Astronomy HW #5

What do we mean when we say that a nucleus undergoes radioactive decay? The nucleus splits into two equal size pieces. The mass of the nucleus is converted into high-energy X rays and gamma rays. The nucleus emits radio waves. The number of protons or neutrons (or both) in the nucleus changes.

Suppose you have a rock that, when it solidifies, contains 1 microgram of a radioactive isotope. How much of this isotope remains after five half-lives? 1/32 microgram 1/8 microgram 1/16 microgram none Cannot be determined without knowing the daughter isotope.

Approximately what is the half-life of uranium-235? 1.25 billion years 2.8 billion years 700 million years 0.5 billion years

Suppose you find a rock and measure that 12.5% of the original uranium-235 still remains it, while the other 87.5% has decayed into lead-207. About how old is the rock? 1.25 billion years 2.1 billion years 2.8 billion years 4.5 billion years

solar nebula

Planetesimal

heavy bombardment

Accretion

solar wind

Condensation

Frost line

Radiometric dating

About how old is the solar system? 4.5 million years 4.5 billion years 4.5 trillion years

The energy that warms Earth's surface comes primarily in the form of __________. View Available Hint(s) visible light from the Sun heat from Earth's interior ultraviolet light from the Sun infrared light from the Sun heat from the Sun

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what form(s) does Earth return most of this energy to space? infrared light emitted by the surface and atmosphere visible light reflected by clouds ultraviolet light reflected by the surface visible light reflected by the surface visible light emitted by the surface and atmosphere

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________. form clouds that emit thermal radiation absorb infrared light emitted by the surface reflect visible light coming from the Sun absorb visible light coming from the Sun

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases? Ancient fossils allow them to infer Earth's temperature at a time before our atmosphere contained greenhouse gases. They calculate this temperature from Earth's reflectivity and distance from the Sun. They assume that this temperature would be about the same as the temperature of Mars, which has much less of an atmosphere than Earth. They estimate it by averaging guesses made by many individual scientists.

All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise? Venus has a higher average temperature than Mercury. Earth is the only planet with an ozone layer in its atmosphere. Mercury is much hotter than the Moon. Earth has a higher average temperature than Mars.

Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true? Global warming poses a grave threat to our future. We do not yet understand the greenhouse effect well enough to make predictions about how it affects our planet. We should expect an increase in the greenhouse gas concentration to lead to global warming. Humans are causing global warming.

Which describes our understanding of flowing water on Mars? It was never important. It was important once, but no longer. It is a major process on the Martian surface today.

Which terrestrial world has the most atmospheric gas? Venus Earth Mars

Percival Lowell's claims of a Martian civilization generated great public interest, but other scientists of his time were highly skeptical of these claims. Which two of the following statements (which are all true) explain why other scientists of the late 19th and early 20th centuries rejected Lowell's claims? Select exactly two of the following choices. Lowell's canals followed perfectly straight lines for thousands of kilometers. Mars rotates with a period only a little longer than Earth's rotation period. Like Earth, Mars has polar ice caps. Lowell's canals did not appear in photographs of Mars taken through telescopes. Mars has an axis tilt very similar to Earth's axis tilt.

Most of the CO2 that was outgassed from Earth's volcanoes is still in the atmosphere. is locked up in rocks. escaped to space.

Where is most of the water on Mars? in its polar caps and subsurface ground ice in its clouds frozen on the peaks of its tall volcanoes distributed evenly throughout its atmosphere in deep underground deposits

Based on Planet Z's size, orbital distance, and rotation rate, which of the following properties is it likely to have? active tectonics an atmosphere produced by outgassing strong winds and violent storms seasons erosion due to liquid water active volcanoes a surface crowded with impact craters polar ice caps

You have found that Planet Z should have active tectonics and volcanism and an atmosphere produced by volcanic outgassing. What single factor explains why the planet should have these characteristics? Planet Z has a large size for a terrestrial planet. closely orbits its star. has a slow rotation rate. lacks axis tilt.

In Part A, you found that Planet Z should not have polar ice caps or liquid water. What single change to Planet Z's characteristics would allow it to have these things? a smaller size a larger axis tilt a greater distance from its star a larger size

In Part A, you found that Planet Z should not have strong winds and violent storms. What single change to Planet Z's characteristics would cause it to have strong winds and violent storms? a greater distance from its star a faster rotation rate a smaller size a larger axis tilt

In Part A, you found that Planet Z should not have seasons. What single change to Planet Z's characteristics would cause it to have seasons? a faster rotation rate a larger axis tilt a greater distance from its star a smaller size

Assuming that features you see on Mars are similar to features found on Earth, what would a casual inspection of the interactive photo of Mars lead you to suspect about water on Mars? Abundant surface water is found in large, brownish pools inside craters. There are numerous small streams flowing with water. Surface water only exists as frozen ice. No surface water currently exists in any form.

Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars? the polar caps the southern highlands Valles Marineris Olympus Mons

Go to the screen in the interactive figure called "Key Evidence of Water," then zoom in on the "Southern Highlands." Which geologic processes are most clearly evident in the southern highlands? volcanism and erosion impact cratering and erosion impact cratering and volcanism tectonics and erosion volcanism and tectonics

Go to the screen in the interactive figure called "Major Geological Features." Which of the following statements about the Tharsis Bulge, often simply called "Tharsis," are true? Tharsis was probably the site of an ancient ocean. Tharsis has higher elevation than surrounding regions. One end of Valles Marineris is connected to Tharsis. Tharsis is the most heavily cratered region of Mars. Tharsis is located close to Mars's north pole. Tharsis has several large volcanoes.

