Science Solar System Quiz

Kepler's 1st law

"Law of ellipses" states that planets orbit the sun in an elliptical fashion

Kepler's 2nd law

"Law of equal areas" an imaginary line connecting a planet to the sun sweeps through equal areas in equal time

Kepler's 3rd law

"Law of periods" states that the planet's period of revolution is proportional to its average distance from the sun

Ave. distance^3 = period of revolution^2

Newton's 1st Law of Motion

"law of inertia" An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.

Newton's Second Law of Motion

"Law of momentum" the acceleration of an object by an unbalanced force is directly proportional to the magnitude of the force and inversely proportional to the mass

Newton's Third Law of motion

For every action there is an equal in magnitude and opposite in direction reaction

Acceleration =

force (net)

------------

mass

Ellipse

A elongated circle, or oval shape, the shape of the planets orbit.

Focus (foci)

One of two special points within an ellipse that lie along the major axis

Major Axis

the longer axis of an ellipse, passing through its foci.

Circle

all points lie at equal distance from the center

Eccentricity

number between 0 and 1 that describes how out of round an ellipse is. 0=circle

Perihelion

the point in the orbit of a planet at which it is closest to the sun.

Aphelion

point in a planet's orbit that is farthest from the sun

Eccentricity =

distance between foci (cm)

---

Length of major axis (cm)

Newton's Universal Law of Gravitation

Mass1*Mass2

Force = G ———————- r=distance between objects

r^2

2 ways that the gravitational force between 2 objects could be increased

1. Increase mass of the object

2. Decrease the distance between the objects

True or False: the object with a larger mass pulls on the object with a smaller mass with a greater force.

FALSE

Gravity is . . .

a force of attraction between 2 objects

Prograde Motion

The eastward (normal) revolution of a planet with respect to the background stars as viewed from Earth

Retrograde motion

the apparent westward motion of the planets with respect to the stars as viewed from Earth

What was the geocentric explanation for retrograde motion

the planets had 2 different orbits

Why does the moon appear bright

it is reflecting light from the sun

How do stars appear to move when you look west

they move down below the horizon

How do stars appear to move when you look east

they rise above the horizon

How do stars appear to move when you look north

The stars move counter-clockwise in a circle

Which star never appears to move

The north star (Polaris)

What did Aristotle contribute to the understanding of the solar system

He believed in a spherical Earth

What did Ptolemy wrongfully contribute in his understanding of the Solar System

He added epicycles to explain retrograde motion

What did Copernicus contribute to the understanding of the solar system

He believed that the sun was at the center of the Solar system and that planets orbit at different velocities

What did Galileo contribute to the understanding of the solar system

He believed that nothing in the universe was a perfect body, he observed the moon, the sun, and other planets, he discovered that other planets have moons

What did Kepler contribute to the understanding of the solar system

He discovered that the planets traveled in elliptical orbits and that planets had changes in velocity during their orbits (didn't know why)

Why do planets have changes in velocity?

As the planet gets closer to the sun, it gets faster because there is more gravity from the sun acting upon it. The planet is fastest at Perihelion. As the planet gets further from the sun, it gets slower because there is less gravity from the sun acting upon it. The planet is slowest at aphelion.

Rotation

Spinning, determines the length of the planet's day

Revolution

Orbiting, determines the length of the planet's year

What is the barycenter?

The common center of mass between two objects

What phase must the moon be in for a solar eclipse to occur?

New

What phase must the moon be in for a lunar eclipse to occur?

Full

what is the umbra?

The band where the sun is totally eclipsed.

what is the penumbra?

The band where the sun is partially eclipsed

What is precession?

The circling of Earth's axis

Brahe

best naked eye astronomer of his day, made very good observations of planetary movement over 20 years, Kepler used his data to make his laws