astronomy midterm Flashcards
Constellations appear to move across the sky at night because
the Earth spins on its axis.
What causes Earth’s seasons?
23.5 tilt of Earth’s rotational axis
What is the path that the Sun, Moon, and planets follow through the constellations?
How long does it take the Sun to complete one circuit of the ecliptic?
How long does it take the Moon to go around the ecliptic?
Stars in a constellation are
in the same part of the sky
A total lunar eclipse occurs
during the full moon phase
The vernal equinox marks the beginning of
Conditions are favorable for a solar eclipse
about every six months at new moon.
The angle of parallax increases as
the baseline gets larger.
Precession is caused by
the gravitational pull of the Moon.
Considering the Moon’s phases, everyone on Earth sees
the same phase in 24 hours.
Mars, Jupiter, and Saturn show retrograde motion because
Earth moves faster in its orbit.
How did the geocentric model account for day and night on Earth?
The Sun orbited Earth.
Epicycles were used in Ptolemy’s model to explain
why retrograde motion occurred.
The geocentric model was supported by Aristotle because
stars don’t seem to show any parallax. b) we don’t feel as though Earth moves. c) objects fall toward Earth, not the Sun. d) we don’t see an enormous wind. e) All of the above were valid reasons.
The heliocentric model assumes
the Sun is the center of the solar system.
Copernicus’ important contribution to astronomy was
he did not assume planets moved in ellipses.
Who published the first astronomical observations made with a telescope?
Which of Galileo’s initial observations was most challenging to established geocentric beliefs?
d) satellites of Jupiter
Which hero of the Renaissance postulated three “laws” of planetary motion?
Kepler’s 1st law of planetary orbits states that
planets orbit the Sun. b) orbits are noncircular. c) orbits are elliptical in shape. d) All of the above are stated.
Earth is closer to the Sun in January. From this fact, Kepler’s 2nd law tells us
b) Earth orbits faster in January.
Kepler’s 3rd law relates a planet’s distance from the Sun and its orbital
Newton’s law of gravity states that the force between two objects
d) increases with mass.
Which of these is NOT a form of electromagnetic radiation?
The distance between successive wave crests defines the ________ of a wave.
The frequency at which a star’s intensity is greatest depends directly on its
Rigel appears as a bright bluish star, whereas Betelgeuse appears as a bright reddish star. Rigel is ______ Betelgeuse.
d) hotter than
If a light source is approaching you, you will observe
its spectral lines are shorter in wavelength.
The wavelengths of emission lines produced by an element
are identical to its absorption lines.
Analyzing a star’s spectral lines can tell us about all of these EXCEPT
c) its transverse (side-to-side) motion.
What types of electro-magnetic radiation from space reach the surface of Earth?
visible light & radio waves
Which of the following has a fundamentally different nature than the other four?
Modern telescopes use mirrors rather than lenses for all of these reasons EXCEPT
reflecting telescopes aren’t affected by the atmosphere as much.
Seeing in astronomy is a measurement of
the image quality due to air stability
Diffraction is the tendency of light to
bend around corners and edges.
Resolution is improved by using
c) larger telescopes & shorter wavelengths.
An advantage of CCDs over photographic film is
) they don’t require chemical development. b) digital data is easily stored & transmitted. c) CCDs are more light sensitive than film. d) CCD images can be developed faster. e) All of the above are true.
Radio dishes are large in order to
a) improve angular resolution.
Adaptive optics refers to
b) reducing atmospheric blurring using computer control
Radio telescopes are useful because
observations can be made day & night. b) we can see objects that don’t emit visible light. c) radio waves are not blocked by interstellar dust. d) they can be linked to form interferometers. e) All of the above are true.
Infrared telescopes are very useful for observing
cool stars & star-forming regions
The Hubble Space Telescope (HST) offers sharper images than ground telescopes primarily because
d) HST orbits above the atmosphere.
Which of the following are terrestrial planets?
) Mercury, Venus, Earth, and Mars
The major difference(s) between the terrestrial and jovian planets involve(s)
e) mass and density.
Which of the following defines density?
b) mass divided by volume
The angular diameter of an object
b) decreases if the object is farther away.
Compared with terrestrial planets, jovian planets share all of the following characteristics EXCEPT
e) slower rotation.
Pluto seems to be more similar to
d) the moons of jovian planets.
Most asteroids are found
c) between Mars and Jupiter.
The asteroid belt is evidence of
) ancient material from the formation of the solar system
Compared to asteroids, comets show all of these properties EXCEPT
a) their densities are higher.
What causes a meteor shower?
c) Earth runs into the debris of an old comet littering its orbit.
