Earth’s Place in Earth’s Place in SpaceSpace

Chapter 2, section 1Chapter 2, section 1

RotationRotation

RevolutionRevolution

OrbitOrbit

The spinning of the Earth about The spinning of the Earth about its axis.its axis.

Creates Creates DAYSDAYS

The movement of the Earth The movement of the Earth about the Sun.about the Sun.

Creates Creates YEARSYEARS

The elliptical (oval) path the The elliptical (oval) path the Earth makes around the Sun.Earth makes around the Sun.

Actually, the Earth’s axis is tilted. 23.5 degrees, to be exact.

The tilted The tilted axis makes axis makes ……

… … seasonsseasons

When you are closest to the Sun, When you are closest to the Sun, it is summer. When you are it is summer. When you are farthest from the Sun, it is farthest from the Sun, it is winter.winter.

This is not because the Earth is This is not because the Earth is all far away, it is because the all far away, it is because the Earth is tilted.Earth is tilted.

Solar EclipseSolar Eclipse Moon moves Moon moves between the sun between the sun and the Earthand the Earth

Can only be seen Can only be seen by a few (moon is by a few (moon is small)small)

Must be during a Must be during a new moonnew moon

Lunar EclipseLunar Eclipse Earth moves Earth moves between the Sun between the Sun and the Moon.and the Moon.

Everyone can see a Everyone can see a lunar eclipselunar eclipse

The Solar The Solar SystemSystemChapter 2, section 2Chapter 2, section 2

Our solar Our solar systemsystem

Planetary Planetary OrbitsOrbits

Includes 8 planets, our Sun, Includes 8 planets, our Sun, and many other objects that and many other objects that orbit the Sunorbit the Sun

Is held together by the Is held together by the Sun’s immense gravitySun’s immense gravity

The orbits of the planets The orbits of the planets are elliptical (like a slightly are elliptical (like a slightly flattened circle). flattened circle).

Measuring in Measuring in Outer SpaceOuter Space

Astronomical UnitsAstronomical Units 1AU = 150 million km, which 1AU = 150 million km, which

is the distance from the Earth is the distance from the Earth to the Sunto the Sun

Inner PlanetsInner Planets Group of planets closest to Group of planets closest to the Sunthe Sun

Mercury, Venus, Earth, and Mercury, Venus, Earth, and MarsMars

Mostly solid, with minerals Mostly solid, with minerals similar to Earthsimilar to Earth

MercuryMercury Closest to the SunClosest to the Sun smallest planetsmallest planet Has many cratersHas many craters No atmosphere No atmosphere extreme extreme

temperatures (425˚C to -temperatures (425˚C to -170˚C) 170˚C)

88 days for 1 revolution88 days for 1 revolution

VenusVenus Second-closest to the SunSecond-closest to the Sun Surrounded by thick cloudsSurrounded by thick clouds Clouds trap solar heat, so Clouds trap solar heat, so

the temperature is always the temperature is always around 472˚C! around 472˚C!

225 days for 1 revolution225 days for 1 revolution

EarthEarth Third planet from the SunThird planet from the Sun Has water; temperature Has water; temperature

allows for ice, water, and allows for ice, water, and vapor.vapor.

Atmosphere with ozone acts Atmosphere with ozone acts as a screen.as a screen.

Very UniqueVery Unique About 365 days for one About 365 days for one

revolutionrevolution Has one moonHas one moon

MarsMars Has seasonsHas seasons Has polar ice capsHas polar ice caps Maybe abundant water at Maybe abundant water at

one time?one time? Looks red because of rust in Looks red because of rust in

rock.rock. Has two small moons Has two small moons

(Phobos, Deimos)(Phobos, Deimos) 687 days for 1 revolution687 days for 1 revolution

Asteroid BeltAsteroid Belt Between Mars and JupiterBetween Mars and Jupiter Pieces of rockPieces of rock Most likely the remains Most likely the remains

from collisions.from collisions.

Outer PlanetsOuter Planets Group of planets farthest Group of planets farthest from the Sunfrom the Sun

Jupiter, Saturn, Uranus, Jupiter, Saturn, Uranus, NeptuneNeptune

Gas GiantsGas Giants

JupiterJupiter Fifth planet from the SunFifth planet from the Sun LARGEST planetLARGEST planet Rotates REALLY fast (only Rotates REALLY fast (only

10hr day)10hr day) Great Red Spot: giant stormGreat Red Spot: giant storm Has Has 6363 moons (Ganymede moons (Ganymede

is bigger than Mercury)is bigger than Mercury) 3 moons have icy water3 moons have icy water Faint ring of dustFaint ring of dust Nearly 12 years for 1 Nearly 12 years for 1

revolutionrevolution

SaturnSaturn Several broad rings made of Several broad rings made of

ice and rockice and rock Has Has 6161 moons moons Titan is the largest moon. Titan is the largest moon.

It resembles Earth during It resembles Earth during primitive times.primitive times.

