The Earth in Perspective• Diameter = 12 700 km• 1 km = 4 times around a race track • Montreal to Quebec City = 250 km
Distance between the Earth and the Moon
• 384 000 km• It would take 160 days to get to the moon if
you drove at 100 km/h.
3 500 km
12 700 km
384 000 km
Solar System• Composed of a star and the celestial bodies that orbit it (8
planets, 3 dwarf planets, satellites, asteroids, and comets).• The star of the Solar System = the Sun• Sun = source of heat and light. Takes 8 minutes for the light of
the sun to reach Earth.
Measuring large distances in our solar system
• In astronomy, the distances are so huge that larger units of measure are needed.
• Distance between the Earth and the Sun = 1 AU• 1 AU (Astronomical Unit) = 150 000 000 km• Used to measure the distances within the Solar System
1 AU
• Mercury = 0.39 AU• Venus = 0.72 AU• Earth = 1 AU• Mars = 1.52 AU• Jupiter = 5.2 AU• Saturn = 9.54 AU• Uranus = 19.19 AU• Neptune = 30.06 AU
Drawing a model to
scale
Is Pluto a planet?
• Considered a dwarf planet– Not large enough to be considered a planet
• Part of the Kuiper belt
Kuiper Belt• strain of asteroids and comets beyond Neptune
(Pluto is a part of this “belt”)• Discovered in 1992• Distance = 40 AU - 120 AU from the sun• Around 80 AU wide
Oort Cloud• Hypothetical cloud composed of asteroids
and comets• Distance = 40 000 - 150 000 AU from the sun• Limit of our solar system
Measuring distances outside our Solar system- The Light Year
• corresponds to the distance travelled by light in one year. • System of measurement used when dealing outside of the
solar system.
• 1 ly = 9 500 000 000 000 km (63 000 AU)
Galaxy• An enormous collection of stars, gas, dust and matter orbiting around its centre.• Organized by their shape (elliptical, spiral, starburst)• Other stars (like our sun) exist in the galaxy. Some are bigger, smaller, hotter, colder, older,
younger. • Scientists have discovered that there are astral bodies around these stars, which means similar
solar systems to ours may exist.
• We can SEE about 6000 galaxies, but there are probably around 200 000 000 000.
Our galaxy = Milky Way VIDEO
- 100 000 light years in diameter- considered a spiral galaxy
Let’s put it all into perspective!