Our Solar System

Our Place in Space

• To us, our Solar System seems HUGE• In the vastness (enormousness) of space, its

actually very small• The Universe contains everything, and within the

Universe are billions of galaxies (the USA doesn’t even have 1 billion people)• Each galaxy is home to billions of stars• Some of those stars have solar systems

Universe

Billions of Galaxies

Milky Way (1 of

billions)

Our Solar System (1 star out of millions)

Our Place in Space• Our Solar System is just one small part of our

galaxy.• The most common thing in our galaxy is empty

space. • We are 4.2 light years from the nearest star

• All objects in the Universe are spread out over extremely long distances

Distances in Space• Kilometers are too small to measure distances in

space.• It would be like measuring the distance to Panama City in

inches.

• Inside of our Solar System, we use Astronomical Units to measure distance

Astronomical Units• Astronomical Units: AU. The distance from the

Earth to the Sun.

Light Years• Outside of our Solar System, we measure

distances in light years: the distance light travels in a vacuum in one year.

• Light-second: 299,792,458 meters• light would make a round trip from London to New York

almost 27,000 times in a single second.• In one light year, this trip could happen 850 BILLION times

So how huge is space, really?• The absolute closest thing to us in the whole

Universe is Alpha Centauri, a star in our OWN galaxy, the Milky Way.

• It is 4.2 light years away.• For light, that’s 3570 BILLION round trips between

New York and London

Formation of the Solar System

• Gravity • The force that causes all matter to move toward other

matter.

• The greater the mass, the greater the gravitational pull.

• The closer the object, the greater the gravitational pull

Once upon a time, in a galaxy really really close… this one, actually…

• There was a nebula: a big collection of dust and gas that gives birth to stars.

• This nebula had areas where there was more dust and gas and areas where there was less.

•Which area had a greater gravitational pull?• The area with the greater mass (more dust and gas)

• Over time, the dust and gas began to rotate around the area of greater mass, pulling tighter and tighter until it formed the sphere that would be our Sun.

• 99% of the matter in the nebula formed the beginning of the Sun. The rest rotated around the center

• This is called a proto –planetary disc

• The remaining matter revolved around the Sun and began to accumulate in areas of greater mass, just like it did with the Sun.

• Spheres called planetesimals, baby planets, formed in these areas.

Finally…• The planets migrated to their current positions

with extra dust and gas either being pushed away by solar winds or forming other objects in the Solar System.

• What caused it all?• GRAVITY!

The Formation of the Solar System

Former model of the Solar System

• The Geocentric Model• A super complex model of the Solar System used to show the Earth at the center of all the known Universe• The stars, planets, and the Sun revolved around Earth

The Heliocentric Model• Helio= of or relating to the Sun• Centric= centered• Heliocentric?• Sun at the center.

Controversy• Copernicus • Theorized the Helio-centric model of the Solar System• Made sense mathematically• Fit with all observations

• Kepler: helped develop model• Galileo Galilee: made supporting observations• Was forced into house arrest by the Vatican for heresy and

treason because the Heliocentric model went against the teachings of the Bible• The pope pardoned Galileo in 1992, everyone agrees that

the Sun is the center of the Solar System now

Heliocentric Model• Widely accepted today• Sun at the center, planets orbit around it• All available evidence supports this model