Solar System

1. Solar System SNC1D0

2. Solar System • A solar system consists of one star and all the matter orbiting around it • A star is a giant ball of gas (mostly H and He) that constantly generates energy by nuclear reactions • Fusion – combining small elements to make larger ones • Eg: combining two hydrogen atoms to make helium atom • There are several objects that orbit around a star due to the immense gravity of the star • Planets, asteroids, dwarf planets, moons, comets, etc...

3. Our Solar System

4. Gravity • What holds objects close to the sun? • Gravity • Gravity is a force of nature that pulls together anything that has mass • The more massive it is, the stronger it pulls things towards itself • The force of gravity of the sun is so strong that it holds several huge objects (like planets) in orbit around it

5. Orbit • An orbit refers to the path an object takes as it moves around another object • These paths are roughly circular • Orbits are often circular, but can also be more elliptical • Orbits can also change over time • Earth’s orbit changes between circular and elliptical every 100 000 years • The amount that an orbit deviates from a perfect circular orbit is called its eccentricity

6. Orbits

7. Eccentricity

8. Irregular Orbits • Objects that are not planets have irregular orbits

10. Celestial Motions • Celestial objects (planets, moons, etc...) have a few types of motions • Revolution • Rotation • Revolution: • Moving in an orbit around a central object (like the sun) • Rotation • Moving in a circle around its axis • Spinning like a top

15. Our Solar System • What are the different orbiting objects? • Planets and dwarf planets • Asteroid Belt and Kuiper Belt • Comets

16. Planets • Planets are very large objects that orbit a star • They are so big that their gravity makes them spherical • Their orbits are roughly circular and regular • They dominate their orbit (meaning there is nothing else in its orbit that isn’t orbiting the planet itself) • There are eight planets in our solar system • 4 Inner planets – Mercury, Venus, Earth, and Mars • 4 Outer planets – Jupiter, Saturn, Uranus, and Neptune • All 8 planets orbit the sun in the same plane • Making the solar system look like a disc

17. Orbits

18. Inner Planets • They are all terrestrial • And much smaller than the outer planets • Mercury • The closest of the planets • Takes 88 Earth days to travel around the sun (1 Mercury year) • It has no moon and no atmosphere • It’s surface temperature ranges from -180 to 426 °C • Having no atmosphere means it cannot retain heat • No greenhouse effect

19. Inner Planets • Venus • Similar size as Earth • Has a thick atmosphere with lots of CO2 and nitrogen • Surface temperature is 470°C • Takes 224.7 Earth days to move around the sun • Takes roughly the same amount of time to rotate once • One year is roughly the same as one day • No moons

20. Inner Planets • Earth • 1 moon • Atmosphere of N2 and O2 • Surface temp. of -85 to 58°C • 365 days to revolve around sun • ~24 hour rotation period • Mars • 2 moons, Deimos and Phobos • Smaller than Earth (1/2 the size) • Atmosphere of CO2 and N2 • Surface Temp. of -120 to 30°C

21. Outer Planets • Jupiter • Made of gas • Mostly hydrogen, helium, and methane • 63 moons • Is more than 10 times bigger than Earth • Has a huge red storm • Saturn • Made of gas • Mostly hydrogen, helium, and methane • Has a system of icy rings • 62 moons

22. Outer Planets • Uranus • Made of gas • Mostly hydrogen, helium, and methane • Has a system of icy rings • 27 moons • Rotates differently from all other planets • Neptune • Made of gas • Mostly hydrogen, helium, and methane • 13 moons

23. How are Planets Formed? • Planets form when the sun and the whole solar system forms • Matter from the universe is pulled together by gravity • The majority of it gathers together in the center to form a star • The matter is constantly spinning around • As gravity pulls the star tighter, fusion begins and the star ignites

24. Formation of a Solar System

25. How are Planets Formed? • The left over matter spinning around the sun ends up becoming planets, moons, asteroids, etc... • The left over matter pulls together in clumps due to gravity

26. Dwarf Planets • There are certain large bodies in the solar system that are not planets • These are dwarf planets • Pluto, Eris, Ceres, Haumea, Makemake • Most of these dwarf planets exist in the Kuiper belt, which is past Neptune • Ceres exists in the asteroid belt between Mars and Jupiter • These bodies are not large enough to clear their orbits of other matter • Many of them also have very irregular orbits

27. Asteroid Belt • Between Mars and Jupiter there is a ring of rocky particles that are too small to be planets • These are asteroids • Made of rock and metals • Since they are small, most are irregularly shaped • Though some of the largest ones are spherical

28. Meteoroid • A meteoroid is a small piece of rock or metal in the solar system • The size of dust up to the size of a car or building • They often get trapped by a planets gravity and get pulled down to the surface of the planet • We call them meteors when this happens • Most meteors burn up in the atmosphere before hitting the ground • If they hit the ground, we call them meteorites

29. Comets • Comets are large chunks of ice, dust, and rock that orbit the sun • When they get near the sun, their icy layers sublimate • Turn from solid to gas • This creates a cloud of gas and dust around the comet called a coma • Solar wind (atoms ejected from the sun) hit the comet and create a tail of gas behind the comet, leading away from the sun • There is also a trail of dust leading in the direction the planet has been moving

30. Comets

31. Homework • Pg 317 # 1 – 9