The Solar System The Sun and the Planets

What does the solar system consist of? The Sun, the eight planets and their moons, and billions of other smaller objects. All of these celestial objects orbit the Sun.

Measuring Distances in the Solar System Distances in the Solar System are so astronomical that “kms” is not enough! Instead, astronomers use the astronomical unit to measure the distances within our Solar System. 1 AU = 150, 000, 000 km and it represents the average distance between the Sun and the Earth. (Jupiter is 780 million km from the Sun which = 5.2 AU)

Planets Big and Small The four planets nearest the Sun are M, V, E and M. These small rocky planets make up the inner part of the Solar System. The four planets beyond Mars are J, S, U, and N. These planets are gas giants. On your Solar System Map Label: All 8 planets Label the terrestrial planets and the gas giants.

Dwarf Planets To be considered a true planet, a celestial object must: Be in orbit around a star (Such as the Sun) Have enough mass to be pulled into a stable sphere by gravity Dominate its orbit (Its mass must be greater than anything else that crosses its orbit)

Why is Pluto No Longer a Planet? From 1930 – 2006 Pluto was considered to be the ninth planet in the Solar System. New definitions of planets excluded Pluto and added it to the “Dwarf Planet” category due to the fact its tilted orbit crosses the orbit of Neptune. Astronomers suspect there are up to 2000 Dwarf planets, with as many as 200 in the region of the outer Solar System called the Kuiper Belt Add the Kuiper Belt onto your Solar System Map beyond Neptune

Why is Pluto No Longer a Planet? http://videos.howstuffworks.com/tlc/29944-solar-empire-pluto-video.htm http://videos.howstuffworks.com/discovery/28845-discover-magazine-pluto-planet-or-not-video.htm

Dwarf Planets Dwarf planets orbit the Sun and have a spherical shape BUT they do not dominate their orbits! Currently, there are 5 recognized dwarf planets- Ceres, Pluto, Haumea, Makemake, and Eris. Most of the dwarf planets discovered lie beyond Neptune’s orbit. (Add these 5 dwarf planets onto your Solar System Map beyond Neptune in the Kuiper Belt)

Smaller Members of the Solar System Asteroid Belt Asteroids are small celestial objects composed of rock and metal. They are too small to be considered planets. The vast majority of asteroids lie in an area known as the asteroid belt, located between the orbits of Mars and Jupiter. (Add the Asteroid Belt onto your Solar System Map) Asteroids vary in size and shape (some round but most are irregular).

Meteoroids A meteoroid is a piece of metal or rock in the Solar System that is smaller than an asteroid. Sometimes meteoroids get pulled in by Earth’s gravity. As they enter Earth’s atmosphere, friction causes them to burn up creating a streak of light across the sky known as a meteor. On rare occasions, larger meteors that do not burn up completely and actually crash to the ground are now called meteorites.

It was not detected before it entered the atmosphere!!!! Meteorite Impacts On February 15th, 2013 a meteor entered the atmosphere above Chelyabinsk, Russia. It was travelling at a speed of 18 km/s or 40 000 mps Exploded with a total energy of 440 kilotons of TNT (20 – 30 x that of an atomic bomb) 90 tons was emitted as visible light and was seen as far as 6 cities away. There were 1500 injuries, mostly from indirect effects. The meteorite had a mass of 11 000 tonnes and was 17 – 25 m wide, it is the largest to hit earth since 1908 It was not detected before it entered the atmosphere!!!!

Chelyabinsk Meteor Video: http://www.space.com/19807-raw-video-meteorite-crash-in-russia-sparks-panic.html http://news.discovery.com/space/videos/space-videos.htm

Meteorite Impacts Several large meteorites have been known to create craters on impact.

Canadian Connection The second largest impact crater in the world is the Sudbury Basin, located in Northern Ontario. It was formed by a 10 km meteorite impact that occurred 1.85 billion years ago. Much of the nickel mined in the Sudbury area today originated from this meteorite!

Comets Comets are large chunks of ice, dust, and rock that orbit the Sun. Some comets take a few years to travel around the Sun, while others can take hundreds of thousands of years! When a comet gets close enough to the Sun, its outer surface begins to sublimate-and its icy nucleus heats up.

Comet Hale- Bopp & Halley’s Comet The Comet Hale- Bopp is the most recent long- period comet to be observed on earth and will take 2380 years to make 1 trip around the Sun. Halley’s Comet last visited in 1986 and will return in 2061.

Comets As this happens, gases and dust escape forming a gaseous cloud around the nucleus called a coma. As a comet approaches the Sun, solar wind pushes on the coma, creating a gaseous tail to form. The direction of the tail points away from the Sun and tells you which direction it came from.

Did you Know? I AM A COMET

Comet Shoemaker- Levy 9 Comet Shoemaker- Levy 9 Crashed into Jupiter in July 1994 after it ventured too close to the planet and was pulled in by the planet’s gravity.