Astronomy Test 3
Based on the frequency with which we see comets from Earth, astronomers estimate the total number of comets in the solar system to be
1 trillion
Which of the following statements is not an observed pattern of motion in our solar system?
Most planets orbit at the same speed.
Which of the following is not a characteristic of the outer planets?
They have very few, if any, satellites.
What is a compound?
a molecule containing two or more elements
What is an artificial star?
a point of light in Earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations
If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels the gas produces
an emission line spectrum.
When light reflects off an object, what is the relation between the angle of incidence and the angle of reflection?
angle of incidence = angle of reflection
The absorption line spectrum shows what we see when we look at a hot light source (such as a star or light bulb) directly behind a cooler cloud of gas. Suppose instead that we are looking at the gas cloud but the light source is off to the side instead of directly behind it. In that case, the spectrum would __________.
be an emission spectrum
In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?
radio
Which of the following best describes Pluto in terms of the general characteristics of terrestrial and jovian planets?
size and solid surface similar to terrestrial planets; distance similar to jovian planets
Terrestrial Planets
solid, rocky surface, located within the inner solar system, small size
Which of the following studies is best suited to a timing experiment?
studying whether a particular star's brightness is steady or variable
The wavelength of a wave is
the distance between two adjacent peaks of the wave.
Which of the following could not be determined by an observation that uses only spectroscopy?
the size of a distant galaxy
Which of the following is not a good reason to place observatories on remote mountain tops?
to be able to observe at radio wavelengths
What is the purpose of adaptive optics?
to eliminate the distorting effects of atmospheric turbulence for telescopes on the ground
What are the main constituents of the jovian planets?
hydrogen and helium
An atom of the element iron has an atomic number of 26 and an atomic weight of 56. If it is neutral, how many protons, neutrons, and electrons does it have?
26 protons, 30 neutrons, 26 electrons
When an atom absorbs a photon containing energy, any of the following can happen except which?
An electron moves from an upper energy level to a lower one.
How do asteroids differ from comets?
Asteroids are rocky bodies and are denser than the comets, which are made of icy material.
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 jovian planets in our solar system?
Both Pluto and Eris are smaller than any of the terrestrial planets.Both Pluto and Eris travel in more elliptical orbits than any of the terrestrial or jovian planets. Both Pluto and Eris are less massive than any of the terrestrial or jovian planets.
Which of the following is a principal advantage of CCDs over photographic film?
CCDs capture a much higher percentage of the incoming photons than does film.
Earth
Most of the surface of ___ is covered with liquid water.
Tessterial planets
Inner planets: Mars, mercury, earth, and Venus
How does the Sun's mass compare with that of the planets?
It is a thousand times more massive than all the planets combined.
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
It is closer to the stars.
What do we mean by the diffraction limit of a telescope?
It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion.
Pluto is different from the outer planets in all of the following ways except which one?
Its surface temperature is very cold.
Which planet has a ring system?
Jupiter Uranus Neptune Saturn
Jovian planets;
Jupiter, Saturn, Uranus, and Neptune.
Which planet, other than Earth, has visible water ice on it?
Mars
The most metal-rich terrestrial planet is
Mercury
Order of planets closet to farthest from sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Jovian Planets
Numerous orbiting moons, extensive ring systems, low average density, primarily composed of hydrogen helium and hydrogen compounds
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Photons of different energy behave differently and require different collection strategies.
Which of the following is not a pattern of motion in our solar system?
Planets all rotate in the same direction.
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them.
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them. (all the same)
Listed following are distinguishing characteristics and examples of reflecting and refracting telescopes. Match these to the appropriate category.
Reflecting Telescopes: most commonly used by professional astronomers today, The Hubble Space Telescope, world's largest telescope Refracting Telescopes: The world's largest is 1-meter in diameter, Galileo's telescopes, very large telescopes become "top- heavy", incoming light passes through glass
Which of the following statements best describes the two principal advantages of telescopes over eyes?
