Module 1 Flashcards
What does the Hubble Space Telescope photo show?
Thousands of galaxies in a region of the sky so small you could cover it with a grain of sand held at arm’s length.
What is the fourth learning goal of Chapter 1?
The Human Adventure of Astronomy: How has the study of astronomy affected human history?
What was the historical belief about Earth’s position in the universe?
Earth was imagined to be stationary at the center of a relatively small universe.
What does a galaxy consist of?
A great island of stars in space, all held together by gravity and orbiting a common center.
What is the Milky Way Galaxy?
A relatively large galaxy containing more than 100 billion stars.
What is the Local Group?
A collection of more than 70 galaxies, including the Milky Way.
What are superclusters?
Clusters of galaxy clusters, regions where galaxies and galaxy clusters are tightly packed.
What is the definition of an astronomical unit (AU)?
Earth’s average distance from the Sun, about 150 million kilometers.
What is a light-year (ly)?
The distance that light can travel in one year, approximately 10 trillion kilometers.
True or False: A light-year is a unit of time.
False: A light-year is a unit of distance.
What does the speed of light measure?
Light travels at approximately 300,000 kilometers per second.
How long does it take light to travel from the Sun to Earth?
About 8 minutes.
What can we infer about distant galaxies?
The farther away we look, the further back in time we see.
What is the significance of studying the Orion Nebula?
It is a giant cloud where stars and planets are forming, located about 1350 light-years away.
What are the three steps in the mathematical problem-solving process?
- Understand the problem
- Solve the problem
- Explain your result
Define a star.
A large, glowing ball of gas that generates heat and light through nuclear fusion in its core.
What is a planet?
A moderately large object that orbits a star and shines primarily by reflecting light from its star.
What distinguishes a dwarf planet from a planet?
A dwarf planet has not cleared most other objects from its orbital path.
What is a comet?
A relatively small and ice-rich object that orbits a star.
What is an asteroid?
A relatively small and rocky object that orbits a star.
What is a solar system?
The Sun and all the material that orbits it, including planets, dwarf planets, and small solar system bodies.
Define small solar system body.
An asteroid, comet, or other object that orbits a star but is too small to qualify as a planet or dwarf planet.
What constitutes a solar system?
The Sun and all the material that orbits it, including planets, dwarf planets, and small solar system bodies.
What is a star system?
A star (sometimes more than one star) and any planets and other materials that orbit it.
Define galaxy.
A great island of stars in space, all held together by gravity and orbiting a common center.
What is a cluster of galaxies?
A collection of galaxies bound together by gravity.
What distinguishes a supercluster?
A gigantic region of space in which many groups and clusters of galaxies are packed more closely together.
What is the universe (or cosmos)?
The sum total of all matter and energy—all galaxies and everything between them.
Define observable universe.
The portion of the entire universe that can be seen from Earth, at least in principle.
What is an astronomical unit (AU)?
The average distance between Earth and the Sun, about 150 million kilometers.
Define light-year.
The distance that light can travel in 1 year, about 10 trillion kilometers.
What is rotation in astronomy?
The spinning of an object around its axis.
What does orbit (or revolution) refer to?
The orbital motion of one object around another due to gravity.
Define expansion of the universe.
The increase in the average distance between galaxies as time progresses.
What is the measured age of the universe?
About 14 billion years.
What size is the model Sun in the Voyage scale?
About the size of a large grapefruit.
How far is Earth from the Sun in the Voyage model?
About 15 meters (49 feet).
What is the significance of the Great Red Spot?
It is a storm on Jupiter that could swallow up the entire Earth.
Fill in the blank: The nearest star system to our own is called _______.
Alpha Centauri.
What was Pluto’s status prior to 2006?
Considered one of nine planets in our solar system.
What is the International Astronomical Union (IAU)?
An organization made up of professional astronomers that decides on astronomical names and definitions.
What is the diameter of the Milky Way Galaxy?
About 100,000 light-years.
On a scale where each light-year is 1 millimeter, how far is the distance to Alpha Centauri?
4.4 millimeters.
What is the speed of Voyager 2?
Close to 50,000 kilometers per hour.
Fill in the blank: The distance to Alpha Centauri is approximately ______ light-years.
4.4 light-years.
What does the term ‘dwarf planet’ refer to?
An object similar to a planet but does not meet the criteria set by the IAU to be considered a planet.
What is the distance between our solar system and Alpha Centauri on a scale where the Milky Way’s diameter is the length of a football field?
4.4 millimeters
Approximately how many stars are there in the Milky Way Galaxy?
More than 100 billion
How long would it take to count 100 billion stars at a rate of one star per second?
More than 3000 years
What is the scale of a 1-to-10-billion model of the Sun’s radius?
About 7 centimeters
What is the diameter of the Sun on a 1-to-10-billion scale?
About 14 centimeters
How many large galaxies are estimated to be in the observable universe?
More than 100 billion
What is the estimated total number of stars in the observable universe?
Approximately 10^22
True or False: The number of stars in the observable universe is comparable to the number of grains of sand on all the beaches on Earth.
True
What event is known as the beginning of the universe?
The Big Bang
Approximately how long ago did the Big Bang occur?
About 14 billion years ago
What process drives the formation of stars within galaxies?
Gravity collapsing clouds of gas and dust
What is the term for the process in which lightweight atomic nuclei fuse to form heavier nuclei?
Nuclear fusion
What materials primarily make up the early universe?
Hydrogen and helium
What percentage of heavier elements in our solar system originated from earlier generations of stars?
About 2%
Fill in the blank: The universe is approximately _______ years old.
14 billion
True or False: The expansion of the universe means that individual galaxies are also expanding.
