The Solar System
by,
Drew Harris 
What’s a Solar System?
A solar system is a set of satellites floating
around a central star. A satellite is an object that
floats around another object. A star is a large sphere
of burning gases.
Our solar system is where the planets, including Earth, orbit the sun,
or rotate around it. A planet is a large object that moves around a star. Our
solar system is a solar system because the sun is a star. It
is also the only star in our
solar system. Our sun is
only a medium size star.
Why does Day and Night Occur?
Day and Night occur because the sun is
Earth’s main light. The part of Earth
having day is facing the sun. The part of
Earth having night is facing away from
the sun.
Why do we have
Different Seasons?
We have different
seasons because of the tilt
of Earth’s axis. Axis is the
imaginary line that goes
through the Earth.
Almost all of the
planets have a tilt in it’s
axis. In fact, Mercury is the
only planet without a
tilt in it’s axis.
Uranus is tilted so far
it’s tipped over and on its
side!
What’s the Difference
Between a Planet and a Star?
A planet looks and moves
different from a star. Stars are
different in size and color. Our
sun is actually a small star, it only
appears big because it’s so close
to us. The color of a star depends
on how hot it is.
Red stars are the coolest and
blue stars are the hottest.
How many Stars are there?
There are more
stars than one
person can count in
an entire lifetime.
Constellations
• What is a constellation?
• Constellations are totally
imaginary things that poets,
farmers and astronomers have
made up over the past 6,000
years to help us tell which
stars are which. On a really
dark night you can see about
1,000 to 1,500 stars.
• The northern hemisphere’s
signpost is the Big Dipper.
• Where did constellations
come from?
• Farmers used the
constellations to help them
know when to plant and when
to harvest their crops because
different constellations are
visible at different times of the
year.
• There are 88 constellations.
• Stars do not appear to move
because they are so far away
from the Earth.
Why do Constellation
locations change?
Constellation locations
change by the Earth
turning on it’s axis. This
may be how it moves in
the sky. Stars do move.
Different stars can be
seen in different seasons.
Stars also have different
colors and sizes.
Stars are
grouped together in
patterns called
constellations.
How are planets and
stars alike and different?
Planets
stars
• look like a point of light
in the night sky.
• appear to change their
positions.
• just a few can be seen.
• are closer to us than
stars.
• look like a point of light
in the night sky
• appear to not change
their positions.
• many can be seen.
• do not change locations
on different days.
• are further away from us
than planets.
What are the planets in
order from the sun?
It’s “My Very Energetic Mother Just Served Us Noodles.” That’s a
mnemonic device, or a way to remember (memory aid), the order of the
planets. The order is: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
and Neptune.
Mercury
Mercury
Mercury is the closest planet to the sun and is about the
size of Earth’s moon. It even looks like the moon. It has the
temperature range of 800.6-361.4 F. It rotates, or turns, on its
axis every 58.9 days and revolves, or circles, the sun every
87.9 days. Mercury has no moons and is the smallest planet.
Galileo Galilei discovered Mercury in 1610. Mercury is 1/3 the
size of the Earth.
Venus
Venus – 2nd planet from the sun
If Earth had a twin it would be Venus. They are similar in size, mass,
composition, and distance from the sun. However, Venus is very dry and has
a thick atmosphere that transfers heat. It has a thick, swirling cloud cover.
The atmosphere presses down100 times that of Earth. Venus is the second
planet from the sun, in between Mercury and Earth. Venus rotates east to
west so the sun rises in the west and sets in the east (opposite of the
Earth). Venus has a cloud covering it, but we know that it has vast plains
covered by lava and mountains with many craters. Venus is the hottest
planet with a temperature of 899.6 F. Venus has no moons or oceans.
Venus has been visited by more spacecraft than any other planet. It has a
thick atmosphere of carbon dioxide and other poisonous gases.
A space probe is an uncrewed space vehicle that carries cameras,
instruments, and other research tools.
