Topic IV: The Solar System & Universe

Earth’s MoonEarth’s Moon

Phases of the MoonPhases of the Moon: the amount of the : the amount of the lighted portion of the moon that faces the lighted portion of the moon that faces the Earth Earth

Why do we have phases of the moon?

Because of the Because of the moon’s revolution around moon’s revolution around the Earth (27.3 days)the Earth (27.3 days)—the moon is in —the moon is in different locations in relation to the sun)different locations in relation to the sun)

New MoonNew Moon: (no moon) the entire lighted side of : (no moon) the entire lighted side of the moon faces away from the earththe moon faces away from the earth

Waxing MoonWaxing Moon: the right side of the moon : the right side of the moon appears to grow (amount of the lighted appears to grow (amount of the lighted portion facing Earth becomes greater)portion facing Earth becomes greater)

Full MoonFull Moon: the entire lighted portion of the : the entire lighted portion of the moon can be seen from Earth moon can be seen from Earth

Waning MoonWaning Moon: the right side of the moon : the right side of the moon appears to get smaller (the amount of the appears to get smaller (the amount of the lighted portion facing Earth gets less)lighted portion facing Earth gets less)

**it takes about 29.5 days for the moon to go **it takes about 29.5 days for the moon to go through the phases (1 month)through the phases (1 month)

Moon Phase Animation

Why is there a dark (Far) side of the Why is there a dark (Far) side of the moon?moon?

Because the moon revolves at the same Because the moon revolves at the same rate as it rotates rate as it rotates

Far Side of the Moon Animation

Eclipses of the Sun and MoonEclipses of the Sun and Moon

Lunar EclipseLunar Eclipse: when the moon revolves : when the moon revolves into the shadow of the Earth—Earth blocks into the shadow of the Earth—Earth blocks moon’s lightmoon’s light

**Full Moon Only!!!

Lunar Eclipse

Solar EclipseSolar Eclipse: when the moon blocks out : when the moon blocks out the sun—casting a shadow on the Earth the sun—casting a shadow on the Earth

**New Moon Only!!!

Solar Eclipse

We do not have eclipses every month We do not have eclipses every month because the Earth, moon, and sun are not because the Earth, moon, and sun are not perfectly lined up every month….perfectly lined up every month….

TidesTidesTides:Tides: the daily rise and fall of the ocean the daily rise and fall of the ocean

waterwater

Every coastal location receives 2 high Every coastal location receives 2 high tides and 2 low tides everydaytides and 2 low tides everyday

6hrs 6hrs → → 6hrs 6hrs → → 6hrs 6hrs → → 6hrs6hrs

HH L L HH L L

Low Tide

High Tide

Why….Why….because of the gravitational pull of the sun because of the gravitational pull of the sun

and the moon! and the moon!

Daily Tide Animation

Remember…..Remember…..Gravity is affected by 2 variables: Gravity is affected by 2 variables:

Mass (Mass (↑ mass, ↑ gravity)↑ mass, ↑ gravity)Distance (↑ distance, ↓ gravity)Distance (↑ distance, ↓ gravity)

**The moon is the primary cause of the tides **The moon is the primary cause of the tides because it is because it is 400400 times closer to the Earth times closer to the Earth than the sun (even though the sun is much than the sun (even though the sun is much bigger)bigger)

Spring Tides:Spring Tides: when the sun and the when the sun and the moon act together to influence the tides moon act together to influence the tides (new & full moons)(new & full moons)

**Get highest high tide and the lowestlow tide

Neap TidesNeap Tides: when the sun and the moon : when the sun and the moon “fight” each other to influence the tides “fight” each other to influence the tides (quarter moons) (quarter moons)

**Get the lowest hightides and the highest low tides (not that dramatic of a change)

Spring & Neap Tide AnimationSpring & Neap Tide Animation

Why does the diameter of celestial objects Why does the diameter of celestial objects appear to change throughout the year?appear to change throughout the year?

Because of how close or how far the Because of how close or how far the celestial object is towards Earthcelestial object is towards Earth

**the closer the object is to Earth—the **the closer the object is to Earth—the bigger it will appear to be (and the bigger it will appear to be (and the opposite is also true)opposite is also true)

How do planets revolve around the sun?How do planets revolve around the sun?

