ASTRONOMY Unit Review (Defenitions)

Solar system

the sun and all the objects in the orbit around it.

planet

a large collection of matter that is generally spherical and revolves around the sun.

cosmology

the study of the origin of the universe

Star

a very large collection of matter that emits on the intense amount of energy (light and heat)

constellation

star groupings

polaris

the north star

longitude

measured from east to west from the 0 degree line that crosses Greenwich, England

latitude

measured from the Equator to either the North Pole or the South Pole

Geocentric

Earth was the center of the universe

Helocentric

sun-centered system

The Sun

A medium sized star composed of 75% hydrogen and 25% helium.

Supernova

Core that collapses and explodes.

Low mass star

Very cool in temp. and ends their life span by forming a cool, dim, star called white dwarf

Intermediate mass star

Fuels hydrogen into helium for energy

High mass star

emits extremely large amounts of energy for a short period of time

Apparent magnitude

the brightness of the star that we see

absolute magnitude

the actual brightness of the star

spectroscope

splits light up into a pattern of colours, like a rainbow

Electomagnetic spectrum

consists of a visible spectrum of energy that we can see, as well as other energy that we cannot see.

Blue shift

When light shifts are compressed, the light emitted appears more purple in colour

Red shift

when light waves are spread out (or further apart), the light emitted appears more red in colour.

Galaxy

huge collections or gas, dust, and billions of stars. The force of gravity attracts the tars in a galaxy to each other.

Quasar

Looks like a small star, limits up to 100 times more energy than our galaxy, emits radio waves.

Star cluster

contain 10 000-1 000 000 stars that are fairly close to each other and travel together.

light year

the distance that light travels in a year

astronomical unit

the distance between the sun and the earth

parsec

measurement for distance that is equal to 3.26 light years

planet

smaller than stars, and do not emit light

asteroid

chunks of rock/metal that orbit the sun but are too small to be called planets. (minor planets)

trojan

asteroids with orbits that cross paths with earth

comet

chunks of ice/dust that orbit the sun

meteroid

lumps of rock that can be trapped by earth's gravity and can be pulled into earth's atmosphere.

meteor

meteoroids that enter earth's atmosphere

shooting star

the streak of light produced across the sky as the meteor burns up.

meteorite

meteoroids that do not completely burn up as meteors in the earth's atmosphere may strike the earth's surface.

crater

bowl shaped holes on the earth's surface, made by large meteorites

meteor shower

when earth passes through debris left behind from an old comet, there may be a swarm of visible meteors in the night sky.

globular cluster

collections of 100 000 to 1 000 000 stars held together by gravity, arrnged in spherical shapes.

neutron star

formed by very high mass stars, contracting even further.

astronomy

the study of all objects in the universe.