How our Solar System (and Moon) came to be…

Learning Objectives

• Be able to explain– How our solar system and moon came to be

• IRAS launched into orbit 1983– Direct evidence that solid matter exists

around stars– Can cloud particles be early stages in the

development of the planets?

• Theory emerged: Planets form while star is forming

Rotating Nebula Theory

• Solar system began as collection of dust and gases (nebula)

• This nebula made up of mainly hydrogen and helium gases – Also some solid particles like iron, rock, ice

• These particles came from massive explosion of an older star called supernova– Supernova = star in it’s final phase of life, when it

explodes it is many time it’s original size– Particles had moved closer together due to gravity

• As nebula collapsed, internal pressure and temperature increased and more particles were attracted to nebula

• Eventually temperature and pressure in the gas cloud was great enough for a complex reaction to begin

• Reaction caused release of large amounts of energy, creating massive explosions

• At core of nebula, our Sun began to develop

• Early stages of the nebula began to rotate due to gaseous material

• The speed of rotation became too great to hold al of matter together at center

• Matter spread out from center like pancake

• Bulge remained at center forming the Sun• While sun formed, smaller clumps of cooler

matter called protoplanets began to appear in outer regions of nebula– Protoplanets condense to form planets of our solar

system getting larger as they pick up debris• Likely how gas giants came to be

• Sun flared up in a sudden burst of energy– Caused helium and hydrogen into the outer

regions– Dense chunks of solid matter left behind• Formation of inner planets

Other bodies in Solar System

• Asteroids– Rocky object, smaller than a

planet that orbits the sun– They orbit the sun between Mars

and Jupiter (asteroid belt)– Asteroids often collide and break

into pieces called meteoroids– “Falling stars” are meteoroids

becoming meteorites as they pass into earth’s atmosphere

• Meteors and Meteorites– Meteor – lump of rock or metal that falls from

space towards earth’s surface– Meteorite – a meteor that is large enough to

survive entry and reach the surface of the earth• Separated into 2 broad groups: stones and irons• Impact of meteorite creates a crater

• Comets:– Usually name after their discoverers– Are made of rock dust and icy matter left over

from the formation of the solar system– Ancients believed comets to be the soul of a hero

or king on its way to heaven or messengers of disasters

• Gas pushed out behind nucleus (Tail)• Nucleus (rocky and metallic particles coated with

H20, ammonia, methane and CO2• Come – formed as frozen substances begin to

vapourize

Formation of our Moon

• Moon about 4.5 billion years old…. Similar in age to the Earth

• How?? Why??

Big Splash Theory

• Large object (size of Mars) collided with Earth• Collision caused high temperatures and

pressures – This ended up in materials like iron to become

part of Earth’s core

• Less dense materials blasted into space – Ended up orbiting around the Earth

• Materials began to condense and gravitate into each other through more heat and pressure