Chapter 1 Flashcards
About where is our solar system located within the Milky Way Galaxy?
about halfway from the center of the galaxy to the edge of the galactic disk
When we speak of the entire universe (as opposed to the observable universe), we mean
the total sum of all matter and energy
Which of the following is the largest distance
diameter of a typical galaxy
Which of the following statements does not use the term light-year in an appropriate way?
It will take me light-years to complete this homework assignment.
One light-minute is the distance that light travels in one minute. How far is this, in kilometers
18 million km (60s x 300,000km/s
Shortly after the Big Bang, the chemical composition of the universe was
almost entirely hydrogen and helium
Earth is made mostly of metals and rocks. Where did most of the elements that make up these materials (carbon, silicon, iron, etc.) from
they were produced by stars
Why would a scientist say that we are star stuff?
Nearly every atom from which we are made once (before the solar system formed)was inside of a star
The Sun is made primarily of
hydrogen and helium
Our Sun formed _______ our galaxy formed
billions of years after
In what sense are galaxies cosmic recycling plants?
New stars in galaxies form from gas that has been ejected by previous generations of stars
On the scale of the cosmic calendar, in which the history of the universe is compressed to 1year, when did the Sun and Earth form
September
On the scale of the cosmic calendar, in which the history of the universe is compressed to 1year, how long has human civilization (i.e., since ancient Egypt) existed
a few seconds
On the scale of the cosmic calendar, in which the history of the universe is compressed into 1year, when did the dinosaurs become extinct
in late December
On the scale of the cosmic calendar, in which the history of the universe is compressed into 1year, when did Kepler and Galileo first discover that we live on a planet in a solar system
1 second ago
On the scale of the cosmic calendar, in which the history of the universe is compressed into 1year, how long is the average human life span?
0.2 second
Approximately how fast is a person located at the Earth’s equator moving around Earth’s axis due to the rotation of the Earth
1700 km/hr
Earth’s rotation causes a person at the North Pole to ____relative to the center of the Earth
spin in place once each day
We say that Earth has an axis tilt of 23-1/2° because this is the angle between Earth’s
rotation axis and a line perpendicular (vertical) to the ecliptic plane
About how long does it take our solar system to complete one orbit around the center of the Milky Way Galaxy
230 million years
From the fact that virtually every galaxy is moving away from us and more distant galaxies are moving away from us at a faster rate than closer ones, we conclude that
the universe is expanding
What do astronomers mean when they say the universe is expanding?
Average distances are increasing between most galaxies
According to astronomers, approximately how old is the universe?
14 billion years
According to current scientific estimates, when did the Big Bang occur
about 14 billion years ago
How many seconds are in one year? (Calculate this, do not look it up.
about 30 million
Which of the following is a general difference between a planet and a star
Stars shine with energy released by nuclear fusion while planets shine primarily with light reflected from stars.
Our solar system consists of
the Sun and all the objects that orbit it
A typical galaxy is a
collection of millions or billions of stars, bound together by gravity and orbiting a common center
Which of the following best describes what we mean by the term universe
The sum total of all matter and energy
An astronomical unit (AU) is
the average distance between Earth and the Sun.
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
The number of stars in the Milky Way Galaxy is approximately
A few hundred billion.
What do astronomers mean by the Big Bang
The event that marked the beginning of the expansion of the universe
What do we mean when we say that the universe is expanding
Average distances between galaxies are increasing with time
Based on observations of the universal expansion, the age of the universe is about
14 billion years
What is the ecliptic plane
the plane of Earth’s orbit around the Sun
How long does it take the Earth to complete one orbit around the Sun?
One year
Which of the following has your “cosmic address” in the correct order
you, Earth, Solar system, Milky Way Galaxy, Local Group, Local Supercluster,Universe
When we look at an object that is 1,000 light-years away we see it
As it was 1,000 years ago
Using the ideas discussed in your text, in what sense are we “star stuff”
Nearly every atom from which we are made was once inside of a star.
Why do the patterns of the stars in our sky look the same from year to year?
Because the stars in the constellations are so far away
