ASTR 1110 Chapter 14

If everything in the solar system is moving around, why do the Perseid meteors repeat regularly around August 11th or so? Because August 11th is when the Sun's rays are the warmest, and thus tend to move the meteor particles toward us at the fastest speed. Because the Earth does not move relative to the meteor particles. Because the Perseids are not in space at all, but in the upper layers of the Earth's atmosphere. Because the Earth in its orbit intersects the same swarm of meteor particles at the same time each year.

Because the Earth in its orbit intersects the same swarm of meteor particles at the same time each year.

The telescope in space that allowed astronomers to find thousands of exoplanets and exoplanet candidates by making very careful measurements during a planet transit was called: Voyager Dawn Hubble Space Telescope Kepler

Kepler

A type of planet that our surveys of exoplanets are revealing around other stars, but we don't have any examples of around the Sun are: terrestrial planets dwarf planets jovian (giant) planets Super-Earth's

Super-Earth's

How can astronomers measure the age of a meteorite that fell from the skies? The age of a meteorite can be found from the angle at which it enters the Earth's atmosphere; so scientists can only get the ages of meteorites they observe falling. Meteorites all contain metals and the metal conducts electricity better and better as it ages. They measure the amount still left of radioactive materials in the meteorite, and how much has turned into decay products. Just like for planets, we measure the age by counting the number of craters on the meteorite.

They measure the amount still left of radioactive materials in the meteorite, and how much has turned into decay products.

The atmosphere of Venus is mostly carbon dioxide, and the atmosphere of the Earth has water vapor. Why are these two gases absent in the atmosphere of the satellite around Saturn called Titan? The energetic particles in the magnetosphere of Saturn have collided with and knocked away all the lighter gases in the atmosphere of Titan. Titan is so cold that carbon dioxide and water vapor freeze out. There is a runaway greenhouse effect on Titan. Titan's atmosphere was captured from the ring system of Saturn, and thus consists of small ice crystals.

Titan is so cold that carbon dioxide and water vapor freeze out.

The typical meteor is about the size of a small one-family house made of evaporated ices a small solid particle, no bigger than a pea visible only from above the Earth's atmosphere

a small solid particle, no bigger than a pea

At the beginning of the solar system's history, a ready supply of proto-planets or mini-planets crashed into the developing planets and each other - something astronomers call the "era of giant impacts." How long do astronomers estimate this era lasted? about four billion years (it only ended about half a billion years ago) about 100 million years (0.1 billion) only a few dozen years - it was over very quickly about two billion years

about 100 million years (0.1 billion)

One of the best proofs that our theory of how the solar system formed is correct is that astronomers now observe no water in the inner solar system. Pluto's orbit, which is not in the plane (or disk) that the other planets orbit in. planets that are called "hot Jupiters". disks around other stars which show evidence of gaps where planets may be forming.

disks around other stars which show evidence of gaps where planets may be forming.

When a chunk of cosmic material the size of a golf ball or a baseball hits the Earth's atmosphere it makes a meteor shower meteorite which breaks into pieces when hitting the ground radiant fireball

fireball

One of the most perplexing issues raised by the discovery of thousands of exoplanets is the existence of "hot Jupiters" - planets with the masses and compositions of Jupiter, but orbiting closer to their stars than Mercury does in our solar system. What is our best idea currently about how such "hot Jupiters" came to be? each hot Jupiter came directly out of the star it now orbits and must be made of the exact same material at only slightly lower temperatures. hot Jupiters formed by the collision and merger of many terrestrial planets - these collisions heated them up. hot Jupiters formed in an asteroid belt and are made of countless asteroids that are hot. hot Jupiters formed further out in their star system, and then migrated inward somehow.

hot Jupiters formed further out in their star system, and then migrated inward somehow.

Some of the early planetesimals that formed the solar system still survive today. Where would you find such planetesimals? on the tallest mountains on Earth. you can't fool me, such planetesimals were swept up by the Sun long ago; none remain. under the permafrost of Mars. in the asteroid and Kuiper belts.

in the asteroid and Kuiper belts.

The first technique that allowed astronomers to find exoplanets involved: looking for the decrease of light from the star during a transit of the planet across its disk. photographing the planets using infrared waves. sending a very small spacecraft to the exoplanet to take close-up images. measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets. simply taking a visible light photo of the planet around the nearest star.

measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets.

Astronomers estimate that about 25 million meteors strike the Earth's atmosphere each day. How come we haven't run out of meteors in the long history of the Earth? meteors are caused by electrical sparking in the Earth's atmosphere and there is a lot of static electricity up there. meteors come from dust from the Earth's surface that winds have blown high into the atmosphere; the Earth is so big it has lots of dust. meteors are pieces of dirt left over from the formation of our solar system and from old comets; there is a huge supply of small dirt particles from both sources. meteors have only been hitting the Earth's atmosphere recently; they are the result of human pollution of space. this is an unsolved problem in astronomy that has a lot of astronomers mystified.

meteors are pieces of dirt left over from the formation of our solar system and from old comets; there is a huge supply of small dirt particles from both sources

Chunks of solid material that survive passing through the Earth's atmosphere and are found on the Earth's surface are called meterorites asteriods meteor shower meteors

meterorites

Three kinds of worlds are round in our solar system. Which of the following is NOT a type of world that is typically round? terrestrial planet jovian planet dwarf planet minor planet (asteroid) all of the above are round

minor planet (asteroid)

The reason that Olympus Mons, the tallest mountain on Mars, is taller than Mount Everest (the tallest mountain on Earth) is that: the gravity on Mars is less, so a larger mass can support itself against its own weight. Mars has a much larger molten core than the Earth. there are no continental plates that move sideways on Mars, while there are such sliding motions on Earth. the Earth's Moon has a much stronger pull than the moons of Mars. more than one of the above.

more than one of the above.

