Earth in Space Flashcards
Apparent Motion
The motion that appears to be happening based on what we’re seeing with our eyes. This motion is not necessarily real. Optical illusion.
For example, when you’re in a car driving past trees, they seem to be moving past the window, but in reality, they’re completely stationary.
Model
A program, image, or data set used to explain a system or predict the habits of a system.
Actual Motion
The realistic motion of an object, regardless of what it appears to be.
For example, when you’re in a car moving past trees, the trees APPEAR to be moving, but the ACTUAL motion is that of the car speeding past the trees.
Geocentric Model
The model used anciently to describe our solar system. This model puts Earth at the center of our solar system and the sun, planets, and stars as objects circling around it.
Heliocentric Model
The model that replaced the geocentric model. This model places the Sun at the center of the solar system, with the planets moving around it.
This model also accounts for the movement of stars; later it was added that stars we could see were in other solar systems and did not revolve around our own sun. But this model can account for that.
True or False: Gravity exists between all objects in the universe.
True
What are the two factors that determine how strong the gravitational pull is between two objects?
- Mass
- Distance between the centers of the two things
How old is the earth?
4.543 billion years
How old is the Milky Way galaxy?
13.61 billion years
How old is the universe thought to be?
13.7 billion years
True or False: Gravity is a pushing force.
False
It is an attractive force
How many galaxies are typically in a “local group”?
Several dozen at most
What holds all the stars, solar systems, and galaxies together in the universe?
Gravity
What is a requirement of gravity?
The objects involved MUST have MASS. Gravity is influenced primarily by MASS.
Distance only affects the strength of the gravity, it does not determine whether gravity exists.
What is the Local Group?
The group of galaxies that includes the Milky Way.
What is a Galaxy Group?
A group of galaxies, typically composed of a few dozen systems, not more than 100.
What is a Galaxy Cluster?
A larger group of galaxies than a galaxy group, containing a large number of galaxies, between 100 and 1000.
What is a galaxy?
A huge collection of gas, dust, and billions of stars and their systems all held together by gravity.
What is gravity?
The attractive force that holds all things in the universe together. One of the most powerful forces in the natural world.
What is the order of planets in our solar system, beginning closest to the sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What causes planets to form?
Gravity pulling dust and gas together in the universe.
All the planets in our solar system were formed billions of years ago.
Where is the asteroid belt in our solar system?
Between Mars and Jupiter. It separates the small planets from the gas giants.
What are asteroids?
Rocks that orbit the sun that are smaller than planets. They are made of nickel and iron.
True or false: Asteroids are round.
False
Where is the Oort cloud located in our solar system?
Beyond Neptune, the farthest planet from our sun.
What is the Oort cloud made up of?
Comets - basically space snowballs
What are comets made of?
Ice and dust
How often does Halley’s comet pass by earth?
Roughly once every 75 years
True or False: Inner planets can also be called terrestrial planets.
True
What are the four terrestrial planets?
Mercury, Venus, Earth, and Mars
What characteristics are used to define the terrestrial planets?
- Rocky, solid surfaces
- Thin atmospheres
- Few, or no moons
- No rings
True or False: Our solar system is flat
TRUE!
That’s crazy. Gravity collapsed our nebula into a disc when the solar system was being formed.
What is a nebula?
A big cloud of gas and dust in space.
How was our solar system formed?
Gravity pulled everything in our nebula towards the center, creating a star and flattening the solar system. The rest of the gas and dust was pulled together into planets, moons, and asteroids. And now gravity holds it all together.
What is the smallest planet in the solar system?
Mercury
True or False: Mercury has 2 moons.
False - it has no moons
Which planet is closest to earth?
Venus
How many moons does Venus have?
None
What is the hottest planet in the solar system?
Venus
Which planet is closest in size to the earth?
Venus
Why is Venus’ atmosphere unbreathable to humans?
Because the atmosphere is a mixture of Carbon Dioxide and Sulfuric acid
How many moons does Mars have?
Two
What is the atmosphere of Mars composed of?
Carbon dioxide, but the atmosphere is thinner than earth’s.
Why haven’t we sent rovers to Venus’ surface?
Because of the crushing air pressure and intense heat. We actually HAVE sent rovers, but nothing survives more than a few hours.
What does it mean to be an outer planet?
To be on the opposite of the asteroid belt as earth, farthest away from the sun.
Which four planets are the outer planets?
Jupiter, Saturn, Uranus, Neptune
What are the outer planets made out of?
Gases and liquids
Why do the outer planets all have many moons?
Because they have more mass than the inner planets, so they were able to capture more solid objects in their gravitational fields.
True or False: The outer planets are colder than the terrestrial planets.
True
What is the atmosphere of Jupiter?
Helium and Hydrogen
How many moons does Jupiter have?
Between 50-100.
Accounts vary due to the presence of asteroids as well.
Which of Jupiter’s moons is the biggest, and how big is it?
Ganymede - has about the same volume of Mercury!
True or False: A day on Jupiter is longer than a day on earth because the planet rotates on its axis much quicker
FALSE
A day is much shorter, about 10 hours, because of the faster rotation.
What are gas giants?
Planets that are composed mostly of helium and hydrogen with no solid surfaces at all.
Why are gas giants sometimes called failed stars?
Because they are composed of the same elements that create stars, but they did not achieve the mass required to compress the materials and begin the fusion process that creates stars.
Who was the first person to see Saturn’s rings?
Galileo
True or False: Uranus has rings similar to Saturn’s
True - although the rings are smaller than Saturn’s
Why is Uranus called the sideways planet?
Because it rotates on its side so the poles almost always point towards the Sun.
What is the windiest planet in our solar system?
Neptune
Why is Neptune the coldest planet in our solar system?
Because it’s farthest away from the Sun… duh
Who proposed the heliocentric theory of the solar system?
Nicolaus Copernicus - Polish astronomer
True or False: Both asteroids and comets orbit the sun
True
