Astronomy Test #2 Review – Flashcards
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photon
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particle of light
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refraction
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bending of light
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spectrum/spectra
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order of colors or wavelengths produced when light is dispersed
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continuous spectrum
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spectrum containing an entire range of wavelengths, rather than separate, discrete wavelengths
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absorption spectrum
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spectrum that is continuous except for certain discrete frequencies (or wavelengths)
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emission spectrum
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spectrum made up of discrete frequencies (or wavelengths) rather than a continuous band of frequencies (or wavelengths)
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radial velocity
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velocity along the line of sight, toward or away from the observer
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redshift
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a change in wavelength toward longer wavelengths
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blueshift
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a change in wavelength toward shorter wavelengths
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wavelength
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distance between two wave peaks
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frequency
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number of times per second that a wave vibrates up and down
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angular size
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angle between two lines drawn from the viewer to the opposite sides of the object
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reflecting telescopes
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mirrors are used
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refracting telescopes
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lenses are used
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spectroscopy
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measurement of wavelengths
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photometry
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measurement of light
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interferometry
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procedure that allows several telescopes to be used as one by taking into account the time at which individual waves from an object strike each telescope
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magnification
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least important property of a telescope
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resolution
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measurement of an instrument's ability to see detail
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light-gathering power
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measurement of the amount of light collected from an optical instrument
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objective
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primary lens
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Solar System
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system that includes the Sun, planets and their satellites, asteroids, comets, and other objects that orbit our Sun
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ecliptic
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apparent path of the Sun on the celestial sphere
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rotation
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spinning of an object about an axis that passes through it
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revolution
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orbiting of one object around another
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asteroids
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small, mostly rocky objects that orbit the Sun
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comets
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small object, mostly ice and dust, in orbit around the Sun
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planetesimals
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one of the small objects that formed from the original matter of the Solar System and from which a planet developed
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accretion
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process by which an object gradually accumulates matter, usually due to the action of gravity
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convection
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transfer of energy in a gas or liquid by means of the motion of the material
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core
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central part
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mantle
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thick, solid layer between the crust and core
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crust
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thin, outermost layer
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greenhouse effect
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infrared radiation is trapped within a planet's atmosphere through the action of particles, such as carbon dioxide molecules, within that atmosphere
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tectonics/plate tectonics
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motion of sections of the Earth's crust (plates) across the underlying mantle
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spring tides (new moon)
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greatest difference between high and low tide
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neap tides (quarter moon)
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least difference between high and low tide
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maria/mare/sea
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seas of hardened rock
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scarps
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transition zones
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albedo
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fraction of incident sunlight that an object reflects
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density
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ratio of an object's mass to its volume
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terrestrial planets
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Mercury, Venus, Earth, and Mars
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jovian planets
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Jupiter, Saturn, Uranus, and Neptune
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age of the Earth
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4.6 million years old
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differentiation
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separation by layers
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impact cratering
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impacts by asteroids or comets
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regolith
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powdered rock under dirt
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geologically active
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Io is the most active body in the Solar System.
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geologically dead
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the Moon is an example
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Caloris Basin
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only basin on Mercury
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Olympus Mons
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volcano the size of Arizona on Mars
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Valles Marineris
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canyon on Mars probably caused by water
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Phobos
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Mar's moon meaning fear
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Deimos
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Mar's moon meaning terror
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Great Red Spot
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high pressure system on Jupiter
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Cassini Division
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gap in Saturn's rings
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Roche limit
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where larger moons can exist without being pulled apart
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Galilean satellites
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Ganymede, Callisto, Europa, Io
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Titan
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Saturn's moon with a mainly nitrogen atmosphere
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Pluto
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dwarf planet
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Charon
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Pluto's moon
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shepherd moons
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keep the rings in place
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asteroid belt
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region between Mars and Jupiter where most asteroids orbit
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Apollo asteroids
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asteroids that cross the Earth's orbit
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centaur
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half solid body/half comet
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coma
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part of a comet's head made up of diffuse gas and dust
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Percival Lowell
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thought there were aliens on Mars that dug canals
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FALSE
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T or F? Different wavelengths of the electromagnetic spectrum travel at different speeds in a vacuum.
