astronomy

How did Kepler deviate from the beliefs of Aristotle and Copernicus in his first law?

Kepler's first law of planetary motion is, all planets orbit move around the sun in elliptical orbits. Aristotle believed the sun, moon, stars, and planets orbited around the Earth. Copernicus believed that the sun was motionless and that the planets orbited around the Earth, while the Earth orbited around the Sun.

How did the Copernican theory explain retrograde motion?

It explained retrograde motion in a way that Venus, Uranus, and Pluto moved around the sun in a westward (retrograde) direction.

How did Johannes Kepler and Tycho Brahe collaborate to arrive at the three laws of planetary motion?

Kepler defined the orbit of Mars for Brahe. Brahe had also collected a lifetime of astronomical observations, which were passed to Kepler after his death

Compare Tycho Brahe's model of the solar system to that of Ptolemy's?

Tycho's model of the solar system has only the Earth orbiting around the sun, while all the other planets orbited around the Earth. Ptolemy's model has all of the planets, including the sun, orbiting around the Earth.

How did the Ptolemaic model of the universe explain retrograde motion?

While the Moon and the planets have their own motions, they also appear to revolve around Earth about once per day.

Explain what an astronomical unit (A.U.) is and why it is practical for measuring in Astronomy.

a unit of length effectively equal to the average, or mean, distance between Earth and the Sun, defined as 149,597,870.7 km (92,955,807.3 miles).

Why was Aristarchus of Samos' model not accepted at the time he proposed it?

Aristarchus of Samos proposed the heliocentric model in 200 Bc. It was not accepted at that time because people believed in the geocentric model and believed that the earth was the center of the universe.

How were Aristotle's predictions of heavenly motion qualitative rather than quantitative?

Aristotle's predictions were qualitative because it did not have any quantitative predictions of motion, e.g where and when to find planets.

What three incorrect ideas held back the development of modern astronomy from the time of Aristotle until the 16th century?

Earth was the center of the Universe Uniform circular motion exist in the heavens objects in the heavens were made from a perfect, unchanging substance not found on the Earth (ether), heavens don't change

Describe Aristotle's model of the heavens?

Ether was the fifth element and perfect, allowed planets to move Planets moved and were carried on spheres like mechanical clock mechanism Earth resided at the center (geocentric) Outermost sphere was the "prime mover" Moon, Sun, Planets carried on inner spheres 55 spheres in all were necessary for the giant clockwork

What did Tycho Brahe see in the sky that convinced him that the heavenly firmament was not as unchanging/perfect as previously believed?

He saw a supernova comet.

Where is the Earth in its orbit when it is traveling the fastest?

In January, the Earth will be traveling it's fastest.

How would you demonstrate parallax with your own eyes?

Parallax is the shift in position of an object caused by your own motion. If you look at an object and cover first one eye then the other, the object will appear to be changing position.

What does Kepler's second law imply about the speed of a planet around the sun?

Planets further from the sun orbit at a slower speed than planets closer to the sun.

Explain in your words the two ways that Galileo demonstrated that sunspots (dark spots) were on the sun as opposed to being a planet or other object simply moving in front of it.

Sun spots move and change their shapes and originate on the sun, not planets close to the sun. The rate of motion of the sunspots was not uniform: slower near the edge of the sun and faster towards the center of the sun.

Describe what occurs during planetary retrograde motion and give an example of how this looks when we see a planet do this from Earth?

The retrograde motion is the apparent motion of a planet to move in a direction opposite to that of other bodies within its system.

How is parallax used to measure the distance to nearby stars?

The distance is measured in parsecs and the parallax angle is measured in arcseconds

Describe how Ptolemy adapted Aristotle's model of the universe into a mathematical one in the Almagest.

The epicycle is the little circle along which the planet moves, which in turn moves along the larger circle, the deferent. This deferent has its center, eccentric (X), which is a constant spot, between the equant and the earth.

Compare and contrast a heliocentric model of the solar system and a geocentric model?

The heliocentric model is sun centered and the geocentric model is earth-centered.

What causes a planet to be at a place of perihelion and then later at aphelion in its orbit?

The location and speed of the planet while in orbit.

Explain the significance of Galileo's observations of the phases of Venus.

The observation of the phases of Venus (like the moon's phases) proved that Venus moved around the sun, therefore providing proof for a sun-centered (heliocentric) universe.