What is the center of the solar system?
The sun
What percentage of the mass of the solar system is contained in the sun?
99 %
How far does the sun's influence go?
Past the orbits of the planets to the outer reaches of the universe.
Why do the planets orbit the sun in the same plane and in the same direction?
They formed from planetesimals in the rotating circumstellar gas and dust cloud.
What are terrestrials?
Inner planets.
What are terrestrials made of?
Rock and metal
What are the terrestrial planets?
Mercury, Venus, Earth and Mars
What are gas giants?
Outer planet
What are gas giants made of?
Gas, ice and dust
What are the gas giant planets?
Jupiter, Saturn, Uranus and Neptune
What are Dwarf planets?
They have gravity sufficient enough to make them round, but not sufficient to clear the orbits of other debris.
What are the dwarf planets?
Pluto, Ceres and Xena
Where do most asteroid lie?
Between Mars and Jupiter
What are astroids?
Small rocky bodies that are thought to be left over remenants of the formation of the solar system.
What sizes are asteroids?
Anywhere from less than 1km to about 1,000 km in diameter.
What are the group of asteroids that travel 60 degrees behind and 60 degrees ahead of Jupiter called?
Trojan asteroids.
What could happen if any of these asteroids are disrupted by Jupiter's gravity?
They could enter orbits that cross Earth's orbit and collide with earth.
What do scientist think happened 65 million years ago to cause the extinction of the dinosaurs?
An asteroid collided with earth.
Where do comets come from?
The Kuiper Belt and the Oort Cloud.
What causes the objects in the Kuiper Belt and Oort Cloud to enter the orbits of the planets?
Nearby stars
Where do comets travel?
From the outer to the inner solar system and back.
What is the center of a comet called?
The nucleus
What is the haze of sublimed gas around the nucleus called?
The coma
What is following behind the comet always pointing away from the sun?
The ion tail
What is in the ion tail?
Gas and dust
Why was Pluto demoted to a dwarf planet?
It is smaller than the gas giants near it, it doesn't orbit in the same plane as all the other planets, it is rocky not gasy, it's orbit comes inside Neptune's orbit, so it is not always the most distant planet and finally there are several Kuiper Belt ob
How do scientist think moons came to be?
Probably some other space object being caught in the planet's gravity.
What is a meteor?
A piece of space debri that hits the earth's atmosphere.
What is a meteorite?
A meteor that survives the earth's atmosphere and hits the surface of the earth.
When do meteor showers happen?
When the earth's orbit crosses that of a comet.