Click on the first tab at the top of the interactive figure (labeled "The Greenhouse Effect"), then explore what happens as you click among the buttons (labeled "none," "low," "medium," and "high") that adjust the greenhouse gas concentration. Which of the following occur as the greenhouse gas concentration increase? more visible light reaches the ground more infrared light comes to Earth from the Sun more infrared light is absorbed in the lower atmosphere the average surface temperature rises less visible light reaches the ground more visible light is absorbed in the lower atmosphere the average surface temperature falls

Now click the second tab (labeled "Terrestrial Planet Temperatures"), then explore what happens as you click the button that allows you to add or remove greenhouse gases. Which terrestrial planet would have its surface temperature the most dramatically changed if its greenhouse gases were removed from its atmosphere? Venus Mars Mercury Earth

Click the third tab (labeled "Global Warming"), then explore the graph and the expanded views you will find by clicking the "?" buttons. Which of the following statements are supported by the data shown? Rises in global average temperature tend to be closely associated with rises in atmospheric carbon dioxide concentration. Human activity has caused the carbon dioxide concentration to swing up and down wildly over the past 800,000 years. Earth's global temperature today is higher than it has ever been before. Atmospheric carbon dioxide levels have risen dramatically over the past century. Earth's global average temperature has generally risen over the past century.

Click the fourth tab (labeled "Computer Models"), then explore how the graph changes as you click among the three buttons to its left. What is the primary message of the full graph (with all three curves shown)? Climate models are unable to account for the major recent trend in temperature data. Climate models successfully reproduce the major recent trend in temperature data only if both human and natural factors are included. Climate models can successfully reproduce the major recent trends in temperature data by considering natural factors alone.

The average temperature over the past 1000 years has been about 15∘C. From the graphs, you can conclude that Earth's average temperature during the past 800,000 years has __________. varied between about 7∘C and 19∘C varied between about −10∘C and +4∘C never been as high as it is today stayed remarkable steady, never varying by more than about 2∘C

On the graphs shown, you can identify an ice age by looking for __________. a trough (bottom of a dip) on the temperature graph a peak on the temperature graph a place on the temperature graph where the temperature curve falls steeply a trough (bottom of a dip) on the carbon dioxide graph

Notice that the peaks and troughs on the temperature graph occur at the about the same times as peaks and troughs on the carbon dioxide graph. What can we infer from this fact alone? Higher carbon dioxide concentrations cause higher global average temperatures. The carbon dioxide concentration is inversely related to the global average temperature. Higher global average temperatures cause higher carbon dioxide concentrations. There is a correlation between the carbon dioxide concentration and the global average temperature.

Although the data show only a correlation between the carbon dioxide concentration and the global average temperature, scientists have other reasons to think that a rise in the carbon dioxide concentration actually causes a rise in the global average temperature. All of the following statements are true. Which statements lend support to the idea that carbon dioxide is a cause of planetary warming? Models of Earth's climate that include recent increases in the carbon dioxide concentration match observed temperature increases better than those that do not include it. Models of the greenhouse effect successfully predict the temperatures of Venus and Mars from their atmospheric carbon dioxide amounts. We understand the physical mechanism of the greenhouse effect, through which carbon dioxide can increase a planet's temperature. Isotope ratios in atmospheric carbon dioxide show that much of the carbon dioxide in Earth's atmosphere today comes from the burning of fossil fuels.

Based on the evidence that atmospheric carbon dioxide is a cause of planetary warming, what aspect of the graphs should most concern us? The carbon dioxide concentration today is significantly higher than at any time in the past 800,000 years and is rapidly rising. Earth's past temperature rises and falls naturally. Earth's past carbon dioxide concentration rises and falls naturally.

Which of the following statements best describes the general pattern of composition among the four jovian planets? Jupiter is made mostly of hydrogen, Saturn is made mostly of helium, Uranus is made mostly of hydrogen compounds, and Neptune is made mostly of rock. Uranus and Neptune contain relatively more rock and hydrogen compounds than Jupiter and Saturn. Jupiter is made mostly of hydrogen and helium, while the other three jovian planets are made mostly of hydrogen compounds. All four planets have essentially the same composition.

Look at the average densities of the jovian planets given in Figure 1. Can you identify a trend in jovian planet densities with mass or distance from the Sun? The more massive the planet, the higher the density. The densities decrease in order of distance from the Sun. The more massive the planet, the lower the density. The densities increase in order of distance from the Sun. There is no clear trend in the densities with mass or distance.

Which of the following statements best explains why the densities of Uranus and Neptune are higher than that of Saturn, even though Saturn is much more massive? They have stronger magnetic fields. They have a higher proportion of hydrogen compounds and rock. They have higher masses. Their interiors are more compressed due to stronger gravity. They are at greater distances from the Sun.

Which of the following best explains why Jupiter's density is higher than Saturn's? Jupiter is closer to the Sun than Saturn. Jupiter is more massive than Saturn. Jupiter has a stronger magnetic field than Saturn. Jupiter has a higher proportion of hydrogen compounds and rock than Saturn.

Part complete Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition than Jupiter and Saturn? The lower temperatures at the locations of Uranus and Neptune allowed more material to condense into solid form into solid form. Jupiter and Saturn formed closer to the Sun, where there was more hydrogen and helium gas and less hydrogen compounds and rock. Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune. The lower masses of Uranus and Neptune allowed more of their hydrogen and helium gas to escape into space.

Which of the following best describes the internal layering of Jupiter, from the center outward? liquid core of hydrogen compounds; liquid hydrogen layer; metallic hydrogen layer; gaseous hydrogen layer; cloud layer core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer solid rock core; layer of solid metallic hydrogen; layer of pure liquid hydrogen; cloud layer core of rock and metal; mantle of lower density rock; upper layer of gaseous hydrogen; cloud layer