24.5 years for 1 revolution24.5 years for 1 revolution

UranusUranus The 7The 7thth planet planet Looks blue due to methane Looks blue due to methane

gasgas Axis is almost horizontal Axis is almost horizontal

(sideways)(sideways) 27 moons27 moons Coldest of the 8 planetsColdest of the 8 planets

NeptuneNeptune The last planet The last planet Looks blue due to methane Looks blue due to methane

gasgas Has 13 moonsHas 13 moons Seasons/stormsSeasons/storms 1 revolution is 165 years!1 revolution is 165 years!

CometsComets Large body of ice and rockLarge body of ice and rock Moves around the Sun in an Moves around the Sun in an

elliptical orbitelliptical orbit Tails appear when near the Sun Tails appear when near the Sun Sun melts a little ice and wind Sun melts a little ice and wind

blows particlesblows particles Tail is always away from the SunTail is always away from the Sun

MeteoritesMeteorites Chunks of extraterrestrial rock Chunks of extraterrestrial rock

that fall to the Earth’s surface.that fall to the Earth’s surface. RareRare because most rocks do not because most rocks do not

make it through the Earth’s make it through the Earth’s atmosphere AND 71% of Earth is atmosphere AND 71% of Earth is water (so it’s unlikely to hit land)water (so it’s unlikely to hit land)

Provide a lot of information about Provide a lot of information about spacespace

Can be stone, metal, or a mixtureCan be stone, metal, or a mixture

Stars & GalaxiesStars & Galaxies

Chapter 2, Section 3Chapter 2, Section 3

ConstellatiConstellationsons

Groups of stars that form Groups of stars that form patterns in the skypatterns in the sky

Change depending on the Change depending on the season (what part of the sky season (what part of the sky we are viewing)we are viewing)

Star ColorsStar Colors

Star SizeStar Size

Stars are different colorsStars are different colors Color gives a clue about Color gives a clue about

temperaturetemperature

Red – coolerRed – cooler

Yellow – warmYellow – warm

Blue – hotBlue – hot The Sun is a yellow starThe Sun is a yellow star

Stars are different sizesStars are different sizes The Sun is a medium starThe Sun is a medium star

BrightnessBrightness

Apparent Apparent MagnitudeMagnitude

Stars have different Stars have different brightnessesbrightnesses

How bright a star appears How bright a star appears from Earthfrom Earth

The star’s distance from The star’s distance from Earth affects thisEarth affects this

(flashlight near or far)(flashlight near or far)

The Life of The Life of a Stara Star

11stst: clouds of dust & gas: clouds of dust & gas Gravity pulls them together, Gravity pulls them together,

temperature rises & atoms temperature rises & atoms fusefuse

Stars have a cycle depending Stars have a cycle depending on their sizeon their size

Our Sun is here

SupergiantSupergiantss

SupernovaSupernova

Large stars onlyLarge stars only When fuel is almost used upWhen fuel is almost used up Expand to a supergiantExpand to a supergiant

When the core of a supergiant When the core of a supergiant collapsescollapses

For a few days, may be For a few days, may be brighter than an entire brighter than an entire galaxy!galaxy!

After After supernova:supernova:

Very large stars Very large stars black hole black hole Large stars Large stars neutron star neutron star

GalaxiesGalaxies

3 types:3 types:

Groups of stars, gas, and dust Groups of stars, gas, and dust held together by gravityheld together by gravity

EllipticalElliptical SpiralSpiral IrregularIrregular

The Milky The Milky WayWay

Our galaxyOur galaxy Large spiral (100,000 light Large spiral (100,000 light

years wide)years wide) Includes hundreds of billions Includes hundreds of billions

of starsof stars The Sun revolves around the The Sun revolves around the

center of the Milky Way about center of the Milky Way about once every 225 million years!once every 225 million years!

Center may be a gigantic Center may be a gigantic black hole?black hole?

The Speed The Speed of Lightof Light

Really fastReally fast Light can go around the Earth Light can go around the Earth

7 times in 1 second!7 times in 1 second! Speed of light = 300,000 km/sSpeed of light = 300,000 km/s

Light YearsLight Years Astronomical units are too Astronomical units are too small in the universe, so we small in the universe, so we use light yearsuse light years

It is the distance light travels It is the distance light travels in one yearin one year

About 9.5 trillion km!About 9.5 trillion km! The Milky Way Galaxy is The Milky Way Galaxy is

100,000 ly away!100,000 ly away!

For most galaxies, we are For most galaxies, we are seeing them as they were seeing them as they were millions of years ago because millions of years ago because they are millions of light years they are millions of light years away.away.

The The UniverseUniverse

Each galaxy includes billions Each galaxy includes billions of stars. Our universe may of stars. Our universe may include as many as 100 billion include as many as 100 billion galaxies!galaxies!

In ten days, the Hubble In ten days, the Hubble Telescope took pictures in a Telescope took pictures in a small area of sky. It small area of sky. It discovered 1500 galaxies!discovered 1500 galaxies!

Scientists believe the Scientists believe the universe is expanding (getting universe is expanding (getting bigger) because some bigger) because some galaxies are moving away galaxies are moving away from our Solar System.from our Solar System.