Stars Galaxies Black Holes Test Questions

What was the first observational evidence that the geocentric model of the Solar System was wrong?

Some planets were observed to undergo retrograde motion in the sky.

Recall that the eccentricity of a perfectly circular orbit is e=0. With what eccentricity would a planet be in an open orbit? In other words, with what orbital eccentricity would a planet not repeatedly orbit the Sun?

Eccentricity greater than 1 (e>1)

If a new planet were to be discovered orbiting the sun at a distance of 2 AU from the Sun, what would be its orbital period?

NONE of the above are correct

What determines the resolution of a telescope?

Size of telescope and the wavelength of the light being observed with the telescope

Which of the following telescope resolutions is the best?

25” (smallest angle is best!)

Scientists use the ____ temperature scale, which sets the point where all thermal motion stops equal to a temperature of 0.

Kelvin

Regions of light spectrum in order of highest to lowest energy

Gamma Rays → X Ray → Ultraviolet → Visible → Infrared → Radio

If the temperature of an object were to double, the wavelength at which it emits the most amount of light will

be cut in half (1/2 x)

If the temperature of an object were to double, the total power radiated by the object will

increase by factor of 16 (16x)

An electron that transitions from a higher energy state to a lower energy state…

emits light

Consider a star emitting light with a wavelength of precisely 486.1 nm. If that star is moving toward you with a speed of 600 km/s, at what wavelength will you detect the light emitted by the star?

485.1 nm

How might you detect that a star is in orbit around another object such as a star or planet?

Its observed spectrum will shift back and forth over time.

How might you detect that a star is rotating very rapidly?

Individual lines in its spectrum will appear very wide.

Copernicus realized that _____ is never found farther than 47º from the Sun in the sky.

Venus

Copernicus realized that _____ is never found farther than 28º from the Sun in the sky.

Mercury

How many different colored filters are required to measure the temperature of a star using a telescope?

Three

Diffraction spikes are caused by

the structure of the telescope that was used

Chromatic aberration is the separation of colors in the light focused by which type of telescope

Refracting telescopes

Which type of telescope focuses light using glass lenses?

Refracting telescopes

The wavelength at which a star emits the most light depends on what property of the star?

Its surface temperature

The color of the star is an indicator of the star’s….

Surface temperature

A star produces an absorption spectrum. Which part of the star provides the brightest continuum?

The surface

A star produces an absorption spectrum. Which part of the star provides the brightest absorption lines?

The atmosphere

The sun’s magnetic activity

Does not affect Earth’s temperature

What is the primary factor that has contributed to the overall rapid increase in Earth’s temperature over the past 100 years?

The amount of greenhouse gases in Earth’s atmosphere

When the Sun was born, it had enough fuel to power itself as a main sequence star for about…

10 billion years

The Sun is currently about _________ years old

5 billion

How does a planetary nebula form?

A low-mass binary star system expels it.

How will the Sun die?

It will expel a planetary nebula and leave a small white dwarf behind

In Albert Einstein’s famous equation, E = mc², what does the c stand for?

The speed of light

A star with a mass of 5 times that of our Sun will last approximately

100 million years

The rate at which a star ages depends primarily on the star’s

mass

Very young star clusters contain more _____ than very old star clusters do.

blue stars

Consider Star 5 and 7 on the HR diagram shown. Assume they are born at the same time in a close binary star system. Which star will evolve into a red giant first?

Star 5

What is the luminosity of a Cepheid variable star that pulses about every 5 days?

1,000 L_☉

A Cepheid variable star that has a luminosity of about 10,000 L_☉ is expected to pulse once every

20 days

What is the mass of a black hole that has an orbital period (P) of 5 years and a semimajor axis (a) of 1,000 AU?

40,000,000 M_☉

If an astronaut weighs 160 pounds on Earth, about how much would they weigh on Pluto?

12 pounds

Neutron stars can spin hundreds of times per second without breaking apart. Why is that?

They have a very high surface gravity

A stellar mass black hole has a mass of 12 times the mass of the Sun. What is the radius of the black hole’s event horizon?

36 km

Who discovered the period luminosity relation for Cepheid variable stars?

Henrietta Swan Leavitt

Who discovered the first pulsar?

Jocelyn Bell Burnell

What does Hubble’s tuning fork classify?

Galaxies based on their shapes

What is a neutron star?

The remnant of a massive star after a supernova