Honors Astronomy Exam 1 (Chapters 1-5)

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field of view
the region you can see in the image
solar system
consists of the sun, its family of planets, and some smaller bodies, such as moons and comets
small, spherical, non-luminous bodies that orbit a star and shine by reflected light
a self-luminous ball of hot gas that generates its own energy
astronomical unit (AU)
the average distance from earth to the sun, which is equal to 1.5 x 10^8
light-year (ly)
distance light travels in one year
a great cloud of stars, gas, and dust held together by the combined gravity of all of its matter
Milky Way
band of stars seen at night in the sky
Milky Way Galaxy
the name of our galaxy
spiral arms
places where stars are formed from clouds, gas, and dust
billions of galaxies, each containing billions of stars and billions of planetary systems
groups of stars given names of celebrated heroes, gods, and mythical beasts
less formally defined groupings of stars
magnitude scale
a system written by Ptolemy that measures the brightness of stars from 1 to 6; the brighter the star the lower the number and vice versa
apparent visual magnitude (mv)
how bright stars appear to the human eyes observing from earth
the amount of light energy that hits one square meter in one second
spot directly overhead
spot directly below
north to your zenith to south
where the sky meets ground
angle above the horizon
circumpolar constellations
stars that never rise or set
angular distance
the angle between two lines extending from your eye to the two objects
arc minutes
1/60th of a degree
arc seconds
1/60th of an arc minute
angular diameter
the angular distance from one edge of the object to the other
the weight of the top tends to make it tip over, and this combines with its rapid rotation to make its axis sweep out of the shape of a cone
the turning of a body on its axis (spin)
the motion of a body around a point outside the body (orbit)
the apparent path of the sun against the background of the stars
evening star
any planet visible in the evening sky
morning star
any planet visible in the sky shortly before sunrise
vernal equinox
the point where the sun crosses the celestial equator going northward
summer solstice
the sun at its most northern point
autumnal equinox
the point where the sun crosses the celestial equinox going southward
winter solstice
the sun at its most southern point
a band around the sky extending 9 degrees above and below the ecliptic
a diagram showing the location of the sun, moon, and planets around the ecliptic and their position above or below the horizon for a given date and time
Milankovitch hypothesis
small changes in Earth’s orbit, precession, and inclination affect Earth’s climate and can cause ice ages
scientific argument
a careful presentation of theory and evidence in a logical discussion
lunar eclipse
the moon moves through the shadow of the earth
the region of total shadow
the region of partial shadow
the period of total eclipse
sidereel period
the moon orbits eastward around the earth in 27.32 days
synodic period
a complete cycle of lunar phases takes 29.53 days
solar eclipse
the moon is just the right size to cover the bright disk of the sun
the surface of the sun
the higher layers of the sun’s atmosphere
the sun’s outer atmosphere
eruptions on the solar surface
diamond-ring effect
a tiny bit of the photosphere does not completely drown out the fainter corona, which forms a silvery ring of light, with the brilliant spot of photosphere gleaming
the moon’s point of closest approach to earth
the most distant point in the moon’s orbit
annular eclipse
a solar eclipse in which a ring of the photosphere is visible around the disk of the moon
the point where the moon passes through the plane of earth’s orbit
Saros cycle
the pattern of eclipses repeats every 6585.3 days
uniform circular motion
Plato concluded that all motion in the sky must be made up of combinations of circles turning at uniform rates
geocentric universes
the argument that Earth was imperfect and lay at the center of the universe
the apparent motion of an object because of the motion of the observer
a small circle that the Aristotle model said the earth followed
a large circle that the Aristotle model said the earth slid around
the point in which Ptolemy supposed that the center of the epicycle moved in such that it appeared to move at a constant rate
heliocentric universe
the sun is the center of the universe
a figure that can be drawn around two points, called the foci, in such a way that the distance from one focus to any point and back to the other focus equals a constant
semimajor axis
(a) half of the longer diameter in an ellipse
(e) half the distance between the foci divided by the semimajor axis in an ellipse
a measure of the amount of matter in the object
inverse square relation
the force of gravity decreases as the square of the distance between the objects increases
circular velocity
the velocity needed to stay in a circular orbit
geosynchronous satellite
the orbit eastward with the rotation of earth and remains above a fixed spot
center of mass
the balance point of the system
closed orbits
return the orbiting object to its starting point
escape velocity
the velocity needed to leave a bodt
open orbit
does not return the orbiting object back to its starting point
spring tides
twice a month, at the new moon and the full moon, the moon and the sun produce tidal bulges that add together and produce extreme tidal changes; high tide is very high and low tide is very low
neap tide
less extreme tides at the first- and third-quarter moons when the sun and moon pull at right angles to each other; and the sun’s tides cancel out some of the moon’s tides
electromagnetic radiation
light made up of both electric and magnetic fields
distance between peaks of the wave
the number of waves that pass a stationary point in one second
a particle of electromagnetic radiation
an array of electromagnetic radiation displayed in order of wavelength
(nm) one billionth of a meter
one-tenth of a nanometer
(IR) non-visible light that your body detects as heat
atmospheric windows
wavelength bands that that allow visible light, some shorter wavelength infrared radiation, and some radio waves to reach earth’s surface
refracting telescope
telescope that uses a lens to gather and focus light
reflecting telescope
telescope that uses a mirror to gather and focus light
primary lens
the main lens in a refracting telescope
primary mirror
the main mirror in a reflecting telescope
a piece used to magnify the image and make it convenient to view
chromatic aberration
color separation
achromatic lenses
lenses with two components made of different kinds of glass, and thereby bring two different wavelengths to the same focus
optical telescopes
telescopes that collect visible light
radio telescopes
telescopes that collect radio waves
light-gathering power
the ability of a telescope to collect light
resolving power
the ability of the telescope to reveal fine detail
diffraction fringe
unavoidable blurring of light
the amount of image blurring due to atmospheric conditions
magnifying power
its ability to make images bigger
light pollution
the brightening of the night sky by light scattered from artificial outdoor lighting
photographic plate
first device used by astronomers to record images of celestial objects
sensitive light meters used to measure the brightness of individual objects very precisely
charge-coupled devices
(CCDs) a specialized computer chip containing millions of microscopic light detectors arranged in an array about the size of a postage stamp
converted to numerical data
colors represent different aspects on the object such as intensity, rather than visible color
spreading out light according to wavelength
spectral lines
dark or bright lines that cross the spectrum at specific wavelengths
adaptive optics
high-speed computers monitor the distortion produced by turbulence in earth’s atmosphere and rapidly alter some optical components to correct the telescope’s image
laser guide star
the laser causes gas in earth’s atmosphere to glow, producing an artificial star
the method of synthesizing a “virtual” large telescope from two or more smaller telescopes
cosmic rays
subatomic particles traveling through space at tremendous velocities
Categories: Astronomy