A journey through our neighboring planets The Solar System A journey through our neighboring planets

Learning Objectives Analyze the size and scale of our solar system. Explain events in the formation of the solar system. Compare the terrestrial (rocky) planets to the Jovian (gaseous) planets. Distinguish key characteristics of the planets and objects in our solar system.

Scale of the Solar System The size of the solar system is HUMONGOUS! Yet our solar system is a tiny speck when compared to stars in our galaxy, which is only one of billions.

Scale of the Planets The Sun makes up 99.86% of the entire mass of the entire solar system. Figure 2 from page 646 shows the scale size of the planets. Look at how tiny our planet is compared to the gas giants and especially the sun!

The NEBULAR THEORY The NEBULAR THEORY provides an explanation of how about 5 billion years ago our solar system was formed. See figure 3, page 647.

ASTRONOMICAL Units Astronomers use astronomical units, AU, to measure how far planets are from each other. AU is the distance from the Earth to the sun - a whopping 150,000,000km It would take 17 years to travel this far in a jet going the speed of a bullet 1,000km/hr!

The Sun: OUR STAR The sun is the biggest, brightest, and hottest object in the solar system. Diameter= 1.4 million km Made of about 70% hydrogen and 28% helium. Could hold a million Earth’s inside.

Mercury Mercury is solid and is covered with craters. Diameter= 4878km Mercury has almost no atmosphere. Mercury is the smallest true planet.

Venus Venus is the sixth largest planet. It’s about three-fourths the size of earth. Diameter= 12,104km The surface is rocky and very hot. The 97% CO2 atmosphere completely hides the surface and traps the heat.

Earth Earth is the fifth largest planet and the third from the sun. A terrestrial planet with an atmosphere made of 71% Nitrogen and 28% Oxygen Diameter= 12,756km Liquid water covers 71 percent of the Earth’s surface. The Earth has one moon.

Moon: Luna

Mars Mars is the fourth rocky planet from the sun. Diameter= 6,794km Mars has a thin atmosphere that contains mostly carbon dioxide. Mars has two small moons.

Moons of Mars Phobos Deimos

Let’s Review How was the solar system formed? What is an astronomical unit and why is it used? What are the name of the terrestrial planets? Which planets have no moons?

Jupiter: The Giant Planet The largest of the planets. Can hold 1,300 and the rest of the planets. Diameter= 143,884km Has hydrogen-helium atmosphere

Jupiter’s Red Spot The Great Red Spot, a huge storm of swirling gas that has lasted for hundreds of years and is the size of 3 Earths. Jupiter does not have a solid surface. The planet is a ball of liquid surrounded by gas.

Moons of Jupiter Jupiter has four large Galilean moons, twelve smaller named moons and over 40 irregular satellites for a total of 63 moons We’ll take a look at the four large Galilean moons which were first observed by Galileo Galilei in 1610.

Io Io is the fifth moon of Jupiter. It’s the third largest of Jupiter’s moons. Io has hundreds of volcanic calderas. Some of the volcanoes are active.

Europa Europa is the sixth of Jupiter’s moons and is the fourth largest. It is slightly smaller than the Earth’s moon. The surface strongly resembles images of sea ice on Earth. There may be a liquid water sea under the crust. Europa is one of the five known moons in the solar system to have an atmosphere.

Ganymede Ganymede is the seventh and largest of Jupiter’s known satellites. Ganymede has extensive cratering and an icy crust.

Callisto Callisto is the eighth of Jupiter’s known satellites and the second largest. Callisto has the oldest, most cratered surface of any body yet observed in the solar system.

Saturn Saturn is the second largest planet and the sixth from the sun. Diameter= 120,536km Saturn is made of materials that are lighter than water. If you could fit Saturn in a lake, it would float! Has 56 Moons

Rings of Saturn Saturn’s rings are not solid; they are composed of small countless particles. The rings are very thin. Though they’re 250,000km or more in diameter, they’re less than one kilometer thick.

Uranus Uranus is the third largest planet and the seventh from the sun. Diameter= 51,118km Uranus is blue-green because of the methane in its atmosphere. Has 27 moons

Neptune Neptune is the fourth largest planet and the eight from the sun. Diameter= 50,530km Like Uranus, the methane atmosphere gives Neptune its color. Has 13 moons.

Pluto Pluto is a dwarf planet and usually the farthest from the sun. Pluto is the only “planet” that has not been visited by a spacecraft. Diameter= 2,300km

Planet Movements Move in an elliptical orbit influenced by the sun’ gravity

Period of Revolution the time it takes to go once around the sun one year on Earth (365.25 days) Mercury 88 days, Pluto 248 years Why is the revolution period longer for farther planets?

What keeps them there? Law of inertia - objects motion won’t change unless acted upon by an outside force. Won’t change speed or direction Why do they curve? Gravity pulls them toward the sun

What keeps them there? Inertia Gravity SUN

Rotation Planets spin on their axes One rotation is a day Mercury 58 days, Jupiter 10 hours Why do you think rotation is faster for larger planets?

Analyze This What trend do you notice within this graph?

Analyze This Notice the materials which make the planets. Which planets are more dense? Read page 648 to learn how gravity also influenced the structure and size of the planets.

Other Space Stuff Comets: chunks of dust and gas that originate from the Oort cloud on the edge of the solar system. Asteroids: chunks of planetlike material floating in space mostly between Mars and Jupiter.

Other Space Stuff Meteor: the shooting star -the light you see the sky Meteoroid: solid rocky objects circling the sun Meteorite: When a meteor hits the ground Most don’t reach the ground because they burn up in the atmosphere