Astronomy Test 2

The large reservoir of comet nuclei in a spherical distribution far beyond Pluto, from which we believe new long-period comets come into the inner solar system, is called:

the Oort Cloud

The tallest mountain on a terrestrial world is:

Olympus Mons (Mt. Olympus) on Mars

The person who really publicized the idea of canals on Mars and impressed it on the public mind was:

Percival Lowell

The Van Allen belt is

a region of trapped charged particles in the Earth's magnetosphere

In radioactive dating, the measure scientists use to note how long (on average) a particular radioactive nucleus will take to decay is called its

half-life

About 75% of the surface of Venus consists of

lowland lava plains

The large, roughly circular, dark, and somewhat younger regions on the Moon are called:

maria

One way to measure how long Jupiter takes to rotate is to watch the giant storms in its atmosphere go around. A more fundamental way to measure the rotation is to:

measure the changes in the planet's radio waves, which are controlled by its magnetic field

The first technique that allowed astronomers to find exoplanets involved:

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

An important way that scientists have been able to study the interior of the Earth is by:

measuring how seismic waves are transmitted through the Earth

How do astronomers know that the age of the solar system is about 4.5 billion years old?

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

All the planets (without exception)

revolve around the Sun in the same direction

According to the theory of plate tectonics,

slow motions within the mantle of the Earth move large sections of the crust around

Today, scientists believe that the main reason the Earth has had periodic ice ages is:

slow periodic changes in the tilt and orientation of our planet's axis of rotation, and periodic changes in the eccentricity of Earth's orbit

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 Antarctic

In its overall composition, the Moon roughly resembles:

the Earth's crust and mantle

In regards to Neptune, what was a surprise to astronomers when they carefully examined Neptune with the Hubble Space Telescope in 1994?

the Great Dark Spot had disappeared

Which of the following characteristics do all four terrestrial planets have in common?

they all have solid surfaces with signs of geological activity on them

The spacecraft that visited Pluto and send back our first images:

was called New Horizons

Which of the following statements about temperature changes on Mercury is correct?

the difference in temperature between Mercury's daylight side and its night side is the greatest difference of any planet in the solar system

Scientists now understand that the Earth consists of layers, with the densest materials in the core. What allowed the differentiation of the Earth's layers to happen?

the early Earth must have been so hot it was like a liquid and denser material sank to the middle

What allowed the Voyager 2 spacecraft to make a "tour" of all four of the jovian planets in the late 1970's and the 1980's?

the four planets were approximately aligned on one side of the Sun and we used the gravity of each planet to speed up the spacecraft to get to the next one in its path

Saturn's ring particles are composed mainly of:

water ice

What is one way that we humans are currently making the atmosphere of the Earth more like that of Venus?

we are adding carbon dioxide and other greenhouse gases to the atmosphere, which is leading to global warming

What is the most important reason that astronomers have learned more about our planetary system in the last 30-40 years than all of history before then.

we have been able to send spacecraft to gather information about planets and moons up close

What theory of Mercury's origin can best explain the fact that its core is made of such dense materials?

giant impacts in its early history may have torn away much of its original crust and mantle

Where has frozen water has been discovered on the Moon?

Deep inside craters in the regions near the Moon's poles

The planet closest to the Sun in the solar system is:

Mercury

The mountains on the Moon

are the result of giant impacts during the Moon's long history of being hit

The smaller objects in the solar system made of rock and metal (most of which orbit between Jupiter and Mars) are called:

asteroids

In 2013, a small stony asteroid collided with the Earth above the Russian city of Chelyabinsk. What was the result?

A fireball briefly brighter than the Sun could be seen in the sky

The person who came up with the continental drift theory that led to our modern understanding of plate tectonics was

Alfred Wegener

If everything in the solar system is moving around, why do the Perseid meteors repeat regularly around August 11th or so?

Because the Earth in its orbit intersects the same swarm of small icy particles at the same time each year

The first asteroid to be discovered (which is also the largest one) is called

Ceres

The four large moons of Jupiter were first discovered by:

Galileo with his early telescope

The largest satellite (moon) in the solar system is:

Ganymede

The Galileo spacecraft measured that the moon Ganymede had a magnetic field, indicating that its interior was at least partly melted and warm. What do scientists think is the most likely reason for this?

Ganymede is heated by tidal forces from Jupiter

The first asteroid confirmed to have a satellite (moon) was

Ida

The world in the solar system that is most active volcanically is:

Io

The largest planet in the solar system (by mass) is

Jupiter

Which of the following is NOT a terrestrial planet?

