Astronomy II Flash Cards -- Song 8th Grade Science H

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Planets in Solar System (in order)

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Astronomy

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1

Planets in Solar System (in order)

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

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2

Mercury

  • terrestrial (rocky surface)

  • smallest planet

  • no moons

  • thin atmosphere →heat doesn’t get trapped →opposite side is cold

  • side that faces sun is very hot

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3

Astronomical Unit (au)

  • 1.5 × 10 ^11 m

  • approximately avg distance btwn Earth & Sun

  • WHY IT’S HELPFUL: VERY CONVENIENT & IS USED FOR THINGS IN SOLAR SYSTEM

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4

Light year

  • 9.46 × 10^15 m

  • used for things OUTSIDE solar system

  • very convenient for large distances

  • the distance light travels in a year (MEASURING DISTANCE, NOT TIME)

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5

Venus

  • Terrestrial

  • Hottest planet due to thick CO2 in atmosphere

  • No moons

  • Rotates clockwise (Sun sets towards east)

  • Day on Venus > year on Venus

  • Earth’s twin (similar size, close orbit)

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6

Earth

  • 1 moon

  • Densest planet in solar system

  • all 3 states of water

  • Plate tectonics → earthquakes

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7

Asteroid Belt

  • Asteroids = rocky objects, diameter = usually <1 km

  • Asteroids orbit btwn Mars & Jupiter

  • Thought to be leftover pieces of early solar system that never formed a planet

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8

Mars

  • Terrestrial

  • 2 moons

  • Red planet due to iron oxide (rusted iron)

  • Tallest mountain

  • May have had water in the past

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9

Jupiter

  • Gaseous planet

  • largest (in terms of mass & size)

  • Rotates very fast (10 hrs per day)

  • Great red spot : super storm, 3X the size of Earth

  • 79 known moons

  • 2 ½ times the mass of all the planets combined

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10

Saturn

  • Gas planet

  • Less dense than water

  • Over 30 rings made of ice, dust, and rocks

  • 82 known moons: the largest moon, Titan, is larger than the planet Mercury

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11

Uranus

  • Ice Planet

  • 27 moons

  • 13 rings

  • Tilted on side

  • Blue-green color from METHANE GAS in atmosphere.

    • Sunlight passes thru atmosphere & reflected back out by Uranus' cloud tops

    • Methane gas absorbs red portion of light => blue-green color

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12

Neptune

  • Ice planet

  • 14 moons

  • 5 rings

  • Blue due to methane gas

  • LONGEST PERIOD OF REVOLUTION

    • Furthest from the Sun → takes longer to revolve

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13

Beginning of universe

  • Singularity

    • point in space in time which is:

      • infinitely hot

      • infinitely dense

      • infinitely small (SMALLER THAN PROTON!!)

      • CONTAINED EVERYTHING IN THE UNIVERSE

      • We do not know where it came from.

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14

Big Bang Theory

  • scientifically accepted theory of the beginning of the universe

  • refers to when singularity began to expand & cool. A LOT HAPPENED

  • Happened about 13.7 billion years ago

  • Expansion, not explosion

  • We do not know what caused it.

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15

Hubble’s Law

  • the farther galaxies are, the faster they are moving away from us

  • strong support for Big Bang Theory

  • Universe is still expanding

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16

Newton’s 1st Law (its relation to this unit)

  • From Big Bang Theory, all things in universe are moving.

  • Once stars are moving, what will cause them to stop?

    • NOTHING. They will continue moving at a constant velocity, until an unbalanced force causes them to change their motion.

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17

Nebula

  • “Star nursery” - where stars are born

  • Clouds of dust (Li) & gas (primarily H & He)

  • GRAVITY keeps the particles together.

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18

Law of Universal Gravitation

  • All things w/ mass are attracted to each other.

  • Based on 2 factors:

    • mass of objects

    • distance btwn objects

      • center to center

  • Gravity & mass = directly related.

  • Gravity & distance = inversely related.

  • Fg = Gm1m2/r²

    • G = gravitational constant (doesn’t change)

    • r = radius (distance btwn 2 objects from center to center)

    • m = mass

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19

Birth of a Star

  • Stars begin in a nebula (clouds of dust & gas).

  • Gravity pulls mass together → particles spin

    • Spins faster & faster → gets hotter

    • Reaches ~ 15 million degrees C = nuclear fusion begins & star is born.

      • Beginning of star’s life (when star will expand & release light / energy)

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20

Nuclear Fusion

  • When gasses get too hot, they turn into 4th state of matter (PLASMA)

    • Plasma = electrons are stripped & nuclei is left bare

  • If nuclei in this state go fast enough, they will fuse into a new element

    • Hydrogen fuses into helium. 4 hydrogen nuclei1 Helium nucleus.

      • Difference in mass in nuclear reaction → energy

        • According to equation E=mc²

          • From mass, you get energy.

            • We see this energy in form of light → how star shines

  • From the Sun, tension btwn 2 competing forces

    • Gravity - wants to pull everything together

    • Energy from fusion - wants to blow it all apart

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21

Convert Venus’ distance from Sun (107.5 BILLION M) to AU & cm if 1 AU is 147.4 billion m.

0.7 AU or 70 CM

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22

How are galaxies classified?

SHAPE & SIZE

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23

Order this from smallest → largest:

Mars, USA, Cell, Jupiter, atom, Cerritos, dog, Sun, Mercury

  • atom, cell, dog, Cerritos, USA, Mercury, Mars, Jupiter, Sun

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24

How are galaxies different from nebulae?

  • Nebulas are solely where stars are born

  • Galaxies contain stars, as well as other things like planets, asteroids, etc

    • Galaxies are larger than nebulas

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25

Mass of planets from smallest → largest

Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, Jupiter

ACRONYM: Mighty Martians Visit Earth, Usually Not So Jovial

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26

Inner planets

  • Mercury, Venus, Earth, Mars

  • Also called terrestrial planets

  • Smaller in size & denser

  • Few moons & no rings

  • Rocky surface

  • Close to Sun & each other

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Outer planets

  • Jupiter, Saturn, Uranus, Neptune

  • Also called gas giants

  • Larger in size

  • Lots of moons & can have rings

  • no solid surface

    • => no defined physical features

    • As a result of gaseous surface

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28

What do planets with the most mass have in common?

  • < density

  • > period of rotation @ equator

  • > period of revolution

  • > distance from Sun

  • Eccentricity of orbit

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29

Why do outer planets not have craters?

Outer planets made of gas → asteroids have no solid surface to fall onto

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30

True or false: less gravitational force = less size & less moons & rings (unable to support them w/ less Fg)

True

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31

What is used to differentiate between inner & outer planets?

  • Surface

  • # of rings

  • Distance from Sun

  • # of moons

  • Size

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32

Kuiper Belt

  • large region in cold, outer reaches of our solar system beyond orbit of Neptune.

  • sometimes called "third zone" of solar system

  • most likely has millions of small, icy objects

    • Some objects, including Pluto, are > 600 miles wide.

    • Objects have frozen compounds i.e. ammonia & methane

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33

Oort Cloud

  • lies beyond Pluto & most distant edges of Kuiper Belt.

  • planets of our solar system orbit in a flat plane, but Oort Cloud is in giant spherical shell surrounding Sun, planets & Kuiper Belt Objects

    • like a big, thick bubble around solar system, made

      of icy, comet-like objects (can be large as mtns, or even larger)

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