Key Terminology - Bigger than Big, Our Journey to Now

Year 10 Brigidine Science Topic Test Term 2

Big Bang

The origin of the universe (In the ________, the observable universe expanded rapidly from a single point)

Black hole

An object that ha gravity so strong that even light can’t escape it (__________ form in supernova explosions of stars with more than 20x the mass of the sun)

Galaxy

A group of millions or billions of stars held together by gravity (The Solar System is a part of the Milky Way _________)

Large Star

A star with more than 8x the mass of the Sun (A _________ becomes a red supergiant and explodes in a supernova, leaving behind either a black hole or a neutron star)

Light-year

A unit of length equal to the distance light travels in one year (used to measure large distances in space)

Main Sequence Star

A star that is fusing hydrogen in a stable state (___________ are stable because the outward force of fusion is balanced by the inward force of gravity)

Moon

A natural satellite that orbits a planet

Nebula

A vast cloud of gas and dust in outer space (Stars form here and can also produce them when they die)

Neutron star

The remains of the core of a large star, made of densely packed neutrons (They form in supernova explosions of stars with 8-20 times the mass of the Sun)

Nuclear Fusion

A nuclear reaction in which two atomic nuclei join together (Occurs in the cores of stars. A heavier nucleus is formed, and light and heat are released)

Photon

A particle of light or heat energy, released during nuclear fusion as protons fuse together in the Sun’s core

Planet

A natural satellite that orbits a star (Must be large enough to be round and have cleared its orbit of debris)

Planetary Nebula

A nebula formed from a red giant star (From when red giants have expanded until their outer gas layers drift into space)

Protostar

A dense ball of gas that hasn’t yet developed into a star

Red giant

A small star that fuses helium, causing its outer layers to expand

Red supergiant

A large star that fuses helium, causing its outer layers to expand

Redshift

the stretching of light waves emitted by objects moving away from us (Provides evidence that galaxies are moving away from us as the universe expands)

Small star

A star with less than 8x the mass of the Sun

Star

A hot, bright ball of gas held together by gravity

Supernova

An explosion of a red supergiant star

Universe

All of space and time, and the matter and energy they contain

White dwarf

The remains of the core of a small star

Evolution

A change in the genetic traits in a population over many generations. (Occurs over generations through repeated genetic variation, natural selection, and reproduction)

Evolutionary Tree

Diagram showing how species are related (Shows how related species evolved from common ancestors)

Natural Selection

The survival of organisms that are better adapted to their environment

Speciation

The formation of a new species (Occurs when a population splits into two isolated populations that evolve under different selection pressures)

Variation

A difference in traits between individuals of the same species

Mutation

A small random change in an organisms DNA that can be passed on to offspring through reproduction.

Competition

The struggle between organisms for resources such as food or mates

Genetic Isolation

The lack of interbreeding or little genetic mixing between organisms of the same species (for geographic reasons or other) that causes a loss of genetic variability, speciation, and occasionally fertile offspring