The solar systemMR. BANKS

8TH GRADE SCIENCE

Ancient astronomers

Ancient peoples noticed that most of the stars stayed in

the same position as one another from night to night, they

called these patterns constellations.

Some stars seemed to move from night to night, they

called these wanderers or planetae.

Geocentric universe

The Greeks believed that the universe was a perfect

sphere with Earth at its center.

The geocentric system is the idea that the Earth is at the

center of the revolving planets and stars.

Geocentric universe

Later the geocentric

model was updated to

account for the retrograde

movement of the planets.

This model was accepted

for almost 1,500 years.

Heliocentric universe

Though it wasn’t accepted until the renaissance (1500’s),

another astronomer developed a different model.

In the heliocentric model, the Earth and other planets

revolve around the sun.

Heliocentric universe

Galileo used a telescope to make

discoveries that supported the

heliocentric model.

Moons revolving around Jupiter

Venus’ position near the sun

The sun

Located at the center of

the solar system.

Made of about ¾

hydrogen and ¼ helium.

Makes up 99.8% of the

Solar System’s mass.

The sun is a giant ball of

glowing plasma that’s

constantly undergoing

nuclear fusion.

It’s NOT a gas, it’s NOT

“burning”

The Sun’s interior

The Sun’s core

Where the Sun’s energy is

produced.

The sun produces energy by

nuclear fusion.

In nuclear fusion, small

atoms are joined together

to make larger ones.

Producing energy when

they do.

~15,000,000 °C and under

high pressure (the conditions

needed for fusion)

The Sun’s interior

The radiation zone

Energy produced in the core

slowly moves, mainly in the

form of electromagnetic

waves, outward from the

core of the Sun over the

course of 100,000 years.

The convection zone

Hot gasses rise from the

bottom and cool as they

rise, gradually moving

energy to the surface.

The Sun’s atmosphere

The photosphere

The gasses at the bottom of the Sun’s atmosphere. This is

where the light is released and what we see when we

look at the sun.

The Sun’s atmosphere

The chromosphere

A faint reddish colored

layer that envelops the

Sun and is only visible

during solar eclipses when

the photosphere is

blocked.

The Corona

The faintest and

outermost layer of the

sun. Made up of fast

moving particles that will

spread out and become

the solar wind.

Sunspots

Darkened areas on the surface of the sun

where cooler gasses collect and appear darker

than the other parts of the photosphere.

Solar flares

Magnetically charged

loops of gasses called

prominences extend out

into space near sunspots.

Solar flares happen when

these loops connect and

an explosive release of

magnetic energy propels

superheated gas out into

space.

Solar wind

A stream of high energy

and high speed, charged

particles that originate

from the sun and blast their

way across the solar system

and out into interstellar

space.

The intensity of the wind

can be greatly increased

by solar flares.

We are protected by

Earth’s magnetic field.

They are responsible for the

auroras (northern lights).

Chapter 20.2 - Page 706

1 a, b, c

2 a, b, c

3 b

The planets

The inner planets

Mercury, Venus, Earth, and Mars

These are known as the terrestrial planets because they

are small, dense (they don’t have super thick

atmospheres), and have rocky surfaces.

Mercury

The first planet

The smallest “planet” in the

solar system. (it’s barely larger

than Earth’s moon)

Mercury has no moons and

barely any atmosphere.

Due to its closeness to the sun

and lack of atmosphere,

Mercury experiences very

extreme temperatures.

430° C in the day and -170° C

at night

Mercury

Mercury’s surface is covered in craters, showing that there

has been very little geologic activity on the surface for the

last few billion years.

So when something hits Mercury the mark stays.

Venus

The second planet

Venus was once considered to be Earth’s “twin”

It’s about the same size as earth as well as the same density

Venus is the closest planet to Earth.

Venus’ atmosphere

The most prominent

feature of Venus is its thick

atmosphere made up

mostly of carbon dioxide.

Venus is also covered in

thick clouds made of

droplets of sulfuric acid.

The atmosphere is so thick

and heavy that the

pressure from its weight is

90 times that of Earth.

Venus’ atmosphere

Due to the thick

atmosphere, most of the

Sun’s energy is reflected

back off into space.

The energy that does

make it through is

converted into heat which

gets trapped by the

planets greenhouse effect.

Due to this, the

temperature on the

surface is ~460° C.

Venus’ surface

Using radar, probes

have found that

Venus has a rocky

surface with fewer

craters than Mercury

as well as many

large volcanos.

Venus’ surface

Many probes have been sent to Venus.

Only four sent back pictures of the surface.

The longest any of them could survive the harsh

environment was 2 hours and 7 minutes.

Earth

The third planet in the

solar system.

The only known place

that has living things.

Water covers 70% of

the planet’s surface.

