## Saturday, February 23, 2013

### Devin Broderick Quizzes

Quiz Chapter 1

What is our place in the universe?
Our place is Earth, which is in our Solar sytem, which is in the Milky Way Galaxy, Which is in a local group of galaxys, and a bunch of these local groups make up a Local supercluser. And a bunch of these make up the universe. As far as we know.

How did we come to be?
It all started with the Big Bang. Which made hydrogen and helium. The rest were produced by the stars.

How can we know what the universe was like in the past?
By just looking into the telescopes we see the universe as is was, billions of years ago. Due to the light years.

Can we see the entire universe?
No, we can only see about 14 billion lightyears away. If we looked any further out we would be looking to a time before the universe existed. As well as the universe is forever expanding.

How big is Earth compared to our solar system?
If the Sun was the size of a grapefruit, Earth would be the size of a ballpoint pen.

How far away are the stars?
To scale it would take only a few minutes to walk from the sun to pluto. To walk from our Sun to the next nearest stars we would have to walk thousands of kilometers.

How big is the Milky Way Galaxy?
It would take thousands of years just to count all of the stars in our Galaxy/

How big is the universe?
So far the observable univers contains about 100 Billion galaxys. The number of stars could be represented by the grains of sand on all of the Earths beaches.

How do our lifetimes compare to the age of the universe?
Using the cosmic callender in the book, if the universe was only a year old, the human civilization is only a few seconds old, and a lifetime is only a fraction of a second.

How is Earth moving in our solar system?
It takes one day to rotate on our axis, it takes one year to orbit the sun. Earth is 1 AU from the Sun.

Quiz Chapter 2

1. What does the universe look like from Earth?
A celestial sphere surrounds Earth. We seperate it into constellations. We see half the sphere at any given time.

2. Why do stars rise and set?
Because of Earths rotation it looks as if the stars rise and set.

3.  Why do the constellations we see depend on latitude and the time of year?
The latitude dedermines the orientation of your horizon. As we orbit the sun, throughout the year, we have different view points of the galaxy.

4.  What causes the seasons?
The tilt of the Earths axis.

5.  How does the orientation of Earth’s axis change with time?
Earths Precession changes the orientation of the axis. It happens every 26000 years.

6.  Why do we see phases of the Moon?
It depends on its position relative to the Sun. Moon facing the Sun is always lit up. From Earth we see different combinations.

7.  What causes eclipses?
Lunar eclipse happens when Earth is between the Sun and the Moon. A Solar eclipse happens when the moon blocks our view of the Sun.

8.  Why was planetary motion so hard to explain?
Planets look like they are moving east relative to the stars. During periods of apparent retrograde motion, Earth passes by another planit in its orbit.

9.  Why did the ancient Greeks reject the real explanation for planetary   motion?
They couldnt detect Stellar parallax. It seemed unlikely that stars were so far away it made stellar parallax undetectable to the eye.

Quiz Chapter 3
1. In what ways do all humans use scientific thinking?
Trial and error thinking in a carefully organized way.

2. How did astronomical observations benefit ancient societies?
They used it to help them keep track of time and the seasons. Which they used for agriculture and navigation.

3. What did ancient civilizations achieve in astronomy?
They learned how to tell the time of day, year, and cycles of the moon. They built structers to help them.

4. Why does modern science trace its roots to the Greek?
The Greeks made models of nature and showed how it was important to have predictions of models agree with nature.

5. How did the Greeks explain planetary motion?
The geocentric and ptolemaic models. They explained retrograde motion by having each planet move on a small circle whose center moves around the Earth's.

6. How did Islamic scientists preserve and extend Greek science?
They moved west to Europe and their knowlage started the Renaissance.

7. How did Copernicus, Tycho, and Kepler challenge the Earth centered model?
Copernicus mad a Sun-centered model, only it used perfect circles as well as the Ptolemaic model. Tycho's eye observations helped improve Copernicus' model. Kepler developed a model of planetary motion the went with Tycho's data.

8. What are Kepler’s three laws of planetary motion?
1. The orbit of each planet it an ellipse with the Sun at one focus. 2. As a planet moves around its orbit, it sweeps out equal areas in equal times. 3. More distant planets orbit the Sun at slower average speeds.

9.  How did Galileo solidify the Copernican revolution?
His experiments and ovservations overcame any remaining objections to the Copernican idea of Earth as a planet orbiting the Sun.

10. How can we distinguish science from nonscience?
Modern science seeks explanations for observed phenomena that rely solely on natural causes. Science progresses through the creation and testing models of nature. A scientifical model must make testable predictions about natural phenomena that would force us to revise or abandon the model.

