Asteroids, Comets, Meteors & The Big Bang Overview

Near-Earth Objects (NEO)

Small bodies orbiting near Earth and the sun.

Asteroids

Irregular rock fragments orbiting the sun.

Asteroid Count

Current known total of 1,088,287 asteroids.

Minor Planets

Another term for asteroids due to size.

Vesta

Largest asteroid, approximately 530 km in diameter.

Ceres

Former largest asteroid, now classified as a dwarf planet.

Main Asteroid Belt

Region between Mars and Jupiter with millions of asteroids.

Near-Earth Asteroids (NEAs)

Asteroids with orbits approaching Earth.

Earth-crossers

NEAs that cross Earth's orbit.

Trojan Asteroids

Asteroids sharing an orbit with a planet.

C-type Asteroids

Carbonaceous asteroids, over 75% of known asteroids.

S-type Asteroids

Stony asteroids, about 17% of known asteroids.

M-type Asteroids

Metallic asteroids, remaining known asteroids.

Comets

Icy bodies releasing gas or dust, known as dirty snowballs.

Comet Count

Currently, there are 3,279 known comets.

Nucleus of a Comet

Solid core, typically 1 to 10 km in diameter.

Coma

Halo of gas and dust surrounding the nucleus.

Gas Tail

Tail made of electrically charged gas.

Dust Tail

Tail composed of small dust particles.

Comet Tails

Point away from the sun, influenced by solar heat.

Solar System Formation

Comets may provide clues about early solar system.

Asteroid Composition

Classified as C-type, S-type, or M-type.

Asteroid Size Variation

Some asteroids are less than 10 m across.

Total Asteroid Mass

Combined mass is less than Earth's moon.

Frozen Comet

Comets are frozen far from the sun.

Comet's Temporary Atmosphere

Formed by gas and dust when heated by the sun.

Comet

A celestial object made of ice and dust.

Short-period comets

Comets with orbits less than 200 years.

Long-period comets

Comets with orbits longer than 200 years.

Kuiper Belt

Region beyond Neptune containing icy bodies.

Oort Cloud

Hypothetical cloud of comets beyond Pluto.

Edmond Halley

Scientist who predicted Halley's comet's return.

Halley's Comet

Famous comet observed since 240 B.C.

Meteoroid

Small rocky or metallic body in space.

Meteor

Bright streak of light from a meteoroid.

Meteor shower

Celestial event with numerous meteors visible.

Meteorite

Meteoroid that survives atmospheric entry.

Stony meteorite

Most common type of meteorite, rocky composition.

Iron meteorite

Meteorite primarily composed of iron-nickel.

Stony-iron meteorite

Rare meteorite containing both rock and metal.

Big Bang Theory

Model explaining the Universe's origin and expansion.

Raisin-bread model

Analogy for galaxies expanding within the Universe.

Cosmological model

Framework explaining the structure of the Universe.

13.8 billion years

Estimated age of the Universe's expansion.

Meteoroid formation

Result of asteroid collisions creating smaller bodies.

Gravitational theory

Newton's theory explaining celestial motion.

Celestial event

Occurrence involving astronomical phenomena.

Composition of meteoroids

Typically rocky materials, iron, and nickel.

Predictable comet appearance

Comets can be forecasted based on orbits.

Superstition

Belief not based on scientific evidence.

Dust tail

Part of a comet pointing away from the sun.

Irregular shapes

Common characteristic of asteroids and meteoroids.

Singularity

Initial state of the Universe before expansion.

Expansion

Space growing outward in all directions.

Radiation Era

Stage dominated by radiation, no matter present.

Epoch

Smaller stages within larger eras of the Universe.

Superforce

Combination of four fundamental forces of nature.

Electromagnetic Force

One of the four fundamental forces, governs electricity.

Strong Nuclear Force

Force that holds protons and neutrons together.

Weak Nuclear Force

Responsible for radioactive decay processes.

Inflationary Epoch

Rapid expansion from atomic to grapefruit size.

Quark Epoch

Subatomic particles present but too hot to form.

Hadron Epoch

Quarks combine to form protons and neutrons.

Nucleon Freezeout

Protons and neutrons combine to form atomic nuclei.

Nucleosynthesis

Formation of hydrogen and helium elements.

Atomic Epoch

Electrons attach to nuclei, forming neutral atoms.

Recombination

Process of electrons attaching to nuclei.

Galactic Epoch

Formation of gas clusters leading to galaxies.

Stellar Epoch

Current stage marked by star formation.

Helium (He)

First chemical element formed in the Universe.

Hydrogen

Second element formed during the atomic epoch.

Matter Era

Era characterized by the formation of matter.

Electroweak Epoch

Last two forces split, forming four natural forces.

Cosmic Background Radiation

Remnant radiation from the early Universe.

Galaxy Formation

Process of gas clouds collapsing to form galaxies.

First Stars

Formed from gas clumps in galaxies.

Universe's Age

Approximately 13.8 billion years old.

Expansion Rate

Rate at which the Universe is expanding.