Our Solar System

What’s a solar system?⦿A collection of objects that are

gravitationally bound (held in orbit) to our sun.●Our solar system contains planets, moons,

asteroids, and comets●All of these objects orbit in elliptical shapes

around our sun

Orbits, Revolutions, Rotations, OH MY!

⦿Orbit/Revolution:●an object moving in

a circular motion around something else

●Ex) Earth revolves around the Sun

○ 1 year●Demonstrate!

⦿Rotation:●an single object

spinning in a circle around a center axis

●Ex) Earth rotates around its center axis

○ 24 hours●Demonstrate!

Our Solar System⦿Order of orbit moving outward from the

sun●Sun → Mercury→ Venus→ Earth → Mars

→ Asteroid Belt→ Jupiter → Saturn→ Uranus→ Neptune

○ → Kuiper Belt, containing Pluto○ → Oort Cloud, cometary sphere completely

surrounding the solar system

Our Solar System⦿All planets, except Pluto, and their

larger moons, follow orbits on the same plane●The ecliptic

⦿They all orbit around the sun in the same direction, as well as rotate in the same direction●Counter-clockwise

Characteristics⦿Scientists split the solar system into two

sections, based on the planetary characteristics●Inner planets: Mercury, Venus, Earth & Mars

○ Small, solid, rocky, dense●Outer planets: Jupiter, Saturn, Uranus &

Neptune○ Large, gaseous, may have rings

The Beginning⦿Our sun, a yellow dwarf, was created just like

any other star●Gravity began to pull dust and atoms together

The Sun⦿The energy source

for everything in our solar system●The reason we are

alive!⦿Heat energy from

sun is converted into chemical energy by living organisms

The Sun’s Structure (center→ outer edge)1. Core: 15 million degrees Celsius, nuclear fusion occurs here

2. Radiation zone: energy from core radiates outward (after millions of years), usually 1-15 million degrees Celsius

3. Convective zone: pressure decreases drastically, temperature drops between 6,000-1 million degrees Celsius

4. Photosphere: about 500 km thick, light finally reaches the visible

wavelengths (hence the name)

5. Chromosphere: most visible during solar eclipse, looks red as light wavelengths in this area emit red light

6. Corona: outer part of the sun where sun flares occur

Inner Planets⦿Emit no light of

their own, just reflect it●All have an outer

atmosphere●All contain a solid,

mineral-containing crust

Mercury⦿Closest to the sun, therefore takes least amount

of time to revolve around the sun●88 days = 1 Mercury year

⦿Only rotates 3 times for every 2 revolutions around the sun → 58.6 days = 1 Mercury day●Daytime is LONG and HOT (430 degrees Celsius)

⦿Because it is so small, it can barely hold on to an atmosphere●Makes night time VERY cold (-170 degrees Celsius)

⦿Very bright because of its closeness to the sun●Can be seen at night from March-April and in

the mornings from September-October

Venus⦿Second planet from the sun⦿Similar in size to Earth, however has very

dense atmosphere made of CO2

●This keeps heat inside, making it HOT ○ Even hotter than Mercury, which is closer to the sun!○ Contains volcanos as well

⦿225 days = 1 Venus year⦿243 days = 1 full rotation/Venus day (day is

longer than a year!)

Earth⦿Nicknamed the “Blue Planet”

●More water than land⦿Atmosphere just perfect enough to contain

enough heat to keep things alive, but not enough to kill all living things●That is why keeping our atmosphere in good shape

is so important!⦿Quick rotation allows for temperate seasons⦿Has 1 orbiting moon

Mars⦿Just over half the size of Earth, with similar

polar ice caps●Scientists believe water may have covered more of

Mars at one time⦿Very thin atmosphere makes for temps to be

very cold, about 30 degrees Celsius during the day and -130 degrees Celsius at night●687 days = 1 Mars year●24 hours 37 minutes = 1 Mars day

⦿2 moons, Phobos and Deimos

Asteroid Belt⦿Located between Mars and Jupiter⦿Half the entire mass of the asteroid belt is found

in the 4 largest asteroids: Ceres, Vesta, Pallas, and Hygiea⦿Ceres is classified as a dwarf planet, just like

Pluto⦿Contrary to popular culture, space in the asteroid

belt is mainly empty and filled with dust.

The Outer Planets⦿Much more massive than

the inner planets.⦿Gaseous, low density

worlds.⦿ Jupiter, Saturn, Uranus,

and Neptune all have ring systems.

●Saturn's rings system can be seen with the naked eye.

Jupiter⦿The Largest of all planets in our solar system.

●Originally thought to be a failed start.●Made up liquid more than gases or solids.

○ More than half of its volume is an ocean made up of liquid hydrogen. 82% of its atmosphere is Hydrogen.

●Completes one day in 10 Earth hours. 1 revolution takes 12 Earth Years.

○ Has 28 Moons. The four largest are Io, Europa, Ganymede, and Callisto.

○ Io and Europa are the size of our moon. Ganymede and Callisto are the size of Mercury.

Saturn⦿Brighter than all but 2 stars in the sky.⦿10 times larger than Earth, not

including its ring system⦿One day on Saturn = 10 hours. ⦿One year = 29 Earth years.⦿Has 24 moons and its atmosphere is

comprised of hydrogen and helium.

Uranus⦿One of the newer discovered planets, was

unknown to ancient astronomers.⦿Contains a faint ring system that is perpendicular

to its rotation.⦿Like other gas giants, Uranus has an atmosphere

composed of hydrogen and helium.⦿Uranus is very cold, has no internal thermal

system (no lava core), day and night are the same temperature⦿One day is 17 hours, one year is 84 Earth years.

Neptune⦿Atmosphere made up of hydrogen and

helium. Methane and ammonia are also present in significant amounts.⦿Has 8 moons and a ring system.⦿1 revolution around the sun takes 165

Earth years, 1 day is about 16 Earth hours⦿Holds 8 or 9 moons and is not very dense

Pluto⦿No longer considered a planet.⦿Found in the Kuiper belt, beyond Neptune⦿Primarily made of rock and ice⦿In 2005, the discovery of Eris, an object 27%

larger than Pluto, bumped Pluto out of official planetary standing⦿Has 5 moons and is often considered a binary

system because it sometimes revolves around its largest moon, Charon.

Comets⦿A small, icy, rock that orbits around the Sun.

●A comet’s tail is actually ice/dust that is the result of solar winds causing a magnetic pulse to remove particles from the comet.

⦿Orbits around the Sun can range from several years to potentially millions of years.⦿On November 12, 2014, the Rosetta probe

attached a lander on an active comet, the first time something has successfully landed on a comet.