Astronomy flashcards 2
which of the following has your “address” in the correct order?
you, earth, solar system, Milky Way, local group, local supercluster
roughly how many stars are in the Milky Way galaxy?
100 billion
which scientist played a major role in overturning the ancient idea of an earth-centered universe, and about when?
Copernicus, Kepler, and Galileo; about 400 years ago.
what is an astronomical unit?
the average distance from Earth to the sun.
which of the following statements about the celestial sphere is not true?
The “celestial sphere” is just another name for our universe.
which of the following about the celestial equator is true at all latitudes?
It represents an extension of Earth’s equator onto the celestial sphere.
what is the ecliptic?
the sun’s apparent path along the celestial sphere.
which of the following correctly describes the meridian in your sky?
a half-circle extending from your horizon due north, through your zenith, to your horizon due south.
how many arcseconds are in 1°?
3,600
what is a circumpolar star?
A star that always remain above your horizon
which of the following is not a phase of the moon?
half moon
If the moon is setting at 6 A.M., the phase of the moon must be
full.
which of the following never goes in retrograde motion?
The sun
How did Eratosthenes estimate the size of Earth in 240 B.C.?
by comparing the maximum altitude of the sun in two cities at different latitudes.
why did Ptolemy have the planets orbiting Earth on “circles upon circles” in his model of the universe?
to explain the fact that planets sometimes appear to move westwards, rather than eastward, relative to the stars in our sky.
where was the sun in Ptolemy’s model of the universe?
between the orbits of venus and mars.
the controversial book of this famous person, published in 1543 (the year of his death), suggested that Earth and other planets orbit the sun.
Copernicus
He discovered that the orbits of planets are ellipses
Kepler
He discovered that Jupiter has moons.
Galileo
From Kepler’s third law, an asteroid with an orbital period of 8 years lies at an average distance from the sun equal to
8 astronomical units
what is meant by a hypothesis?
an explanation for a phenomenon that makes a prediction.
if your mass is 60kg on Earth, what would your mass be on the Moon?
60 kg
what would happen if the space shuttle were launched with a speed greater than Earth’s escape velocity?
it would travel away from Earth into the solar system.
the movement of a pool ball, rolling on a table at a constant velocity, is an example of
Newton’s first law of motion.
The force of gravity is an inverse square law. this means that if you double the distance between two large masses, the gravitational force between them
weakens by a factor of 4
According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will
increase by a factor of 4
how are wavelengths, frequency, and energy-related to photons of light?
longer wavelength means lower frequency and lower energy.
From the lowest energy to the highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
radio, infrared, visible light, ultraviolet, x-rays, gamma rays
