Quiz Week 1
What are the two ways that the tilt of Earth's axis causes the summers in the United States to be warmer than the winters?
(1)During the summer the Northern Hemisphere is tilted towards the sun (2) The sun stays above the horizon longer allowing it to heat things up longer than in the winter when days are shorter.
What is the phase of the Moon during a total solar eclipse? During a total lunar eclipse?
-The lunar eclipse can only occur at the time of full moon. Because when the moon is full then only whole of the shadow of Earth can cover the moon and moon can be hidden by Earth's shadow. -The solar eclipse can only occur at the time of new moon. Because when moon comes in between Earth and the Sun, the Sun is covered with moon. And when Moon is in between the Earth and Sun, the phase of the moon is New moon.
Why do lunar eclipses typically last much longer than solar eclipses?
Because the earth's shadow is so much bigger than the moon and it takes a long time for the moon to cross it.
During a retrograde loop of Mars, would you expect Mars to be brighter than usual in the sky, about average in brightness, or fainter than usual in the sky? Explain.
Brighter, because the planet comes closer to the Sun on this retrograde loop and the distance between Earth and Mars also decreases.
What two factors made it difficult, at first, for astronomers to choose between the Copernican heliocentric model and the Ptolemaic geocentric model?
The Ptolemaic model was widely supported by the Roman Catholic Church, and was a fierce critic of the heliocentric model. Additionally, there was no empirical evidence at the time to state that either model was correct.
What were two arguments or lines of evidence in support of the geocentric model?
We do not feel any motion. There is no wind or vibration indicating that Earth is moving. Also, because we do not see stellar parallax, the simplest explanation is that there is no movement of Earth around the Sun.
What is the phase of the Moon if it . . . -rises at 3:00 p.m.? -is highest in the sky at sunrise? -sets at 10:00 a.m.?
-The phase of the moon if it rises at 3:00 pm is Waxing Gibbous because in this position of the sun, the moon is not fully illuminated but more than half illumination. -The phase of the Moon if it is highest in the sky at sunrise is the Third quarter because at this position moon will rise at midnight and will be at the highest point at sunrise. -The phase of the Moon if it sets at 10:00 am is Waning Gibbous because at this position the Moon is now going towards becoming New Moon but it is illuminated more than the half illumination.
Give four ways to demonstrate that Earth is spherical.
-The shadow cast on the moon is always a round shape. -When ships sail away on the ocean they appear to sink because of the curvature of Earth's surface. -Orbiting satellites taking photographs of Earth shows it round on every direction. -The Sun is at different altitudes in the sky for different longitudes.
Why did Copernicus want to develop a completely new system for predicting planetary positions? Provide two reasons.
1) Copernicus wanted to improve data for planetary positions 2) He also thought that the new system seemed more simple and elegant for astronomers as well as the general public.
What are three lines of evidence you could use to indicate that the phases of the Moon are not caused by the shadow of Earth falling on the Moon?
1. During the waxing crescent phase of the moon, it is visible above the Western horizon of the Earth. It is not too distant from the Sun which has just set. 2. Full moon observation from the Earth is impossible to see if the moon is in the same direction as the sun and if the moon was in the opposite direction as the Sun, Earth's shadow could only eclipse the Moon. 3. The shape of the gibbous phase of moon is a crescent which is not one that can be cast by a spherical object like the Earth.
What fraction of the Moon's visible face is illuminated during first quarter phase? Why is this phase called first quarter?
A half fraction of the moon's visible face is illuminated during first quarter phase. This phase is called the first quarter because the moon is one-quarter of the way around its orbit.
The Sun was once thought to be a planet. Explain why.
In the geocentric system all objects moving in the sky were considered "wanderers", so the Sun was considered a planet.
Although the Copernican system was largely correct to place the Sun at the center of all planetary motion, the model still gave inaccurate predictions for planetary positions. Explain the flaw in the Copernican model that hindered its accuracy.
Copernicus assumed all motion must be uniform circular motion. Because planets orbit the Sun in elliptical paths with varying speeds, there is no way to reproduce that motion faithfully with the planets in circular motion at constant speed around the Sun.
How did Aristotle deduce that the Sun is farther away from Earth than the Moon?