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the temperature of the star
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wavelength where the peak of the spectrum of a star is located tells us...
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absorption spectrum?
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a number of bright lines
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When is a photon emitted?
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When an electron falls from an outer to an inner orbit
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When a galaxy moves away from Earth...
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spectral lines can change the measurement of their wavelengths
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Which are the only two categories of electromagnetic energy that we can use ground-based telescopes to observe?
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Radio waves and visible light
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Photometry is...
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measuring the intensity of light at various wavelengths
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Purpose of spectrometry...
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separate light from celestial objects into its colors
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TRUE
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T or F? The light-gathering power and resolution of a telescope are determined by the diameter of the objective
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FALSE
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T or F? The Earth and Moon have very similar densities, and their interiors are very similar.
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Nitrogen and oxygen
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Earth's atmosphere is mostly made up of these two elements
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What is continental drift caused by?
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motion of plates within the Earth
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What are the Van Allen belts?
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regions of charged particles trapped in Earth's magnetic field
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Large impact theory
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The best theory for the Moon's origin
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Weather has removed evidence
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Why are craters more visible on the Moon than on Earth?
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TRUE
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T or F? The Earth's rotational speed is being slowed down by tidal friction.
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Spring v. neap tides
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A spring tide is when the lunar and solar tides correspond. A neap tide is when the solar tide partly cancels the lunar tide.
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FALSE
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T or F? The terrestrial planets rotate faster than the Jovian planets.
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FALSE
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T or F? A gas cloud's speed of rotation slows as its parts come closer to the center of rotation.
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Saturn
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Which planet has the lowest density?
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Earth, Venus, Mars, Mercury
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List the terrestrial planets in order of size from smallest to largest by mass
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Jupiter, Saturn, Neptune, Uranus
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List the terrestrial planets in order of size from smallest to largest by mass
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Mercury has no maria
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What is one difference in appearance between Mercury and the Moon?
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Why is it difficult to observe Mercury from Earth?
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because its orbit keeps it close to the Sun
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Venus rotates backwards.
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What is unusual about Venus' rotation?
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The length of its day
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How is Venus NOT similar to the Earth?
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Why is Venus hotter than Mercury?
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because all the clouds and gases on Venus trap the heat in
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FALSE
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T or F? Mars' crust has a uniform thickness.
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How are Mars' seasons observed?
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in the changing size of the polar caps
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24 hours and 40 minutes
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How long is a day on Mars?
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buried in lava flows
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Why are there no impact craters on the surface of Io?
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water ice
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The Galilean satellites all have a cover of meteoritic dust over a crust of...
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about the size of Mercury
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How big is Jupiter's largest moon?
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tidal forces caused by Jupiter
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Besides energy from the Sun, Io and Europa are heated by...
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FALSE
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T or F? Jupiter's composition is mainly methane and ammonia.
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FALSE
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T or F? The primary constituent of all the Jovian planets' ring systems seems to be water ice.
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Why is Saturn so hot?
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in the atmosphere, helium condenses to a liquid and then falls downward
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Nitrogen
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What is Titan's atmosphere primarily made up of?
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less than a mile thick
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As viewed on edge the ring system of Saturn would be...
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William Herschel in 1781
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Who discovered Uranus and when?
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Why is Uranus unusual?
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its equatorial plane is tilted about 90 degrees with its plane of revolution
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What is unusual about Triton?
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Triton revolves around the planet in a clockwise direction as seen from the North. Only moon to move in retrograde motion.
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What is unusual about Nereid?
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Most eccentric orbit for a moon
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What are the five dwarf planets?
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Ceres, Haumea, Makemake, Pluto, Eris
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Sedna
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What is the most distant body found in the Solar System?
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Trojan asteroids
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orbit the Sun in Jupiter's orbit 60 degrees in front of and behind Jupiter
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FALSE
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T or F? Vesta is the largest object in the asteroid belt.
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meteorite
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chunk of rock that lands on Earth
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Edmund Halley
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predicted Halley's comet
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Halley's Comet
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named after Edmund Halley