On which world besides the Earth could a human being step out of his spacecraft without a space suit and air tanks and be confident of surviving? Mars Venus Europa Titan none of the above

none of the above

The Murchison meteorite that was found in Australia in 1969 is important to scientists because it contained organic materials, such as amino acids more metal than any other meteorite radioactive elements which we do not have on the Earth large flecks of gold

organic materials, such as amino acids

When the solar system was forming, the building blocks from which the protoplanets gathered together were the: planetesimals (a few km to tens of km wide). gold, iron, and nickel atoms. extremely hot clouds of gas torn out of the Sun, which was already shining brilliantly. dirty ice balls, about the size of a snowflake.

planetesimals (a few km to tens of km wide)

How do astronomers know that the age of the solar system is about 4.5 billion years old? they estimate the date from the number of impact craters on the Earth. they estimate that age from the number of comets that are still located in the Kuiper Belt. radioactive dating of the primitive meteorites indicates they have that age (since they are left-over building blocks of the solar system). radioactive dating of all the rocks on Earth shows that age.

radioactive dating of the primitive meteorites indicates they have that age (since they are left-over building blocks of the solar system).

Astronomers now believe that the differences in composition among the planets reflect what characteristic in the early solar system orbital speed temperature whether or not a planet had rings the age of the material none of the above

temperature

Which of the following is not a characteristic that worlds in our solar system have in common: that many of the larger moons go around their planets in the same direction. that all the planets have solid surfaces on which we can see impact craters. that the planets all revolve around the Sun in the same direction. that most of the planets spin in the same direction that they revolve. that the planets' orbits lie in roughly the same plane.

that all the planets have solid surfaces on which we can see impact craters.

One region on Earth that has become a rich source of new meteorites in recent decades (including the meteorite from Mars that got famous because some scientists claimed they had found evidence for the building blocks of life on Mars) is: the Great Salt Lake the Yucatan peninsula of Mexico the Antarctic south pacific islands with white sand beaches

the Antarctic

The main reason that worlds like the Earth are differentiated is that planetesimals with different types of composition hit at different times, with the heaviest ones hitting first. the heat of the Sun vaporized much of their solid material early on. the continuing impacts on a growing protoplanet eventually melted the entire body. the heaviest chunks that hit early on were able to bore through solid rock to the center.

the continuing impacts on a growing protoplanet eventually melted the entire body.

Some years some meteor showers, such as the Leonids, feature many more meteors than at other times. What is the cause of these "meteor storms"? the dust freed from some comets is clumpy and not evenly distributed along its orbit. we get meteor storms at the same time and for the same reason we have more hurricanes on Earth. meteor storms happen when Halley's Comet is near the Earth in its 76-year orbit. how many meteors we see in a given year depends one which side of the Sun we are on.

the dust freed from some comets is clumpy and not evenly distributed along its orbit.

For solid rocky worlds, a general rule is the larger the world, the closer it is to the Sun. the smaller the world, the more likely it is to have an atmosphere. the smaller the world, the more likely it is to have a moon or moons. the larger the world, the slower it cools off and the more it will keep its internal heat. the shorter a world's year (time to orbit the Sun), the more likely it is to harbor life.

the larger the world, the slower it cools off and the more it will keep its internal heat.

The ages of stony meteorites have been measured to be roughly equal to: you can't fool me, we have no way of measuring the ages of stony meteorites. the oldest ages we have measured for any bodies in the solar system. the time since the great impact that killed the dinosaurs. the time since the last Ice Age on Earth.

the oldest ages we have measured for any bodies in the solar system.

Which of the following pieces of observational evidence does our modern "solar nebula" theory of the formation of the solar system NOT explain directly? the existence of comets in the outer solar system made mainly of frozen gases. the ages of the oldest rocks on Earth, the Moon, and meteorites the plane of the orbit of Pluto. the difference in the composition of the terrestrial and jovian planets. the fact that all the planets revolve around the equator of the Sun in the same direction.

the plane of the orbit of Pluto.

Astronomers call the vast, rotating cloud of vapor and dust from which the solar system formed: the proto-Sun the Kuiper Belt the Oort Cloud the solar nebula

the solar nebula

Which of the following is NOT a way that Jovian planets can be distinguished from terrestrial planets? they are farther away from the Sun. they include much more gas and liquid. they have many more craters from collisions that happened early in solar system history. they are larger. their average density is lower.

they have many more craters from collisions that happened early in solar system history.

A key difference between the protoplanets that formed in the outer solar system and those that formed in the inner solar system was that those in the outer solar system did not have enough planetesimals nearby. those in the inner solar system were much larger than those in the outer solar system. those in the outer solar system included far more metal and rock, and thus the outer planets could be denser. those in the outer solar system were in a place where ice, not just rock, condensed and thus could grow larger.

those in the outer solar system were in a place where ice, not just rock, condensed and thus could grow larger.

Among solid worlds, which type of world is most likely to have significant geological activity? those that are the smallest (and thus easiest to heat) those that have a moon (satellite) those that have strong magnetic fields those that are the largest (and retain heat the best)

those that are the largest (and retain heat the best)

Your ASTR1110/H classmate asks you come to watch a meteor shower. What exactly are you being invited to? a once-in-a-lifetime experience at the end of which you will be completely covered with dust particles from space. the closest approach of an active bright comet to the Earth. watching the left-over dirt from a comet burn up by friction as the pieces hit the Earth's atmosphere. something quite dangerous where you are likely to be hit when many larger rocks fall from above.

watching the left-over dirt from a comet burn up by friction as the pieces hit the Earth's atmosphere.