astronomy exam 3 Word Scramble

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Question	Answer
If we are searching for life that is at least somewhat similar to life on Earth, the most important criterion in identifying a potentially habitable world is ________.	the presence of surface or subsurface liquid water
Based on current evidence, the elements needed for life are found ________.	throughout the universe
96% of the mass of living organisms on Earth is made up of just four elements. What are they?	Hydrogen, Carbon, Oxygen, Nitrogen
Jupiter is about five times as far from the Sun as Earth. Therefore, the strength of sunlight at Jupiter is about ________ as strong as it is at Earth.	1/25
How does the strength of sunlight (per unit area) depend on distance from the Sun?	it decreases in proportion to the square of the distance
Suppose you were genetically engineering plants that you hoped to grow in a greenhouse on one of Jupiter’s moons. response - correct In this scenario, you would want to engineer these plants to have	larger leaf surfaces, so that they could collect more sunlight.
One advantage of water as a liquid medium for life is the fact that it stays liquid over a higher and wider range of temperatures. If we want to find another medium for life that has similar properties, which substance should we pick?	Methanol
Which of the following is not an advantage of water over methane, ethane, and ammonia as a potential liquid medium for life?	Water is the only one that melts from solid to liquid form as the temperature increases.
What are the three advantages of water that make it seem far more suitable as a liquid medium of life than other liquids?	Water remains liquid over a higher and wider range of temperature. The solid (frozen) form of water is less dense than the liquid form. Water molecules have charge separation (are polar).
Media reports sometimes say that there is "water on the Moon." What really has been found is strong evidence for	water ice in polar craters
Which of the following explains why Venus is so much hotter than Earth?	Venus's atmosphere contains far more carbon dioxide than Earth's.
Is there any place where we might find liquid water on Uranus or Neptune?	Yes, but probably only very deep in their interiors.
If you choose a small moon at random from the moons of the jovian planets in our solar system, which of the following are you most likely to find?	Water ice
Why do the solar system's many small bodies, such as asteroids, comets, and small moons, seem unlikely as potential homes to life?	They are too cold inside to have liquid water
The feature on Mars called __________ is a long, vast network of canyons.	Valles Marineris
The __________ vary in size with the martian seasons.	Polar Caps
The _________ is a high elevation region dotted with large volcanoes.	Tharsis Buldge
The feature called __________ is the largest known mountain in the solar system which is also a volcano.	Olympus Mons
The __________ have low elevation and may possibly have once been the location of an ocean.	Northern Plains
The __________ are heavily cratered	Southern Highlands
Mars has seasons because of its ______, but the southern hemisphere has more extreme seasons because of _____________ .	Axis tilt, Mars' varying distance from the sun.
Liquid water is unstable on Mars because of the _________.	Low atmospheric pressure.
Which of the following provides the evidence that has allowed scientists to conclude that Mars's southern highlands are geologically older than its northern plains?	The large number of craters in the Southern Highlands
Which of the following best explains why scientists conclude that Mars must once have had a much thicker atmosphere and a much stronger greenhouse effect than it does today?	Evidence that liquid water was once stable on Mars.
The term “Martians” (as opposed to, say, “Venusians” or “Jupiterians”) became nearly synonymous with alien life because	the idea of a civilization on Mars was popularized by the writings of Percival Lowell and H. G. Wells’s novel The War of the Worlds.
In regard to Percival Lowell's claims of a vast canal system on Mars, Alfred Russel Wallace wrote "[a network of canals,] as Mr. Lowell describes, would be the work of a body of madmen rather than of intelligent beings." Why?	The canals claimed by Lowell ran in straight lines for great distances.
When we say that liquid water is unstable on Mars today, we mean that ________	any liquid water on the surface would quickly freeze or evaporate.
Why does Mars’s axis swing much more wildly over time than Earth's?	Mars lacks a large moon
Models indicate that over hundreds of thousands to millions of years, Mars undergoes large changes in axis tilt. What do we expect to happen when Mars has a larger axis tilt?	Seasons become more extreme, which can enhance the atmosphere and greenhouse effect.
Which statement about the martian seasons is not true? Responses	All of Mars has summer at the same time, and half an orbit later all of Mars has winter.
The martian “blueberries” are ________.	pebble-sized spheres containing the mineral hematite.
Which of the following is NOT a key piece of evidence in favor of past liquid water on Mars?	Orbital photos show a relatively small number of craters on volcanic slopes.
Key evidence that Mars may once have had much more water than it does today—perhaps enough to form an ocean—comes from ________	measurements of the atmospheric ratio of deuterium to ordinary hydrogen.
Evidence indicates that Mars’s era of being significantly warmer and wetter ended at least about ________	3 billion years ago.
According to the leading hypothesis, what happened to most of Mars’s ancient atmospheric gas?	It was stripped away by the solar wind.
What must be true if Mars was warmer and wetter in the past?	Mars once had a much thicker atmosphere than it does today.
The martian meteorite ALH84001 has structures that look like fossilized bacteria. Why do most scientists doubt that they are actually fossil life?	The structures are too small.
Why are robotic landers and rovers sterilized before launch to Mars?	To prevent terrestrial microbes from hitching a ride on the probe and contaminating the Martian surface
If life exists on Mars today, it is most likely to be found _____________	beneath the surface.
