astronomy exam 3 - quiz questions

One main limitation of the microlensing technique for detecting exoplanets is

The planets detected by microlensing will not be observed again

Microlensing is good at detecting systems that are far away from us; in terms of how planets are situated from their host star what orbital distances in microlensing most sensitive to?

Most sensitive to planets tat orbit in moderate to large distances from their star

The gravitational microlensing technique is centered around what gravity actually is and what it does. So according to the general theory of relativity, what really is happening when somehting massive is present?

The presence of mass causes a curvature (or warping) of spacetime

Orbital angular momentum

Angular momentum associated with an object’s orbit around another object

Spin angular momentum

Angular momentum associated with an object’s rotation around its own axis

Approximately how long ago did the Solar System form

4.6 billion years ago

What is the primary theory explaining how our Solar System formed?

Solar Nebula theory

Why can't Earth's oldest rocks accurately determine the age of the entire Solar System?

Geological processes have melted and re-solidified rocks

Which object provides the best evidence for the original age of the Solar System?

The oldest meteorites

In radioactive dating, what is the unstable original element called?

Parent element

What happens during condensation?

A gas transitions directly into a solid

How did temperature vary throughout the early solar nebula?

The inner disk was hotter

What is the frost line?

The boundary beyond which hydrogen compounds can condense into ices

Approximately where was the frost line located?

Between Mars and Jupiter, around 3-4 AU

Why do planets have different chemical compositions?

Different materials could condense at different temperatures and distances

What is accretion?

The accumulation of smaller materials into larger bodies

What are planetesimals?

Small solid bodies involved in planet formation

What helped explain the differences between gas giants and ice giants?

Accretion of planetisimals and accumulation of gases

Where did most of the Solar System's angular momentum end up?

In the planets and disk

Which statement about the Solar System's mass and angular momentum is correct?

The Sun contains 99.9% of the mass, while planets contain about 98% of the angular momentum

What is orbital angular momentum?

Orbital angular momentum describes the angular momentum associated with orbital motion

17. What is spin angular momentum?

An object;s rotation around its own axis

Why does the Sun contain most of the Solar System's mass but relatively little angular momentum?

Angular momentum was transferred to the disk or carried away in jets

Why do most planets orbit in a relatively thin plane?

The formed within the same rotating disk

What does the discovery of planet-forming disks around other stars suggest?

Planet formation is common in our galaxy

What are the two main proposed mechanisms for forming gas giant planets?

Core accretion and disk instability

What is the main difference between the formation timescales of core accretion and disk instability?

Disk instability is faster

Which is an advantage of the core accretion model?

It easily explains the composition of gas and ice giants

What is one major disadvantage of core accretion?

It takes too long to build planetsimals and accrete gas

Why is forming Neptune and Uranus challenging for the core accretion model?

There may not be enough time to form them before disk gas disperses

Which is an advantage of the disk instability model?

It can form giant planets quickly and potentially at large distances

Which is an disadvantage of the disk instability model?

Disks may not become unstable or cool quickly enough

Which statement about the two giant planet formation models is correct?

Both can produce giant planets, but they differ in formation timescales

What is the approximate formation timescale for giant protoplanets in the core accretion model?

3-10 million years

What is the approximate formation timescale for giant protoplanets in the disk instability model?

.1-1 million years

What did observations of Jupiter's interior reveal about its core?

It may be a large, fuzzy core mixed with metallic hydrogen

Which spacecraft mission provided important information about Jupiter's interior?

Juno

Which explanation could account for Jupiter's fuzzy core?

A large early collision dissolved its original core, mixing material upward

What is another proposed explanation for Jupiter's fuzzy core?

Jupiter formed from vaporized rock and gas from the beginning

What do Cassini observations suggest about Saturn's core mass?

15-18 Earth masses

How does Saturn's core compare with Jupiter's according to the lecture?

Saturn may have a higher concentration of heavy elements and a more compact core

Where is most of Jupiter's lightning activity located?

Near its poles

What unusual storm pattern was observed at Jupiter's north pole?

Eight masses storms arranged around a central storm

How fast were winds in Saturn's north polar storm measured to be?

330 mph

What is the approximate distance of Jupiter from the Sun in AU?

5.2 AU

According to Kepler's Third Law, what happens to a planet's orbital period as its orbital distance increases?

The orbital period increases

A planet orbits a Sun-like star at 4 AU. Using Kepler's Third Law, approximately how long is its orbital period?

8 years

What was significant about the discovery of 51 Peg b in 1995?

It was one of the first exoplanets detected around a Sun-like star

What is the approximate semi-major axis of 51 Peg b?

.05 AU

Why do astronomers believe Hot Jupiters did not originally form so close to their stars?

Temperatures so close to the star are too high for gas giant formation

What is the leading explanation for the existence of Hot Jupiters?

