Astronomy Practice Quiz 4 (Canvas)
The presence of HCN (hydrogen cyanide), a key ingredient in ______, is found on the surface of ______, indicating the possibility of life there.
DNA, Titan NOTE: The 1980 Voyager flyby of Titan determined that the surface density of its atmosphere is four times greater than that on Earth. The atmospheric pressure on this moon is 1.6 bars, higher than that on any other moon and, remarkably, even higher than that of the terrestrial planets Mars and Earth. The atmospheric composition is primarily nitrogen, an important way in which Titan's atmosphere resembles Earth's. Also detected in Titan's atmosphere were carbon monoxide (CO), hydrocarbons (compounds of hydrogen and carbon) such as methane (CH4), ethane (C2H6), and propane (C3H8), and nitrogen compounds such as hydrogen cyanide (HCN), cyanogen (C2N2), and cyanoacetylene (HC3N). Their presence indicates an active chemistry in which sunlight interacts with atmospheric nitrogen and methane to create a rich mix of organic molecules. For example, under pressure and with traces of water and ammonia, HCN produces adenine, one of the bases needed to construct DNA.
The largest terrestrial planet and giant planet are, respectively:
Earth and Jupiter
We find strong clues from several solar system objects that they may harbor some forms of life. These worlds are...
Earth, Mars, Europa, Titan, Triton NOTE: http://www.space.com/15716-alien-life-search-solar-system.html
Which have more moons on average?
Giant (jovian planets NOTE: Jupiter has 67 known moons, including four large moons Callisto, Ganymede, Europa, and Io; Saturn has at least 62 known moons, in which Titan is the only moon with a substantial atmosphere and lakes or seas of liquid hydrocarbons (such as methane and ethane) on the surface. ; Uranus has 27 currently known moons. Neptune has 14 known moons, including Triton, a relatively large moon in a retrograde orbit, with a very thin atmosphere.
The most abundant element in the Solar System, as well as the rest of the Universe, is...
Hydrogen NOTE: Hydrogen is the most abundant element in the Universe; helium is second.
Which one of the following statements about Pluto is true?
It has more in common with comets in the Kuiper belt than it does with terrestrial planets like Earth.
Ceres, the largest asteroid, has an orbital semi-major axis of 2.77 AU. Name the planets that orbit just inside and outside Ceres's orbit.
Mars and Jupiter NOTE: Distance from Sun: 1AU (Earth), 1.5 AU (Mars), 5.2 AU (Jupiter), 9.5 AU (Saturn), and 19.5 AU (Uranus)
All of the following statements are true. Which one can be explained by Kepler's second law " equal area in equal time "?
Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun
Neptune's existence was uniquely predicted before it was ever observed. What evidence was this prediction based on?
Neptune was invoked to explain observed irregularities in Uranus' orbit. NOTE: Adams and Leverrier independently predict Neptune's location based on perturbations to the orbit of Uranus.
Pluto is closest in size to...
The United States NOTE: The diameter of Pluto is 2300 kilometers, and the distance from Washington, D.C. to Los Angeles is 3700 kilometers.
Of the following worlds (all moons), the one with the densest atmosphere is...
Titan NOTE: Radius of Titan is 2900 km, but only 2635 km of surface--- 265 km of Atmosphere! 9 times as thick as Earth's.
If you can jump 1 foot on Earth then you can jump about 15 feet on Pluto. On which of the following giant planets can you jump highest?
Uranus NOTE: Gravity relative to Earth: 2.54(Jupiter) 1.07(Saturn), 0.8(Uranus), and 1.2(Neptune)
Which planet seems to be turned on its side with an axis tilt of 98 degrees?
Uranus NOTE: The spin axis of Jupiter is tilted by only 3°, so there are no seasons to speak of. Saturn, however, does have seasons, since its spin axis is inclined at 27° to the perpendicular to its orbit. Neptune has about the same tilt as Saturn (29°); therefore, it experiences similar seasons (only more slowly). The strangest seasons of all are on Uranus, which has a spin axis tilted by 98° with respect to the north direction. Uranus has extreme seasons because the tilt is 98°. Sometimes one hemisphere is pointed almost directly at the Sun, then 1/2 an orbit later the opposite pole is.
