Science Quiz 2

What does Orbit mean?

The curved path an object follows as it moves around a larger object.

Orbital path are typically not a perfect _____. Instead we describe the orbits as elliptical.

circle

Ellipse - It has 2 centers called _____

foci

One of the foci is a celestial object, like a star, the other foci isn’t _______ but mathematical. Each of the foci is equidistant to the center of the orbital path.

physical

For our solar system one of the foci is the _____ for any celestial object.

Sun

A line drawn from one side of the ellipse to the other, through the two foci at the widest part of the ellipse is called the ______ axis

major

The eccentricity of an ellipse is calculated by dividing the distance bewtween ____ by the _____ of the major axis.

foci; length

When you calculate the eccentricity you’ll get a _______ 

decimal

The closer to zero, the ___ eccentric the ellipse

less

The closer to one, the ___ eccentric the ellipse

more

The number will never get to ____ or _____

zero; one

How do satellites stay in orbit?

Balance between gravity and inertia.

Gravity pulling towards the central body and inertia keeping them in _____ around the body

motion

How many laws of Kepler are there.

3

What is Kepler’s 1st law?

The planets revolve in elliptical orbits with the sun at one focus.

Since the orbit is slightly eccentric, there are times when a ______ is closer to the central body and times when it is further from the ___________

satellite; central body

What is Periapsis?

The point of the orbit when the satellite is closer to the central body. (perihelion)

What is Apoapsis?

The point when the satellite is further from the body. (aphelion)

What is Apparent Diameter?

1. The closer an object is, the faster it appears to be.

2. Further objects appear smaller.

What is Kepler’s 2nd law?

Planets sweep out equal areas in equal period of time.

Planets sweep out equal areas in equal period of time because when the planet is closer to the Sun, it _____ up, and when it is further away from the Sun it ____ down.

speeds; slows

What is Kepler’s 3rd law?

Planets that are farther from the sun have a longer orbital path than a closer planet and it travels slower, since the Sun’s gravitational pull on it is less.

The _____ planets take longer to revolve around the Sun.

jovian

The force of gravity depends on the _____ of the objects and the ______ between them.

mass; distance

The larger the mass of the objects, the ______ the force of gravity

greater

The closer the objects are, the ________ the force of gravity

greater

Therefore, as a planet moves closer to the Sun, the force of gravity ______ and their orbital velocity _______.

increases; increases

What is the Gravitational force formula?

F= Gm₁m₂/r²

What does F mean in gravity?

The force of gravity between two objects (in Newtons)

What does G mean in gravity?

Universal gravitational constant

What does m₁m₂ mean in gravity?

masses of the objects in kg

What does r mean in gravity?

the distance between the two objects in meters

How is distance related to the force of gravity?

Inversely

How does the force of gravity change when the distance of two objects is doubled?

It decreases/ ¼ the force of gravity

What is the specific shape of a planet’s orbit?

Ellipse

Where is the central body (the sun) located within an ellipse?

It is located near the side of one of the foci

What does the term eccentricity measure?

It measures how stretched out the ellipse is compared to a perfect circle.

According to Kepler’s second law (Law of Areas), how does a planet’s speed change during its orbit?

It changes during its orbit because if it is further from the sun, it has a longer period and there is less gravity pulling the planet.

What force causes the satellite to travel fastest when it is closest to the central body?

Gravity

What are the two main factors that determine the strength of the gravitational force between any two objects?

the masses of the objects and the distance between them

How does increasing the distance between two objects affect the gravitational force between them?

Increasing the distance makes the object slower

If the Sun’s mass were to suddenly double, how would the gravitational force on Earth be affected?

Earth would spin faster and days and years would go faster.

What is the relationship between the eccentricity of a celestial object and its percent increase in orbital velocity?

The larger the percentage increase, the larger the eccentricity.

What is a constellation?

A grouping of stars that form a picture or pattern

What does the word planets mean?

Wanderer, because they appear to “wander” when compared to the stars which appear in the same place relative to each other.

Over long periods of time outer planets (compared to Earth) appear to move _______ (west to east) against the background of the stars over a period of weeks.

backwards

What is retrograde motion?

When the outer planets (compared to earth) appear to move backwards.

Earth overtakes slow outer planets so the outer planet so the outer planet ______ to slow down, move in reverse, and then move forward again with respect to the fixed stars.

appears

What is a moon?

A satellite of Earth. It influences the tides and eclipses observed on Earth.

What is the Moon’s period of revolution and rotation?

27.3 days

Why do we only see one side of the moon?

Because the period or rotation and revolution are the same.

The apparent diameter (apparent size) of the moon changes because the moon follows an _______ orbit around Earth.

Elliptical

What is the Moon’s average distance from Earth?

0.385 million km

The moon’s orbit around Earth causes the Moon phases we observe on Earth. It depends on how much of the __________ side of the Moon faces _____.

Illuminated; Earth

The diagram below shows the Moon’s orbit around the Earth. Half the _____ is always illuminated. The orbital path is labeled with the angle between the Earth, Moon, and ______. A picture of each phase, as observed from Earth, is shown next to the orbital positions of the Moon. On the lines provided, label the observed phase at each of the positions of the moon. On the lines provided, label the observed phase at each of the positions of the Moon shown.

Moon; Sunlight

Venus orbits the Sun, circling ______ Earth’s orbit in about 225 Earth days. This means that Venus is sometimes _____ Earth, while at other times it is positioned on the other side of the _____. It is this change in relative positions of Venus that causes an observer on Earth to see phases of Venus

Inside; closer to; Sun

Tides