| A | B |
|---|
| Accretion | Coming together of smaller pieces of matter to form larger ones |
| Planetesimal | When large amounts of dust and pebbles clumped/fused/joined together into larger objects called PLANETESIMALS |
| Protoplanet | Objects that are even larger than planetesimals that are formed by the joining of super big planetesimals (the gravitational attraction of these big planetesimals cause them to collide (during which many are destroyed but many also join together to form super big planetesimals)= The resulting gravitational of these planetesimals cause them too to merge together to form protoplanets) |
| Protoplanetary Disks | (a.k.a. Proplyds) Disks of gas and dust (that seem similar to our solar system before planets formed) which surround other young stars= These systems are undergoing evolution (just like our solar system did) |
| Protosun | Deep inside the solar nebula (=the cloud fragment from which the solar system was formed), which consists of ice and dust, the gravitational attraction begins to pull the dust/ice inward towards its center= The resulting density and pressure of at the center began to increase and caused a concentration of matter called the protosun= (In short, it is a star that is still forming during the early stages of a solar system) |
| Solar Nebula | The cloud fragment from which the solar system formed= Was initially very cold inside the solar nebula and consisted of ice and ice-coated dust grains composed of heavy elements (that were scattered across its LARGE volume) |
