Chapter 4 Flashcards
The diagram below shows a view of the eastern horizon (horizontal line ——–) with the direct eastern horizon point labeled B. The direction to points northeast of the direct east point is labeled with an A and an arrow. The point southeast of the direct east point is labeled with a C and an arrow.
A B C
——————EAST——————
For a mid-latitude northern hemisphere observer, what point corresponds to the rising point of the sun on the date of the vernal equinox?
B
The diagram below shows a view of the eastern horizon (horizontal line ——–) with the direct eastern horizon point labeled B. The direction to points northeast of the direct east point is labeled with an A and an arrow. The point southeast of the direct east point is labeled with a C and an arrow.
A B C
——————EAST——————
For a mid-latitude northern hemisphere observer, what point corresponds to the rising point of the sun on the date of the autumnal equinox?
B
If you lived on Mars, which planets would exhibit retrograde motion?
All of these choices are correct.
If you lived on Mars, which planet would be visible as a crescent phase?
Venus
Galileo’s telescope showed him that Venus has a large angular diameter of 61 seconds of arc when it is a crescent; a small angular diameter of 10 seconds of arc when it is nearly full and, finally, when Venus is “half full,” an angular size of 59 seconds of arc. At which point described below is Venus closest to the Earth?
a large angular diameter of 61 seconds of arc when it is a crescent
Galileo’s telescope showed him that Venus has a large angular diameter (61 seconds of arc) when it is a crescent and a small angular diameter (10 seconds of arc) when it is nearly full. When Venus is “half full,” its angular size is about 59 seconds of arc.
This sequence of phases and angular sizes indicates that Venus:
circles the sun.
Why is Stonehenge thought to be an ancient astronomical observatory?
Stones are aligned with significant rising and setting positions.
Plato proposed that all heavenly motion is which of the following?
both circular and uniform
How did Claudius Ptolemy account for the retrograde motion of the planets?
Each planet moves on an epicycle that in turn moves on a deferent that circles around Earth.
Who accurately determined the size of Earth by considering sun angles at Syene and Alexandria?
Eratosthenes (c. 200 BC)
One of the first principles of ancient astronomy is that the heavens beyond _____ are perfect, and the Earth is corrupt.
the moon
Who taught that the Earth is stationary and at the center of the universe with the sun, the moon, and the planets moving around Earth in perfect circles?
Aristotle (384-322 BC)
How did Nicolaus Copernicus account for the retrograde motion of the planets?
Inner planets orbit the sun faster and pass outer planets as they orbit around the sun.
What feature of Aristotle’s model of the universe was included in the model proposed by Copernicus?
uniform circular motion
Why did the model of the universe proposed by Copernicus gain support soon after its publication?
It was a more elegant explanation of retrograde motion.
When Tycho observed the new star of 1572, he could detect no parallax. Why did that result undermine belief in the Ptolemaic system?
This star is farther away than the moon and thus the heavens are not perfect and unchanging.
What was the most important contribution of Tycho Brahe to modern astronomy?
twenty years of accurate measurements of planetary positions
How was Tycho Brahe able to make more accurate astronomical measurements than had been made before his time?
He designed and used large devices to measure small angles.
How did Kepler’s first law of planetary motion alter the Copernican system?
It changed the perfect circles to ellipses and it placed the sun at one focus of each orbit.
Which of the “First Principles of Ancient Astronomy” did Kepler’s laws contradict?
Earth is at the center of the universe and all heavenly motion is uniform and circular.
What does Kepler’s second law indicate about the orbital speed of a planet?
A planet moves at its fastest when it is closest to the sun.
Galileo’s discovery of four moons orbiting Jupiter showed that planetary bodies could move and carry moons. This supports the model of the universe presented by whom of the following?
Nicolaus Copernicus
What phases of Venus are predicted by the Ptolemaic system?
new and crescent phases only
What phases of Venus were observed by Galileo?
new, crescent, quarter, gibbous, and full phases
