Unit 8 Astronomy Flashcards

Flashcards of key vocabulary and concepts from astronomy lecture notes.

Big Bang

End of the spectrum.

Galaxy Clusters

A group of galaxies.

Galaxy

A huge body of billions of stars held together by gravity.

Spiral Galaxy

Central lens-shape w/2 arms, contains a lot of dust gas (e.g., Milky Way).

Elliptical Galaxy

Nearly spherical to lens-shaped, no arms, most stars are close a the center, little or no gas + dust.

Irregular Galaxy

No regular structure, a lot of gas+dust, many young stars.

Nebula

A large cloud of gas + dust in space, Shines by reflected light from nearby stars; Birthplace of Stars.

Solar System

The sun + its family of orbiting planets, moons, asteroids, comets, + meteoroids. Formed 4.6 billion years ago from a cloud of dust + gas.

Nuclear Fusion

12 hydrogen atoms fuse together to form a helium atom, huge amounts of energy, light theat are produced.

Luminosity

Brightness of a star compared to the Sun as seen from the same distance.

H-R Diagram

Classified stars according to their temperature + brightness.

Constellation

Group of stars that appears & form a pattern

Planet

Large, non-luminous, object-that orbits a star, their shape is an oblate spheroid.

Terrestrial Planet

Small, rocky, dense, solid Surface , No vings, few moons (e.g., Mercury, Venus, Earth, Mars).

Jovian Planet

large, gaseous, low density, No Solid Surface, Many rings + moons (e.g., Jupiter, Saturn, Uranus, Neptune).

Exoplanet

Out of the Solar System.

Moon

A natural satellite of a planet.

Comet

A chunk of frozen water + methane w/rock+metal debris; very eccentric stretched out circle in orbit.

Asteroid

Solid, rocklike masses moving through Space; revolve around the sun between Mars+Jupiter.

Meteoroid

rock traveling in space; grain size- boulder Size

Meteor

light made by a meteoroid as it passes into Earth's atmosphere; "Shooting Stars"

Meteorite

A meteoroid that hits Earth's surface.

Space Junk

Over 30,000 pieces of orbital debris; leftover man-mude junk around Earth