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General Definition |
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Clumps of
Matter Questions
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Q1. Describe the major constituents of the universe. Give a simple description of how matter is distributed in the universe. Answer
Q2. How are stars and planets distinguished from each other? What role does the mass of an object play in determining whether it is a planet or a star? Answer
Q3. Describe the three types of objects which exist in the universe. Answer
Q4. How is the term "planet" defined? Why must more obvious definitions be rejected? Answer
Emptiness of the
Universe Questions
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Q1. What does the phrase "empty but clumpy" mean when describing the universe? Answer
Q2. What is the universe? What are its most basic properties? Explain. Answer
Q3. What are the general, overall properties of the universe? How is it different from the solar system? Answer
Philosophy of Science Questions
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Q1. Describe the role of models and evidence in science. Your description should explain how science works to understand something, and how that understanding is improved. Answer
Q2. Describe the three-step process of science. Why should it not surprising when you read that a scientific theory has been shown to be incorrect? Answer
Q3. How do scientists use models to improve their understanding of nature? Answer
Q4. In what way is astronomy generally different from the other sciences? Answer
Q5. What is the role of predictions in the process of science? Answer
Q6. How is an idea turned into a scientific "law?" Answer
Q7. How does the necessarily observational nature of astronomy change the way we study celestial objects, compared to the subjects of other sciences? Answer
Q8. What is a scientific model? Explain how a scientific model is refined or improved? Answer
Q9. When evaluating the claims of any scientific (or scientific sounding) theory, what are some of the key questions that should be asked? Answer
Q10. How can you distinguish between a scientific idea and a pseudoscientific idea? What are some of the key questions that must be asked of any idea to determine which type it is? Answer
Q11. Describe the process of science? What is the central question of any science? Answer
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Q1. What is a light year? How is it defined? Answer
Scale of the Universe Questions
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Q1. Why is a different unit of distance used in astronomy, compared to everyday life? How is it defined? In what sense does it help us understand the concept of viewing "back into time" as we view distant objects? Answer
Q2. What is a scale model? In a scale model where the sun is the size of a grapefruit (or softball), how far away would the nearest star be? Answer
Q3. Describe a scale model of the solar system. Be sure to describe the properties of the scale model (for example, what sets the scale in your model). What does this scale model tell us about the solar system? Answer
Clumps of Matter Answers
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A1. The types of objects seen in the universe are planets (objects which do not generate any energy), stars (objects which do generate energy), and galaxies (collections of a large number of stars). These clumps of matter are widely distributed from each other, with vast nearly empty space in between.
A2. Stars shine from an internal source of energy while planets do not shine. The distinction is the result of the mass of an object. Above a certain mass limit, gravity is strong enough to heat the interior of the object to the point that nuclear reactions begin to produce energy. Below that limit, no energy is produced.
A3. Stars are objects which shine with an internal energy source. Planets do not shine. Galaxies are independent collections of millions (or billions) of stars.
A4. A planet is any object which does not shine from an internal source of energy.
Planets are not all rocky bodies like Earth; some are gaseous. Not all planets are smaller than the smallest stars. Planets do not necessarily go around a star, nor are all objects which orbit a star called planets.
Emptiness of the Universe Answers
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A1. The matter which is observed in the universe is found in isolated clumps, such as planets, stars, and galaxies. The space in between these objects is mostly empty space. This empty space is vast compared to the size of the objects themselves.
A2. The universe consists of all matter and energy that exists. It is everything. The most general description of the universe is that it is mostly empty space and that the matter of the universe tends to occur in clumps. That means that most positions in the universe contain no matter at all. There are vast empty distance between the objects (such as stars or planets) which do exist in the universe.
A3. The universe is mostly empty space, and the matter in the universe occurs in clumps. The solar system is a very tiny part of the universe, consisting of a single star and the objects whose motion is controlled by its gravity.
Philosophy
of Science Answers
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A1. A model is a proposed explanation of a particular phenomenon. This proposed explanation is used to predict future events. Evidence is gathered by observing to see if those predictions are correct. If they are not, the difference between the prediction and the observation is used to improve the model. This cycle is then repeated again with more predictions and observations until the model provides a satisfactory explanation of all events which can be observed.
A2. Science begins with an idea or model that proposes an explanation for some phenomenon. The model is then used to make predictions about future events or observations. Those predictions are tested against reality. If the predictions are not followed exactly, then the model must be refined or modified to better explain everything which is observed. Scientific progress requires that scientific models be updated as new observations show their deficiencies.
A3. A scientific model is a suggested explanation for some observation. Scientists use models to make predictions of future observations. A comparison of the predictions with the actual events allows scientists to improve their model so it more accurately explains what is seen.
A4. Unlike other sciences which can perform experiments to test specific ideas, astronomy is primarily an observation science
A5. When a prediction is made by a scientific model, scientists can test the prediction against actual events in nature. If the prediction is verified, then it establishes the explanatory nature of the model. If the prediction is not verified, then the results can be used to further improve the model.
A6. Scientific ideas are never proven, but repeated tests of their predictions in a variety of different circumstances ultimately give us greater and greater confidence in their reliability. At some point an idea becomes sufficiently widely accepted to be considered a law.
A7. Most other sciences can perform controlled experiments to study phenomena of interest. In such an experiment, an originally complex phenomenon can be isolated into simpler components which can be more easily understood. Astronomy, on the other hand, can only observe natural objects and events, which are usually quite complex.
A8. A scientific model is a proposed explanation of how or why something occurs. For example, if we see an object fall to the ground, we propose that the force of gravity of the Earth puled it downward. We test a scientific model by using it to predict future events and then comparing those predictions to reality. If the future event does not occur exactly as the model predicted it would, then we use the difference between prediction and reality to refine the model so that its predictions are more accurate.
A9. Among others: Could the idea be proven wrong? Does it consider all available information? Are the observations it is based on repeatable and verifiable? Do the proponents do research which adds new knowledge?
A10. Pseudoscience deceptively appears to be science, but generally contains no new knowledge, the relevant observations are not repeatable or verifiable, and its ideas do not make testable predictions.
Among the questions to ask about any idea are:
1 - Is the hypothesis at risk -- could it be proven wrong?
2 - Do they consider all relevant observations?
3 - Do they provide simplistic answers for myriad, complex problems?
4 - Do they do research?
A11. Start with an idea. Use the idea to make predictions about what will happen. Test those predictions with observations. Refine the idea so that the predictions more accurately describe what is observed. The central question of all of science is "Why?" Why do things occur or appear the way they do?
General Definition Answers
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A1. A light year is a unit of distance. It is defined as the distance a beam of light moves in one year, and is equal to approximately 6 trillion miles.
Scale of the Universe Answers
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A1. Because the distance in space are so huge, a very large unit of distance is more convenient for describing those distances. The most common unit used by astronomers is the light year, the distance light travels in one year. When we look at a distant object (say one that is 10 light years away), we are also looking back into time, since we see the object as it was when the light left 10 years ago.
A2. In a scale model the size of every object is reduced (or expanded) by exactly the same amount, so that relative proportions are preserved. In a scale model in which the sun is the size of a softball, the nearest star will be about 2,000 miles away.
A3. If the sun is the size of a softball, then Earth’s orbit is about 30 feet in radius, Jupiter orbits at about 200 feet and Pluto is half a mile from the sun. Each of the planets is an object that ranges from a speck of dust (for Earth) up to a large grain of sand (Jupiter). The most important fact illustrated by this model is just how empty the solar system really is, and how small the objects in it are compared to the distances between them.