False
What role do galaxies play in the recycling of stellar material?
They recycle material expelled from dying stars into new generations of stars and planets
What is one way that telescopes help us understand the history of the universe?
They allow us to observe parts of the universe as they were long ago
How much of human civilization’s history falls into the last half-minute of the cosmic calendar?
The entire history
The ancient Egyptians built the pyramids about 11 seconds ago on this scale.
What are powers of 10?
Indicate how many times to multiply 10 by itself
Negative powers are the reciprocals of the corresponding positive powers.
What does a positive exponent in powers of 10 signify?
How many zeros follow the 1
For example, 10^3 is a 1 followed by three zeros.
What does a negative exponent in powers of 10 signify?
How many places are to the right of the decimal point
For example, 10^-2 has two places to the right of the decimal point.
How do you multiply powers of 10?
By adding exponents
Example: 10^2 * 10^3 = 10^(2+3) = 10^5.
How do you divide powers of 10?
By subtracting exponents
Example: 10^5 / 10^2 = 10^(5-2) = 10^3.
What is scientific notation?
A format where a number between 1 and 10 is multiplied by a power of 10
Example: 6,000,000,000,000 is written as 6 × 10^12.
How do you convert a number to scientific notation?
Move the decimal point to come after the first nonzero digit and determine the power of 10
Positive if the decimal moves left, negative if right.
What must you do before adding or subtracting numbers in scientific notation?
Convert them to ordinary notation
If both numbers have the same power of 10, factor out the power first.
What is the basic unit of length in the SI metric system?
The meter, abbreviated m
The primary measurement system in nearly every country except the United States.
What is the basic unit of mass in the SI metric system?
The kilogram, abbreviated kg
SI was formally established in 1960.
What does the prefix ‘kilo’ mean in the metric system?
One thousand
Example: A kilometer is 1000 meters.
How many seconds are in 1 day?
86,400 seconds
Calculated using conversions: 1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds.
What is a ratio?
A comparison of two quantities by division
It tells us how many times one quantity contains the other.
What do powers of 10 indicate?
How many times to multiply 10 by itself.
What is 10^2 equal to?
100
What is 10^6 equal to?
1,000,000
What does a negative power of 10 represent?
The reciprocal of the corresponding positive power.
What does a positive exponent in powers of 10 indicate?
How many zeros follow the 1.
What does a negative exponent in powers of 10 indicate?
How many places are to the right of the decimal point.
How do you multiply powers of 10?
Add the exponents.
How do you divide powers of 10?
Subtract the exponents.
What is the rule for raising powers of 10 to other powers?
Multiply the exponents.
How do you add or subtract powers of 10?
Write them out in longhand notation.
What is scientific notation?
A format where a number between 1 and 10 is multiplied by a power of 10.
What are the steps to convert a number to scientific notation?
- Move the decimal point after the first nonzero digit
- Count the places moved; positive if left, negative if right.
How do you convert a number from scientific notation to ordinary notation?
Move the decimal point according to the power of 10.
How do you multiply numbers in scientific notation?
Multiply the coefficients and add the exponents.
How do you divide numbers in scientific notation?
Divide the coefficients and subtract the exponents.
What must you do before adding or subtracting numbers in scientific notation?
Convert to ordinary notation.
What is the first guideline for working with units?
Identify the expected units for the final answer.
Can you add or subtract numbers with different units?
No, they must have the same units.
What does ‘per’ indicate in units?
Division.
What does ‘of’ indicate in units?
Multiplication.
What does ‘square’ indicate in units?
Raising to the second power.
What does ‘cube’ indicate in units?
Raising to the third power.
How do you convert units?
Multiply by a conversion factor.
What is the conversion factor for kilometers to meters?
1000 m / 1 km.
How many seconds are there in 1 day?
86,400 seconds.
Convert 108 cm to km.
0.00108 km.
If you accelerate at 9.8 m/s² for 4 seconds, what is your speed?
39.2 m/s.
How do you calculate the area of a rectangle?
Multiply length by width.
What is the area of a reservoir that is 2 km long and 3 km wide?
6 km².
What is the speed after 4 seconds of acceleration at 9.8 m/s²?
39.2 m/s
How do you calculate the area of a reservoir that is 2 km long and 3 km wide?
Area = length x width = 2 km x 3 km = 6 km²
How do you convert 6 km² to square meters?
6 km² = 6,000,000 m²
What does SI stand for in the metric system?
Système Internationale d’Unites
When was the modern version of the metric system formally established?
1960
What are the basic units of length, mass, and time in the SI?
- Meter (m) for length
- Kilogram (kg) for mass
- Second (s) for time
What does the prefix ‘kilo’ represent in the metric system?
10³ (1000)
What is the value of the prefix ‘micro’?
10⁻⁶
How many centimeters are in 1 inch?
2.540 cm
What is the conversion factor from miles to kilometers?
1 mile = 1.6093 km
How many square kilometers are in 1 square mile?
2.5898 km²
What is the ratio of Earth’s average density to Jupiter’s average density?
4.15
True or False: Earth’s average density is 4.15 times Jupiter’s average density.
True
What is the formula for kinetic energy?
Kinetic Energy = 1/2 mv²
What is the ratio of a car’s kinetic energies at 100 km/hr and 50 km/hr?
4
How do you compare the strength of gravity between Earth and the Sun to that between Earth and the Moon?
By taking the ratio of Earth-Sun gravity to Earth-Moon gravity
What is the simplified formula for comparing gravity strength using Newton’s law?
(dEarth-Moon / dEarth-Sun) = (Msun / MMoon) * (dEarth-Sun)²
What is the strength of Earth-Sun gravity compared to Earth-Moon gravity?
179 times stronger
