4. The Solar system Flashcards
Describe the main objects in our solar system
Sun Terrestrial planets Jovian planets Dwarf planets Comets Asteroids
Patterns among the planets give us insight into the general processes that govern planets: planets orbit the Sun in the same direction and in nearly the same plane. What are the exceptions to the rule?
Rotation of Venus: backwords (clockwise)
Tilt of Uranus: tilt of 97.77 degrees. Equator is nearly at right angle to its orbit
Why are there two major types of planets?
Some formed within the frost line where only metal and rock could condense (terrestrial)
Some formed beyond the frost line where cooler temperatures allowed for hydrogen compounds to condense into ice (Jovian)
Name the terrestrial planets
Mercury
Venus
Earth
Mars
Name the Jovian planets
Jupiter
Saturn
Uranus
Neptune
What are the main differences between the terrestrial planets and the
Jovian planets?
Jovian planets: larger, further from Sun, rotate faster, more moons, rings, less dense, gaseous
Terrestrial planets: closer to Sun, rotate slower, smaller, less moons, rocky surface
Where did asteroids and comets come from?
Asteroids are left over from the formation of our solar system, Comets are believed to have two sources. Long-period comets (those which take more than 200 years to complete an orbit around the Sun) originate from the Oort Cloud. Short-period comets (those which take less than 200 years to complete an orbit around the Sun) originate from the Kuiper Belt.
What are asteroids like?
Nearly all asteroids are irregularly shaped, although a few of
the largest are nearly spherical, such as Ceres. Composition:
clay, silicate rocks, nickel-iron
How are meteorites related to asteroids?
Sometimes one asteroid can smash into another. This can cause
small pieces of the asteroid to break off. Those pieces are
called meteoroids. Meteoroids can also come from comets.
Sometimes meteoroids don’t vaporize completely in the
atmosphere. In fact, sometimes they survive their trip through
Earth’s atmosphere and land on the Earth’s surface. When they
land on Earth, they are called meteorites.
What are comets like?
Comets are cosmic snowballs of frozen gases, rock, and dust
that orbit the Sun.
Is Pluto a planet?
No
What is the definition of a planet?
It must orbit a star (in our cosmic neighbourhood, the Sun).
It must be big enough to have enough gravity to force it into a
spherical shape.
It must be big enough that its gravity cleared away any other
objects of a similar size near its orbit around the Sun.
How do we use cratering to age date worlds in the Solar System?
Rate at which impacts have occurred in the solar system has been
roughly constant for several billion years. The number of craters
on a planetary surface is determined by the age of the surface and
the average crater production rate. Know one of these variables
and you can constrain the other.
What is radioactive dating and how does it tell us the age of the Solar
system?
The half-life of a radioactive element is the time it takes for half the
sample to decay; we determine how many half-lives have passed
by how much of a sample remains the radioactive element and
how much has become the decay product. In this way, we have
estimated the age of the Moon and Earth to be roughly 4.5 billion
years. If you had 1 gram of pure radioactive nuclei with a half-life
of 100 years, then after 100 years you would have 1/2 gram; after
200 years, 1/4 gram; after 300 years, only 1/8 gram; and so forth.
The only world besides the Earth that humans have visited is
Moon
Volume of a sphere =
Energy flux F =
Energy flux F =
Stefan-Boltzmann formula with luminosity (R=distance from the source)