EllipseEllipse: oval shape of a planet’s orbit: oval shape of a planet’s orbit

EccentricityEccentricity: the mathematical way to : the mathematical way to show the “oval-ness” of an ellipse.show the “oval-ness” of an ellipse.

**all eccentricity values will fall between 0 **all eccentricity values will fall between 0 and 1 with 1 being a straight line and 0 and 1 with 1 being a straight line and 0 being a perfect circle being a perfect circle

ESRT’s—Page 15ESRT’s—Page 15

**only careful measurements show that the **only careful measurements show that the Earth’s orbit is an ellipse—not a circle Earth’s orbit is an ellipse—not a circle

NOT EXACT

Why do objects revolve (orbit)?Why do objects revolve (orbit)?

1.1. Gravity: Gravity: force of attraction between a force of attraction between a satellitesatellite and the object it revolves and the object it revolves around around

**Object Needs to have mass

2.2. Inertia: Inertia: the tendency of an object in the tendency of an object in motion to continue in motion in a straight motion to continue in motion in a straight path path

****it is the it is the balancebalance between gravity and between gravity and inertia that keeps a planet in orbit inertia that keeps a planet in orbit

So how does this balance happen? Orbital SpeedOrbital Speed: the speed of a planet : the speed of a planet

around the sunaround the sun

→→The speed of a planet changes as it gets The speed of a planet changes as it gets closer to and farther away from the suncloser to and farther away from the sun

Perihelion:Perihelion: when a planet is closest to the when a planet is closest to the sun—orbital speed is fastest (our winter) sun—orbital speed is fastest (our winter)

ApAphelion:helion: when a planet is farthest from when a planet is farthest from the sun—orbital speed is slowest (our the sun—orbital speed is slowest (our summer)summer)

** “APART”

Planet motion as seen from EarthPlanet motion as seen from Earth

**because planets speed up and slow down **because planets speed up and slow down in their orbit, they sometimes appear to go in their orbit, they sometimes appear to go “backwards” as viewed from Earth“backwards” as viewed from Earth

Planet Motion

The Solar SystemThe Solar System

Solar SystemSolar System: the sun (in the center) and : the sun (in the center) and all objects that revolve around the sun all objects that revolve around the sun

Parts of the Solar SystemParts of the Solar System

1.1. Planets (2 types)Planets (2 types)

TerrestrialTerrestrial: Earth-like planets that have : Earth-like planets that have a small diameter, solid surface (high a small diameter, solid surface (high density), and are close to the sundensity), and are close to the sun

MercuryMercury (no atmosphere, cratered) (no atmosphere, cratered)

VenusVenus (thick CO (thick CO22 atmosphere—high atmosphere—high

temp. because of green house effect)temp. because of green house effect)

EarthEarth (O (O22 rich atmosphere, liquid water, rich atmosphere, liquid water,

sustains life) sustains life)

MarsMars (red planet, thin atmosphere, cold (red planet, thin atmosphere, cold temp.) temp.)

Jovian (Gas Giants)Jovian (Gas Giants): Jupiter-like planets : Jupiter-like planets that have a large diameter, low density, that have a large diameter, low density, rings, and are far from the sun rings, and are far from the sun

JupiterJupiter (largest planet) (largest planet)

Saturn Saturn (extensive ring system) (extensive ring system)

UranusUranus (really, this time)

NeptuneNeptune

ESRT’s—Page 15ESRT’s—Page 15

2.2. AsteroidsAsteroids: small rocky bodies that orbit : small rocky bodies that orbit the sun (the sun (asteroid beltasteroid belt: millions of : millions of asteroids concentrated between Mars asteroids concentrated between Mars and Jupiter) and Jupiter)

3.3. MoonsMoons: natural : natural satellitessatellites that orbit that orbit planets (a satellite is anything that orbits planets (a satellite is anything that orbits something else) something else)

4.4. CometsComets: dirty snowballs that orbit the : dirty snowballs that orbit the sun in a VERY ECCENTRIC Orbit (see sun in a VERY ECCENTRIC Orbit (see the tail because the sun heats the comet) the tail because the sun heats the comet)

5.5. MeteorsMeteors: very small (pebble) solid fragments : very small (pebble) solid fragments that orbit the sunthat orbit the sun

**sometimes they enter the Earth’s **sometimes they enter the Earth’s atmosphere and burn up—shooting stars atmosphere and burn up—shooting stars

MeteoritesMeteorites: meteors that hit the Earth’s : meteors that hit the Earth’s surface and create a surface and create a cratercrater——Impact Impact EventEvent

Stars—Including our SunStars—Including our SunStarsStars: large ball of gas that produces : large ball of gas that produces

tremendous amounts of energytremendous amounts of energy

**the Sun is the star nearest to Earth—which **the Sun is the star nearest to Earth—which is why it looks big (the only star in our is why it looks big (the only star in our solar system) solar system)

Nuclear FusionNuclear Fusion: energy source for all : energy source for all stars—nuclei of smaller elements combine stars—nuclei of smaller elements combine to make larger ones to make larger ones

H H He+ + Energy

Classification of StarsClassification of Starsstars are classified by comparing their stars are classified by comparing their

luminosity luminosity (brightness) and their (brightness) and their temperature temperature (color)(color)

Pg. 15

.

Main SequenceMain Sequence: stars that have an : stars that have an average size and temperature (90% of all average size and temperature (90% of all stars fall into this category—including the stars fall into this category—including the sun) sun)

How do stars form and evolve?How do stars form and evolve?

Originate from clouds of gas and dust—Originate from clouds of gas and dust—pressure causes fusion (pressure causes fusion (nebulanebula))

Orion Nebula

Orion Nebula

Star Evolution:Star Evolution:

Gas → Formation → Main Sequence → Giants → Dwarfs

Super Nova (exploded star)

(protostar)

Our Sun:Our Sun:SunspotsSunspots: dark patches that disappear : dark patches that disappear

and reappear at different places on the and reappear at different places on the surface of the sun surface of the sun

Our Galaxy:Our Galaxy:GalaxyGalaxy: collection of billions of stars, gas, : collection of billions of stars, gas,

and dust all held together by gravity and dust all held together by gravity

**our galaxy is called the **our galaxy is called the Milky WayMilky Way

Billions of stars make up galaxies and Billions of stars make up galaxies and billions of galaxies make up the universe!billions of galaxies make up the universe!

Universe Size—pretty amazingUniverse Size—pretty amazing

Universe Size

Evolution of the UniverseEvolution of the Universe

UniverseUniverse:: everything—size is everything—size is incomprehensibleincomprehensible

About 10-17 billion years oldAbout 10-17 billion years oldAbout 25 billion About 25 billion light-yearslight-years across across

Big Bang TheoryBig Bang Theory: explanation of how the : explanation of how the universe started—still not provenuniverse started—still not proven

→ Says that all matter and energy was concentrated into Says that all matter and energy was concentrated into an area the size of an atom and then it exploded—an area the size of an atom and then it exploded—matter went out in all directionsmatter went out in all directions

**universe is still expanding—objects are **universe is still expanding—objects are moving away from each other (this is true) moving away from each other (this is true)

Evidence that the Universe is expandingEvidence that the Universe is expanding

1.1. Background RadiationBackground Radiation: microscopic : microscopic particles that are still in motion—can be particles that are still in motion—can be picked up as staticpicked up as static

2.2. Doppler EffectDoppler Effect: “messing up” of sound : “messing up” of sound or light waves as they move toward youor light waves as they move toward you

**So what does this have to do with the Universe?

Page 14—ESRT’s

……lets look at light from a starlets look at light from a star

Stars burn different elements—and each Stars burn different elements—and each element is unique in the way it gives off element is unique in the way it gives off light (aka: wavelength or spectral lines)light (aka: wavelength or spectral lines)

Hydrogen—our Sun

But light from stars in But light from stars in galaxies moving galaxies moving away from usaway from us look different because their look different because their waves or spectra are “messed up”waves or spectra are “messed up”

Red ShiftRed Shift: movement of spectral lines of : movement of spectral lines of distant stars towards the red end of the distant stars towards the red end of the electromagnetic spectrum—moves away electromagnetic spectrum—moves away from Earth (longer wavelengths)from Earth (longer wavelengths)

Blue ShiftBlue Shift: movement of spectral lines of : movement of spectral lines of towards the blue end of the towards the blue end of the electromagnetic spectrum—moves electromagnetic spectrum—moves towards Earth (shorter wavelengths) towards Earth (shorter wavelengths)