Ch 1 & 2 Questions
Why don't we see a lunar and solar eclipse every month?
We do not see a lunar and solar eclipse every month because the Moon-Earth orbital plane is tilted by 5 degrees with respect to the Earth-Sun orbital plane. At new moon phase, when the Moon lies between the Earth and the Sun, we do not always have a solar eclipse (a blocking of the Sun as viewed from the Earth) because the Moon is either slightly above or below the Sun as viewed from Earth. During full moon phase, the Moon is mostly found above or below the shadow of the Earth. On the occasion when the Moon crosses into the shadow of the Earth, we have a lunar eclipse. -Due to the orbit of the moon's orbital plane having a tilt five degrees from the ecliptic. From this, the moon is either above or below the sun, making eclipses not occur monthly.
If the Earth did not have precession, what would also not happen? To have no seasons, what has to happen?
We wouldn't have season and the earth wouldn't be tilted on it's axis
When all stars rotate around a single point in the sky, what does that mean?
When all stars rotate around a single point in the sky, this means that the Earth's rotation axis is pointing directly to that location in the sky. For the northern hemisphere, this point (represented by the north celestial pole) is located fairly close to the star Polaris (the North star).
An object moves in a circular orbit at a constant speed. Are there any forces on the object? Explain.
Yes. Since the object moves in a circular orbit at a constant speed, the object's velocity is constantly changing due to the constantly changing direction of motion. Since the velocity is changing, the object is experiencing an acceleration. Newton's second law states that if an object experiences an acceleration, there must be an external force applied on the object. -1. Yes, the force of gravity is keeping the object in orbit. This is how satellites orbit the Earth. To be in the circular orbit, the object is constantly changing directions and from that will accelerate.
Does the moon follow the Zodiac or celestial equator or both? Explain why it is one and why it is not the other or why it is the same.
celestial equator?
The astronomical unit is __________ and measures_______.
distance, length
How is the Earth able to stay at approximately the same distance from the Sun (1 AU) despite the fact that the Sun exerts a gravitational pull on the Earth?
earth's accelerated 33,000 times greater than the sun
If you look at a fixed point that all stars rotate about in the sky and you measure how far up from the horizon, what does that tell you?
earth's rotation
A month after a solar eclipse, what is the phase of the moon? Explain how you can prove your answer.
full moon?
If the Earth were located 0.5 AU from the Sun, what would be the length of the year?
it would be half as short or 129 days
Two weeks after a lunar eclipse what is the phase of the moon? Explain how you can prove your answer.
new moon
What would happen to the Earth's motion if the Sun suddenly disappeared?
the Earth (and all the other objects in the Solar System) would continue their forward motion in a straight line off into space, instead of following their almost-circular orbits.
Describe Kepler's three laws of planetary motion.
1- orbit on ellipticals with the Sun at one focus 2- faster near the sun / An imaginary line between the Sun and a planet sweeps out equal areas of the ellipse in equal time intervals. 3- The square of a planet's orbital period (P) is proportional to the cube of its semi-major axis (a). P^2 =a^3
If we could see a star that was 10 billion light-years in distance away, how long would it take for a pho-ton to travel to us?
10 billion years?
Which particle of light (photon) lived the longest, one that came from your looking at your TV or one that came from the Sun? One that came from looking at Pluto or one from Venus? One that came from comet Halley or one from the star Betelgeuse?
?
What is astronomy in your own words?
the study of the universe and understanding it. It is the analysis of light and can be understood through computer programs as well.
Can you use ratios to convert years to seconds, kilometers to nanometers, light-years to seconds, and miles per hour to light-years per minute?
yes
Briefly describe the contributions of each to the advancement of astronomy: Aristarchus, Copernicus, Tycho Brahe, Kepler, Galileo, and Newton.
Aristarchus- sun is the center of the universe- heliocentric model -rotate around the sun and earth on its axis -went against religion and philosophy Copernicus- The Sun's unchanging appearance and smooth motion along the ecliptic plane is explained by Earth's orbit around the Sun -The changes in brightness of the planets are due to changes in their distance from the Earth -Wandering and retrograde motions of the planets result from the movement of the planets and the movement of the Earth (our vantage point) around the Sun Tycho Brahe- kept careful and extensive records of the stars and planets Kepler- realized that circular orbits could not explain the motions of the planets. He eventually realized that ellipses provide a more natural explanation Galileo- Venus phases, sun sport, moon isn't perfect, Jupiter's moons, Saturn's rings Newton- 3 laws of motion and the universal law of gravity
Explain why astronauts in the International Space Station are weightless.
