Our Solar System

The Sun• It is a medium-sized yellow star

in the middle of its life cycle.• Its the center of our Solar

System and holds objects in orbit by gravity

• More than 1,000,000 Earths can fit inside the Sun

• The only source of energy, it’s fueled by nuclear fusion of small atoms to form larger ones

• Has sun spots, solar flares, and prominences

Mercury• Terrestrial planet with a

solid rocky surface• Covered with craters• Extreme temperatures

(from -170 ºC up to 467 ºC)

• Thin atmosphere so its temperatures vary by day and night

• Fastest planet to revolve around the Sun, thus named “Mercury”

• No moons

Venus• Terrestrial planet with

a solid, rocky surface• Earth’s “twin” in size• Extremely hot

temperatures (470 ºC) due to thick atmospheric cloud cover and green house effect.

• Retrograde motion (it rotates clockwise)

• No moons

Earth• Terrestrial planet with a

solid, rocky surface• Frozen caps at North &

South Poles• Capable of supporting

life due to [C], 70% water, and protective atmosphere

• Seasons due to axis tilt• 1 Moon: “Luna” where

we have landed multiple times and sent more than 70 spacecraft

Earth’s Moon “Luna”• The moon acts like a

mirror; it reflects sunlight to Earth

• Phases of the moon occur as the moon revolves around Earth and reflects sunlight.

• Tides -- high tide and low tide -- are caused by the moon’s gravitational pull

Mars• Terrestrial planet with

a solid, rocky surface• Red surface due to [Fe]• Enormous active

volcanoes and dust storms

• Thin atmosphere• Frozen polar caps like

Earth• Liquid water once?• 2 Moons: Phobos and

Deimos

Asteroids• Made of rock, minerals,

and rare elements• More than 100,000 orbit

in the “Asteroid Belt” between Mars and Jupiter

• Could collide with Earth, but probably won’t

• One asteroid named “Ceres” is a dwarf planet

• Moons: a few asteroids have moons

Meteors or “Shooting Stars”

• Pieces of rock that are falling toward Earth are meteors

• They glow brightly as they are burning up due to fluid friction

• Called “meteoroids” if they are far away, “meteors” if they have a bright tail, and “meteorites” once they hit Earth

Answer this…• What is a solar system?

• Where does energy come from in our solar system?

• Name one characteristic of each planet we’ve talked about so far.

• What do the first few planets in our solar system have in common?

• What are “shooting stars?”

Jupiter• The largest “gas

giant” with no solid surface

• Faint rings• Made of elements [H]

and [He] with a hot, solid core of [Fe] -- almost a star!

• “Red Spot” is a massive storm

• 62 Moons: the four largest are named Io, Europa, Ganymede, Callisto, but there are more…

Saturn• Second largest gas giant

without a solid surface• Famous for bright, icy

rings that we can see from Earth with a telescope. The rings have large divisions.

• Mostly made of elements [H] and [He]

• Less dense than water!• 60 Moons: Titan and

Pheobe and more, some orbit in the gaps of the rings

Uranus• Gas giant without a solid

surface• Made of elements (H) and

(He) and water, ammonia and methane

• Bluish reflection due to methane (CH4) gas

• Faint rings, but the brightest clouds

• Axis is turned “sideways” so it has wild seasons

• Retrograde motion• 27 Moons: Ariel and more…

Neptune• Gas giant without a

solid surface• Bluish reflection due

to methane (CH4) gas but more vivid than Uranus

• Six faint rings• Farthest planet from

the Sun, usually• 13 Moons: Triton is

the largest and 12 more…

Dwarf Planets• “Pluto” has a solid, icy

surface, three moons, and it orbits in a tilted plane. “Charon” is one of 3 moons of Pluto.

• Makemake is ¾ the size of Pluto and takes 310 years to orbit the sun.

• “Eris” is larger than Pluto, but farther away

• “Ceres” is the largest asteroid in the asteroid belt

• More dwarf planets are expected to be named or discovered…

Comets• Made of rock, ice and

dust• Comets consist of a

head, coma, and two tails that point away from the Sun

• Short-period comets come from the “Kuiper Belt” and orbit the Sun every 200 years or less

• Long-period comets come from the “Oort Cloud” and take longer to orbit the Sun

Think About this…• What do the last of the planets in our solar

system have in common?

• Name one characteristic of each of the outer planets.

• What is the relationship between the size of a planet and the number of moons it has?

• What makes a planet a “dwarf planet?” Name the dwarf planets.