It is unique in that it

has water in all three

physical forms. (solid,

liquid, and gas)

Has an atmosphere

that is not too thick or

too thin.

The moon

The moon is Earth’s only

natural satellite.

In ancient times, people

thought that the surface of

the moon was more like

Earth’s.

They thought the dark spots

were oceans, the light spots

mountains, and the craters

volcanos.

The moon is made up of

mostly solid rock.

The moon

We now know that the moon is

made up of mostly rock.

The top layer is a very fine

powder.

There is no atmosphere on the

moon.

There is evidence that water

exists as ice at the poles of the

moon.

Due to the lack of atmosphere,

lunar temperatures vary

greatly from 130° C in the day

to -180 ° C at night.

The moon

The moon is only about 1/50

the size of earth. It is about as

wide as the US.

The other planets in the solar

system could fit in the space

between Earth and the moon.

Origin of the moon

The moon might have formed along with the Earth or it

might have been captured by Earth’s gravity after

forming elsewhere.

The collision hypothesis

About 4.5 billion years ago a planet sized object collided

with Earth. The collison ejected material from earth’s outer

layers into space. The ejected material collected together

in orbit around the earth eventually forming the moon.

Mars

The fourth planet

Reddish in color due to an

abundance of iron rich

rocks on its surface.

Mars

Mars is the most Earth-like

planet in the solar system,

however you wouldn’t want

to live there.

Mars is a little over half the

diameter of earth.

Mars’ atmosphere is very

thin compared to ours, and

is 95% CO2

Temperatures range from

20° C to -130° C.

Mars’ surface

Mars has a rocky

surface that is

reshaped by erosion

from dust storms.

Mars has giant

volcanos on its surface,

however they are no

longer active.

Water on Mars

Today, the only water on Mars

is frozen at the poles.

Scientists think that long ago

before Mars’ core solidified, its

atmosphere was thicker,

temperatures were warmer,

and there was a large amount

of liquid water.

Mars’ moons

Mars has two moons.

Both moons are very small.

Deimos – 15 kilometers in

diameter.

Phobos – 27 kilometers in

diameter.

Phobos has a degrading orbit

and is slowly spiraling in

towards Mars. It’s expected to

crash into the Martian surface

in about 40 million years.

The outer planets

Jupiter, Saturn, Uranus, and Neptune

The outer planets

All four are gas giants, incredibly large, massive planets

that do not have a solid surface, instead they have a

thick atmosphere surrounding a super thick liquid layer

around a small solid core.

Jupiter

The fifth planet

Largest planet in the

solar system.

1,300 Earths could fit

inside Jupiter.

Jupiter alone is 2 ½

times the size of all

the other planets

combined.

Jupiter is mainly made

of hydrogen and

helium (like the sun)

Jupiter’s layers

Jupiter is thought to have 4 primary layers

Hydrogen and helium gas

Liquid-metallic hydrogen and helium

Liquid water and heavier elements

Solid, rocky core

The air/liquid pressure goes up as you go down deeper.

At the core it’s 30 million times the pressure on Earth

The red spot

Jupiter’s “red spot” is a

storm, similar to a

hurricane.

It was first observed in

the 1600’s.

Current observations

show that it is changing

shape and possibly

shrinking.

However, it is still very,

very large.

Jupiter’s moons

Jupiter has 67 known moons

There are four large moons and the rest are

comparatively tiny

Galilean moons

Io, Europa, Ganymede, and

Callisto.

All four are larger than the

dwarf planets and

Ganymede is larger than

Mercury.

Galilean moons

Io – The most geologically

active object in the solar

system, covered in volcanos

and huge mountains.

Callisto – Not as active as the

other large moons, rocky

surface, may have water

deep underground.

Ganymede – Covered in

thick layers of ice, liquid

water may exist sandwiched

between ice layers.

Europa

A rocky moon with a crust

made of ice likely with

liquid water underneath.

Slightly smaller than Earth’s

moon.

Heated from below by an

active core.

Now thought to be the

most likely home of

extraterrestrial life in our

solar system.

Saturn

The sixth planet

Second largest planet in the solar system

It is a gas giant similar to Jupiter

Mostly made of hydrogen and helium

Saturn’s rings

Planetary rings are made of small particles (99.9% ice) of

material individually orbiting the planet.

Saturn’s rings vary from 10 meters to 1 kilometer in thickness.

All the gas giant planets have rings of varying sizes.

Earth

Saturn’s moons

Saturn has 62 known moons

and many small moonlets.

Titan - Saturn’s largest moon,

has a thick atmosphere and a

cycle, similar to Earth’s water

cycle, that occurs with the

compounds methane and

ethane.

Uranus

Pronounced YOOR-uh-nus

The seventh planet in the

solar system.

Its blue-green color

comes from the methane

present in its atmosphere.

