astronomy quiz four

What is the difference between a Meteoroid, meteor, and meteorite?

A meteoroid is a piece of debris in space. A meteor is the streak of light we see whenever a meteoroid travels through our atmosphere. A meteorite is a meteoroid that successfully reached the ground.

What interaction is likely to cause Mercury to have an unstable orbit?

A near-resonance between Mercury and Jupiter could ultimately cause Mercury's orbit to be unstable. This resonance is strongly suppressed by General Relativity.

When does a protostar become a Main Sequence star?

A protostar becomes a main sequence star when it stops collapsing and begins fusing Hydrogen to Helium in its core

Where does a protostar get its energy?

A protostar gets its energy from gravitational collapse.

Which planets have rings?

All of the Jovian planets have rings

How does the composition of asteroids differ from the composition of Kuiper Belt Object?

Asteroids are made of rock and iron, while Kuiper Belt Objects are made of ice and rock.

What are the classes of small bodies in the outer solar system?

Centaurs (asteroid-like objects orbiting between Jupiter and Neptune), the Trojans of Neptune (objects which orbit ahead of and behind Neptune), and Kuiper Belt Objects (of which Pluto is one)

What is Pluto's largest moon?

Charon

How do comets differ from asteroids in composition?

Comets are made of rock and ice while asteroids lack ices. This parallels the difference between the composition of Kuiper Belt Objects and asteroids.

Why do comets have tails?

Comets have tails because when they get too close to the Sun, the Sun's radiation and the solar wind causes them to sublimate. The material that sublimates off forms the tail.

How do the orbits of comets differ from other solar system bodies?

Comets have very elliptical orbits compared to asteroids or planets. Those orbits take them from the outer solar system to the inner solar system where the Sun's radiation and solar wind causes them to sublimate.

What was Edmund Halley's important realization about comets?

Edmund Halley (of Halley's comet fame), realized that comets can be seen multiple times as they return on the same orbit.

What is special about Saturn's moon Enceladus?

Enceladus has geyser's of water, indicating that there may be liquid water under the surface

Why was Pluto's status as a planet revisited in 2006?

Eris

What do we call the large moons?

Galilean

Do the surfaces of Ganymede and Callisto look young or old?

Ganymede and Callisto have darker, heavily cratered surfaces, so they must be old

Why are there gaps in the asteroid belt?

Gaps in the asteroid belt are caused by resonance with Jupiter.

What is needed in order to get a cloud to collapse?

Giant Molecular Clouds need a trigger to collapse. This trigger could be a nearby supernova explosion, a collision with another cloud, etc.

Why don't giant molecular clouds immediately collapse due to gravity?

Giant molecular clouds don't collapse by themselves because they are held up by their gas pressure and magnetic fields.

What do we call Jupiter's largest storm?

Great Red Spot

What are the major components of the atmosphere of Uranus and Neptune?

Hydrogen and Helium

What are the primary constituents of Jupiter's atmosphere?

Hydrogen and Helium

What do protostars look like in the visible? Infrared?

In the visible, a protostar looks like a dark spot since the dusty cloud blocks out background light. In the infrared, you can look through the dust and see the protostar directly.

Which moons produce Jupiter's ionized gas torus?

Io

What are the compositions of Io and Europa compared to Ganymede and Callisto?

Io and Europa are mostly rocky. Ganymede and Calliso are mostly made of ice

Where do long-period comets come from? What about short-period comets?

It's believed that long-period comets come from the Oort Cloud, very far away. Short-period comets come from the Kuiper belt.

What is the large collection of icy bodies on the outskirts of our solar system called?

Kuiper Belt

Why do large gaps in the rings occur?

Large gaps in the rings are often caused by resonance with a massive moon. This occurs when the time an object in the ring to make an orbit is an exact multiple of the time it takes for themoon to make an orbit. The 2:1 resonance with Mimas is the cause of the Cassini division.

How do the orbits of long-period and short-period comets differ?

Long-period comets have very long orbits that come in from any direction, not just in the ecliptic plane. Short-period comets are still confined to the ecliptic plane.

What is the difference between long-period and short-period comets?

Long-period comets take longer than 200 years to orbit the Sun; short-period comets take less.

What chemical gives Uranus and Neptune their distinctive blue color?

Methane

Why aren't most asteroids round?

Most asteroids aren't massive enough for gravity to make them round.

Are Uranus and Neptune gas giants like Jupiter and Saturn?

No

Are rings made of one solid material?

No, rings are made of many small particles

Are the orbits of the planets unchanging?

No. Although the planets seem to be regular over human timescales, the planets interact with each other through gravity and their orbits change over millions of years.

Is it simple to calculate orbits when more than two objects are involved?

No. When you have more than two objects, it becomes extremely difficult to calculate orbits. And orbits which don't initially look like they should be stable can end up being stable.

Why do we think that Titan had to be captured into its orbit?

Our current understanding of moon formation require the moon to be formed in a prograde orbit, not retrograde. Since Triton is in a retrograde orbit, it's likely that it was a captured object.

