Planets / Solar system
We can classify the objects of the solar system into 9 categories
1) The Sun, average star 2 1030 kg. The mass of the Sun is 99% of all the mass of the solar system and produce most of its energy.
The inner " terrestrial planets" or rocky planets (silicon, iron). They
all have a thin layer of ice (could be water, methane or ammonia)
The ice can me melted or in a gaseous form. They are 10-7 to 10-4 the mass of the Sun.
mercury = rocky planet, looks like the moon with many craters. It is not true that Mercury always show the same face to the Sun
more on moon and mercury
Venus = extremely hot. example of run away global warming. rain of sulfuric acid. Some devices were dropped to take photos.
Earth-Moon = The Moon is huge
Mars= has ice caps, dust storms (people thought these changing storms were forests). Some features seem to show that running water
was present on this planet. Scientists thought given the pressure and temperature, water can not be at the liquid state.
The water can only goes from the solid state to the gaseous state. (like CO2 on Earth = dry ice)
However, the questions remains open after they found a new deposit on Mars not seen before. (see here more info)
more on Venus and Mars
website to learn more
3) the asteroid belt. The asteroids are irregular and small rocks.
chunks of rocks. Most of them are between Mars and Jupiter. Some have been bumped into other orbits.
4) outer " jovian" planets/ Made of gas(He /H) and ice (ammonia, methane or water) . 10-4 to 10-3 the mass of the Earth.
The orbits are circular and in in a plane. Have many moons and they have rings.
2 satellites voyager 1 and voyager 2 reached the outer planets and took photos of them.
They used the gravity of the planets to swing around.
Jupiter = very massive. It is the main cause of the Sun motion. Elaborate weather. The red spot is a hurricane . has been
there for the last 350 years. See this movie recorded by voyager 1. The 4 largest moons are called Galilean moons:
Io (volcanic, spew out sulfur), Europa,Gallimede, Callisto.
Voyager 1 discovered the rings of Jupiter.
more on Jupiter and Saturn
Uranus: rotates sideway . has rings and moon. Miranda is a moon that blew apart but fell back together.
Neptune: has a weather too. mystery since not much energy is available. Triton is a large moon and has weather too.
more on Uranus and Neptune
5) Kuiper belt objects = dwarf planets including Pluto. probably rocky. Less then 10-7 the mass of the Sun.
and its Moon Charon (about same ration than EArth-Moon). Plus other
dwarf planets recently discovered. Eris is larger than Pluto.
These objects are called Largest Known transNeptunian objects or TNOs
Recently they were able to plot the orbit of ERis and compute the angular distance with its moon.
The orbit of Pluto is elliptical and tilted.
6) Oort cloud = comets = ball of ice.
After collisions comet can be kicked out of its orbit and fall on a planet like the shoemaker Levy comet. (1994)
Then the solar system ends with the influence of the Sun
see image below for scales: