ast 103 - test 1 Flashcards
Roughly how many stars are in the Milky Way Galaxy?
100 billion
Approximately how fast are you moving with the rotation of Earth?
1,300 km/hr
How long does it take our solar system to complete one orbit around the Milky Way Galaxy?
230 million years
Which scientists 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
Earth is made mostly of metals and rocks. Where did this material come from?
it was produced by nuclear fusion in the stars
What is the ecliptic?
the Sun’s apparent path along the celestial sphere
Momentum is defined as
mass times velocity
Kepler’s third law, p^2 = a^3, means that:
A) a planet’s period does not depend on the eccentricity of its orbit
B) all orbits with the same semimajor axis have the same period
C) the period of a planet does not depend on its mass
D) planets that are farther from the Sun move at slower average speeds than nearer planets
all of the above are correct.
Why do we have seasons on Earth?
as Earth goes around the Sun and Earth’s axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight
When are eclipse seasons?
when the nodes of the Moon’s orbit are nearly aligned with the Sun
According to the universal law of gravitation, the force due to gravity is
inversely proportional to the square of the distance between objects
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
The names of the seven days of the week are based on the
most popular Norse gods
Which of the following statements about scientific models is true?
a model can be used to explain and predict real phenomena
Considering Einstein’s famous equation, E = mc^2, which of the following statements is true?
a small amount of mass can be turned into a large amount of energy
How did the Ptolemaic model explain the apparent retrograde motion of the planets?
it held that the planets moved along small circles that moved on larger circles around Earth
Kepler’s second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that
a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun
What do scientists mean by verifiable observations?
statements that a person can, in principle, verify for themself
Suppose an object is moving in a straight line at 50 miles/hr. According to Newton’s first law of motion, the object will
continue to move in the same way until it is acted upon by a force
Newton’s second law of motion tells us that the net force applied to an object equals its
mass times acceleration
Changing the orbit of a spacecraft by firing thrusters is an example of
Newton’s third law of motion
Which of the following best describes the origin of ocean tides on Earth?
Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth
Which of the following statements about circumpolar stars is true at all latitudes?
they always remain above your horizon
What is stellar parallax?
it is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth’s orbit of the Sun
