Astronomy

Astronomy Information from //The Universe, 5th edition.// **This is an excellent presentation. Well done. Easy to read and well researched. 5 out of 5**

**__ Chapter 1 __**
How far has the Hubble Telescope ever looked into space? **All the way? How far is that? Can you tell me in time?** I haven't been able to find out the answer to that question even though I typed all different variations of it in on Google and the N.A.S.A. website. I am going to keep looking. **The farther a telescope looks into the cosmos, the farther back in time it is looking. If you look 1 light year away or something that is 10 billion light years away, you are also seeing that object 1 or 10 billion years ago. This is what I meant. Hubble has looked all over the universe and the farthest out (back) is about 14 billion light years.**

2. Q: Describe the role that skepticism plays in science. A: Skepticism is important because if it didn't exist people could "scientifically" claim anything and this possibly false information could mislead huge amounts of people if unchecked. This does go on today. For example everyone just accepted the fact that the Earth was flat until a few hundred years ago, until that claim was proven wrong. Even then, people were still called crazy for thinking the Earth was round. **Nice work**

1. Q: What is the difference between a theory and a law of physics? A: Theories are a body of related hypotheses put together, but laws of physics are proven theories.

Theory:

Example: It is known that on June 30, 1908 in Tunguska, Siberia, there was an explosion equivalent to the detonation of about 15 million tons of TNT. Many hypotheses have been proposed for what caused the explosion. It is theorized that the explosion was caused by a natural extraterrestrial phenomenon, and was not caused by man. Is this theory a fact? No. The event is a recorded fact. Is this theory generally accepted to be true, based on evidence to-date? Yes. Can this theory be shown to be false and be discarded? Yes.

Law: Example: Consider Newton's Law of Gravity. Newton could use this law to predict the behavior of a dropped object, but he couldn't explain why it happened. As you can see, there is no 'proof' or absolute 'truth' in science. The closest we get are facts, which are indisputable observations. Note, however, if you define proof as arriving at a logical conclusion, based on the evidence, then there is 'proof' in science. I work under the definition that to prove something implies it can never be wrong, which is different. If you're asked to define hypothesis, theory, and law, keep in mind the definitions of proof and of these words can vary slightly depending on the scientific discipline. What is important is to realize they don't all mean the same thing and cannot be used interchangeably.

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3. Q: Describe one reason why it is useful to have telescopes in space. A: Telescopes in space are useful because they can take high quality images without light pollution and our atmosphere getting in the way and distorting the images. **Good job. Can you find a really cool space based telescope that you might like to research? Try looking at NASA or ESA. I would like to research the Hubble Space Telescope. __GREAT! I'll give you some details on how to proceed at the bottom of this page.__**

13. Q: How is an astronomical unit (AU) defined? Give an example in which this unit of measure would be convenient to use. A: An AU is the average distance between the earth and the sun. An AU would be a convenient measuring length when finding the distance between another planet and the Sun or Earth. **Yes, the general rule is to use AU in the solar system, LY outside of the solar system, and meters here on Earth.**

**__ Chapter 4 __**
13. Q: What are Kepler's three laws? Why are they important? A: Kepler's First Law: The orbit of a planet about the Sun is an eclipse with the Sun at one focus.

Kepler's Second Law: A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.

Kepler's Third Law P² = a³ ( P squared equals a cubed)

P = planter's sidereal period, in years a = planet's semimajor axis, in AU

Kepler's three laws are important because they made it possible to calculate the motions of the planets with better accuracy that any geocentric model ever had, and they helped to justify the idea of a heliocentric model. **GREAT**

19. Q: What are Newton's three laws? Give an everyday example of each law. A: __Newton's First Law of Motion__ (Law of Inertia) - A body remains at rest, or moves in a straight line at a constant speed, unless acted upon by a net outside force. If you left a calculator on a desk it would not move unless someone picked it up, slid it, etc.