Earth
Earth
Earth is the only planet known to have life. It’s the 3rd planet from the
sun and the 5th largest. Earth is 70% covered with oceans. The oceans have
the most life (habitats). Earth is the only planet with liquid water and the
largest of the inner planets. Earth has an atmosphere that protects us from
meteors. The Earth was last in its present position in the Milky Way at the
beginning of the age of Dinosaurs. The 1st artificial satellite of Earth was
Sputnik 1 U.S.S.R. Earth has one moon. It takes Earth 23.93 hours to rotate
around its axis and 365.26 days to revolve around the sun. Earth’s
atmosphere is mostly made of nitrogen and oxygen.
Earth has seasons because of its tilt on its axis as it revolves around the
sun.
Earth has day and night because it rotates on its axis.
Mars
Mars
Mars, the fourth planet from the sun, is known as the Red Planet
because of chemical weathering of its iron rich rocks and was thought of
as the most likely planet to hold life besides Earth. Mars may have held life
long, long ago. They also believe that the dryness of the soil, the sun’s
ultraviolet radiation, and the soil chemistry prevent life on Mars. Mars is
most like Earth of all planets. It has polar ice caps and seasons. Mars has
two moons. Mars’ atmosphere is carbon dioxide. Water ice was found on
Mars in June 2008. Mars has the largest volcano in the solar system called
Olympus Mons.
4
The Inner Planets
The Inner Planets
The 1st four planets, Mercury, Venus, Earth, and Mars, are known as
the Inner Planets and terrestrial planets, or most likely to be possible to
have life, because of their rocky surfaces. There is an asteroid belt
separating the inner and outer planets. Asteroids are small, rocky objects
that move around the sun.
Jupiter
Jupiter
Jupiter, the fifth planet from the sun, has 50 known moons, a ring
system of three, and a complex atmosphere. Jupiter is the largest planet in
the solar system and outer planets. It’s so big that it’s bigger than all the
other planets combined. It has an “Easter egg” appearance due to its many
different colors. It’s mostly known for its Great Red Spot, a hurricane-like
storm cell so big it could swallow Earth. It’s lasted for over 300 years.
Galileo Galilei discovered four of Jupiter’s moons. Jupiter has three thin,
barely visible rings.
Saturn
Saturn
Saturn is the 6th planet from the sun and one of the outer planets.
Saturn is a giant, gaseous planet and has seven rings and 53 known
moons. Saturn is so light it could float. Wind on Saturn is 10 times stronger
than a hurricane. Saturn is the most distant planet visible without a
telescope, or a tool to make things in space appear closer. Galileo Galilei
discovered Saturn’s rings in 1610. The other two planets can be seen with
a telescope.
The rings are made of dust and ice.
Uranus
Uranus
Uranus has 27 moons and 11 rings. The 1st nine were discovered in
1977. Uranus looks blue green because of methane gas in its atmosphere.
Uranus is tipped on its side, maybe because of a collision with a planet sized
object like a comet or asteroid. A comet is a small mass of dust and ice that
orbits the sun in an oval shaped path. Sir William Herschel discovered
Uranus in 1781.
All the asteroids put together would make an object less than half the
size of Earth’s moon.
Neptune
Neptune
Neptune is the 8th, and furthest planet from the sun. Johann Galle
discovered Neptune in 1846. It has 13 moons. It also has four rings.
Neptune is aqua blue because its clouds contain methane ice crystals and
has the strongest winds of any planet.
The Outer Planets
The Outer Planets
On the other side of the asteroid belt are the outer planets. They
are Jupiter, Saturn, Uranus, and Neptune. They are all large and made
mostly of gases so they’re called the gas giants. They are mostly hydrogen
and helium.
Comets
Comets are dirty leftovers from the creation of our solar system about
4.5 billion years ago. Most come from a distant region called the Oort Cloud
about 100,000 astronomical units from the sun. There is another belt that
orbits the sun outside of Pluto called the Kuiper Belt.
Dwarf Planet Pluto
Dwarf Planet Pluto
Pluto isn’t a planet, but a dwarf planet because its orbit changes. It is
smaller than the normal planets and it has a moon (Charon) that is close to
its own size. Pluto’s moon, Charon, is smaller than Earth’s moon. Pluto has
never been visited by spacecraft. Pluto was discovered in 1930. Every 20
years, Pluto trades places with Neptune (is in front of Neptune). From Pluto
the sun looks like a very bright star. Little heat or light reaches Pluto or its
three moons. Pluto is 6 billion Kilometers from the Sun.
