The great contribution of Tycho Brahe was to ________.
discover that planets orbit the Sun in elliptical orbits with varying speed
offer the first detailed model of a Sun–centered solar system, thereby beginning the process of
overturning the Earth–centered model of the Greeks
discover four moons orbiting Jupiter, thereby lending strong support to the idea that the Earth
is not the center of the universe
observe planetary positions with sufficient accuracy so that Kepler could later use the data to
discover the laws of planetary motion
the 18–year, 11–day period over which the pattern of eclipses repeats.
used to predict the future orientation of the Earth’s axis in space.
used to keep lunar calendars approximately synchronized with solar calendars.
the ancient Greek name for the cycle of lunar phases that repeats every 29 1/2 days.
Which of the following statements about scientific theories is not true?
A theory can never be proved beyond all doubt; we can only hope to collect more and more
evidence that might support it.
If even a single new fact is discovered that contradicts what we expect according to a
particular theory, then the theory must be revised or discarded.
A theory cannot be taken seriously by scientists if it contradicts other theories developed by
scientists over the past several hundred years.
A theory must make predictions that can be checked by observation or experiment.
A theory is a model designed to explain a number of observed facts.
Suppose a comet orbits the Sun on a highly eccentric orbit with an average (semimajor axis)
distance of 1 AU. How long does it take to complete each orbit, and how do we know?
It depends on the eccentricity of the orbit, as described by Kepler’s second law.
It depends on the eccentricity of the orbit, as described by Kepler’s first law.
Each orbit should take about 2 years, because the eccentricity is so large.
Each orbit takes about 1 year, which we know from Kepler’s third law.