Any theory of the origin of the solar system must explain all of these EXCEPT
the direction that planets orbit the Sun is opposite to the Sun’s spin.
The condensation sequence theory explains why
c) terrestrial planets are different from jovian planets.
Astronomers have detected most extrasolar planets by observing
a) the “wobble” of their parent stars using spectroscopy.
Extrasolar planets the size of Earth have NOT been seen yet with current techniques because
large planets orbiting near to their stars are more easily detected
The Moon’s internal structure is similar to Earth’s, but the Moon lacks
d) It lacks all of the above.
The principal greenhouse gases in our present atmosphere are
c) water vapor and carbon dioxide.
Without the greenhouse effect in our atmosphere
b) the Earth’s oceans would be frozen.
The region around Earth where the magnetic field traps charged particles is the
c) Van Allen radiation belts.
At what lunar phase would the variation between high & low tides be greatest?
e) both new and full moon
What force riveted the Moon’s near side to constantly face Earth?
c) Earth’s tidal force
Lunar maria are found
b) mostly on the side facing Earth.
A planetary atmosphere with ozone could protect surface dwellers from
a) ultraviolet radiation.
Which of these is NOT a result of the Earth’s magnetic field?
b) The giant impact theory
Mercury’s surface most resembles which of these?
a) the Moon’s far side
Mercury is very hard to observe from Earth because
it is never more than 28° from the Sun.
How do the atmospheres of the Moon and Mercury compare?
Neither body has a permanent atmosphere.
Mercury has extreme high and low temperatures between night and day because
it has no atmosphere to moderate temperatures over the globe.
Which statement about the rotations of Mercury & the Moon is FALSE?
Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun
Which of the following inner solar system bodies has the densest atmosphere?
The greenhouse effect on Venus is due to ______ in its atmosphere.
c) carbon dioxide
Venus’ surface shows all of the following EXCEPT
a) many impact craters of all sizes.
What effect does the greenhouse effect have on the surface environment of Venus?
to raise the surface temperature by hundreds of degrees Celsius
Which of the following inner solar system bodies has the largest volcanoes?
Venus and Mars probably evolved differently from Earth because
) they orbit at different distances from the Sun
The weakness of the magnetic field of Mars is because
b) its core may no longer be molten. c) its core contains less iron than our Earth.
What was the most likely source of the water that formed the huge outflow channels of Mars?
b) catastrophic but rare flooding
Both Jupiter and Saturn
a) have liquid metallic hydrogen in their interiors. b) have rings. c) emit more energy than they absorb from the Sun. d) rotate very rapidly. e) All of the above.
Jovian planets share all of the following traits EXCEPT
a) a low-density gaseous core.
Jupiter and the other jovian planets are noticeably oblate because they have
c) rapid rotation and a fluid interior.
What is the probable source of the variations in Jupiter’s belts and zones?
b) differential rotation and underlying zonal flow
What is the source of Jupiter’s large magnetic field?
e) metallic hydrogen swirling in its interior
Saturn radiates even more excess energy than Jupiter because
helium rain gives off heat as it falls toward Saturn’s center.
The two outer jovian planets appear bluish in color because
b) methane absorbs red light.
Which of these is TRUE about the seasons on Uranus?
a) Its strange tilt produces extreme seasonal variations.
The magnetic fields of which two planets are most unusual?
e) Uranus and Neptune
As their distance from Jupiter increases, the four Galilean satellites show a consistent
d) decrease in density.
The surface of which jovian moon most resembles the pack ice of the Arctic Ocean?
What is thought to cause Io’s volcanism?
c) tidal stress from Jupiter and Europa
How was the ring of Jupiter discovered?
b) by Voyager I as it passed Jupiter
The Roche limit is defined as the critical
distance from a planet, inside of which a moon can be tidally destroyed.
Shepherd satellites are defined as
moons that confine a narrow ring.
Why are the rings of Saturn so bright?
They are made of relatively new ice
Which moon in the solar system shows a dense atmosphere?
Which of the Uranian moons displays the widest range of surface terrains, suggesting some catastrophic disruption?
The rings of Neptune
a) were confirmed by Voyager 2 in 1989. b) appear both narrow and diffuse. c) all lie within Neptune’s Roche limit. d) often appear as clumpy ring arcs, rather than complete and symmetrical rings. e) All of these are correct
Neptune’s moon Triton shows
b) volcanic features similar to those on Io.
Many astronomers believe Pluto is perhaps best classified as
a large Kuiper belt object
Which of these moons are most exciting to exobiologists?
b) Titan and Europa