11. What is a scientific theory?
A model that has survived repeated and varied testing.

Quiz Chapter 4

How do we describe motion?
Speed is the rate an object is moving. Velocity is the speed in a certain direction. Acceleration is a change in velocity, meaning change in either speed or direction. Momentum is mass x velocity. And a force can change an objects momentum.

How is mass different from weight?
Mass is the same everywhere, where as Weight depends on the strengh of gravity

How did Newton change our view of the universe?
He showed that the same physical laws that work on Earth also operate in the heavens, making it possible to learn about the univers by studying the laws on Earth.

What are Newton's three laws of motion?
1. An object moves at a constant velocity if there is no net force acting upon it. 2. Force = mass x acceleration. 3. For any force, there is always an equal and opposite reaction force.

What keeps a planet rotating and orbiting the Sun?
Conservation of angular momentum. It means that a planets rotation and orbit cannot change unless it transfers angular momentum to another object.

Where do objects get their energy?
Energy is always conserved, and never created nor destroyed.

What determines the strength of gravity?
Every object attracts every other object with gravatational force. It is directly proportional to the product of the objects masses and declines with the square of the distance.

How does Newton's law of gravity extend Kepler's laws?
He showed that Keplers first two laws apply to all orbiting objects. He showed that orbits can be unbound. His version of Keplers third law allows us to calculate the masses of orbiting objects from their orbital periods and distances.

How do gravity and energy allow us to understand orbits?
The gravity determines orbits and an object cannon change its orbit unless it gains or loses orbital energy.

How does gravity cause tides?
The moons gravity creats a tidal force. It makes the Earth bulge both toward and away from the Moon.

Quiz Chapter 5

What is light?
Light is an electromagnetic wave. The forms of light are, radia waves, microwaves, visible light, infared, ultraviolet, x rays, and gamma rays.

What is matter?
Matter is made up of atoms, which are made up of protons neutrons and electrons. Matter is everything.

How do light and matter interact?
Matter can emit, absorb, transmit, or reflect light.

What are the three basic types of spectra?
Continuous spectrum, absorption line spectrum, and emission line spectrum.

How does light tell us what things are made of?
We determine the composition by identifying wavelengths that match a particular energy level.

How does light tell us the temperatures of planets and stars?
The produce thermal radiation, hotter the object the more total emitted radiation per unit area.

How does light tell us the speed of a distant object?
Doppler effect tells us how fast an object is moving toward or away from us. Shorter wavelengths for objects moving toward us.

How do telescopes help us learn about the universe?
They help us see farther, and certain ones allow us to see different wavelengths of light we couldnt see with visible light alone.

Why do we put telescopes in space?
They are not subject to light pollution, atmospheric distortion of light, or that most forms of light don't make it through our atmosphere.

How is technology revolutionizing astronomy?
It makes it possible to build more powerful telescopes and to enhance the capabilities of existing telescopes.

Quiz Chapter 6
1. What does the solar system look like?
Looks like a Sun, the planets and their moons, and a vast number of asteroids and  comets.

2. What features of our solar system provide clues to how it formed?
The sun planets and large moons rotate and orbit in an organized way. The planets  divide into two groups, jovian and terrestrial. and the solar system contains vast  numbers of asteroids and comets.

3. What theory best explains the features of our solar system?
The nebular theory, which holds the solar system formed from the gravatational collapse  of a great clous of gas.

4. Where did the solar system come from?
A cloud of gas that was the product of recycling of gas through many generations of  stars.

5. What caused the orderly patters of motion in our solar system?
Our solar system began as as spinning disk of gas and dust, so the motions we observe came from the motion of this spinning disk.

6. Why are there two major types of planets?
The inner solar system temperatures were so high that only metal and rock could  condense. In the outer solar system cold temperatures allowed for ices to  condense and hydrogen and helium gas to get drawn in.

7. Where did asteroids and comets come from?
Asteriods are rocky leftovers, while comets are icy leftovers.

8. How do we explain the existence of our Moon and other exceptions to  the rules?
Our moon is most likely the result of a giant impact between a mars size planetesimal  and Earth.

9. When did the planet form?
Planets began to accrete in the solar nebula about 4.55 billion years ago.

10. How do we detect planets around other stars?
We observe the planets effects on the star it orbits. Most discoveries have been made  with the Doppler technique.

11. How do extrasolar planets compare with planets in our solar system?
Most have masses that suggest they are jovian, but some metal and rock planets have  been discovered.

12. Do we need to modify our theory of solar system formation?
No. So far it works. Small modifications have been made.