Planetary Astronomy [Topic Test 1]
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(1) Why were early astronomers astrologers?
They had to make a living somehow, and because humans have long reasoned there must be meaning in wonders of the night sky and the motions of comets, planets, the Sun and the Moon.
(1) What were the "world views" during these early times?
Early astrology was brought about to attempt to tell the future and predict our own Earthly fates. Many believed that the Sun and other planets were orbiting the Earth because the Earth upon which man lived was surely the center of the universe. Everything was thought to originate from Earth, and gravity was explained by saying that things merely wanted to return to where they came from.
(2) How and why did astronomy help change the world socially, culturally, and historically?
Astronomy has been used for navigation and to mark time. Through astronomy we have learned that the Earth is not flat, but in fact spherical, and early on we were able to estimate the size of Earth with astronomical calculations. Copernicus theorized that the planets all orbited the Sun, and Galileo's telescope 60 years later helped to support that theory. Challenging Geocentric beliefs brought him into conflict with the Catholic Church. Knowledge about the Moon's affect on the tides helped the US in the battle at Normandy. During the Cold War, society wanted to beat the USSR in the Space Race.
(3) Small Angle Formula:
Diameter = (arc sec * distance) / 206265
The NMC telescope has and angular resolution of 0.3 arcseconds. Determine the smallest object observed on the Moon from Earth. The Moon is approx. 384,400 kilometers away.
- D = (0.3 * 384400) / 206265
- D = 115320 / 206265
- D = 0.56
(4) Why cannot we see all the stars in one night and why are we limited to seeing just a small amount with the unaided eye?
We cannot see all of the stars because the Sun blocks out some of them and it also depends on the position on Earth from which we are looking. The human eye has a greater field of view than a telescope but it is limited in comparison to a telescope which has greater light-gathering ability and resolution (sharpness of vision).
(5) Explain the "cause" and the "reason" for the changing seasons here on Earth.
- The Reason for the seasons is the tilt of the Earth.
- The Cause is the amount of sunlight over time.
(5) What is occurring during a Solar Eclipse?
A Solar Eclipse is when the Earth passes through the Moon's shadow. The Moon is between the Earth and the Sun and it blocks the Sun from Earth's view.
(5&6) Why not an eclipse every month?
Eclipses are infrequent because the respective orbits of the Moon and Earth ate not aligned and to have an eclipse the Moon, Sun and Earth need to happen along a straight line.
(6) Why do we see only one side of the Moon?
Because the Moon takes as long to rotate on it's own axis as it does to make one orbit around the Earth.
(6) Why does the Moon appear to change in appearance?
Because as it orbits around Earth the angle of light from the Sun changes how it reflects upon the Moon's surface.
(6) What is occurring during a Lunar Eclipse?
A Lunar Eclipse is when the Moon passes through the Earth's shadow. The Earth is between the Moon and Sun and it blocks the Sun's light from reaching the Moon.
(7) Explain the Geocentric model and why people thought it was true.
Geocentric means "Earth centered", therefore the model had Earth at the center with everything else orbiting around it. They believed it because from their point of view everything did move around the Earth and nobody ever felt the Earth beneath them moving. "Seeing was believing".
(7) Explain what was wrong with the Geocentric model.
It was too complicated. There were too many epicycles and they just kept changing the model until it was fitting with their views of things orbiting Earth.
(8) Explain the Heliocentric model.
Heliocentric means "Sun centered", therefore it depicts the Earth and other planets orbiting the Sun.
(8) Why was the Heliocentric concept so difficult to accept?
Earth is the home of mankind, the center of the universe. We are significant. In the eyes of Christians, the Earth and men came from the Creator. People also thought that because they didn't feel the Earth moving, it wasn't.
(8) Explain some supporting evidence for the Heliocentric model.
The model became simpler, no more chains of epicycles to explain things. The Earth is also too small in size to have such a great mass like the Sun or Jupiter orbiting around it.
(9) Give Kepler's Laws and explain each briefly.
- 1) Planets orbit the Sun in ovals
- 2) Planets move faster as they get closer to the Sun and slower when they're further away
- 3) a^3 = p^2 There is a direct relationship between a planet's distance and its orbital period.
(9) Give Newton's Laws and explain each briefly.
- 1) Objects in motion stay in motion unless acted upon by an outside force
- - Earth's gravity is holding the Moon, otherwise it would keep spinning off into space
- 2) F = m*a
3) For every action there is an equal and opposite reaction
(10) What are Constellations?
Patterns of stars in the sky. Man created them to remember them.
(10) Give some examples for each classification of Constellations.
Circumpolar: Draco, Ursa Major, Ursa Minor
- Seasonal: Orion, Cetus,
- ~ Zodiacal: Leo, Taurus
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