are produced from cool diffuse gas when electrons go from low to high orbit as they absorb energy

What is a photon’s energy

The energy of a photon is directly proportional to its frequency and inversely proportional to its wavelength, given by the equation $E = h \nu$, where $E$ is energy, $h$ is Planck's constant, and $\nu$ is frequency.

What is Doppler Effect?

Doppler effect is a method of measuring radial velocity by finding the difference between observed and emitted wavelengths and diving by emitted wavelength

Name one reason why bigger telescopes are better

The have a larger collecting area to gather more light (in the form of wavelengths) in a shorter time frame, increasing the angular resolution. This is because angular resolution is directly proportional to wavelength and inversely proportional to the diameter of the len’s aperture)

Name a different reason why bigger telescopes are better

Larger telescopes can take images with greater detail

What is Wien’s law?

Peak emission wavelengths of blackbody radiation only depends on temperature

What is Stefan-Boltzmann law?

Energy is directly proportional to the temperature raised to the fourth power and area of the blackbody. It essentially states hotter objects emit more energy over all wavelength’s while having a massive area can result in more energy emitted as well.

How does blackbody radiation emit?

Radiates on a continuous spectrum

How do we identify elements in the Sun?

By analyzing the spectral lines that come from light emitted from the sun and analyzed using a spectroscope. The spectral lines absorbed by the Sun match the emission spectral lines of elements, which is used to identify the composition of the Sun (and other stars)

Which wavelength band yields the highest spatial resolution?

If observations are being held in space, outside the Earth’s atmopshere, gamma rays yield the highest resolution. Radio waves, however, have an overall higher spatial resolution despite being partially absorbed by radio waves since they can be combined with additional radio telescopes across the world to drastically increase the spatial resolution.