During a Solar Eclipse, the Moon passes in front of the Sun and it was not the opposite of that.This made Aristotle deduce that the Sun is farther away from Earth than the Moon.
Explain, according to both geocentric and heliocentric cosmologies, why we see retrograde motion of the planets.
Geocentric model: Mars orbits outside of the Sun on its deferent path while moving in a circular motion on its epicycle. If the planet moves faster backward on the epicycle, it moves forward on the deferent making it appear to move in a retrograde manner. Heliocentric model: Mars moves slower than Earth. When Earth passes Mars, Mars seems to look like it's going backwards.
If you were to drive to some city south of your current location, how would the altitude of the celestial pole in the sky change?
If you are in the Northern Hemisphere, the north celestial pole should be lower in altitude. In the Southern Hemisphere, the south celestial pole should be higher in altitude.
Make a list of each main phase of the Moon, describing roughly when the Moon rises and sets for each phase. During which phase can you see the Moon in the middle of the morning? In the middle of the afternoon?
New moon rises at sunrise and sets at sunset. Waxing crescent rises mid-morning and sets between sunset and midnight. First quarter rises at noon and sets at midnight. Waxing gibbous rises mid-afternoon and sets between midnight and sunrise. Full moon rises at sunset and sets at sunrise. Waning gibbous rises between sunset and midnight and sets midmorning. Third quarter rises at midnight and sets at noon. Waning crescent rises between midnight.
Is the ecliptic the same thing as the celestial equator? Explain.
No. Ecliptic is the Sun's apparent annual path in the sky and the celestial equator is the projection of Earth's equator onto the sky
Suppose you lived in the crater Copernicus on the side of the Moon facing Earth. How often would the Sun rise? How often would Earth set? During what fraction of the time would you be able to see the stars?
On moon, as it orbits the Earth, it takes 29 and a half days to complete one cycle of sunrise and sunset. So, the would rise once in 29 and a half day. The moon orbits the Earth in such a way that the its same side faces the Earth always which concludes that the Earth is overhead every time resulting in no Earth rise or Earth set on Moon. Due to the thin atmosphere, it can't impart any specific color to the sky on the moon as a result of which the moon's sky is always black and hence, stars can be seen every time.
Why do you think so many people still believe in astrology and spend money on it? What psychological needs does such a belief system satisfy?
One concept is that people are comforted by the idea of a higher power controlling some aspects of their lives or fate so they don't have to take full responsibility. Also, such a "cosmic" system can give meaning to everyday triumphs and challenges; it can explain events in life that people find confusing, unfair, or difficult.
Describe what an observer at the crater Copernicus would see while the Moon is eclipsed on Earth. What would the same observer see during what would be a total solar eclipse as viewed from Earth?
The lunar eclipse will be seen by the person as the solar eclipse. If there is a total solar eclipse on the Earth, then the person on the moon would observe a full face of the Sun as the moon will be in the middle of the Earth and the Sun.
Parallaxes of stars were not observed by ancient astronomers. How can this fact be reconciled with the heliocentric hypothesis?
The parallax is the shift of an object in the sky when seen from two separated vantage points. It depends inversely on the distance to the object. Stars are so far away, compared to the size of Earth's orbit, that their parallax angle could not be measured to the necessary precision attainable at the time.
Explain three lines of evidence that indicate that the seasons in North America are not caused by the changing Earth-Sun distance as a result of Earth's elliptical orbit around the Sun.
The seasons in North America are not caused by the changing Earth-Sun distance as a result of Earth's elliptical orbit around the sun because although the Earth's orbit around the sun is an eclipse its distance from the sun varies by only about 3%, which is not enough to cause significant variations in the sun's hearting. Furthermore, Earth is actually closest to the sun in January, when it is the coolest. Finally, if the distance were the governing factor, the two hemisphere would not have opposite seasons as they do.
Why don't lunar eclipses happen during every full moon?
They do not happen every month because the Earth's orbit around the sun is not in the same plane as the Moon's orbit around the Earth.
Describe a practical way to determine in which constellation the Sun is found at any time of the year.
Use a star chart to determine which zodiacal constellation rises at sunset (or, if it is easier, which zodiacal constellation crosses the meridian near midnight). Then, the constellation on the opposite side of the sky (with dates 6 months different from the constellation you observed) is likely the constellation in which the Sun will be found.