What do we think Plutinos tell us about how the outer solar system developed?

Plutinos are a large class of objects which are in a 3:2 resonance with Neptune, like Pluto. Since these objects are locked in an orbit with Neptune, it's thought that Neptune first formed closer in, and slowly migrated out, sweeping up Kuiper Belt Objects in this resonance as it migrated

Why doesn't Pluto collide with Neptune, despite the orbits crossing?

Pluto doesn't collide with Neptune because it is in resonance. Over time, it settled into an orbit where whenever it crosses Neptune's orbit, Neptune is always far away.

How is the orbit of Pluto related to the orbit of Neptune?

Pluto is in a 3:2 orbital resonance with Neptune.

What characteristics of Pluto's orbit made it unlike the other planets?

Pluto's orbit is much more eccentric than any of the other planets, and is also tilted outside of the plane of the solar system. It is also closer than Neptune at certain times in its orbit.

What is the closest distance a moon can get to a planet before it is ripped apart by tides?

Roche radius

What is the composition of Saturn's rings?

Saturn's rings are mostly made of rock and ice.

What does this imply about what lies underneath Europa's surface?

Since there is a source of water underneath Europa's surface, it's possible that there is a liquid water ocean underneath.

How does a chaotic system differ from a regular one?

Small changes in chaotic systems can cause extremely large changes over time. This causes them to be highly unpredictable.

In what material are stars born?

Stars are born in Giant Molecular Clouds (GMCs).

Why are some asteroids made of iron, others made of rock, and some made of both?

Stony and iron meteorites are thought to be remnants of larger, differentiated asteroids which broke apart. Iron meteorites came from the metal cores while the stony meteorites came from the rocky upper layer.

What was special about the discovery of Neptune?

The existence of Neptune was predicted from the orbit of Uranus

What is the difference between the ion and dust tails?

The ion tail consists of atoms and molecules ionized by the Sun and pushed back by the solar wind. The dust tail consists of particles of rock and ice that leave a trail behind the comet pushed by sunlight.

What happens to the leftovers of the star?

The leftover dust and gas is either ejected or coalesces to form planets.

Why don't the finely-defined thin rings spread out?

Thin rings are often held in place by shepherd moons, which keep them confined in tight orbits

What is the giant icy moon that orbits Neptune?

Triton

What is the ultimate consequence of Triton's orbit?

Triton's retrograde orbit means that it will slowly spiral in as a result of tidal friction. Once it enters Neptune's Roche radius, it will be broken apart and form rings.

Why is Uranus' axial tilt remarkable?

Uranus' axis is tipped on its side, in the plane of the solar system

How do we think Jupiter formed?

We think Jupiter formed from a solid rocky core which grew large enough to gravitationally capture a large gaseous atmosphere from the proto-solar nebula

Does Saturn have bands like Jupiter does?

Yes, Saturn has bands. However, since it's further away from the Sun and colder, the bands are less chemically complex and more subdued.

Why do belts look dark and zones look light?

Zones are light clouds very high in the atmosphere where material rises up. Belts are gaps in the clouds that sink where you can see the darker molecules underneath.

What name is given to small bodies in the inner solar system?

asteroids

How do we know the primary composition of the Galilean moons?

based on densities. The outer moons are less dense than the inner ones.

Why does Uranus have fewer features in its atmosphere than the other Jovian planets?

because it does not have much internal heat left

How do we know that Saturn has a magnetic field?

because it has auroras at the poles.

Why is Io volcanically active even though it is less massive than Mercury?

because its interior is tidally heated by Jupiter

Why does Europa's surface look so young?

because the ice repaves the surface

Why is the surface of Triton young?

because there are cryovolcanoes and geysers repaving the icy surface.

What are the main features we see in Jupiter's atmosphere?

belts, zones, and storms.

Where do storms typically occur?

between belts and zones

What properties of Jupiter give rise to belts?

convective atmosphere and its fast rotation

Where does Jupiter get most of its radiated energy from?

gravitational settling

Where does Saturn get most of its radiated energy from?

gravitational settling and helium raining down

What makes Titan a unique moon in the solar system?

has an atmosphere

What is Europa's surface made of?

ice

What is the surface of Triton made of?

ice

What are Saturn's moons largely composed of?

ice and rock

Why do we say that methane is Titan's equivalent of "water"?

it exists in all three phases

What is strange about the magnetic fields of Neptune and Uranus?

magnetic fields not aligned with their spin axes or their centers.

Does Jupiter mostly have large moons or small moons?

mostly small

What is the main constituent of Titan's atmosphere?

nitrogen

What are the two parts of a comet?

nucleus and coma

What makes Triton's orbit unlike any that of every other major moon in the solar system?

orbiting in retrograde

What is the most prominent feature of Saturn?

rings

Where does Jupiter's magnetic field come from?

rotation of metallic hydrogen layer

What do we call the features on Enceladus where water bursts out of the icy surface? 29

tiger stripes/ geysers

What are needed in order for a planet to have an ionized gas torus?

when a nearby moon expels ions which get caught in the planet's magnetic field