ASTRO 107 FLASHCARDS

Term Which type of electromagnetic radiation has the longest wavelength?	Definition radio
Term Which kind of photon has the highest energy?	Definition x-ray
Term An astronomer finds that the spectrum of a mysterious object shows bright emission lines. What can she conclude about the source?	Definition It contains hot, relatively tenuous gas
Term If an object's spectral lines are shifted to longer wavelengths, the object is	Definition Moving away from us
Term Scientists think the Earth's core is composed mainly of	Definition iron
Term Our knowledge of the composition of the Earth's core comes from	Definition analysis of earthquake waves
Term The slow shifts of our planet's crust are believed to arise from	Definition heat from the interior causing convective motion, which pushes on the crust.
Term If the shape of the Earth's orbit was unaltered but its rotation axis was shifted so that it had no tilt with respect to the orbit, seasons would be	Definition essentially nonexistent, with little temperature change at a given place throughout the year.
Term What evidence indicates that part of the Earth's interior is liquid	Definition No S type of seismic waves are detectable at some locations after an earthquake.
Term We don't get eclipses every month. This is because	Definition the Moon's orbit is tilted with respect to the Earth's orbit.
Term How are the Moon and eclipses related?	Definition Both A and B
Term What causes the phases of the Moon?	Definition The Moon's motion around the Earth causing us to see different amounts of it lit.
Term Why does the Moon shine in the sky?	Definition It reflects light from the Sun
Term What are the large smooth dark areas on the moon called?	Definition Mare
Term Which of the following planets are primarily rocky with iron cores?	Definition Mercury, Venus, and Earth
Term One explanation of why the planets near the Sun are composed mainly of rock and iron is that	Definition the Sun's heat made it difficult for other substances such as ices and gases to condense near it
Term Which of the following features of the Solar System does the solar nebula hypothesis explain?	Definition All of the above
Term The numerous craters we see on the solid surfaces of so many Solar System bodies are evidence that	Definition they were bombarded in their youth by many solid objects
Term Why is Pluto not considered a Jovian planet?	Definition Its mass and radius are so small, and it lacks the thick atmosphere of hydrogen seen on the other Jovian planets
Term Why does Mercury have so many craters and the Earth so few?	Definition Erosion and plate tectonic activity have destroyed most of the craters on the Earth
Term Which body in the inner Solar System has the densest atmosphere?	Definition Venus
Term Why is Venus's surface hotter than Mercury's?	Definition Carbon dioxide in Venus's atmosphere traps heat radiating from its surface thereby making it warmer
Term What are the Venusian clouds made of?	Definition Sulfuric acid droplets
Term Mercury's average density is about 1.5 times larger than the Moon's even though the two bodies have similar radii. What does this suggest about Mercury's composition?	Definition Mercury's interior is much richer in iron than the Moon's
Term The low average densities of Jupiter and Saturn compared with the Earth suggests	Definition they contain large quantities of light elements, such as hydrogen and helium
Term What makes some astronomers think that Uranus was hit by a large body early in its history?	Definition Its rotation axis has such a large tilt with respect to its orbit.
Term Why would it be foolish to send astronauts to land on Jupiter	Definition It has no solid surface for them to land on
Term What is the Roche limit?	Definition The distance at which a moon held together by gravity will be broken apart by the planet's gravitational attraction.
Term Astronomers think that the inner core of Jupiter is composed mainly of	Definition Rock and Iron