They formed outside the frost line and migrated inward

Which planets are considered the terrestrial planets?

Mercury, Venus, Earth, Mars

What is a primary atmosphere?

An atmosphere caputres directly from the solar nebula

Why did terrestrial planets lose their primary atmospheres relatively quickly?

Their gravity was too weak to retain light gases like hydrogen and helium

How did Earth, Venus, and Mars develop their secondary atmospheres?

Through volcanism, outgassing, and comet impacts

Which planet has an atmosphere composed of approximately 96% carbon dioxide?

Venus

What percentage of Earth's atmosphere is nitrogen?

78.1%

Why does Venus experience a runaway greenhouse effect?

Its atmosphere contains enormous amounts of CO2, trapping heat

Why did Venus potentially lose its oceans?

Its increasing solar heating caused more evaporation, releasing greenhouse gases and creating a runaway greenhouse effect

What happened to much of Earth's CO2 over time?

It became chemically bound in rocks or dissolved in ocean water

How does Mars's atmosphere compare to Venus's?

Their relative gas proportions are similar, but Mars’s atmosphere is much thiner

What is the approximate surface pressure of Mars compared with Earth?

Less than 1% of Earth’s

What happened to liquid water on early Mars?

It likely existed early on, but cooling caused it to freeze

What caused Mars to lose much of its thicker early atmosphere?

Solar wind and radiation, along with chemical reactions locking gases into surface rocks

What is the runaway refrigerator effect associated with Mars?

Atmospheric loss weakens the greenhouse effect, causing cooling and water to freeze

Which of the following is evidence that the early Solar System was chaotic?

Craters on planetary surfaces, planets with unusual rotations, the formation of Earth’s Moon

Why might Mercury have such a large iron core relative to its rocky mantle?

It may have lost much of its lighter rocky material through catastrophic impacts

What is unusual about Venus's rotation?

It rotates clockwise, unlike the other planets

What is unusual about Uranus's orientation?

It has an axial tilt of approximately 97 degrees

What is the leading explanation for the formation of Earth's Moon?

Giant Impact Hypothesis

What is the fission theory of Moon formation?

The Moon was once part of Earth and broke away

What is the sister theory of Moon formation?

Earth and Moon formed together but independently

What is the capture theory?

The Moon formed elsewhere and was later gravitationally captured by Earth

How does the Giant Impact Hypothesis explain the similar compositions of Earth and the Moon?

The collision ejected molten and vaporized debris from Earth that eventually formed the Moon

Which are the three basic types of satellite formation discussed in the slides?

Normal giant planet systems, captured satellites, and giant impacts

Why are normal satellite systems around giant planets sometimes called miniature Solar Systems?

Their moons formed from disks of gas and dust surrounding the giant planets

Which of the following is characteristic of captured satellites?

They are often small, outer moons with unusual or retrograde orbits

Which moon of Neptune is an example of a captured satellite with a retrograde orbit?

Triton

What does it mean for a moon to be tidally locked?

Its rotation period matches its orbital period, so the same side faces its planet

Which pair is tidally locked to each other?

Pluto and Charon

Which statement about the giant planets' rings is correct?

All four giant planets have ring systems made of dust and ice particles

What is the most likely origin of planetary ring systems according to the slides?

The disruption of a moon that gets too close to its planet

What is the Roche Limit?

The minimum distance a satellite can approach its parent without being torn apart by tidal forces

Assuming the densities of a planet and moon are approximately equal, what is the Roche Limit distance according to the lecture?

2.4 times the planet’s radius

What role can moons play in maintaining planetary ring systems?

They can continually supply material to rings

What is the role of Saturn's moon Daphnis?

It creates vertical waves in the rings as it orbits in a gap

Which planets in our Solar System have the most satellites (moons)?

Giant planets

How many moons do the terrestrial planets have altogether?

3N

What are the three basic types of satellite systems discussed in lecture?

Normal, captured, and giant-impact

Normal satellite systems around giant planets are often described as:

Miniature solar systems

How do the orbits of moons in normal giant-planet satellite systems generally compare?

They orbit in the same direction as the planet’s orbit around the Sun and have low inclinations

What is a likely origin of many captured satellites?

Asteroids captured by a planet’s gravity

Captured satellites are usually:

Small moons, often among the outermost satellites

What does retrograde motion mean for a moon?

it orbits in the opposite direction from the usual direction

Which moon of Neptune is thought to be a captured satellite?

Triton

What is the most likely explanation for the formation of Earth's Moon?

A giant impact with early Earth produced debris that formed from the Moon

Which other moon was mentioned as possibly forming through a giant impact?

Charon

What does it mean for a moon to be tidally locked?

its rotation period equals its orbital period

Which of the following is an example of a tidally locked moon?

Earth’s Moon

Which pair of objects is mutually tidally locked?

Pluto and Charon