Our Solar SystemUnit 5: Sixth Grade

Our Solar System Did you know that

planets, when viewed from Earth, look like stars to the naked eye?

Ancient astronomers were intrigued by these “stars” which seemed to wander in the sky

Our Solar System Ancient astronomers

named these “stars” planets, which means “wanderers” in Greek.

These astronomers knew planets were physical bodies and could predict their patterns.

But it was not until Galileo used a telescope in the 1600’s that we able to explore these other worlds.

A Combination of Systems

Our solar system includes the Sun, the planets and many other smaller objects.

Some planets, such as Saturn, have several moons that orbit them, and in this way, our solar system is a combination of many other systems

The Discovery of the Solar System

Up until the 1600’s, the universe was thought to have only 8 bodies (things): the Earth, the Sun, the Earth’s Moon, and Mercury, Venus, Mars, Jupiter and Saturn.

They are the only bodies visible without a telescope

The Discovery of the Solar System

After the discovery of the telescope, more discoveries were made and the current model of our solar system was in place by the 1900’s

Inner and Outer Solar System

Our solar system is divided into two main parts: The inner solar system The outer solar system

The inner solar system contains the four planets that are closest to the sun

The outer planets contains the planets farthest from the sun

Inner and Outer Planets

Inner Planets Mercury, Venus, Earth,

Mars. More closely spaced Known as terrestrial

planets as they are dense and rocky

Outer Planets Jupiter, Saturn,

Uranus, Neptune, Pluto*

Larger in size and tend to be made of gases

Known as “Gas Giants”

The Inner Planets Inner planets are

also called terrestrial planets because they are very dense and rocky.

They are the four planets closest to the sun: Mercury, Venus, Earth, Mars

Mercury Distance from the sun: 3.2

light minutes Period of revolution: 88

days (year) Period of rotation: (59 days) Average temperature:332F,

167C Diameter: 3,032 miles,

4,879 K Closest planet to the sun. Because there is less

gravity, you would only weigh 38% of what you do here on Earth!

Venus 6.0 light minutes from the

sun Period of revolution: 224

days Period of rotation: 243 days Average temperature:457F,

854C Diameter: 7,520 miles,

12,100K Sun rises in the west and

sets in the east. Sometimes called “Earth’s

Twin” as it is similar in size and distance from the sun.

Earth Distance from the sun:

8.3 light minutes Period of revolution:

365.25 days Period of rotation: 24

hours Average temperature:

57F, 15C Diameter:7,926 miles,

12,756K The only planet to

support life in our solar system.

What makes our Earth different from other planets?

We have life on Earth due to several reasons:

The “perfect” star The right distance

from the star Revolution around the

star 23.5 degree tilt Rotation on our axis WATER

Mars Distance from the sun: 12.7

light-minutes Period of revolution: 687 days Period of rotation: 24 hours,

40 minutes Average temperature: - 81 °F,

--63 °C Diameter: 4,222 miles, 6,794

km The most studied planet after

Earth. While there is no water on

Mars presently, there is evidence that it was once present

The Outer Planets Because they are so much

larger than the inner planets, the outer planets are called gas giants.

Gas giants are planets that have deep, massive atmospheres rather than hard, rocky surfaces like the inner planets have.

The Outer Planets include: Jupiter, Saturn, Uranus, Neptune, and Pluto*

Jupiter Distance from the sun: 43.3

light minutes Period of revolution: 11

years, 313 days Period of rotation: 9 hours,

54 minutes Average temperature:-

202F,- -130C Diameter: 88,846 miles,

142,984 km The largest planet in our

solar system The red spot is a 400 year

old storm that is 3 times the diameter of Earth!

Saturn Distance from the sun:

1.3 light-hours Period of revolution: 29

years, 155 days Period of rotation: 10

hours, 42 minutes. Average temperature:-202

°F, 130 °C Diameter: 74,900 miles,

120,536 km The second largest planet. The rings around Saturn

are made of icy particles.

Uranus Distance from the Sun: 2.7

light-hours Period of revolution: 83 years,

273 days Period of rotation: 17 hours,

12 minutes Average temperature:-328 °F,

--- -200 °C Diameter: 31,763

miles,51,118 km Uranus is tipped on its side

and one of its poles is always dark, depending on where the planet is on its journey around the sun.

This tilting is thought to be a result of being hit by a massive object.

Neptune Distance from the Sun: 4.2

light-hours Period of revolution: 163

years, 263 days Period of rotation: 16 hours, 6

minutes Average temperature:-328

°F, -200 °C Diameter: 30,779 miles,

49,532 km Neptune has a Great Dark

Spot similar to Jupiter’s Great Red Spot.

Neptune has a narrow set of rings.

Pluto* Distance from the Sun: 5.4 light-

hours Period of revolution: 248 years,

4 days Period of rotation: 6 days, 10

hours Average temperature:-378 °F, -228 °C Diameter: 1430 miles,2,390 km Pluto was reclassified as a dwarf

planet in 2006. Less than half the size of

Mercury and mainly made of ice and rock.

It’s moon, Charon, is almost the same size as Pluto.

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What keeps us, and the other planets in orbit around the sun?

Two words: gravity and inertia!

Gravity is the force that keeps the planets in the Sun’s orbit.

Inertia is the law that an object in motion will stay in motion unless acted upon by an outside force.

Gravity In the case of the sun

and the planets, the Sun is larger and has more mass, and thus a stronger gravitational pull.

It’s always tugging us toward it, wanting to suck us in and burn us alive!!!

So it’s a wonderful thing that we also have inertia…

Inertia Inertia works against

that gravity to keep us from being sucked into the sun.

Because of inertia, planets want to travel in a straight line and never stop moving in that straight line.

So it’s a good thing that we have gravity …

Gravity and Inertia Because gravity

keeps us from flying off into space (never to be seen again)!

Gravity and inertia’s fight for the planets is what keeps us in the Sun’s orbit.

Fun Space Facts Pluto never made a full orbit around the sun from

the time it was discovered to when it was declassified as a planet.

There are more stars in space than there are grains of sand on every beach on Earth.

It rains diamonds on Saturn and Jupiter. If you dug a hole to the center of the Earth and

dropped a book down, it would take 42 minutes to reach the bottom.