vocabulary the words are in lesson order with the lesson the word is from written as: – l # 1

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CHAPTER 3: STARS, GALAXIES, AND THE UNIVERSE

VocabularyThe words are in lesson order with the lesson the word is from written as: – L #

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light-year – L 1

The distance that light travels in one year, about 9.46 trillion kilometers

Is a unit of distance NOT time

3

parallax – L 1

The apparent change in position of an object when you look at it from different places

4

scientific notation – L 1

Uses powers of 10 to write very large numbers in shorter form

Example: 37,000,000,000,000 3.7 x 1013

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universe – L 1

All of space and everything in it

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binary star – L 2

• Star systems that have 2 stars, called double stars

• Often 1 of the stars is much brighter & more massive

• solarsystem.nasa.gov• solarsystem.nasa.gov

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elliptical galaxy – L 2

• It looks round and flattened• Billions of stars• They don’t have much gas or dust between

the stars• Contains old stars

• solarsystem.nasa.gov

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galaxy – L 2

A huge group of single stars, star systems, star clusters, dust, and gas, bound together by gravity

solarsystem.nasa.gov

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irregular galaxy – L 2

• They are not regular shapes; smaller• Contains you, bright stars• Includes a lot of gas & dust to form new stars


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planet – L 2

• An object that orbits a star• Large enough to have become rounded by its

own gravity• Has cleared the area of its orbit


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quasar – L 2

• Active, young galaxies with black holes at their center

• Gas spins around the black hole• Heats up, & glows


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solar system – L 2

• Contains a star and the planets and other objects that revolve around the star


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spiral galaxy – L 2

• Looks like a pinwheel• Its arms are full of young stars & new stars

form there


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star – L 2

• A giant ball of gas in a small volume• Primarily composed of hydrogen and helium,

which undergoes nuclear fusion (combining)


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accretion – L 3

The process of building something up gradually by the gathering together of smaller pieces

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force – L 3

A push or a pull

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gravity – L 3

The force that pulls objects towards each other

The strength of the force of gravity between 2 objects depends on the masses of the objects & the distance between the 2 objects

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inertia – L 3

The tendency of an object to resist a change in motion

Example: when a car stops suddenly, you keep moving forward

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Law of universal gravitation – L 3

Every object n the universe attract every other object

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Newton’s first law of motion – L 3

An object at rest will stay at rest and an object in motion will stay in motion; unless acted upon

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orbit – L 3

The path of an object as it revolves around another object in space

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absolute brightness – L 4

• Also known as luminosity• It is the brightness that a star would have if it

were at a standard distance from Earth


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apparent brightness – L 4

• Also known as apparent magnitude• It is a star’s brightness as seen from Earth


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Hertzprung-Russell diagram (H-R) diagramL 4

• A graph of stars’ surface temperature versus their absolute brightness

• Astronomers use H-R diagrams to classify stars and to understand how stars change over time.


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main sequence – L 4

• A diagonal area of the H-R diagram where most of the stars are located


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spectrograph – L 4

• A device that breaks light into colors and produces an image of the resulting spectrum


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black hole – L 5

An object with gravity so strong that nothing, not even light, can escape

Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

Credit: NASA/ESA

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nebula – L 5

A large cloud of gas and dust that is spread out in an immense (large) volume


Credit: NASA/ESA

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neutron star – L 5

The remains of a supergiant explosion

Smaller and denser than white dwarfs

May be 3 times the mass of the sun


Credit: NASA/ESA

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Protostar – L 5

The first stage of a star’s life A contracting cloud of gas and

dust with enough mass to form a star


Credit: NASA/ESA

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pulsar – L 5

Rapidly spinning neutron stars May spin hundreds of times per

second


Credit: NASA/ESA

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supernova – L 5

When a supergiant runs out of fuel – it can explode

The explosion blazes millions of times brighter


Credit: NASA/ESA

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white dwarf – L 5

When a star runs out of fuel, it is the blue-white core of the star that is left behind


Credit: NASA/ESA

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chromosphere – L 6

The middle layer of the sun’s atmosphere


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Convection zone – L 6

The outermost layer of the sun’s interio

Energy moves toward the sun’s surface by convection


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core – L 6

It is the central region of the sun


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corona – L 6

The outer layer of the sun’s atmosphere

It extends far into space It gradually thins into streams of

solar wind


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nuclear fusion – L 6

A process where hydrogen atoms join together to form helium;

Requires extremely high temperature and pressure


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photosphere – L 6

The inner layer of the sun’s atmosphere


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prominence – L 6

Huge loops of gas that link different parts of sunspot regions together


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radiation zone – L 6

A region of very tightly packed gas where energy moves mainly in the form of electromagnetic radiation


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solar flare – L 6

When loops in sunspot regions connect, it releases energy and causes gas to erupt into space


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solar wind – L 6

Electrically charged particles Can enter the Earth’s

atmosphere near the North and South poles – causes auroras

They can also cause magnetic storms


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sunspot – L 6

Areas of gas on the sun’s surface

They are cooler than the gases around them

They give off less light – so they look dark


vocabulary the words are in lesson order with the lesson the word is from written as: – l # 1

Documents

stars brightness

young stars new stars

starscontains old stars

star systems

star clusters

it5binary star

object n

huge group of single