Jupiter

Why do astronomers today think that we have an asteroid belt and not a planet between Mars and Jupiter?

Jupiter's gravity prevented material in that zone from getting together

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:

Kepler

The comet that broke into more than 20 pieces and then collided with Jupiter in 1994 was

Shoemaker-Levy 9

Why does Mars have an overall reddish color when we see its surface from afar?

The material of Mars' surface contains a lot of iron oxide, the same chemistry that makes rusting metals look reddish

What do astronomers think is the origin of the many irregular moons around the outer planets (irregular meaning they are orbiting backwards and/or have eccentric orbits)?

These moons were likely formed elsewhere and captured by the giant planets

The satellite which has the thickest atmosphere (so thick that it's quite a surprise for a satellite) is:

Titan

The planet that orbits "on its side" (i.e. has its rotation axis perpendicular to the plane of its orbit) is:

Uranus

The spacecraft that soft-landed successfully on the surface of Venus (and briefly sent back pictures while sitting in that destructive environment) were called

Venera

Of the following planets, which do NOT have satellites (moons)?

Venus

What planet can come closest to the Earth in its orbit and look brightest in our skies?

Venus

Radioactive dating techniques have revealed that our Earth and Moon are approximately how old?

about 4.5 billion years

One way in which the ozone layer is useful for life forms on the Earth's surface is that it

absorbs ultra-violet light, preventing much of it from reaching the surface

Which of the following is NOT a correct statement about the ways the jovian planets differ from the terrestrial planets?

all the jovians have satellites around them and none of the terrestrials do

If there are at least a million asteroids, how did spacecraft like Galileo survive their trip through the asteroid belt?

although there are many asteroids, they are small and widely spaced (there is lots of space between them)

We believe the maria on the Earth's Moon are:

ancient impact craters in which lava beds welled up from inside the Moon

Astronomers estimate that the plains of Venus are only about 500 to 600 million years old. How do they estimate dates like this?

by counting the craters visible on the surface and comparing crater counts to other worlds

The same gas makes up most of the atmosphere of Mars and Venus. This gas is:

carbon dioxide

The average temperature on planet Earth is higher than you would expect just from the heating of sunlight alone. What is the explanation for this?

carbon dioxide (and other gases) in the atmosphere cause a greenhouse effect

The smaller objects in the solar system composed mainly of ices (frozen gases) that usually orbit far from the Sun are called:

comets

Which of the following is NOT something that was accomplished by the Apollo missions to the Moon?

discovering that the Moon has a great deal of water under its surface

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?

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

By far the most abundant element in the giant (jovian) planets is:

hydrogen

The element that can act like a metal when it is under tremendous pressure and is probably responsible for Jupiter and Saturn's magnetism is:

hydrogen

A main difference between asteroids and comets is that asteroids are mostly made of rock and comets are mostly made of

ice

Any rock in the Earth's crust that has cooled from an originally molten state is called

igneous

What features are abundant on Callisto and Ganymede and almost absent on Europa and Io?

impact craters

Which of the following is a way that the planet Mercury is similar to the Moon?

its surface is heavily cratered

The most likely models of the planet Mercury indicate that more than half the planet may be composed of

metals

Chunks of solid material that survive passing through the Earth's atmosphere and are found on the Earth's surface are called

meteorites

The bluish color that makes the atmosphere of Neptune so beautiful to the human eye is caused by the interaction of sunlight with what gas?

methane

The lakes found in the north polar region of Titan are filled with liquid

methane

A crucial difference that helps explain why Venus is so hot and the Earth isn't is that:

on Venus, there was eventually no ocean to remove carbon dioxide from the atmosphere

Earthquake producing faults are much more likely to be found

on the boundaries of continental plates, where they meet other plates

If our estimates of the number of comets in every part of the solar system are correct, the total mass contained in comets must be:

on the order of the mass of all the planets put together

The Murchison meteorite that was found in Australia in 1969 is important to scientists because it contained

organic materials, such as amino acids

One reason that we have such a complex system of belts/zones/storms in Jupiter's atmosphere is that:

the planet rotates very rapidly

The process by which Venus became so much hotter than the Earth is called:

the runaway greenhouse effect

Halley's Comet was given that name because Edmond Halley was

the scientist who pointed out that the orbit of the comet was such that it should return every 76 years or so

Astronomers call the vast, rotating cloud of vapor and dust from which the solar system formed:

the solar nebula