ASTR 264 - Chapter 1 (HW 1)
What are the real motions of our "spaceship Earth?"
- Earth and our solar system move with the Milky Way galaxy relative to other galaxies in our Local Group - Earth moves with the Sun on an orbit around the center of the Milky Way galaxy - Earth orbits the Sun
Place each statement in the correct bin corresponding to whether it represents 1 astronomical unit (1 AU), 1 light-year, or neither of those
1 (AU): about 150 million kilometers, Earth's average distance from the Sun, Jupiter lies about 5.2 of these from the Sun 1 light-year: the distance light travels in 1 year, about 10 trillion kilometers, the star Sirius lies about 8 of these from the Sun Neither: Mars's average distance from the Sun, the diameter of Earth
Based on observations of the universal expansion, the age of the universe is about ________.
14 billion years
If you have a 100-watt light bulb, how much energy does it use each minute?
6,000 joules
Which of the following is not a general difference between a planet and a star?
All planets are made of rock and all stars are made of gas
What do we mean when we say that the universe is expanding?
Average distances between galaxies are increasing with time.
On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth?
Just a few hours before midnight on December 31
Rank the following objects from largest to smallest. Sun Earth Galaxy Solar System
LARGEST Galaxy Solar System Sun Earth SMALLEST
Rank the following items according to their size (diameter) from largest to smallest. the Sun the Milky Way Galaxy Earth the local supercluster Jupiter the Local Group the universe our solar system
LARGEST the universe the local supercluster the Local Group the Milky Way Galaxy our solar system the sun Jupiter Earth SMALLEST
Rank the following items that describe distances from longest distance to shortest distance. the distance from Earth to the Alpha Centauri the distance across our solar system (to Neptune) one light-year the distance from the Sun to the center of the Milky Way Galaxy one astronomical unit (AU) the distance from the Milky Way Galaxy to Andromeda Galaxy the average distance from Earth to the Sun
LONGEST the distance from the Milky Way Galaxy to Andromeda Galaxy the distance from the Sun to the center of the Milky Way Galaxy the distance from Earth to the Alpha Centauri one light-year the distance across our solar system (to Neptune) the average distance from Earth to the Sun AND one AU SHORTEST
Consider the indicated events in the history of the universe that have helped make human life possible. Rank the events based on when they occurred, from longest ago to most recent.
LONGEST AGO The Big Bang & the universe begins to expand Elements such as carbon and oxygen first exist Nuclear fusion begins in the Sun Earliest life on Earth Dinosaurs go extinct Earliest humans MOST RECENT
Rank the forms of light in order of increasing energy. visible light X rays gamma rays ultraviolet radio waves infrared
LOWEST ENERGY radio waves infrared visible light ultraviolet X rays gamma rays HIGHEST ENERGY
Rank the forms of light in order of increasing frequency. visible light X rays gamma rays ultraviolet radio waves infrared
LOWEST FREQUENCY radio waves infrared visible light ultraviolet X rays gamma rays HIGHEST FREQUENCY
Mars is ________ from the Sun. Jupiter is ________ from the Sun. The star Sirius is ________ from the Sun. The diameter of the Milky Way Galaxy is ________. The distance from Earth to the Moon is ________.
Mars is ABOUT 1.5 AU from the Sun. Jupiter is ABOUT 5 AU from the Sun. The star Sirius is ABOUT 8 LIGHT-YEARS from the Sun. The diameter of the Milky Way Galaxy is ABOUT 100,000 LIGHT-YEARS. The distance from Earth to the Moon is LESS THAN 0.01 AU.
