The solar systemMR. BANKS

8TH GRADE SCIENCE

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

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 collision 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, most of the 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

A large object in space resembling a planet, but doesn’t

meet the technical definition of a planet.

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.

The surface of Pluto is mostly

of nitrogen ice with a thick

layer of water ice and a

rocky core.

The lack of craters on several

areas of Pluto’s surface

indicates that there is

geologic activity. Probably in

the form of glaciers.

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.

Pluto

Pluto has five moons – the largest,

Charon is about 1/10 the size of

Pluto itself.

Charon is big enough that it and

Pluto orbit each other.

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.

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.

Dwarf Planets

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.

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 10 meters

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.