ASTR 3 Study Guide - Midterm Guide: Observable Universe
Chapter 1 Concept Questions –
To get a better overall understanding of the lecture main points and viable test questions
DO THESE FOR STUDYING!!!!
Suppose we have a scale model of our solar system, with the Sun the size of a grapefruit…
The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun,
while the rest planets are spread much farther
If you could count stars at a rate of about 1/sec, how long would it take?
• Several thousand years
The total number of stars in the observable universe is about
• Same as the number of grains of sand on all the beaches on Earth
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 a star
How are galaxies important to our existence?
Galaxies recycle material from one generation of stars to the next, and without this recycling we
could not exist
Relative to the age of the universe, how old is our solar system?
It is about one-third the age of the universe
• The universe is about 14 billion years old and the solar system about 4/5 billions years old
How do the speeds at which we are moving with Earth's rotation and orbit compare to the speed of
more familiar objects?
Earth's rotation carries people around the axis faster than a commercial jet travels, and Earth's
orbit carries us around the Sun faster than the Space Shuttle orbits Earth
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
• Although nearby stars move relative to us at typical speeds of tens to hundreds of thousands of
kilometers per hour, they are so far away that it would take thousands of years for their motion to
be noticeable to the eye
Where is our solar system located within the Milky Way Galaxy?
Roughly halfway between the center and the edge of the visible disk of the galaxy
Which statement about motion in the universe is not true
A. Except for a few nearby galaxies, all other galaxies are moving away from us
B. Your speed of rotation around Earth's axis is faster if you live near the equator than if you leave
near the North Pole
C. Some stars in the Milky Way are moving toward us and others are moving away from us
D. The mysterious dark matter is the fastest-moving material in the universe
D is correct bc the statement is not true. In fact, dark matter is thought to reside galaxies and clusters of
galaxies, and hence moves with these galaxies and clusters; it does not move faster than them
Document Summary
Suppose (cid:449)e ha(cid:448)e a scale (cid:373)odel of our solar syste(cid:373), (cid:449)ith the su(cid:374) the size of a grapefruit . To get a better overall understanding of the lecture main points and viable test questions. The planets are all much smaller than the sun. Four planets are within about 20 meters of the sun, while the rest planets are spread much farther. The total number of stars in the observable universe is about. Same as the number of grains of sand on all the beaches on earth. Nearly every atom from which we are made was once inside a star. Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist. It is about one-third the age of the universe: the universe is about 14 billion years old and the solar system about 4/5 billions years old.
