Comets, Asteroids, and Meteors

Comet Definition

A celestial object made primarily of ice mixed with dust and rocky particles, often described as a 'dirty snowball.'

Nucleus

The core of a comet, typically about 10 km in diameter, composed mainly of ice, dust, and rocky particles.

Coma

An expanding region of gas and dust that forms around a comet's nucleus as it approaches the Sun.

Gas (Ion) Tail

A tail that develops from a comet, made of lightweight gases pushed away from the Sun by solar wind, and always points directly away from the Sun.

Dust Tail

A tail consisting of heavier particles like dust and small rocks, usually appearing yellowish or whitish with a fuzzy shape.

Oort Cloud

A theoretical spherical region believed to contain billions of comet nuclei, extending about 50,000 AU from the Sun.

Meteor

The visible streak of light produced when a meteoroid enters Earth's atmosphere and burns up due to friction.

Meteoroid

A small object in space, typically ranging from the size of a grain of sand to a boulder, which can originate from comets or asteroids.

Meteorite

A fragment of a meteoroid that survives its journey through Earth's atmosphere and lands on the surface.

Asteroid

A small, rocky body that orbits the Sun, primarily found in the asteroid belt between Mars and Jupiter, composed mostly of rock and metal.

Near Earth Asteroids (N.E.A.)

Asteroids that can cross Earth's orbit and pose a potential threat, with some classified as Potentially Hazardous Asteroids (PHA).

Perseids

An annual meteor shower that occurs in August, known for producing a high number of meteors.

Composition of Meteors

The color of a meteor indicates its composition, e.g., orange-yellow for sodium, blue-green for magnesium.

Trojan Asteroids

Asteroids that orbit along the paths of larger planets, like Jupiter, and can be found both ahead and behind the planet.