Astronomy Definitions and Quiz Answers

Sphere of gas shining under its own power

Distance light travels in one year

Celestial body we reside on. 6400km in radius

Angular distance north or south of equator

Angular distance around Earth measured from equator

Imaginary sphere centered on center of earth to which it appears the stars are fixed

Model used to explain to observers

Point directly above observer in a clestial sphere

Stars that neither rise or set but circle around a celestial pole above horizon at all times

Anything that moves night to night (wanders around)

Apparant annual path of the sun on celestial sphere

One of 88 sectors into which astromers divided the celestial sphere

Notable star pattern in the sky

Belt around sky around 180 degrees wide centered on the ecliptic

Apparent motion of a planet when it appears to move backward direction it normally moves with respect to the stars

Apparant displacement of an object caused by a change in position from which it is viewed

Passing of one body into shadow of another

Phenomenon that occurs when the moon moves into shadow of the earth

Very influential greek philosopher who presented arguments in favor of earth having a spherical shape (325bc)

Greek astronomer, math matician, geographer, in 200bc estimated the circumference of earth. (200BC)

Small circle riding on a larger cirlce on which planet moves

Wrote the almagest

Earth Centered

Sun centered

Proposed or considered heliocentric theory

First proposed heliocentric model of the solar system with calculations

System of sun, planets, other objects revolving around the sun

Popularized geocentric model by providing calculations adn resonable models on why geocentric makes sense
Wrote the Almagest

Instrument that collects light and makes distant objects appear larger and brighter; invented in 1608

He was the first person to point telescope at the sky to observe planets.
He discovered Venus' phases and this lead to him declearing heliocentric was more likely.

Ability to make testable predictions

Changing relative positions of the earth, sun, and moon as moon revolves around the earth

The tilt of earth's axis of rotation

Slow concial change in orientation of earth's axis of rotation

Discovered precession of earth's axis adn created star catalog (150BC)

IN absense of air, all bodies fall at the same rate

Every body continues doing what it was already doign unless another force exertes energy and acts upon it

Pendulm whos change in swining direction shows and proves earth's rotation

What precise paths do planets take around the sun?

Why do the planets follow the paths they do

Small, stony object orbiting the sun

Region between mars and jupiter where many asteroids are located

Physical space occupied by a body

Amount of mass per volume

Momentum associated with motion around an axis or fixed point

Gravity

Force of gravity decreases as inverse square of the distance seperating the object

1/2 Length of major axis of an elipse.
Average orbital distance of a planet to the sun

How squished an elipse is

1.) Each planet moves about the sun in an orbit that is an elipse, with the sun at one focus of the elipse
2.) The straight line joing a planet and the sun sweeps out equal areas in spaces in equal intervals of time
3.)The squares of planets' periods of revolution are in direct proportion to the cubes of the semimajor axes of their orbits

Passing of one body into the shadow of another

Phenomenon that occurs when the moon moves into shadow of the earth

Angle subtended by an object in the sky, typically measured in degrees

Eclipse of sun by moon, caused by passage of moon infront of the sun

Outer atmosphere of the sun

Cloud of Gas and dust out fo which the solar system was formed

Small bodies that formed in solar system nebula that ultamately formed planets

Small body of icy and dusty mater that orbits the sun

4.5 billion years ago

Gravitational separation of materials of different density into layers in the interior of an object

Closest planet to the sun
Orbits sun quickly (88 days)
Smallest and least massive planet
450 degrees
no moons
Heavily cratered

Flash of light observed when a small piece of solid matter enteres earth's atmosphere and burns up; called shooting star

A particle or chunk typically rocky or metallic materiial in spac ebefore any enounter with earth

A portion of a meteroroid that survives passage through earth's atmosphere and strikes the ground

Similar size to earth
Blanketed by thick atmosphere
Experiences runaway green house effect - Warming that results when the sun's light is trapped by an atmosphere
Incrediblhy hot surface 1000 degrees
No moons
Slow backwards rotation fo 243 days

Only planet we know of with life
Only planet we know of with liquid water on surface
Closest planet to sun with a moon

Orbits earth every 27 days
About 1/4 the diameter of Earth (very big relative to earth)
Has no atmosphere
is the only solar system object other than earth humans have stepped foot on

Comparatively small planet only 1/10 mass of earth
rotates every 24 hours like earth
No liquid water today but likely had it in the past
Has largest volcano in solar system
Has two small moons

Largest adn most massive planet in solar system
No solid surface - first of the four giant planets
Similar chemical composition to the sun
Over 60 known moons

No solid surface - second giant planet
Least dense of all planets
Famous for ring system
over 60 known moons

First planet discovered by telescope
No solid surface - Third giant planet but significantly smaller than Jupiter or Saturn
very cold -350 degrees
over 25 known moons

Predicted by mathematical calculation, then discovered in 1846
Similar in size to urnanus
over a dozen moons
no solid surface - last of the giant planets

Located 40 AU away from sun (takes 5 hours for light to reach it)
5 moons
solid surface
Orbit that is more incliend and more eccentric than any of the 8 planets
discovered in 1930, demoted in 2006

1.)Orbit aorund the sun
2.)Nearly round in shape
3.)Cleared the neighborhood around its orbit
- Nothing else large that orbits sun in same vacinity