6 - Unit 5, Section 2

The Solar System

Unit 5, Section 2

• Solar System

• Astronomical Unit

• Inner Planet

• Outer Planets

• Dwarf Planet

• Comet

• Meteoroid

• Meteor

• Meteorite

Vocabulary

• Solar System - the Sun, its eight planets, their moons, and everything else that orbits it

• The Solar System is held together by the Sun's gravity

What is the Solar System?

The Planets, In Order

• Mercury

• Venus

• Earth

• Mars

• Jupiter

• Saturn

• Uranus

• Neptune

​Do you want the remember these?

Make a mnemonic!

Open Ended

Would you measure the distance from here to Dallas in millimeters (mm)? Explain your answer.

The Astronomical Unit

• Astronomers use astronomical units to measure distances in the Solar System

  • One astronomical unit (AU) = the average distance from the Sun to Earth

  • 1 AU ~ 150,000,000 km

  • The distance from the Sun to Earth is 1 AU

• Example: Jupiter is 5.2 AU from the Sun

• There are two types of planets in the Solar System:

  • Inner Planets

  • Outer Planets

• These are separated by the asteroid belt

The Planets

• Inner Planets - the four planets closest to the Sun

• Mercury, Venus, Earth, and Mars

• Also called rocky planets because they are mostly solid and contain minerals similar to those found on Earth

The Inner Planets

• Mercury is the smallest planet in the Solar System

• That means it has very little gravity

Mercury

• Venus' atmosphere is mostly carbon dioxide

• It's covered in clouds made of sulfur dioxide and sulfuric acid

Venus

• Hey, that's us!

• We're not too hot, nor too cold

• We have liquid water on our surface

• Our atmosphere blocks solar wind and ultraviolet radiation

Earth

• The last of the inner planets

• It has polar ice caps and seasons

• There's evidence it once had liquid water

Mars

• The asteroid belt is between Mars and Jupiter

• Asteroids - pieces of rock that contain minerals to those similar to the rocky planets

• We're not sure why it exists!

The Asteroid Belt

• The outer planets are also called gas giants because they're made almost entirely of gas

• They also have multiple moons

The Outer Planets

• The largest planet in the Solar System - it could hold 125 Earths

• It also has the Great Red Spot, which is a huge storm

Jupiter

• It has visible rings made of dust and small rocks!

• It has Titan, a moon with an atmosphere similar to Earth's early atmosphere (we think)

Saturn

• It's "tilted" on its side, with its axis pointing almost directly at the Sun

• It has a hydrogen/helium atmosphere

• It also has faint rings

Uranus

• It's a lot like Uranus!

  • Similar atmosphere

  • Similar color

  • It has faint rings

• Lava likely flows on its surface

Neptune

What Makes a Planet a Planet?

• The International Astronomical Union have decided that a planet must:

  • Orbit the Sun, or another star

  • Have enough mass to be round, or nearly round

  • Is not a satellite of any other object than its star

  • Has removed all debris and small objects from the area around its orbit

• If it doesn't meet the last requirement, it's classified as a dwarf planet

• One of five dwarf planets in the Solar System

• It's also a rocky dwarf planet outside the asteroid belt

• Huh, that's neat

Pluto

In addition to planets, dwarf planets, and asteroids, there are two other types of objects in our Solar System:

• Comets

• Meteorites

Other Solar System Objects

• Comet - a large body of ice and rock that revolves out the Sun

• Comets can come from:

• The Oort Cloud (50,000 AU from the Sun)

• The Kuiper Belt (just beyond Pluto's orbit)

• As they approach the Sun, solar wind vaporizes some of the ice, which trails behind the comet as a tail

Comets

A smaller asteroid made of rock and/or ice

Meteoroid

The light a meteoroid or asteroid gives off as it burns up in the atmosphere

Meteor

The remaining fragments of a meteoroid that land on Earth

Meteorite

Why Are Meteorites Important?

• A lot of meteorites are approximately 4.5 billion years old, which is close to the age of the Solar System

• So, they may give us clues about how the Solar System formed

• Larger ones can be. . .destructive?

• How destructive?

• The Chicxulub Impact, which likely killed the dinosaurs

• That's the Yucatan Peninsula (Mexico) that it's hitting

• So, yeah, maybe it's important that we study them

This Destructive.