Astronomy- The Copernican Revolution

Earth- Bottom
Water- Above Earth
Air- Above Water
Fire- Upward

Aristotle described gravity as 4 elements: list them in order of how they each took their own place.

Aristotle.

Who mistakenly proposed the Earth was in the center of the universe?

Geocentric Model

An earth-centered model of the universe.

Retrograde Motion

The apparent backward motion of the planets against the background stars.

Ptolemy

What astronomer further promoted the geocentric model of the universe despite the problem of retrograde motion?

Epicycle

A loop in a planet's orbit used to explain retrograde motion in ancient times.

Copernicus

What astronomer was the first person to propose that the Sun was in the center of the solar system?

Heliocentric Model of the Universe

Model based on the idea that the sun is the center of the universe.
- Moon only orbits around Earth; planets orbit around the Sun.
- Retrograde motion is actually when the Earth passes up an outer planet.

The Earth passing up the outer planets (Retrograde motion).

What really causes planets to appear to move backwards in the sky?

Galileo.

What astronomer continued to promote the heliocentric model of the solar system and is most famous for building the telescope?

- Many more stars than ever imagined.
- Sunspots on the Sun.
- Mountains and craters on the moon.
- Four moons of Jupiter.
- Rings of Saturn.
- Phases of Venus.

When the telescope was first used to look at the sky, what things were seen that had never been seen before?

Tycho Brahe.

Who spent more than 20 years charting planets to try to improve Copernicus's model but was never able to?

Johannes Kepler.

Who was able to take Tycho's data and develop the Three Laws of Planetary Motion?

1st Law of Planetary Motion

Each planet's orbit is an ellipse, with the Sun at one of the focuses of the ellipse of Planetary Motion.

2nd Law of Planetary Motion

An imaginary line connecting Sun and planets that sweeps out equal areas in equal times.

Closer to the Sun.

Due to the 2nd Law of Planetary Motion, we know that a planet moves faster when it's...

Farther from the Sun.

Due to the 2nd Law of Planetary Motion, we know that a planet moves slower when it's...

3rd Law of Planetary Motion

The ratio of the planet's period (P) squared to its average distance (a) to the Sun cubed is the same for each planet.

Eccentricity

The ratio of the distance between the foci to the length of the major axis; defines the shape of a planet's elliptical orbit.

0 and 1.

For eccentricity, the number is always between...

0.

For eccentricity, the more circular the ellipse the closer the number is to...

1

For eccentricity, the less the ellipse is like a circle, the closer the number is to...

Perhilion

The point in a planet's orbit closest to the Sun.

Aphelion

The point in a planet's orbit that is farthest from the Sun.

Astronomical Unit (AU)

The average distance from the Earth to the Sun, 93 million miles or 1.5x10^11m.

Mass

The amount of matter in an object; the measure of inertia.

No.

Does mass change if the object is taken into space or to the moon?

Weight

The attractive force between an object and the Earth.

Less; weightless.

The weight of an object is __________ if it is taken to the moon and is _________ if it is taken to outer space away from all other objects.

Issac Newton (1642-1727).

Who developed the three laws of motion and the Law of Universal Gravitation?

Newton's First Law

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Inertia.

What is another word for Newton's First Law?

Newton's Second Law

When a force is exerted on an object, it will accelerate in the direction of the force.

F=ma.

What formula describes Newton's Second Law?

Newton's Third Law

For every action there is an equal and opposite reaction.

The Law of Universal Gravitation

There is an attractive force between ALL objects that is proportional to the masses and inversely proportional to the square of the distance between them.

More the force.

According to the Law of Universal Gravitation, the more massive the object, the...

Lesser the force.

According to the Law of Universal Gravitation, the more distance between the masses, the...

Perigee

Closest point in a moon's elliptical orbit to its planet.

Apogee

Farthest or highest point in a moon's elliptical orbit to its planet.