The Sun

&

The Solar System

Structure of the Sun

• The Sun has layers which can be compared to the Earth’s core, mantle, crust, and atmosphere

• All of these layers except the core has a unique name as a part of the sun

Structure of the Sun (continued)

• Core = Center of the Sun, comparable to the inner core on Earth

• Radiative Zone = Layer surrounding the core, similar to the Earth’s outer core

• Convective Zone = Similar to the Earth’s mantle

Structure of the Sun (continued)

• Photosphere = The surface of the sun. Equivalent to the Earth’s crust. The photosphere is what we see from Earth.

• Chromosphere = The Sun’s atmosphere. The uppermost part is known as the corona

Sunspots

• Sunspots are cool, dark areas of gasses in the photosphere caused by magnetic fields

• Sunspot cycles are variations in the number of sunspots which occur on average every 11 years

Formation of the Solar System

• The Solar Nebular Theory• The Big Bang describes the origin of the universe• After the Big Bang, clouds of gas and dust formed

solar nebulas• This is the same way all new stars are formed

• Gravity caused the gas and dust to begin to condense, collide, and heat up

• When the temperature gets hot enough, fusion begins; the sun was born ~5 billion years ago

Kepler’s Laws of the Solar System

• Johannes Kepler (1571-1630) developed the mathematical calculations which explain planetary motion• 1st Law = Planets circle the sun in elliptical orbits

• 2nd Law = Planets travel at different speeds at different points in their orbit

• 3rd Law = Describes the relationship between a planet’s distance from the sun and the amount of time it takes to complete a revolution around the sun

The Inner Planets (The terrestrial planets)

• Mercury: • One Year = 88 days• One Day = 59 Earth days

• Venus:• One Year = 225 days • One Day = 243 Earth days• Venus rotates on its axis opposite all the other planets.

This is known as retrograde rotation.

The Inner Planets (continued)

• Earth:• The only planet with liquid water• Extremely active geology (plate tectonics)

• Mars:• One Year = 687 days• One Day = One Earth day• The largest volcano in the solar system is on Mars. The

name of the volcano is Olympus Mons

The Outer Planets (the gas giants)

• Jupiter:• The largest planet, mass is twice all the other planets

combined• One Year = 12 Earth years• One Day = 9 hours and 50 minutes, rotates fastest• Moons include Io, Europa, Ganymede, & Callisto;

collectively known as the Galilean moons

• Saturn:• Complex ring system, has the most moons• One Year = 29.5 Earth years; One Day = 10.66 hours

The Outer Planets (continued)

• Uranus:• One Year = 84 Earth years; One Day = 17 hours• Green color caused by methane in the atmosphere

• Neptune:• One Year = 165 Earth years; One Day = 16 hours• Bluish-green color with white “clouds” of frozen

methane• Pluto:

• No longer considered a planet; One Year = 250 Earth years; One Day = 6 Earth days; Discovered by accident in 1930

Other Celestial Bodies

• Asteroids = Fragments of rock which orbit the sun• Asteroids are made of the same materials the planets are

composed of• Most asteroids exist in a belt between Mars and Jupiter

• Comet = A body of rock, dust, methane, ammonia, and ice which orbits the sun in long ellipses• Comets have a head and a tail • Comets lose mass as they orbit the sun, ice melts when

the comet is near the sun

Other Celestial Bodies (continued)

• Meteoroids = small bits of rock and metal which move randomly through the solar system• Comets leave behind the smallest meteoroids• Asteroids which collide can break up into larger

meteoroids• Meteor = a meteoroid which enters the Earth’s

atmosphere5• Meteorite = any part of a meteor which remains after it

hits the Earth’s surface