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Mr. Jackson's Chapter 4 Test
Flashcard's for Mr. Jackson's chapter 4 test.
28
Astronomy
8th Grade
10/09/2012

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Term
What is the difference between rotation and revolution of planets? Which one is responsible for days and which for years?
Definition
A revolution is how long it takes a planet to revolve around the sun and is responsible for years. A rotation is how long it takes a planet to rotate on it's axis and is responsible for days.
Term
How did gravity cause the formation of the solar system?
Definition
Accretion pulled planetesimals together to form what is now our solar system.
Term
What objects can be found in our solar system?
Definition
The Sun, planets, dwarf planets, comets, meteors, asteroids, and stars.
Term
Why do we use astronomical units instead of light years when describing distances in our solar system?
Definition
Because our solar system is too small to use light years.
Term
What are planetesimals?
Definition
Small bodies of ice and rock that come together to form planets and other things in the solar system.
Term
How old is our solar system according to scientists?
Definition
4.6 trillion years old.
Term
What is the relationship between a planet's length of year, temperature, and distance from the sun?
Definition
If the distance from the sun is greater, the colder the planet becomes, and it results in a longer orbit so the year is longer.
Term
Why are the four inner planets classified as terrestrial planets and what characteristics do they share?
Definition
The inner planets are small and dense and have rocky surfaces.
Term
Describe three unique characteristic for each of the four terrestrial planets.
Definition
Mercury is the smallest planet, is closest to the sun, and has no atmosphere. Venus is the hottest of all planets, the atmosphere traps in gas through a process called the greenhouse effect, and has a thick atmosphere. Earth has liquid water, is and oxygen rich atmosphere, and is able to support life. Mars appears reddish because of the break down of iron-rich rocks, it's atmosphere is 95% carbon dioxide, and had liquid water in the past.
Term
Why does Venus have a day longer than it's year?
Definition
Venus spins very slowly and in the opposite direction.
Term
Explain the greenhouse effect and explain why it doesn't effect Mercury.
Definition
The greenhouse effect is when an atmosphere traps in the sun's rays and it doesn't effect Mercury because Mercury doesn't have at atmosphere.
Term
What planet is believed to have had liquid water on it's surface in the past?
Definition
Mars.
Term
Why are the four outer planets classified as gas giants and what characteristics do they share?
Definition
Gas giants are large and more massive than Earth, do not have solid surfaces, and have many moons and rings.
Term
Describe three unique characteristics of the outer planets.
Definition
Jupiter is the biggest planet, has a mass of about 2.5 times that of all planets combined, and has a Great Red Spot. Saturn has a moon larger than Mercury, has very visible rings, and has many moons. Uranus' axis of rotation is tilted, going at about 90 degrees from the vertical, and viewed from Earth it rotates top to bottom. Neptune is a cold, blue planet, has visible clouds, and it is blue because of methane in the atmosphere.
Term
What are the four outer planets made out of?
Definition
Ice and rock.
Term
What are the Great Red Spot and the Great Dark Spot?
Definition
The Great Red Spot is on Jupiter and is a storm larger than Earth. The Great Blue Spot is on Neptune and is dispersed years ago.
Term
What planet's axis is tilted almost 90 degrees?
Definition
Uranus.
Term
What do we call the region between Mars and Jupiter?
Definition
The asteroid belt.
Term
Other than planets and the sun, what other objects are found in our solar system?
Definition
The major categories include dwarf planets, comets, asteroids, and meteoroids.
Term
What four ways do scientists classify the smaller objects in our solar system?
Definition
Based on their sizes, shapes, compositions, and orbits.
Term
Compare and contrast a planet and dwarf planet.
Definition
Dwarf planets orbit the sun and have enough gravity to pull themselves into spheres, but have other objects in the area of their obits. Both planets and dwarf planets can have moons.
Term
Describe the differences between a comet and an asteroid.
Definition
Comets are loose collections of ice and rocks, where as asteroids are rocky and don't have tails which comets can have.
Term
Describe a comet's orbit around the sun.
Definition
Comets orbit takes the close to the sun and then really far out again.
Term
What is the difference between a meteoroid, meteor, and a meteorite.
Definition
A meteoroid are chunks of rock or dust smaller than asteroids, and when they enter Earth's atmosphere they are then called meteors, and then once they hit Earth's surface they are called meteorites.
Term
Describe a geocentric model of the solar system. Why did ancient astronomers believe in a geocentric model?
Definition
In a geocentric model, Earth is at the center of the revolving planets and stars. Early astronomers thought this because they didn't have space shuttles or telescopes and from Earth it appears that everything in the sky is orbiting Earth, not the sun.
Term
Describe a heliocentric model of the solar system. What astronomers helped to prove this model was the correct model?
Definition
A heliocentric model is a model of the solar system where planets orbit the sun. Aristarchus, Nicolaus Copernicus, Brahe and Kepler, Galileo, and Isaac Newton helped to prove this model correct.
Term
What is an elliptical orbit and what scientists discovered this?
Definition
Brahe and Kepler discovered that planets rotated in a elliptical orbit, and orbit in an oval shape.
Term
According to Newton, what two factors work together explaining how planets and moons orbit larger bodies in space?
Definition
Newton proved that gravity and inertia worked together to explain why the plants rotate the sun and moon rotate planets.
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