However, it’s atmosphere

is mostly hydrogen and

helium.

Uranus rotates on its side.

It is thought that at some

point the planet was hit

by a large object that

caused its odd rotation.

Neptune

The eighth and last

planet.

Like Uranus, Neptune’s

atmosphere is mostly

hydrogen and helium and

its blue color comes from

methane.

Uranus and Neptune are

also similar temperatures,

averaging around -200° C

The “great black spot” is a

storm similar to Jupiter’s.

It reforms and disappears

every few years.

Ice giants

Many scientists want to

reclassify Uranus and

Neptune as “ice giants”

They are only about

20% hydrogen and

helium (vs Saturn and

Jupiter’s >90%)

The majority of each

planet is made up of a

thick layer of “fluid”

ices.

Dwarf planets

Following the discovery of multiple objects similar to Pluto

(and one that was even bigger than Pluto) a new

classification for planets was created.

1. The object must be in orbit around the Sun.

2. The object must be massive enough to be a sphere by its

own gravitational force.

3. It must have cleared the neighborhood around its orbit.

There can’t be any other large objects near the path the “planet” orbits in.

Dwarf planets

There are currently five

confirmed dwarf planets

Pluto, Ceres, Haumea,

Makemake, and Eris

There are an estimated

200 dwarf planets in the

area “near” Pluto, and as

many as 10,000 dwarf

planets orbiting the sun at

extreme distances.

Pluto

The first dwarf planet

discovered.

Pluto is small, about 2/3 the

size of our moon.

We know little about Pluto, it is

likely rocky and very cold.

It has five moons – the largest,

Charon is about 1/10 the size

of Pluto itself.

Pluto

Pluto has a very odd orbit

compared to the other

planets, another reason it

didn’t make sense to

include it as a planet.

New horizons

A space probe launched in 2006 on a mission to

investigate Pluto.

It has also investigated an

asteroid and Jupiter on

the way.

It’s currently 59,000,000 mi

from Pluto.

The dwarf planets

Eris – The largest dwarf

planet, ¼ the size of Earth.

Takes 558 years to orbit the

sun.

Haumea – Has two moons,

observations of telescope

images suggest that

Haumea is an ellipsoid.

Makemake – Not much is

known about it besides that

it is about 2/3 the size of

Pluto.

Ceres The largest object in the

asteroid belt between Mars

and Jupiter.

There are a pair of bright

spots located in a crater,

it’s not clear what they are.

It accounts for 1/3 of the

total mass of the asteroid

belt.

Ceres has a thin dusty outer

layer over a layer of water

ice with a rocky core.

The Dawn space probe

entered into orbit on April

24th and should help gather

more info on Ceres.

Pluto update

Comets

A small object orbiting the sun

in an elliptical orbit.

When it passes close to the sun,

the comet heats up and the

materials that make up the

comet begin to escape out into

space.

The materials are blown away

in the solar wind and from a

stream of visible particles

known as the tail of the comet.

This can include water, carbon

dioxide, methane, ammonia or

even rock dust.

Rosetta

Launched in 2004.

Investigated several asteroids

before achieving successful

orbit around the comet 67P.

Asteroids

Also known as minor planets or planetoids.

Defined as anything above a certain size that isn’t

rounded like a planet and isn’t a comet.

Can range in size from 1,000 km to 10 m.

Generally composed of rock and ice.

Meteors

A small rocky or metallic

object traveling through

space.

They range in size from a

grain of sand to 1 meter

wide.

Most are fragments that

have broken off comets or

asteroids.

Meteors that enter Earth’s

atmosphere are the

“shooting stars” seen at

night.

Meteors

As they fall through the

atmosphere, friction from air

molecules heat the surface of

the meteor and melt/break it

apart.

What lands is only a small

fraction of the original object.

In space they are known as

meteoroids.

When falling through the

atmosphere they are meteors.

And on Earth they are

meteorites.

The asteroid belt A region of space roughly

between Jupiter and Mars

that is occupied by

millions of asteroids.

We’ve identified

hundreds of thousands.

Over 200 are greater

than100 km wide.

Collisions between

asteroids happen

frequently (on an

astronomical time scale)

with large asteroids

colliding about every 10

million years.

The Kuiper belt

Similar to the asteroid belt in that it contains large numbers of “small” objects.

However it is far wider and there are much more massive objects located there.

All the known dwarf planets besides Ceres are located there.

It extends from the orbit of Neptune outward another 1,800,000,000 miles.

The Oort cloud

A theoretical sphere of icy bodies that extends out far away from the Sun, as far as 2 light years.

Studies of comets and their orbits have given rise to the hypothetical existence of this region.

The Oort cloud comprises the theoretical extent of the gravitational influence of the sun.

None of our current probes will reach what is thought the be the outer edge of the cloud before their batteries run out.