Beginnings Of The Universe, Earth and Life

Question 1

Galaxies

Answer 1

Accumulations of debris from the Big Bang

Question 2

Big Bang theory

Answer 2

Theory suggesting that all matter originated as a dense, hot, supermassive ball with extremely high temperature and pressure conditions that underwent a cataclysmic explosion. Occurred about 13.7bn yrs ago and created the raw materials in the universe to produce galaxies.

Question 3

Stars

Answer 3

Result from accumulation of gaseous masses that collapsed in on themselves, resulting in internal temperatures and pressures extreme enough to set off fusion reactions, burning hydrogen to produce helium. Stars give rise to heavier elements by successive expansions and contractions.

Question 4

Nebular hypothesis

Answer 4

Solar system (sun and nine planets) most likely formed from huge cloud of gas and space dust called a nebula. Nebular matter contracted to form from sun and the planets were formed from eddies of material that remained. The sun, composed of hydrogen and helium, was massive enough and concentrated enough to emit lots of energy. Sun also emitted ionized particles that swept away any nebular gas that remained from the formation of the planets and their satellites.

Question 5

Protoearth

Answer 5

More massive and larger than earth today, was molten and homogenous. Initial atmosphere composed of mostly of hydrogen and helium was later driven off into space by intense solar radiation.

Question 6

Density stratification

Answer 6

Protoearth began period of rearrangement, forming a layered structure of core, mantle and crust

Question 7

Outgassing

Answer 7

During period of density stratification, lowest-density material contained within earth was composed of various gases. These gases rose to surface and were expelled to form earths early atmosphere.

Question 8

Milky Way

Answer 8

Our galaxy which is composed of numerous starts and is one of countless galaxies in universe