Astronauts in the International Space Station are weightless because they are falling around the Earth as they orbit the planet. Since they are not "pushing" on anything, they feel weightless (i.e. a bathroom scale would record zero weight). - They are weightless in space because they are unable to push their weight against anything. The astronauts are falling at the same rate as their surroundings and that makes them appear as weightless.
What is the main difference between Kepler's view of the solar system and that of Copernicus?
Copernicus thought that planet orbits were circles. But Kepler found after studying data from Tycho Brahe's observations data that the orbit of planets were ellipse.
How did Galileo's observations of Venus help to bring the downfall of the geocentric model?
Galileo discovered that Venus undergoes a series of phases, and that when Venus displays a crescent phase it has a bigger apparent size than when Venus displays a nearly full phase. The heliocentric model provides an explanation of these telescopic observations, while the geocentric model does not. - Galileo discovered that Venus, like the moon, has phases. The phases were correlated with the size of Venus as well. Which led to the conclusion that Venus orbits the Sun and not the Earth. The geocentric model could not explain the correlation, but the heliocentric could.
Briefly describe the geocentric and heliocentric models.
Geocentric- earth center with epicycles Heliocentric- Sun centered
Galileo was reported to have dropped objects of various mass from the Leaning Tower of Pisa and discovered that objects fall at the same rate regardless of their mass. Use Newton's laws to show how this is possible.
Gravity is acting on the objects
What is the language of astronomy? In our analogy we travelled to France, what would an analogous symbol representing astronomy be compared to the Eiffel tower for France?
Greek. ....
What would happen to the Earth's motion if the Sun were suddenly replaced by a black hole with exactly the same mass as the Sun?
If the Sun were replaced by a black hole with exactly the same mass, the gravitational pull on the Earth from the black hole would be exactly the same as the gravitational pull on the Earth due to the Sun. Thus, the Earth's motion would be the same and we would orbit the black hole in the same manner as we orbit the Sun.
Explain how a rocket can operate in the vacuum of space
In space, rockets zoom around with no air to push against. ... Rockets and engines in space behave according to Isaac Newton's third law of motion: Every action produces an equal and opposite reaction. When a rocket shoots fuel out one end, this propels the rocket forward — no air is required
What are the smallest particles known, what are the largest structures known in the universe?
Photon and superclusters
Why are powers of 10 important to know?
Powers of ten are important to know because in astronomy (like other sciences) things that we measure span a very large range of values. The size of an atom, for example, is many powers of ten smaller than the distance to the edge of the observable Universe. Describing these numbers using powers of ten is convenient. Able to do mental math and get estimates.
If the Earth were located 2 AU from the Sun, would the Sun's gravitational pull be stronger or weaker than at its present position? How many times weaker or stronger would it be?
Since the force of gravity gets weaker with increasing distance, the Sun's gravitational pull on the Earth would be weaker if the Earth were located 2 AU from the Sun (i.e. twice its current distance). The force of gravity decreases as the inverse square of the distance. If we double the distance between the Earth and the Sun (from 1 AU to 2 AU), the force of gravity will be 𝟏 = 𝟏 as strong (four times weaker).
Why does the sun rise in the East and set in the West?
The Sun rises in the East and sets in the West due to the West-to-East rotation of the Earth.
What causes all the stars to move in the sky in a single night?
The motion of the stars over the course of a single night is due to the rotation of the Earth from west toward the east. Unless you are at the North or South Pole, this results in stars rising in the east and setting in the west.
Why do we say that a rock falls toward the Earth rather than the Earth falls toward the rock?
The rock falls straight down because the Earth's gravity acts on only the rock's vertical motion. If the rock is thrown straight up, it does not fall behind you as the Earth rotates.
Discuss how Galileo's observations supported the Copernican model of the solar system.
Venus having phases. But if the geocentric model was true, and the Earth was in the centre with the Sun further out, these phases of Venus would not be seen. A sun centered model was a far simpler way of trying to explain why the phases occurred.