We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light in order of increasing wavelength. visible light X rays gamma rays ultraviolet radio waves infrared
SHORTEST WAVELENGTH gamma rays X rays ultraviolet visible light infrared radio waves LONGEST WAVELENGTH
Listed following are various physical situations that describe how light interacts with matter. Match these to the appropriate category. (Transmission, Absorption, Reflection or scattering, Emission) - visible light does not pass through a black wall - white light hits a white piece of paper - light comes from your computer screen - light comes from a light bulb - cell phone signals pass through walls - visible light meets clear glass - blue light hits a red sweatshirt - red light hits a red sweatshirt
TRANSMISSION: cell phone signals pass through walls, visible light meets clear glass ABSORPTION: visible light does not pass through a black wall, blue light hits a red sweatshirt REFLECTION OR SCATTERING: red light hits a red sweatshirt, white light hits a white piece of paper EMISSION: light comes from a light bulb, light comes from your computer screen
Suppose we made a scale model of our Milky Way Galaxy in which the disk of the galaxy is the size of a football field. Which (if any) diagram represents the Sun on the same scale?
The Sun on this scale would be microscopic and too small to see on the screen.
What do astronomers mean by the Big Bang?
The event that marked the beginning of the expansion of the universe
Is the actual size of the universe larger than 14 billion light-years?
The observable universe is 14 billion light-years in each direction, so the actual universe is greater than 14 billion light years across.
What is the ecliptic plane?
The plane of Earth's orbit around the Sun
NASA plans soon to launch a spaceship that will photograph our Milky Way Galaxy from beyond its halo. What is true about this statement?
The statement doesn't make sense, because even if we could build a spaceship that traveled close to the speed of light, it would take tens of thousands of years to get high enough into the halo to photograph the disk, and then tens of thousands of years more for the picture to be transmitted back to Earth.
Which of the following best describes what we mean by the term universe?
The sum total of all matter and energy
Rank the forms of light from left to right in order of increasing speed. visible light X rays gamma rays ultraviolet radio waves infrared
They are all the same speed
Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?
They have a frequency of 2 hertz
T/F: Key elements of which Earth and life are made, including carbon, oxygen, and iron, did not exist when the universe was born and were created later in stars.
True
The number of stars in the Milky Way Galaxy is approximately ________.
a few hundred billion
A light-year is ________.
about 10 trillion kilometers
According to current scientific estimates, when did the Big Bang occur?
about 14 billion years ago
The Andromeda Galaxy is faintly visible to the naked eye. When you look at the Andromeda Galaxy, the retina of your eye is absorbing light that has traveled through space for ______ to reach you.
about 2 ½ million years
On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun?
about the distance across the U.S.
Consider a raisin cake expanding uniformly in an oven. Viewed from one of the raisins, you would see ________.
all other raisins moving away from you, with more distant raisins moving faster
Suppose that someone in the Andromeda galaxy had a super-telescope through which they were looking at Earth right now. They would see Earth ______.
as it was about 2 ½ million years ago
A typical galaxy is a ________.
collection of millions or billions of stars, bound together by gravity and orbiting a common center
On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth?
in September
On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form?
in early September
What are examples of forms of light (electromagnetic radiation)?
infrared, visible light, radio waves, microwaves, ultraviolet, X rays, gamma rays
Grass appears green because
it reflects green light and absorbs other colors
A television advertisement claiming that a product is light-years ahead of its time does not make sense because ________.
it uses light-years to talk about time, but a light-year is a unit of distance
Red light has a ________ wavelength and a ________ frequency than does blue light.
longer, lower
Suppose that you had "X-ray vision" that allowed you to see X rays. What would you notice when you looked at a friend standing near you that you could not notice with your visible light vision alone?
nothing
How long does it take the Earth to complete one orbit around the Sun?
one year
If you have a telescope that is observing light with wavelengths of a few meters, you are observing ________.
radio waves
X ray photons have a ________ wavelength, ________ frequency, and ________ energy than do ultraviolet photons.
shorter, higher, higher
On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is ________.
small enough to fit within your hand
The term observable universe refers to ________.
that portion of the universe that we can see in principle, given the current age of the universe
Our solar system consists of ________.
the Sun and all the objects that orbit it
An astronomical unit (AU) is ________.
the average distance between Earth and the Sun