Why is it considered unlikely that martian microbes could infect Earth organisms after being brought back by a future sample return mission?	Martian microbes are likely to be quite different from terrestrial microbes and, hence, not adapted to infecting Earth life.
The process of changing a planet like Mars so that it is more suitable for human colonization is referred to as __________	terraforming.
From the standpoint of the search for life, what is the most significant concern about sending humans to Mars?	The high probability of contamination of the martian surface by microbes associated with human beings
Which statement about synchronous rotation is true?	It is a natural consequence of tidal forces acting on a moon.
Based on what we know about the terrestrial worlds, why is it surprising to find geological activity on jovian moons?	They are too small.
Tidal heating is stronger for Io than for Europa because ________.	Io is closer to Jupiter.
If Europa really has an ocean, life that gets energy through photosynthesis is unlikely in this ocean because________.	The icy crust is too thick.
What are the observable pieces of evidence that Europa has a subsurface ocean?	Surface features that look like jumbled icebergs, Variations in Europa's magnetic field, Calculations of Europa's internal tidal heating
The geological activity of Io and Europa is caused primarily by ________.	tidal forces from Jupiter that heat the interiors
Scientists think that Ganymede, like Europa, ______ a subsurface ocean of liquid water because __________________________.	Has, its magnetic field varies with Jupiter’s rotation.
How do the possibilities for life on Ganymede and Callisto compare to those on Europa?	Life seems less likely because these moons have less energy available for life.
If Europa really does have geysers on its surface, how might the Europa Clipper mission be able to make use of them to learn whether Europa has life?	The spacecraft’s spectrometers could analyze the gas for the presence of organic or biological molecules.
Which of the following have we found on Titan?	Abundant organic compounds.
Titan shares all of the following geological features with Earth except________.	Volcanoes erupting with molten rock
Assuming Enceladus really has a subsurface ocean, which of the following probably contribute to keeping it liquid?	Ammonia acting as an antifreeze, heat form radioactive decay, tidal heating.
Why were scientists surprised to find active geology on Enceladus?	Because of its small size.
The list of moons in our solar system on which life seems at least potentially possible are:	Europa, Ganymede, Callisto, Triton, Titan, Enceladus.
If you have a situation in which there is a chemical disequilibrium, it means that______.	Chemical reactions are likely to occur.
The general definition of a redox reaction is a chemical reaction in which ______.	One or more electrons is transferred from an electron donor to an electron acceptor.
Chemical disequilibrium is likely to be present in all the following places except ________________.	Icy boulders in the rings of Saturn.
What describe the features of what we call "The Habitable Zone" around a star?	It gradually moved outward from a star with time and it is the region around a star in which a suitable sized world could have surface oceans of liquid water.
What would happen to Earth if we could somehow move it to Venus's orbit?	It would suffer a runaway greenhouse effect that would presumably kill off life on our planet.
Which of the following statements about Venus and the habitable zone is correct?	Venus is not in the Sun's habitable zone today, but might have been in the distant past.
What best describes current thinking of Mars and the Sun's habitable zone?	Mars might be in the Sun's habitable zone today, in which case it might be habitable if it were larger in size.
Is Europa in the Sun's habitable zone?	No!
If we want to restore the climate to a state more like it was before humans started to cause global warming, we need to _______.	Stop using fossil fuels, convert out energy to use renewable energy only, find a way to remove carbon dioxide from the atmoshpere.
Key evidence that Venus once had much more water than it does today comes from _____.	Venus's relatively high ration of deuterium to ordinary hydrogen atoms
In terms of the gases outgasses by volcanoes, Venus's atmosphere today seems to have _______.	too little water vapor.
A key piece of the runaway greenhouse effect is that fact that warm air holds _____ water vapor. This ____ the greenhouse effect.	More, strengthens.
Known on Earth, what is the only natural source of phosphine?	Life
Based on all current evidence, if Venus had been born at Earth's distance from the Sun, the Venus today would probably ______.	have oceans and an atmosphere much like Earth.
The reason that some scientists think that Venus might have had oceans early in its history is that ____.	The sun was probably dimmer at that time.
What will happen to the Sun's habitable zone in the future?	It will move outward.
Which of the following is most likely to render out planet Earth no longer habitable in the future?	A runaway greenhouse effect, between about 1 to 3 billion years from now.
Warmer temperatures allow water vapor to reach higher altitudes. As a result, water vapor is dissociated by UV light and lost to space.	Moist greenhouse effect
Higher temperature increases evaporation and warmer air holds more water vapor. As a result the green house effect is strengthened and the planet warms more.	Runaway greenhouse effect
Atmospheric carbon dioxide condenses into snowflakes and falls to the surface. As a result, the atmosphere thins and the greenhouse effect weakens.	Cold atmosphere
Beyond this distance, no greenhouse effect can warm the planet enough to keep it from freezing.	Thick atmosphere, strong greenhouse effect
Why is having a substantial atmosphere thought to be a requirement for surface oceans?	Water would be unstable without enough atmospheric pressure.
Global warming refers to _____.	an increase in Earth's average surface temperature.

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