Midterm 1 Flashcards
(48 cards)
How is Earth moving in our solar system? (2 ways)
It rotates on its axis once a day and orbits the Sun at a distance of 1 AU = 150 million kilometers.
How is our solar system moving in the Milky Way Galaxy?
2 ways
Stars in the Local Neighborhood move randomly relative to one another and orbit the center of the Milky Way in about 230 million years.
How do galaxies move within the universe and what does their distance from us imply?
All galaxies beyond the Local Group are moving away from us with expansion of the universe: the more distant they are, the faster they’re moving.
How has the study of astronomy affected human history? (4 things)
- Earth is not the center of the universe (Copernicus)
- Study of planetary motion led to Newton’s laws of motion and gravity
- Newton’s laws laid the foundation of the industrial revolution.
- Modern discoveries expand our “cosmic perspective.”
In what ways do all humans use scientific thinking? (1 way)
Scientific thinking involves the same type of trial and error thinking that we use in our everyday live
How did astronomical observations benefit ancient societies? (3 ways)
Keeping track of:
- time
- seasons
- navigation.
What did ancient civilizations achieve in astronomy? (4 things)
- To tell the time of day and year
- to track cycles of the Moon
- to observe planets and stars
- Ancient structures aided in astronomical observations.
Why does modern science trace its roots to the Greeks?
They developed models of nature and emphasized that the predictions of models should agree with observations. (developed scientific method in that way)
How did Ptolemy explain planetary motion?
The Ptolemaic model had each planet move on a small circle whose center moves around Earth on a larger circle.
Who challenged the earth centered model?
3 people
Copernicus, Brahe, Kepler
What are Kepler’s three laws of planetary motion?
- The orbit of each planet is an ellipse with the Sun at one focus.
- As a planet moves around its orbit it sweeps out equal areas in equal times.
- More distant planets orbit the Sun at slower average speeds: p2 = a3.
What is the distance between earth and sun in km?
150 mil km
What is perihelion?
The part of the earths orbit where it moves faster and is closer to the sun
What is aphelion?
The part of the earths orbit where it moves slower and is farther away from the sun
Galileo overcame 3 Aristotelian objections of the heliocentric model which are:
- Earth cannot be moving because objects in air would be left behind.
- Non-circular orbits are not “perfect” as the heavens should be.
- We would detect stellar parallax if earth were orbiting the sun
Galileo discovered what law of motion?
All objects in motion stay in motion (Newton’s first law)
How did Copernicus, Tycho and Kepler challenge the Earth-centered idea?
- Copernicus created a sun-centered model
- Tycho provided the data needed to improve this model
- Kepler found a model that fit Tycho’s data.
What was Galileo’s role in solidifying the Copernican revolution?
His experiments and observations overcame the remaining objections to the Sun-centered solar system model.
Universal law of gravitation (3 points)
- Every mass attracts every other mass.
- Attraction is directly proportional to the product of their masses.
- Attraction is inversely proportional to the square of the distance between their centers.
F=(m1*m2)/d^2
A scientific theory must: (3 points)
- Explain a wide variety of observations with a few simple principles
- Be supported by a large, compelling body of evidence, - Have not failed any crucial test of its validity.
How do we experience light? (2)
- Light is a form of energy.
- Light comes in many colors that combine to form white light.
How do light and matter interact? (4+1)
Matter can:
- emit light
- absorb light
- transmit light
- reflect (or scatter) light.
- Interactions between light and matter determine the appearance of everything we see.
What is light? (3)
Light as a wave: - Is a vibration of electric and magnetic fields. - Has a wavelength and a frequency. Light as a particles: - Are photons
What is the electromagnetic spectrum? (2)
- The entire range of wavelengths of light is known as the electromagnetic spectrum
- humans cannot see most of it
