88 terms

Astronomy Test 1 (1-5)

What is the history of the universe that made human life possible (longest to newest)
1. Universe began to expand/big band 2.elements first existed 3. nuclear fusion begins in the sun 4. earliest life on earth 5. dinosaurs go extinct 6. earliest humans
when did the big bang occur?
14 billion years ago
when did earth form?
early september
when did life arise on earth
which is longer, sidereal day or solar day?
solar day is slightly longer
what makes a solar day longer?
to account for the earth's rotation around the sun, it rotates about 1 degree more than a sidereal day
you can measure the length of the sidereal day by measuring the time from when _____ crosses your meridian on one day (or night) until it crosses the meridian on the next day (or night)
any star( b/c the daily motion of the stars across the sky is due only to Earth's daily rotation)
a solar day is longer than a sidereal day by about
1/360 of 24 hours (4 minutes)
how long is a sidereal day
about 23 hours, 56 min
The Moon takes about 1 month to orbit Earth (more precisely, about 27 1/3 days), and it travels in the same direction that Earth orbits the Sun. Therefore, during the time it takes the Moon to complete one orbit around Earth, Earth moves __________ around its orbit of the Sun.
1/12 of the way
The North Celestial Pole is 35.0 above your northern horizon. This tells you that:
you are at latitude 35(degree) N.
what is the order of the seasons in relative from the distance from the sun? (closest to furthest)
In winter, Earth's axis points toward the star Polaris. In spring:
the axis also points toward Polaris.
If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars's __________ over a period of __________.
position among the constellations/ several months
apparent retrograde motion
Apparent retrograde motion can be observed by noticing changes in Mars's position among the constellations.....Mars's periods of apparent retrograde motion begin as Earth approaches the orbital position where it passes Mars and end after Earth has passed Mars by. In other words, apparent retrograde motion occurs as Earth "laps" Mars in their respective orbits around the Sun.
Consider a time when Mars is in the middle of one of its periods of apparent retrograde motion. During this time, Mars appears _____ in our night sky and crosses the meridian around _____.
retrograde motion
The middle of a period of apparent retrograde motion occurs when Mars is closest to Earth in its orbit and in a full phase as viewed from Earth, which is why it is brightest in our sky at that time. It is also directly opposite the Sun in the sky at that time, which is why it crosses the meridian at midnight.
explanation of parallax
parallax for the person being photographed and the trees, because their positions appear to shift even though they are not really moving.
The amount of parallax depends on an object's distance, with greater parallax for nearer objects.
stellar parallax
stellar parallax provides direct proof that Earth is not stationary at the center of the universe, but rather is a planet orbiting the Sun; if Earth did not move around the Sun, there would be no apparent shift in stellar positions.
When we see Saturn going through a period of apparent retrograde motion, it means
Earth is passing Saturn in its orbit, with both planets on the same side of the Sun.
If you are in the Earth's umbra, then
it is night time.
If the Moon is setting at noon, the phase of the Moon must be
third quarter
The place in a planet's orbit that is closest to the Sun is called
Right ascension in the sky is very similar to____ on the Earth.
If we have a new moon today, when we will have the next full moon?
two weeks
What causes the apparent retrograde motion of the planets?
As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not really change.
During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?
Earth is catching up with and passing by Mars in their respective orbits
If you are in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location
The altitude of the north celestial pole equals your latitude.
The Sun's path, as viewed from the equator, is highest in the sky on ________.
spring and fall equinoxes
What makes the North Star, Polaris, special?
it appears very near the north celestial pole
Which of the following best describes why we have seasons on Earth?
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because ________.
our evening view of space depends on where Earth is located in its orbit around the Sun
TRUE/FALSE: From Earth, the Sun and Moon have about the same angular diameter.
TRUE/FALSEAt the equinoxes, the declination of the Sun must be zero degrees.
It's 6 a.m. and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase?
third quarter
facts about celestial sphere:
1.When we look in the sky, the stars all appear to be located on the celestial sphere
2.The celestial sphere does not exist physically.
3.The Earth is placed at the center of the celestial sphere.
If part of the full moon passes through Earth's umbra, we will see a ____
partial lunar eclipse
In the sky, ____ is measured in degrees north or south of the celestial equator.
By locating the north celestial pole (NCP) in the sky, how can you determine your latitude?
The altitude of the NCP is the same as your latitude.
From the horizon to the observer's zenith is an angle of
90(degrees) for everyone on earth
That Polaris will not always be the pole star is due to
precession is shifting the celestial pole
Suppose it is full moon. What phase of Earth would someone on the Moon see at this time?
New Earth (opposite phases for moon/earth)
Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. what are characteristics of the solar system that is explained by Kepler's first law?