Telescopes can collect far more light with far better angular resolution.
Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?
Terrestrial planets will likely be located nearer the planetary system's star than any jovian planets.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight?
The atomic number is 79, and the atomic weight is 197.
Which of the following statements about light focusing is not true?
The focal plane of a reflecting telescope is always located within a few inches of the primary mirror.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. If it is doubly ionized, what is the charge of the gold ion and how many electrons remain in the ion?
The gold ion has a charge of +2 and 77 electrons.
Mars
The only rocky planet to have more than one moon
Mercury
The planet that orbits closet to the sun
Saturn
The planet with the lowest average density
We can learn a lot about the properties of a star by studying its spectrum. All of the following statements are true except one. Which one?
The total amount of light in the spectrum tells us the star's radius.
Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?
The two stars will look like a single point of light.
Which of the following observations indicates that conditions on Mars may have been suitable for life in the past?
There are dried-up riverbeds on Mars.
Which of the following is not a characteristic of the inner planets?
They all have substantial atmospheres.
Which of the following is always true about images captured with X-ray telescopes?
They are always displayed in false color.
Which planet is approximately halfway between Pluto's orbit and the Sun?
Uranus, the seventh planet from the Sun
The planet closest in size to Earth is
Venus
Which planet has the highest average surface temperature, and why?
Venus, because of its dense carbon dioxide atmosphere
Study the graph of the intensity of light versus wavelength for continuous spectra, observing how it changes with the temperature of the light bulb. Recall that one of the laws of thermal radiation states that a higher-temperature object emits photons with higher average energy (Wien's law). This law is illustrated by the fact that for a higher temperature object, the graph peaks at __________.
a shorter wavelength
What type of visible light spectrum does the Sun produce?
an absorption line spectrum
What causes stars to twinkle?
bending of light rays by turbulent layers in the atmosphere
Where are most of the known asteroids found?
between the orbits of Mars and Jupiter
If our eyes were sensitive only to X rays, the world would appear __________.
dark because X-ray light does not reach Earth's surface
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects.
extreme infrared
Order the following in order of increasing efficiency of detecting photons of visible light.
eye, photographic film, CCD
We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light from left to right in order of increasing wavelength. To rank items as equivalent, overlap them.
gamma rays, x-rays, ultraviolet, visible light, infrared, radio waves
Which of the following objects is not a close approximation of a thermal emitter?
hot, thin air
Where does nuclear fusion occur in the Sun?
in its core
If you had only one telescope and wanted to take both visible-light and ultraviolet pictures of stars, where should you locate your telescope?
in space
When an atom loses an electron, it becomes
ionized
Neptune
is about 30 times as far from the Sun as our planet
Jupiter
is the jovian planet that orbits closest to the sun
Venus
is the planet with the highest average surface temperature
Grass (that is healthy) looks green because
it reflects green light and absorbs other colors.
Uranus
jas a rotational axis that is tilted so much it lies nearly in the plane of its orbit
How many atoms fit across the period at the end of this sentence?
millions
Compared to terrestrial planets, jovian planets are __________.
more massive and lower in average density
Click "show" for the emission line spectrum, then click "choose gases" and study the emission line spectrum for neon. The neon "OPEN" sign appears reddish-orange because __________.
neon atoms emit many more yellow and red photons than blue and violet photons
Rank the forms of light from left to right in order of increasing energy. To rank items as equivalent, overlap them.
radio waves, infrared, visible light, ultraviolet, x-rays, gamma rays
Rank the forms of light from left to right in order of increasing frequency. To rank items as equivalent, overlap them.
radio waves, infrared, visible light, ultraviolet, x-rays, gamma rays
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
radio, infrared, visible light, ultraviolet, X rays, gamma rays
We can see each other in the classroom right now because we
reflect visible light.
Which of the following forms of light can be observed with telescopes at sea level?
visible light, radio waves
