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Most of the galaxy is made up of...

dark matter

are galaxy interactions and collisions common?


If two galaxies collide, what is the chance of the stars colliding?

chances are they would not collide

variable stars & how they extend the distance ladder

a variable star is a star thats luminosity changes over a short period of time. by measuring the time it takes to pulsate we can determine the distance

Why are spiral arms so bright?

Because that is where star formation occurs and the young stars are very bright.

Tully-Fisher relation & how it extends the distance ladder

based on redshift and blueshift in the arms of the spiral galaxies, you can judge the luminosity and therefore the distance

Which emits more energy, an active galaxy or a normal galaxy?

An active galaxy

The four characteristics of life

grow by eating, ability to react to changes in environment, reproduce & pass on genetic material to next generation, capacity for genetic change - evolution

Which element are organic molecules based on?



the universe looks the same in any direction


assumed property of the universe such that the number of galaxies in an imaginary large cube of the universe is the same no matter where in the universe the cube is placed

What causes the acceleration in the accelerating universe?

dark energy/cosmological constant

Three types of galaxy

ellipticle, spiral, irregular

galaxies are found in

clusters and superclusters

Huble's Law (V=Ho d)

rate at which a galaxy recedes is directly proportional to its distance from us

spectrum of a normal galaxy

looks like a regular blackbody curve

spectrum of an active galaxy

does not look like a regular blackbody curve

source of energy in active galaxies

supermassive black hole devouring material

elliptical galaxies

no cool gas, no new stars, hot interstellar gas

irregular galaxies

new stars created, irregular in shape, cool gas, random orbit

Gravitational Lensing

light from quasar bending around an object in front of it and making it appear as if there is 2 Quasars

spiral galaxy formation

gas & dust clouds & stars combine, formation is slow, fast rotation causes gas clouds to flatten

elliptical galaxy formation

star formation fast, slow rotation

galaxy cluster

mutual attraction of galaxies

synchroton radiation

comes from emission from black hole, because of accretion disc spiraling toward black hole

Seyfert Galaxy

Type of active galaxy whose emissions come from a very small region within the nucleus of an otherwise normal looking spiral system

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