STAO PRESENTATION – FALL 2009 Getting Your Grade 9’s (and You) Excited About Astronomy! Mrs. Jennifer Regular, Fletcher’s Meadow Secondary School, Brampton, ON Slide 1: Astronomy Catch Ball Activity
Slide 2: Science Department Head at FMSS Teaching Grade 12 Physics and Grade 9 Science Studied some astronomy at the university level Our school: 2300 kids, 25 portables, and 24 sections of grade 9 science this year! o My first semester: Space was started after Christmas Break with only 2 weeks left before exam review. Students read the textbook and filled out charts with information like the density and mean radius of each planet. The highlight of this unit was watching Bill Nye the Science Guy ride a bike to demonstrate how far apart the planets were. Smallville Clip depicting Meteor Shower
Slide 3: Ask for examples of students asking questions. o What will happen to us if the sun explodes / stops shining? o What happens if you get “Sucked” into a black hole?
Slide 4: Solar Nebula Theory (Large cloud of rotating dust and gas condenses) Uranus: Rotates on its side due to collision with a large planetessimal late in its formation Venus: Collides with and absorbs a large planetessimal which changes its angular momentum from counterclockwise to clockwise Large impact from a big planetessimal early on, knocks of large amounts of debris which forms a ring around the earth, eventually swept up to form our moon 1994: fragments of comet “Shoemaker Levy” struck Jupiter with energy equivalent to millions of megatonnes of TNT (50 kilotonnes of TNT = Atomic Bomb) So its like 2 trillion atomic bombs.
Slide 5: 65 million years ago an asteroid 10km or more in diameter hit the earth (equivalent to 1000 atomic bombs). Caused a mass extinction event. 300 km wide Crater found near the Yucatan Peninsula (under limestone) 10 000 people killed by falling stones (may have been a break up of large asteroids) Mile Wide Asteroid reported in newspaper to be on a collision course with earth . The data was recalculated and it will miss earth by 600 000 miles (just shy of 100 000 km which is 2.5 times the distance to the moon. High probability of an asteroid greater than 1 km colliding with earth Has anyone heard students talking about this??? Mayan Calendar ends after 5000 years, Unseen Planet Nibiru on the far side of the sun to crash into the earth, High solar maximum (around 2012).
Slide 6: 1910 – Earth passed through the tail of comet Halley. Spectroscopic evidence indicates Cyanide gas in the tail. Bottled O2 sold out, residents were stuffing their windows and doors with rags, Con artists in Texas made a lot of money selling Comet Pills and Comet Inhalers to ward off noxious fumes Neat science and society connection – a little knowledge can be a dangerous thing!
Slide 7: Big stars (4 times the sun’s mass and more) live short, exciting, and flashy lives ending in dramatic supernovas, planetary nebulas, and black holes. Really small stars (red dwarfs) have incredibly long lives up to 100 billion years (since the universe itself is only 14 billion years old – no red dwarf has ever died!) Our Sun – in a few billion years it will run out of H, ignite He, and swell to about the distance of the earth where it will evaporate the oceans, drive away the atmosphere and vaporize much of the earth’s crust. The burned up earth will continue to rotate around the sun as it then sloughs off gases and shrinks to a white dwarf star. Embarrassingly, it might not even have enough heat to ionize the gases and form a planetary nebula.
Slide 8: What would happen if you replaced the sun with a black hole of equal mass? Heavy stars will supernova and leave behind contracting mass so great that nothing can support its weight and it will turn into an infinitely small and very massive black hole. The force of gravity is so great that even light can not escape it. What would happen if you jumped into a black hole? Force on your feet would be greater than the force on your head and your body would be stretched longitudinally. The friction from these severe distortions would heat you up to millions of degrees and you would start emitting x-rays and gamma rays!
Side 9: First, think about our solar system. Most of the mass is in the centre (sun). Inner planets rotate quickly and outer planets rotate slowly (according to Kepler’s law). Galaxies should be the same due to the high concentration of stars in the centre (and the likelihood of a black hole). What we find is that outer stars are moving faster than they should be yet still maintaining a stable orbit. The only explanation for this is that there must be some mass that we can’t detect affecting their orbits. This unknown invisible mass is called dark matter (some as yet unknown form of matter)
Slide 10: Look at earth/sun model – talk about misconceptions about scale Sun is a small orange, Earth is a grain of table salt, Moon is a speck of pepper 1 cm away, Mercury, Venus, and Mars are grains of salt. Jupiter is an apple seed 20 m from the sun. Saturn is a smaller apple seed 36 m away. Uranus and Neptune are grape seeds. Pluto is a speck of pepper 150 m away. Big planets close to their stars have been found (but not seen). They don’t give off light and are so close to the star, they are difficult to see. They are detected by their gravitational effect on the star which causes it to wobble. Is there life? - too close = too hot = water evaporated away, too far = too cold = ice -If you believe that life evolved from the right chemicals being at the right place at the right time, you need stationary liquid water for life to evolve. Will we find it? Even if life were close (10 ly away) it would take 20 years for a message to be sent to them and returned to us – if they had the technology to be looking for our message, decoding it, and sending it back. Regardless, don’t look for alien invaders coming in their spaceships anytime soon (since nothing can travel faster than light, even if they had advanced technology) Conclusion: Space is exciting, beautiful, and at the cutting edge of our knowledge