Astronomy Study Set
Light travels 3 x 10^5 meters every second. That number in words is
300,000
Lunar Eclipse
FULL MOON, when it's farthest from the sun
The scientist who formulated the three laws of planetary motion by analyzing the data on the precise location of planets in the sky was
Johannes Kepler
The planet in our solar system with the shortest period of revolution is:
Mercury
Solar Eclipse
NEW MOON, when it's closest to the sun
Of these, which is the largest?
The Universe
Umbra
The darkest part of a shadow
What is Kepler's first law?
The orbit of each planet around the Sun is an ellipse with the Sun at one focus
What's Kepler's second law?
The planets speed up as they get closer to the Sun, and slow down as they pull away
Universe
The sum total of all matter and energy; that is, everything within and between all galaxies
The 17th century astronomer who kept a roughly 20 year continuous record of the positions of the Sun, Moon, and planets was
Tycho Brahe
Which of the following has the greatest density?
a cubic meter of lead
Newton showed that to change the direction in which an object is moving, one needs to apply
a force
Galaxy Cluster
a group of galaxies being held together by gravity
The location of the Earth in the Milky Way Galaxy is
a little less than 30,000 LY from the center
constellation
a patch of sky (or sector) that gets the name, rather than the set of stars themselves
Asterism
a subset of stars that form a widely recognized shape (ex: Big Dipper)
From a particular location on Earth, why can we see many more total eclipses of the Moon than total eclipses of the Sun?
a total lunar eclipse is visible over a much larger part of the Earth's surface than a total solar eclipse
We now know that the orbit of a stable planet around a star like the Sun is always in the shape of
an ellipse
If you could see the new moon, at what time of day (roughly) would it rise?
at sunrise
Galaxy
big island of stars in space, all held together by gravity and orbiting a common center
When the authors of our textbook say that astronomers are like police detectives trying to solve crimes, they are explaining that
both astronomers and detectives must test their hypotheses against any evidence that they gather
How did Eratosthenes measure the size of the Earth?
by measuring the height of the Sun in the sky on the same day in two cities at different latitudes
The minimum speed required to launch an object so that it remains the same distance above the ground and just falls around the Earth is called:
circular satellite velocity
The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called
constellations
According to Kepler's third law, there is a relationship between the time a planet takes to revolve around the Sun and its
distance from the sun
The way scientists know that a hypothesis in astronomy is a reasonable description of nature is to
do experiments and observations about the predictions of the hypothesis
To leave the gravitational pull of the Earth, and explore other planets, satellites must have at least:
escape velocity
By the term universe, astronomers mean
everything that we can observe
Which of the following statements about eclipses of the Sun is true?
for a total eclipse of the Sun to happen, the Moon must get directly in front of the Sun, as seen from Earth
During what phase of the Moon is the Moon up only during the night hours and all night long?
full moon
What phase of the Moon must it be to have a lunar eclipse?
full moon
Angular Momentum
if the shape of an object changes while it is spinning, becomes more compact, it spins faster, momentum has to do with how spread out the object is (ex: figure skater)
Which of the following statements about the force of gravity is FALSE?
its strength is inversely proportional to the mass: the more mass, the less gravity
In Newton's Law of Gravity, the force of gravity goes up as the
more than one of the above
When a planet, in its orbit, is closer to the Sun, it
moves faster than average
For a person who lives at a latitude of +40°, when is the Sun directly overhead at noon?
never
What phase of the Moon must it be to have a solar eclipse?
new moon
What's Kepler's third law?
p^2=a^3
When a comet like Comet Hale-Bopp comes closest to the Sun in its orbit, we say that it is at:
perihelion
When a planet temporarily moves westward in the sky over the course of several weeks or months (instead of eastward, as it typically does), we call it
retrograde motion (ex: passing car on highway)
When the Sun and Moon are lined up and pull together, the tides they raise are called:
spring tides
A partial lunar eclipse occurs when
the Earth passes through part of the Moon's shadow
The south celestial pole and the north celestial pole lie in the sky directly above
the Earths axis
What causes the seasons?
the Earths tilt, when the sun is higher in the sky, the sunlight is more direct and the sun is in the sky for longer, (turn heat up higher and longer)
The Earth's escape speed (the speed you need to get away forever) is about 25,000 miles per hour. Escape speed depends on the gravity of the object trying to hold the spacecraft from escaping. Based on your understanding of gravity, how will the escape speed from the Moon compare to the escape speed from Earth?
the Moon's escape speed will be smaller than Earth's
Solar and lunar eclipses are rare because
the Moon's orbital plane is tipped by 5.2° relative to Earth's orbital plane
Which of the following is NOT an argument for showing that the Earth must be round
the Sun is seen blocking different constellations in the course of a year
Why does the Moon show phases in the course of a month?
the angle the Moon makes with the Sun changes and we see differing amounts of reflected sunlight
The Astronomical Unit (AU) as defined by astronomers is
the average distance between the Earth and sun
A light year is
the distance light travels in one year
In the Northern Hemisphere, the altitude (height in degrees above the horizon) of the North Star is always roughly equal to the
the latitude of the observer
What would happen if the Earth's tilt was at extremes
the more extreme the tilt, the more intense the seasons would be
Altitude of the celestial pole above the horizon always matches...
the observers latitude on Earth
Prograde
the planet looks like it's going forward
The celestial sphere turns once around each day because
the planet on which we live is rotating
In Ptolemy's system the planets orbit the Earth and not the Sun. How did the system explain the retrograde motion of planets like Jupiter?
the planets moved on a small circle whose center, in turn, circled a point near the Earth
Zenith
the point directly over your head
North Celestial Pole
the projection of Earths geographic North Pole into space
South Celestial Pole
the projection of Earths geographic South Pole into space
Celestial Equator
the projection of the Earth's equator into space
The period of the moon's rotation on its axis is
the same as its revolution around the Earth
Which of the following is NOT a result of the Earth's precession?
the stars twinkle when seen from the surface of planet Earth
Orbital Period
the time it takes to orbit
All molecules (like molecules of water or carbon dioxide) are made up of
two or more atoms
A solar eclipse occurs
whenever there is a NEW moon AND the moon is on the ecliptic
Horizon
where the dome of the sky that you can see meets the ground from your point of view
A single star in the process of forming starts by spinning slowly (while it is quite large and relatively cool.) As the star collapses under the pull of its own gravity, its size decreases. As a result, its rate of spinning
will increase
Earth is closest to the Sun when the Northern Hemisphere experiences
winter (think of the opposite)
The point in the sky directly above your head at any given time is called the
zenith