Unit 3 Vocab - Star Life Cycle and Kepler's Laws

nuclear fusion

The reaction that fuels the sun, where hydrogen nuclei are fused to form helium

atomic nuclei

the small, dense region consisting of protons and neutrons at the center of an atom

temperature

a measure of how hot or cold something is

luminosity

the amount of light emitted by a star

nebulae

clouds of dust and gas in space, usually illuminated by one or more stars, which represents the raw material the stars were made of

main sequence

the stage in which a star is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward

red giant

A stage in the evolution of a star when the fuel begins to exhaust and the star expands to about fifty times its normal size. The temperature cools, which gives the star a reddish appearance.

white dwarf

a very small and hot star that is the remnant core of a star that has completed fusion in its core. they are typically composed primarily of carbon, have about the radius of the earth

supergiant

an extremely bright star of very large diameter and low density

supernova

the death explosion of a massive star resulting in a sharp increase in brightness followed by a gradual fading. The most powerful force in the universe. all the heavy elements were created in these explosions

neutron star

the compressed core of an exploded star made up almost entirely of neutrons. It has a strong gravitational field and some emit pulses of energy along their axis. they are sometimes known as pulsars

black hole

The collapsed core of a massive star. Stars that are very massive will collapse under their own gravity when their fuel is exhausted. The collapse continues until all matter is crushed out of existence into what is known as a singularity. The gravitational pull is so strong that not even light can escape.

ellipse

An elongated circle, or oval shape, the shape of the planets orbit.

eccentricity

a measure of how an orbit deviates from circular

perihelion

orbital point nearest the sun

aphelion

point in a planet's orbit that is farthest from the sun

revolution

The movement of an object around another object

rotation

The spinning of Earth on its axis

orbit

The path of an object as it revolves around another object in space

Kepler's 1st law

The orbit of each planet around the Sun is an ellipse with the Sun at one focus.

Kepler's 2nd law

As a planet moves around its orbit, it sweeps out equal areas in equal times

Kepler's 3rd law

The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.