How Does Earth Orbit the Sun?

​How Does Earth Orbit the Sun?

​

​by Michael J. cummings

​Every planet is drawn toward the Sun by gravity!

​So, what exactly is Gravity?

​Gravity is the force of attraction, or pull, between any two objects. So, everything has an attraction

to all other objects around them.​

Multiple Choice

The force of attraction, or pull, between

any two objects is known as;

• inertia

• centrifigal

  force

• gravitational

  force

• centripital

  force

​Gravity is affected by two things in nature!

One is the size, or mass, of the objects, the larger the

object the stronger the gravitational pull. The second is the distance between objects, the farther the objects are away the less gravitational force there is.​

Multiple Select

What are the two factors that

affect gravitational pull?

• size, or

  mass of

  the objects

• what the

  object is

  made of

• the shape

  of the

  object

• distance

  between

  objects

​If we compare the gravity of the Moon with that of the Earth we can see a difference.

​Earth is 6 times larger than the Moon. This means that your weight on Earth is 6 times that of the Moon! So, if you weighed 60 pounds on Earth you would weigh only

10 pounds on the Moon.​

Multiple Choice

What is the size of the Earth

compared to Moon?

• 4 times

  larger

• 1/5th as

  large

• 9 times

  larger

• 6 times

  larger

Multiple Choice

If you weighed 120 pounds on Earth,

what would you weigh on the Moon?

(think 6 times less)

• 720 pounds

• 20 pounds

• 120 pounds

• 60 pounds

​Distance is the second factor influencing gravity! This is why we become weightless in space, we are so far away from Earth that the attraction or pull between us is not there because we are to small.

​Gravity can work across great distances. The Sun's gravitational pull reaches far out beyond Pluto and out to the Oort Cloud. The distance between the Earth and the Sun is 93 million miles or what we call an Astronomical Unit.

Multiple Select

What is the distance between

the Sun and the Earth? (choose 2)

• one

  Astronomical

  Unit

• a light year

• 93 million

  miles

• a parsec

​The effect of gravity between the Sun and Pluto is less than the gravitational pull between the Sun and the Earth!

Multiple Choice

Is gravitational pull greater the closer a planet

is to the Sun or farther away

• closer

• farther

​Gravity helps keep objects like planets and moons in their orbit around planets. An orbit is the imaginary pathway an object takes as it moves around another object.

​The lines in this image are imaginary...they are NOT REAL!

Multiple Choice

What do we call the imaginary path that

objects take as they move around

another object on?

• revolutions

• orbits

• rotations

• lines

​If gravity is pulling us into the Sun, then why aren't we getting closer?

​There are other properties that all objects have. One of those is inertia. Inertia is the tendency for a moving object to keep moving in a straight line.

​You see inertia wants to pull Earth and other objects away from the Sun in a straight line!

Multiple Choice

What is the property that wants to make a

moving object keep moving in a straight line?

• gravity

• centrifagal

  force

• centripetal

  force

• inertia

​The combination of gravity and inertia is what keeps objects like the Earth and the Moon in their orbital paths.

Multiple Select

The combination of these two properties/forces

are what keeps an object in orbit around another

object in space.

• an orbit

• inertia

• gravity

• astronomical

  unit

​As a result of these opposite forces, Earth is

kept in a nearly circular motion around the Sun called an ellipse.​

​Gravity is pulling us in and inertia is pulling us out. These forces balance each other out and keeps us moving around the Sun.

Multiple Choice

The shape that the Earth makes as it

moves around the Sun is known as;

• a circle

• an ellipse

• an oval

• a square

​Earth orbits the Sun in an elliptical motion! At perihelion, we are closer to the Sun (winter) and at aphelion we are farther away (summer), this gives us a slightly oval orbit.

Multiple Choice

Which season is it for us in the northern hemisphere

when we are closer to the Sun?

• Spring

• Summer

• Autumn

  (fall)

• Winter

Multiple Choice

What would Earth do if inertia took over?

• continue

  going around

  the Sun

• go flying out

  into a straight

  line in space

• get pulled

  into the Sun