MidTerm Answers Flashcards
The greatest triumph of Newton’s theory of gravity was
Its ability to mathematically predict all 3 of Kepler’s laws
Which sentence best describes how Rømer first measured the speed of light?
He predicted when Jupiter’s moons would be behind the planet, and compared to observed time ½yr apart.
A scientific theory can be shown to be wrong if:
scientists gather new data that contradicts its predictions.
When an electron moves from a higher energy level in an atom to a lower energy level:
a photon is emitted
Light from the Moon takes about how long to reach Earth?
1 second
What are good reasons to put an telescope in Earth’s orbit?
to observe at wavelengths blocked by Earth’s atmosphere; to avoid light pollution; to avoid weather; to avoid atmospheric distortion
The ancients observed and recorded the motions of the Sun, Moon and Planets in the sky primarily for:
Religion, keeping time, charting seasons
The visible light spectrum from the Sun shows which of the following features?
Absorption lines and Continuum
EM radiation in order of decreasing wavelength (largest to smallest)?
Radio waves, infrared, visible, ultraviolet, X-rays.
Which principle does a telescope with lenses make use of to create a focus point?
Refraction
Which one of Galileo’s observations directly refuted the Ptolemaic mode of the Universe?
the phases of Venus
How did Kepler fix the “Great Martian catastrophe”?
By correctly positioning the Earth’s orbit relative to the Sun in Copernicus’ heliocentric model of the universe.
For northern latitudes, the day that the Sun is seen lowest in the southern half of the sky marks the
winter solstice
During the formation of a planetary system why does a spinning cloud begin to spin faster as it collapses?
The cloud rotates faster to conserve the angular momentum it had when it was larger & spinning slower.
If the moon is new and is on the ecliptic, what would we see from Earth?
A total or annular Solar eclipse.
Earth doesn’t experience an eclipse of the Sun every month because
the moon’s orbit is not in the same plane as the Earth’s orbit.
Which condition below is true for a total Solar eclipse?
The Moon must be new and on the ecliptic.
If you are lucky enough to see a total solar eclipse, you must be standing in the:
Moon’s umbra.
Which best describes where in the sky the Sun (and hence the ecliptic) is during the
spring equinox?
The Sun (and the ecliptic) is 0 away from the equator.
Why are the seasons on Mars so similar to those on Earth?
Mars rotation axis is tilted with respect to its orbital plane by the same amount as Earth’s.
Like Mars and Venus, Earth originally had a lot of carbon dioxide in its atmosphere. Where is the majority of the carbon now?
It is bound up in rocks.
Mars, Venus and the Earth are much less heavily cratered than Mercury or the Moon. This is explained by the fact that:
Mars, Venus and Earth were geologically active for a longer period of time than Mercury or the Moon.
When was the most recent (i.e. youngest) crater on the moon’s surface made?
Today!
At what point in its appearance in the sky is Mars furthest from the Earth?
Conjunction
What is the most direct cause of the temperature increase in the North hemisphere’s summer season, as compared to winter?
Sunlight strikes the ground most directly and hence each square meter receives more energy during summer.
If the Sun is just setting, and the Moon is full that night, the Moon will be
just on or above the eastern horizon.
What is the precession period of the Earth’s rotational axis?
26000 years
From where did planetary geologists get their oldest samples of the moon’s surface?
The lunar highlands.
The Moon’s phases cycle with its:
synodic period
The difference in composition between the giant planets and the terrestrial planets is most like caused by the fact that:
the terrestrial planets are closer to the Sun.
The ______ is the imaginary line that divides eastern and western halves of the sky for an observer.
meridian
What happens to the kinetic energy (energy of motion) of cloud of gas as it falls toward and eventually hits the accretion disk surrounding a protostar?
It is converted into thermal energy, heating the disk.
Why is it not possible to ever see a planet directly overhead (at the zenith) in Brandon?
The planets follow the ecliptic and the maximum distance the ecliptic is above the southern horizon is 23½o + 40o which does not equal 90o.
Besides producing spectacular observational evidence for the Solar Nebula Theory, what else did astronomers learn from the recent ALMA image of protoplanetary disk surrounding the protostar HL Tauri?
Planets may form faster than previously thought.
Angular sizes ordered smallest to largest:
1 arcsecond, 1 arcminute, 1 degree.
What two variables go into Newton’s formulation of gravity?
mass and distance
The observational data that Kepler used to compare his model of the planets’ motions to came from
Tycho Brahe’s naked-eye observations
Light from the Sun takes how long to reach Earth?
8 minutes
Which formula denotes how the speed of light c is related to its wavelength λ (metres) and frequency f (1/seconds)?
c=λf
Looking down on the Solar System, the geometric arrangement of Mercury, the Earth and the Sun when Mercury is at greatest elongation in our sky is?
a right-angle triangle
Which formation theory of the Moon was most supported by moon rocks returned by the manned lunar missions in the ‘70’s?
The collisional ejection theory
Which star will be our pole star in 12,000 years?
Vega
What defines a planet?
orbits around the sun; a nearly spherical shape; has cleared the neighborhood around its orbit
What are Mars’ two moons?
Phobos and Deimos
What are Jupiter’s four Galilean moons?
Io, Europa, Ganymede, Callisto
When last was Saturn’s rings viewed edge-on?
2009
What is meant by recombination?
An electron recombines with an atom, the atom emits light
What is meant by ionization?
An electron is ejected, absorbs light, becomes “ionized”
Which two are the most important measures of a telescope’s power?
Light-gathering power and Resolving power
What do objective lenses or mirrors accomplish?
gathers light and bends it into focus
What does an eyepiece do?
brings the bright image from the focus and magnifies it to the size of your eye’s pupil
Which two telescope properties determine the instrument’s angular resolution?
Diameter and Wavelength of observation
What information does the albedo of a planet’s surface tells us?
the variation of types of rocks across the surface: dark volcano rocks have low albedo, more reflective and brighter rocks have higher albedo
What is special about the opposition of Mars?
Mars is closest to Earth, and appears large enough that telescopes can see remarkable detail!
A lunar eclipse occurs when __________ shadow falls on__________.
Earth’s; the Moon
What does light-gathering power mean for a telescope?
the number of photons a telescope can collect simultaneously
What does the resolving power mean in a telescope?
the smallest angular size the telescope can separate and image distinctly
What are the two basic designs of telescopes?
Refractors (lens) and Reflectors (mirrors)
