Terrestrial- Mercury, Mars,Earth,Venus- formed from minerals similar to earth - silicate rocks. Metallic core, silicate mantle with a secondary atmosphere via internal vulcanism/crater impacts.
Gas Giants- Jupiter, Saturn, Uranus, Neptune- have a rocky/metallic core- majority of mass is from: hydrogen, helium with water/methane/ammonia and hydrogen compounds.
Origins- Big Bang theory- led to formation of the universe 14 billion years ago, ths was the point where all matter and energy was created. Nebula hypothesis= giant molecular cloud of gas and dust collapsed, possible by shock wave from an exploding star, eventually formed a rotating disc which dragged materials to the centre causing nuclear reactions. Forming the sun. Gradually other materials stuck by accretion, forming the larger planets.
Dating planets- Accepyed age= 4550 million years old. Using radiometric dating (decay of radioactive isotopes to determine age.) To do this we must know the half life of the isotope, rate at which it decays, and amount of isotope compared to what is incorporation into the object when its formed. Rubidum 87 decays to Strontium 87. Its a complex process so a degree of uncertainty is quoted.
Space exploration- Moon- first landing was 1969, soil/rock brought back dated…