The Sun
The Sun
The sun is the only body in our solar system that gives light of its own
and is the source of almost all the energy in our solar system. It’s over 100
times wider than Earth. It takes up as much space as 1,000,000 (1 million)
planets the size of Earth. The sun is mostly hydrogen which is basically its
fuel. The sun is a star and has been shining for nearly 5,000,000,000 (5
billion) years.
One revolution of the Earth around the sun is one year. Revolution is
the movement of any object in an orbit.
The dark areas of the sun are called sunspots which are cooler than
the rest of the sun’s surface and do not give off much light.
The Moon
The Moon
The moon is about ¼ the size of Earth. The moon’s outer crust was
shed during its formation leaving an egg shape. That shape makes the same
side face the Earth at all times. Galileo Galilei discovered the moon in 1610.
The Apollo 11 mission went to the moon in 1969. There Armstrong stepped
on the moon and said the famous quote, “That’s one small step for man;
one giant leap for mankind!”
The Moon … continued
The reason the moon changes
shape is that the moon’s light
is actually being reflected off
of the sun. It uses that light to
reflect light so it doesn’t really
change shape.
Vocabulary
• satellite – An object that moves around another
object in space; the moon is a satellite of Earth.
•
• orbit – The path that an object such as a planet
makes as it revolves around a second object.
•
• phase – One of the different shapes the moon
seems to have as it orbits around Earth.
•
• revolution – The movement of any object in an
orbit, such as Earth moving around the sun.
•
Vocabulary
• axis – An imaginary line which runs through both poles of a
planet.
• rotation – The motion of a planet or other object as it turns
on its axis.
• solar system – A group of objects in space that move around
a central star.
• star – a huge, burning sphere of gases; for example, the sun.
• planet – A large object that moves around a star.
Vocabulary
• asteroid – A small rocky object that moves around the sun.
• comet – A small mass of dust and ice that orbits the sun in a
long, oval-shaped path.
• inner planets – The planets closest to the sun; Mercury,
Venus, Earth, and Mars.
• outer planets – The planets farthest from the sun; Jupiter,
Saturn, Uranus, and Neptune.
Vocabulary
• Gas giants – Planets which are large spheres made up mostly
of gases – for example Jupiter, Saturn, Uranus, and Neptune.
• telescope – A device people use to observe distant objects
with their eyes.
• space probe – An uncrewed space vehicle that carries
cameras, instruments, and other research tools.
Facts
www.nasa.gov
• Our Solar System – in order from the sun:
• Sun – Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune
• The sun is about 150,000 kilometers (93 million miles) from the Earth. It would take you about 193
years to travel this distance in a car at highway speed!
• About 500,000 craters can be seen on the moon through telescopes on Earth. It would take you more
than 400 hours to count them all. And this doesn’t include the craters on the far side of the moon!
• Like most of the planets, Earth has seasons because it is tilted on its axis. But no planet is tilted like
Uranus. Uranus is tilted so far that it is tipped over on its side! This gives Uranus a winter that lasts
about 21 years!
• The planets from smallest to largest:
Mercury, Mars, Venus, Earth,
Neptune, Uranus, Saturn, Jupiter
• (MMVENUSJ)
More Facts
• Background Information:
• Johannes Kepler’s Laws of Planetary Motion – Johannes
Kepler, a German mathematician who lived from 1571 to
1630, recognized that planets travel around the sun in
elliptical rather than circular orbits. His observations
resulted in what are now called Kepler’s three laws of
planetary motion:
• 1. All planets move in elliptical orbits having the sun as
one focus (Law of Orbits).
• 2. A line joining any planet to the sun sweeps out equal
areas in equal times (Law of Areas). This means that the
velocity of a planet is different at different places in its orbit.
• 3. The square of the orbital period (year) of any planet
about the sun is proportional to the cube of the planet’s
mean distance from the sun (Laws of Periods).