SCIENCE TERM 2 SECOND SUM

Comet

Celestial body made mainly of ice, dust, and rocky materials that orbits the Sun.

Dirty snowballs

A nickname given to comets because they contain ice mixed with dust and rocky materials.

Nucleus

The solid central part of a comet that contains most of its mass.

Coma

A cloud of gas and dust surrounding the nucleus, formed when the Sun heats the comet.

Comet tails (Dust tail and Ion tail)

Features that develop when a comet approaches the Sun, pointing generally away from the Sun due to sunlight and solar wind.

Short-period comets

Comets with an orbital period of less than 200 years.

Long-period comets

Comets with an orbital period of more than 200 years.

Kuiper Belt

A disk-shaped region where short-period comets originate.

Oort Cloud

A spherical shell surrounding the solar system where long-period comets originate.

Meteoroid

A small rocky or metallic object traveling through space.

Meteor

The visible streak of light ("shooting star") produced when a meteoroid enters Earth's atmosphere.

Meteorite

A piece of space rock that survives passage through Earth's atmosphere and reaches the surface.

Meteor shower

An event that occurs regularly when Earth passes through a stream of debris left behind by a comet.

Asteroid

A rocky or metallic object that orbits the Sun, generally larger than meteoroids with an irregular shape.

Main Asteroid Belt

The region located between Mars and Jupiter where many asteroids are found.

Dwarf planet

A celestial body that orbits the Sun and has enough gravity to be nearly round, but has not cleared its orbital neighborhood.

Five officially recognized dwarf planets

Pluto, Ceres, Haumea, Makemake, and Eris.

Significance of small solar system bodies

They are remnants of the early solar system that help scientists learn about its formation and history.

Pluto

A dwarf planet associated with the Kuiper Belt; reclassified from a major planet because it has not cleared its orbital neighborhood.

Ceres

The only officially recognized dwarf planet located inside the Main Asteroid Belt (between Mars and Jupiter).

Haumea

A dwarf planet associated with the Kuiper Belt, known for its elongated shape and distant orbit.

Makemake

A dwarf planet associated with the Kuiper Belt, located in the outer regions of the solar system.

Eris

A distant dwarf planet associated with the Kuiper Belt region, whose discovery prompted the reclassification of Pluto.

Characteristics of Dwarf Planets

Celestial bodies that orbit the Sun and have enough gravity to be nearly round, but have NOT cleared their orbital neighborhoods.

Seismic waves

Waves of energy produced by earthquakes, volcanic eruptions, or explosions that travel through Earth's interior or along its surface.

Seismology

The scientific study of earthquakes and seismic waves used to investigate Earth's internal structure.

Seismograph

An instrument used by scientists to detect and record seismic waves.

Body waves

Seismic waves that travel through the inner layers/body of the Earth (includes P-waves and S-waves).

Primary waves (P-waves)

The fastest moving seismic waves that arrive first at a seismograph; compressional waves that can travel through solids, liquids, and gases.

Secondary waves (S-waves)

Slower seismic waves that arrive second; shear waves that move in a side-to-side/perpendicular motion and can ONLY travel through solids.

Surface waves

Slowest moving seismic waves that travel along Earth's outer crust and cause the most destruction during an earthquake.

Outer Core (Seismic Evidence)

Layer of Earth proven to be liquid because S-waves completely disappear and cannot pass through it.

Shadow Zone

An area on Earth's surface where seismographs fail to pick up seismic waves due to how P-waves and S-waves bend or stop when hitting core boundaries.

Crust

The thin, solid, outermost layer of the Earth.

Mantle

The thickest layer of Earth consisting of hot, solid rock that can flow slowly.

Inner Core

The solid, extremely hot innermost layer of Earth composed mainly of iron and nickel.