General Astronomy Quiz 7 Flashcards
Is it hard to get a sense of the scale of our solar system?
Yes
What is the main star in our solar system?
The Sun (99.8% of the mass)
How many planets are in our solar system?
Eight planets (four inner/outer)
How many dwarf planets are in our solar system?
Five
What are the names of the dwarf planets?
-Ceres (formerly an asteroid)
-Pluto (formerly a plent)
-Haumea
-Makemake
-Eris
What are cosmic debris?
-Asteroids
-Comets
-Meteors
What was the FIRST definition of a planet?
A planet is a celestial body that
1. has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
2. is in orbit around a star, and is neither a star nor a satellite of a planet.
What would have been a planet based on the FIRST definition?
-The current eight
-Ceres
-Pluto
-Charon
-Eris
What is the CURRENT definition of a planet?
A planet is a celestial body that
1. is in orbit around the Sun,
2. has sufficient mass to assume hydrostatic equilibrium
3. has “cleared the neighborhood” around its orbit
Which planets fall under the CURRENT definition?
The current eight
How do the eight planets orbit?
In the same, nearly circular plane
How do dwarf planets orbit?
In tilted, elliptical orbits
What are the inner planets?
-Mercury
-Venus
-Earth
-Mars
What is another name for the inner planets?
Terrestrial planets
What type of surface do planets have?
Solid and rocky
What are the outer planets?
-Jupiter
-Saturn
-Uranus
-Neptune
What is another name for the outer planets?
Jovian or giant planets
What are the outer planets made out of?
Mostly gas and ices
How do astronomers estimate surface age?
By counting craters, the more craters means the surface has been around for longer
How do scientists estimate the age of complete objects?
Radioactive dating
What is radioactive dating?
A method of dating rocks and minerals using radioactive isotopes
What is a half-life?
The time required for half of the radioactive atoms to disintegrate
How can you tell how much time has passed for a half-life?
By comparing the fractions of the elements from half of the original sample changes
How old is Earth’s surface?
4.56 billion years old
What does the age of Earth tell us?
The formation age of the solar system
What is the solar nebula model?
The leading explanation that accounts for all the evidence we have about our solar system and observations we have of other star systems
What does the protoplanetary disk allow us to do?
Look at the formation of stars and the material that forms around those stars
What is the Sun made of?
Mostly hydrogen and helium, less than 2% of other elements
Is the extra material near the Sun solid?
No, it is not solid
Where do inner planets form?
Where temperatures are high, which leads to them not having a lot of solids to build with
What is the ice line?
The distance from a sear where water and other compounds turn into ice
Why are inner and outer planets separated?
The difference of temperature