__Newton's Second Law of Motion__ - F = ma F = net outside force of an object m = mass of object a = acceleration of object When a 50-kg swimmer falls from a diving board, the only outside force acting on her as she falls is her weight (gravity). The air around her would slow her down a little, but at this height, it would be minimal. **Pretty Good. How about air resistance?**

__Newton's Third Law of Motion__ - Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body. If you set down your backpack that weighs ten pounds on the floor, Newton's third law states that the floor is pushing up with an equal force of ten pounds. **Good, but can you think of a better, more obvious, example. I'm thinking about stepping off of a boat...or you can just apply these to your force and motion page.** This law is an example of what happens if we step off a boat onto the bank of a lake: as we move in the direction of the shore, the boat tends to move in the opposite direction. **YES!**

21. Q: What is the difference between weight and mass? A: Mass is the measure of the total amount of material in the object but weight is the force of gravity that acts on a body. **Good.**

**__ Chapter 5 __**
5. Q: What is meant by the frequency of light? How is frequency related to wavelength? A: The frequency of a wave is that number of wave crests that pass through a given point in one second. But wavelength is the distance between two successive wave crests. **Good. This is a really nice illustration. Just so you know, wavelengths can also be measured from tough to trough also.**



10. Q: Explain why astronomers are interested in blackbody radiation. A: Astronomers can tell the temperature of a star by looking its blackbody radiation. Yes, this concept makes sense to me.

17. Q: Explain how we know that atoms have massive, compact nuclei. A: We know that atoms have a massive compact nuclei because of Earnest Rutherford's experiments.

19. Q: Why do different elements display different patterns of lines in their spectra? A: Because each kind of atom can only be in certain energy levels, the pattern of spectral lines is likewise unique to that particular type of atom. **PERFECT!**

Spectra of Hydrogen (top) and Helium (bottom) :

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My hypothesis is that these two atoms might have different spectra because lower wavelengths of visible light might not be allowed to pass through helium atoms because of the larger amounts of protons, neutrons, and electrons, whereas they would pass through hydrogen atoms because of the lower amount of protons, neutrons, and electrons. This is just my hypothesis and I am not sure I am correct. **This is a good guess, but not quite on the mark. The process is described in your astronomy book. Look at their spectrums again. They both display all of the same visible light range, but different wavelengths are absorbed and emitted.** **Read the section on this topic and come back here to report back. VERY GOOD GUESS! Each atom has different spectra because they absorb and emit different wavelengths of light. I also learned (after reading about it) that the motion of a light source can also affect the wavelengths permitting us to deduce how fast stars and other objects are approaching or receding.**

20. Q: What is the Doppler effect? Why is it important to astronomers? A: The Doppler effect is the effect of relative motion on wavelength. The Doppler effect is important to astronomers because it uncovers basic information about the motion of planets, stars, and galaxies. What does a red shift and a blue shift mean in relation to an objects motion? **A red shift means that because of the velocity (away from us) of the object the wavelengths are stretched slightly and so the spectra appear to be accurate but shifted towards the longer red wavelengths. So Hydrogen’s spectra (as you see above) would be slightly to the right of what we see above. Blue shift is the same idea but the wavelengths are getting shorter (shifted to the left as seen above) because the object is zooming towards us. Make sense? Yes this made sense. Thank you.**

**__ Chapter 7 __**
How did the Voyager Satellites increase our understanding of our solar system?

** Chapter 8 **
Are we able to study other solar systems to learn more about how ours was formed?

Chapter 9 What kind of El Nino are we expected to have this year?

Chapter 10 Does the moon have a permanent dark side?

Chapter 11 How much more intense is the Sun’s light on Mercury than it is on Earth?

Chapter 12 What would be different about Earth if it had retrograde rotation like Venus?

Chapter 13 Could animals with gills live under the surface of Mars if there was liquid water under the surface?

Chapter 14 Could Saturn’s rings be possibly reproduced in a different on our own planet in a phenomenon we can’t detect or see?

Chapter 15 They suggest that there might be single-cell organisms in a “world-wide” ocean. If this is true could a more intelligent form of organism eventually evolve from the single-celled organisms.

Chapter 16 Why are Uranus and Neptune’s rings different colors and pigments than Saturn’s

Here is a pretty rough model of the solar system:




 * __WORK TO BE DONE:__**

Lets not work through the book so quickly. For now I would like for you to describe how Newton's Laws as well as density, velocity, and gravity are manifested in the universe. (i.e. what are the structures in the universe that show the affects of gravity or high rates of speed?) Try talking about red and blue shift again. Can you give me three examples to start with? Post your answers to the force and motion page.
 * 1) Let's take a look at your book again when I see you and we'll continue your way through the book.****