Earth and Space science Ultimate Study Guide

The Big Bang

The initial singularity from which the universe expanded, starting at time t = 0.

Cosmic Microwave Background (CMB)

Faint leftover heat from the early universe, detectable today as a low temperature of about 2.73 K.

Hubble's Law

The observation that galaxies farther away are moving away faster, described by the equation v = H_0 × d.

Stellar Nebula

A giant, cold cloud of gas and dust that collapses under its own gravity to form stars.

Hydrostatic Equilibrium

The balance between the inward pull of gravity and the outward push of heat and radiation in a star.

Main Sequence Star

A stable star that has achieved hydrostatic equilibrium and fuses hydrogen into helium.

Supernova Explosion

A massive explosion resulting from the collapse of a massive star's core once fusion stops, leading to the formation of neutron stars or black holes.

Redshift

The phenomenon where light from distant galaxies is shifted towards longer wavelengths due to the expansion of the universe.

Iron Wall

The point beyond which fusion of iron does not release energy, causing a star to collapse.

Hertzsprung-Russell (H-R) Diagram

A graph that plots stars based on their luminosity and surface temperature, used to classify stellar evolution stages.

Big Bang Nucleosynthesis

The process during the first few minutes of the universe where hydrogen and helium were formed from fusion.

Protostar

An early stage in star formation where gas clumps together and the core heats up before reaching hydrostatic equilibrium.

Massive Stars

Stars that have more than 8 times the mass of the Sun, which burn fuel quickly and end their lives in supernovae.

Planetary Nebula

The outer layers of an average star expelled into space, forming a glowing shell of gas.

White Dwarf

The dense, hot core that remains after an average star sheds its outer layers.

Neutron Star

The ultra-dense remnant of a supernova explosion, made almost entirely of neutrons.

Light Element Formation

The process by which light elements, primarily hydrogen and helium, formed during the early cooling of the universe.