All of Chapter 7 Flashcards
What shape is our solar system’s orbit?
Elliptical
How many stars does our solar system contain?
100-400 billion stars
What is an astronomical unit (AU)
The average distance between the sun and the earth
What is our nearest star named? How far away is it?
Proxima Centari, 4.3 light years away
What is a light year?
The distance light travels in a year
What is the Nebular Hypothesis?
The theory that the solar system was developed from a primeval nebula
What is Geocentric?
The idea that earth is the center of the universe
Who had a working model with the EARTH as the center of the solar system?
Ptolemy (Ideas commonly accepted for 1500 years)
Why did Ptolemy’s idea’s survive?
The theory fit the observations of the day
What is Heliocentric?
The idea that the sun is the center of our solar system
Who was first to propose the SUN centered model?
Copernicus
What was Galileo’s 2 greatest contributions?
1) The improved telescope
2) The new observation/evidence that the earth is not the center of the universe
Who was Kepler and what was his contribution to the idea of our solar system?
He was a mathematician that correctly described how planets move around the sun
What were the 3 laws Kepler discovered?
1) Planets do not move in perfect circles
2) When an object is closer to the sun it moves faster
3) Third law is used to determine distance planets are away from the sun.
What are 2 reasons why the ideas of our solar system changed?
1) Technology improved
2) Better observations led to better understanding
When did our planetary system form?
4.6 billion years ago
What is a planetary system?
Any star system that includes planets is called a planetary system
According to the nebular hypothesis how was our solar system formed?
A swirling mass of gas and dust that condensed, 4.6 billion years ago sun ignited
What is mass?
Amount of stuff in an object (does not change form place to place)
What is weight?
The pull of gravity on an object (changes from place to place)
What is volume?
Amount of space an object takes up
What is density?
Mass divided by volume
What is Accretion (the play-dough effect)?
The gradual build up of gasses or particles to make something larger (Its how the planets were formed)
Why did heavier/denser materials form nearer to the sun?
Gravity pulled denser materials toward sun.
What are planetismals?
Smaller than a normal planet w/no rotation
What planets have moons?
Outer planets have moons while inner planets do not
When did Theia crash into earth?
4.5 billion years ago
What are 3 results of Theia?
1) Earth’s rotation
2) Earth’s tilted axis
3) Moon formed from debris
What is evidence to support Theia?
They have found rocks on the moon that are the same age and type as some on earth
How do we know the age of the solar system?
Age of meteorites
Oldest rocks on earth?
3.9 billion years old
Oldest rocks on moon?
4.4 billion years old?
Oldest meteorites?
4.6 billion years old
What does radioactive decay/radiometric dating do?
Give the precise age of the sample
What is a dwarf planet?
An object that has not gravitationally “cleared out orbital neighborhood
What are dwarf planets made of?
Ice or rock
What are the 3 necessary ingredients for life?
1) Liquid water
2) Source of energy
3) Moderate temperature
Where did water come from?
Volcanoes and meteorites
List 8 planets in our solar system order
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
