Unit 2: Stars, Nebular Hypothesis and Impacts

Asteroid

A solid, rocklike mass that revolves around the sun. originate & typically orbit within region between Mars and Jupiter.

Black Dwarf Star

The remains of a white dwarf star after it has expended all of its energy

Black Hole

A point in space with a gravitational field so strong that not even light can escape. Created by the explosion of the most massive stars.

Comet

a mass of rock, ice, dust, and gas traveling around the sun usually in a highly eccentric orbit. most originate from region beyond Neptune

Conservation of Angular Momentum

The law of physics stating that the total amount of angular momentum in an isolated system remains constant. Cam=Mass x Width x velocity

event horizon

the location around a black hole where the escape velovity equals the speed of light; the boundary of a black hole

exoplanet

A planet outside of our Solar System.

gas pressure

the outward pressure exerted by gas in a star as it is heated by fusion in the core

Kuiper Belt

A region outside the orbit of Neptune where most short-period comets are thought to originate

Light Year

The distance that light travels in a year, about 9.5 trillion kilometers

Meteor

the light a meteoroid creates as it passes through Earth's atmosphere

Meteorite

The part of a meteoroid that survives its trip through the atmosphere and strikes Earth's surface

Meteoroid

Umbrella term for all fragments that travel through space and sometimes our atmosphere

Milky Way Galaxy

the galaxy that contains our solar system. Spiral shaped with at least 3 arms, billions of stars in a disk 100,000 ly across and 10,000 ly thick at the galactic bulge center

Nebula

A large cloud of dust and gas in space

Neutron Star

The very small, very dense core of a massive star, left behind after a supernova.

Planet

A celestial object that revolves around the sun, is a spheroid, and has cleared most of its orbit of large debris

Planetary Accretion

The process by which planets grow through collisions and sticking due to gravity and chance. From planetary embreyos to planetessimals to protoplanets to true planets.

Planetary Nebula

The expanding shell of gas that is escaping a dying, Sun-like (medium mass) star.

Protostar

The piled up mass that has been pulled together by gravity at the center of a nebula. It has not yet undergone nuclear fusion.

Red giant

The stage in the life cycle of a sun-like mass star during which the star increases in size and begins to fuse helium in its core.

Red Supergiant

The stage in the life cycle of a massive star during which the star increases in size and begins to fuse helium in its core.

Spagettification

The theory that you will become a long, thin stream of atoms, kilometers in length, but narrower than a hair wide when you get pulled into a blackhole

Star

A mass of incandescent gas, where a balance exists between the nuclear reactions pushing outward from the interior and the gravitational forces pushing inward.

Super Nova

Brilliant burst of light that follows the collapse of the core and explosion of a massive star

Terrestrial Planet

Earth-like planets: Mercury, Venus, Earth, Mars

Tunguska

Siberian site where an asteroid struck in 1908 with the power of 1000 atomic bombs

Virgo Supercluster

The super cluster of galaxies of which our local group is a member. Contains roughly 2000 galaxies

White Dwarf

a small, very dense star the size of earth that remains after a middle or low mass star runs out of fuel and is collapsed by gravity

Walter Alvarez

A scientist who proposed that a large meteorite hit the earth in the Yucatan area of Mexico around 65 million years ago causing the extinction of the dinosaurs

Iridium

An element that is rare on Earth but common in meteorites.

Chixulub

Crater that is located in Yucatán peninsula from asteroid responsible for dinosaur extinction.

Differentiation

The separation of material based on their density

fusion

the process of two atoms coming together under tremendous pressure to form a new atom. 2 Hydrogen atoms fusing to make a Helium atom

extinction

Definition: When 100% of a species dies, not even one member survives

Mass Extinction

at least 66% of all species go extinct