1. Earth is slightly closer to the Sun on one side of its orbit than on the other side. 2. The Sun is located slightly off-center from the middle of each planet's orbit.
Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. What is a characteristic of the solar system that is explained by Kepler's second law?
Objects moves faster when they are closer to the Sun than when they are farther from the Sun.
Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship . What are characteristics of the solar system that is explained by Kepler's third law?
1. Inner planets orbit the Sun at higher speed than outer planets 2. Venus orbits the Sun faster than Earth orbits the Sun.
In Ptolemy's Earth-centered model for the solar system, Venus's phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.
full whenever it is on the opposite side of the Sun from Earth, although we cannot see the full Venus because it is close to the Sun in the sky
Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?
noon (Because Venus is full when it is on the opposite side of the Sun from Earth, the Sun and Venus both appear to move through the sky together at that time. Venus therefore rises with the Sun, reaches its highest point at noon, and sets with the Sun.)
When would a new Venus be highest in the sky?
When would you expect to see Venus high in the sky at midnight?
never (For Venus to be high in the sky at midnight, it would have to be on the opposite side of our sky from the Sun. But that never occurs, because Venus is closer than Earth to the Sun. )
ptolemy v. galileo system
In the Ptolemaic system, we should never see more than a crescent in Venus. Because we do in fact see more, the Ptolemaic model must be wrong. The full range of phases that we see for Venus is consistent only with the idea that Venus orbits the Sun. Galileo was the first to observe the phases of Venus
earth is located at one ___ of the moon's orbit
the mathematical form of Kepler's third law measures the period in years and the ______ in AU
semimajor axis
Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be __________.
greater than your normal weight at rest
Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be __________.
less than your normal weight at rest
For what motions would your weight also be greater than your normal weight? (in an elevator)
the elevator moves downward while slowing in speed and moving upward with increasing speed
If you are standing on a scale in an elevator, what exactly does the scale measure?
the force you exert on the scale (weight)
Consider Earth and the Moon. As you should now realize, the gravitational force that Earth exerts on the Moon is equal and opposite to that which the Moon exerts on Earth. Therefore, according to Newton's second law of motion __________.
the moon has a larger acceleration than Earth because it has a smaller mass
the light from polaris travels through space in the form of _____ energy
rapidly moving coments have more ___ energy than slow moving ones
an apple contains ____ energy that your body can convert into other forms of energy
chemical potential
nuclear fusion in stars converts some of the ____ energy of hydrogen nuclei into light and heat
due to its much higher density, water heated to 80 degrees celsius contains more ___ energy than air at the same temp
an asteroid that is moving farther from the sun is gaining ____ energy
gravitational potential
strength of the gravitational force law
Gravity follows an inverse square law with distance, which means the force of gravity between Earth and the spaceship weakens as the spaceship gets farther from Earth.
How did the Ptolemaic model explain the apparent retrograde motion of the planets?
The planets moved along small circles that moved on larger circles around the Earth.
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?
Each orbit takes about 1 year, which we know from Kepler's third law.
which observation of Galileo offered direct proof of a planet orbiting the Sun?
phases of venus
Tycho Brahe's contribution to astronomy included:
collecting data that enabled Kepler to discover the laws of planetary motion.
Galileo's contribution to astronomy included:
making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.
As long as an object is not gaining or losing mass, a net force on the object will cause a change in ____
free- fall =
Momentum is defined as ________.
mass times velocity
A net force acting on an object will always cause a change in the object's ________.
The planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that ________.
a force is acting on the planets
Consider the elliptical orbit of a comet around the Sun. Where in its orbit does it have the largest amount of total orbital energy?
it always has the same orbital energy
When a spinning ice skater pulls in his arms, he spins faster because ________.
his angular momentum must be conserved, so reducing his radius must increase his speed of rotation
The energy attributed to an object by virtue of its motion is known as ________.
kinetic energy
According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them ________.
decreases by a factor of 9
Which of the following statements correctly describes the law of conservation of energy?
The total quantity of energy in the universe never changes.
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be:
1/4 as strong
rank the forms of light from left to right in order of increasing speed
The speed of light is a constant (in empty space) for all forms of light, meaning that all forms of light travel at the same speed, regardless of wavelength, frequency, or energy.
a light bulb emits visible light
when you place your hand near a light bulb, your hand absorbs some of the light, this absorbed energy warms your hand.
visible light does not pass through a black wall; blue light hits a red sweatshirt
a red chair ___ red light and ____ all other light
scatters; aborbs
some forms of matter, such as glass or air, transmit light, which means allowing it to pass through
light can bounce off matter (white light hits a piece of paper; red light hits a red sweatshirt)