Which planet is approximately halfway between Pluto's orbit and the Sun?
Uranus, the seventh planet from the Sun NOTE: Distance from the Sun: 19.5 AU (Uranus) and 39.5 AU (Pluto)
Which one of the following planets has no moons?
Venus
When is Pluto moving fastest in its elliptical orbit around the Sun?
When it is at the closest point in its orbit to the Sun.
The dwarf planet Eris was discovered in 2005, orbiting the Sun at an average distance about twice that of Pluto. In which of the following ways do Pluto and Eris differ from the terrestrial and giant planets in our Solar System?
a. Both Pluto and Eris are smaller than any of the terrestrial planets. b. Both Pluto and Eris travel in more elliptical orbits than any of the terrestrial or giant planets. c. Both Pluto and Eris are less massive than any of the terrestrial or giant planets. Answer: all of the above NOTE: Using data from the New Horizons probe, astronomers have measured the diameter of Pluto as 2370kilometers, only 60 percent as large as our Moon. Eris is nearly the same size as Pluto. Therefore, it was called a dwarf planet, meaning a planet much smaller than the terrestrial planets.
Which gas giant do we suspect may have a rocky core?
a. Jupiter b. Saturn c. Neptune d. Uranus e. all of the above Answer: all of the above NOTE: All four of the giant planets have rings, with each ring system consisting of billions of small particles or "moonlets" orbiting close to their planet. However, the four ring systems are very different from each other in mass, structure and composition.
Which one of the following statements is INCORRECT?
a. The Sun has most of the mass. b. Planetary orbits are nearly circular. c. The orbits of the planets lie roughly in the same plane. d. Distances between planets usually obey Bode's Law. e. Every planet in our solar system rotates counter-clockwise as seen from above the North Pole. Answer: e NOTE: All eight planets in the Solar System orbit the Sun in the direction that the Sun is rotating, which is counterclockwise when viewed from above the Sun's north pole. Six of the planets also rotate about their axis in this same direction. The exceptions— the planets with retrograde rotation— are Venus and Uranus.
Kepler's third law (the cube of the semi-major axis is proportional to the square of the orbital period) applies to
a. all the terrestrial planets b. all the outer (giant) planets c. all the asteroids d. all the comets Answer: all of the above
The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region(s) of the solar system that we call __________.
a. the Kuiper belt b. the Oort cloud c. the asteroid belt Answer: All of the above. NOTE: The short-period comets (such as Halley) are thought to originate in the Kuiper belt, where small gravitational perturbations from Neptune can gradually shift their orbits until they can penetrate the inner solar system. The long-period comets, however, come from a much more distant reservoir of icy objects, called the Oort cloud.
Bode's law is called an empirical law because...
it explains an observed phenomenon without providing any underlying theoretical explanation for why the Solar System seems to work that way. NOTE: Bode's law is a hypothesis that the bodies in some orbital systems, including the Sun's orbit at semi-major axes in a function of planetary sequence. The formula suggests that, extending outward, each planet would be approximately twice as far from the Sun as the one before. No solid theoretical explanation underlies the Bode's law. Since it may be a mathematical coincidence rather than a "law of nature", it is sometimes referred to as a rule instead of "law".
Comets change from dirty snowballs in appearance to beautiful objects with tails when?
the Sun boils off the gases and pushes away the dust NOTE: A tail of a comet consisting of two parts: the gas (sublimated/evaporated ice) makes up the ion tail, it is swept outward by the Sun's magnetic field. The dust is pushed away by the solar wind.
The ring system of Saturn most probably resulted from...
the movement of a large moon within Saturn's Roche limit, where tidal forces ripped the moon apart. NOTE: Close to the planet, tidal forces can tear bodies apart or inhibit loose particles from coming together.
