Formation of the Solar System
• How was the solar system formed?
o Scientists believe a cloud of gas and dust in space was disturbed by a supernova :A massive explosion
of a star
• When did this occur?
o 4.6 billion years ago
• The Nebular Hypothesis
o The explosion made waves in space
o This caused the formation of a solar nebula (a flattened cloud of gas and dust)
Formation of the Planets
• The centre of the cloud grew hotter resulting in the formation of the Sun.
• The outer edges of the cloud cooled clumps of particles to stick together and form planets
Components of Outer Space
• Galaxy: A cluster of billions of stars. Our solar system makes up a tiny portion of the Milky Way Galaxy
• Star: A hot glowing ball of gas that generates energy by converting hydrogen to helium
The Milky Way Galaxy
• The Sun is located approximately 30 quintillion kms from the centre of the galaxy.
• It takes light nearly 100,000 years to travel from one side of the galaxy to the other
• In the core of the Sun, the temperature is 15 million degrees Celsius.
• The surface of the Sun is called the photosphere and it is 6000 degrees Celsius.
• Energy from the Sun controls the Earth’s climate system
• The earth only receive one twobillionths of the Sun’s total energy!
The Solar System
• The solar system is composed of 8 planets, 60 moons, and millions of bolides.
• Order of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
Life Cycles of Stars
• The lifetime of a star depends on its mass.
• The Sun is the closest star to Earth and it has a life expectancy of 10 billion years.
• When stars die, massive amounts of energy are released (supernovas)
• Definition: An extraterrestrial body that travels rapidly through space
• Asteroid: A rocky metallic material 10 km – 1000 km in diameter originating from the asteroid belt.
• Meteoroid: Small particles ranging from dust to objects a few metres across. Basically a smaller asteroid. Less
than 10km diameter
• Meteor: A meteoroid that has entered Earth’s atmosphere.
• Meteorite: A meteor that strikes the Earth’s surface
• Comet: These are indistinguishable by their glowing tail of gas and dust
o It is believed that comets formed in an area outside the solar system called the Kuiper Belt.
• Comets are composed of a rocky core surrounded by ice.
• They create light as gases are released from the ice as it is heated by solar radiation.
• Halley’s Comet is most famous because it is visible with the naked eye and passes close to Earth every 75 years • It will be visible next in 2061.
• Bolides travel at velocities of 1272 km/s.
• As they heat up upon entering Earth’s atmosphere, they produce bright light
• The object may explode in an airburst at an altitude between 12 km and 50 km, or it will collide with Earth’s
• The explosion destroyed over 2000 km of forest in a sparsely populated area of northeast Russia in 1908.
• Scientists have determined it was an airburst because no crater has ever been found
• The asteroid responsible is believed to be 25 to 50 metres in diameter.
• On Feb. 15, 2013 a meteor exploded over the city of Chelyabinsk in southwest Russia.
• It is believed to be the largest object to enter Earth’s atmosphere since the Tunguska event
• Over 1500 people were injured, mainly from broken glass.
• These provide evidence of past meteor impacts.
• A layer of debris called an ejecta blanket consists of rock fragments that were blown out of the crater on impact.
• Craters today are not as deep as the original impact crater due to erosion and fragmented rock falling back into
it shortly after impact
• This rock is referred to as breccia.
• This crater is about 50,000 years old and is located in Arizona.
Complex Impact Crater
• Impact craters can be defined as either simple or complex.
• Simple craters are less than a few km in diameter and do not have an uplifted centre.