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Premium member Presentation Transcript Slide1: This page is intentionally blankA new view of the Universe VII Fred Watson, AAO April 2005: A new view of the Universe VII Fred Watson, AAO April 2005In the Universe, things aren’t always what they seem… : In the Universe, things aren’t always what they seem… …in fact, they hardly ever are!Building-blocks of illusion…: Building-blocks of illusion… Natural (stereoscopic) depth perception is limited. Understanding Solar System dynamics extends our perception of depth to more than 10 billion km. Stellar parallax extends depth perception to a thousand or so light-years. A 2-dimensional view of the sky Stellar parallax: Stellar parallax Earth Earth 6 months later Star appears to move against background SunBuilding-blocks of illusion…: Building-blocks of illusion… A fixed vantage-point Building-blocks of illusion…: Building-blocks of illusion… Natural sensitivity only to visible light Building-blocks of illusion…: Building-blocks of illusion… Lookback times: Moon… 1.3 seconds Sun… 8 minutes Jupiter (this evening)… 35 minutes Nearest star… 4.2 years Large Magellanic Cloud… 165,000 years Andromeda Galaxy… 2.2 million years Finite speed of lightThe Moon Illusion: The Moon IllusionSpot the Moon…: Spot the Moon… What’s that beside your head, Liam? Only my love for you, my sweet. Oh, Yukkk!!! Our perception of the sky—not a hemisphere, but an inverted dish: Our perception of the sky—not a hemisphere, but an inverted dishAre we at the centre of our Galaxy?: Are we at the centre of our Galaxy?The Milky Way— relatively uniform.: The Milky Way— relatively uniform.Are star-counts telling the truth?: Are star-counts telling the truth? No—they ignore the presence of dustGlobular clusters: Globular clusters About 150 known in our Galaxy Most are in one part of the sky (Sagittarius) Many are above or below the plane of the Galaxy—no dust In 1919, Shapley measured their distances from the SunDeductions: we are in the galactic suburbs— and the Galaxy is much bigger than anyone thought: Deductions: we are in the galactic suburbs— and the Galaxy is much bigger than anyone thought The Galaxy’s halo of globular clustersSupernovae: SupernovaeVela supernova remnant: Vela supernova remnantSupernova 1987a photographed 6 Feb 1989: Supernova 1987a photographed 6 Feb 1989Supernova Light Echo: Supernova Light Echo Earth Supernova Light Echo: Supernova Light Echo Earth Dust sheetsWhat puts the spirals into spiral galaxies?: What puts the spirals into spiral galaxies?What are the spiral arms?: What are the spiral arms? Just strings of stars? No, because they would be tightly wound up. Suppose the age of the galaxy is 10 billion years. Its inner regions rotate once in 200 million years… Therefore, we’d expect about 50 turns. The galaxy would look like a clock spring.Slide28: This density wave triggers star-formation, producing masses of hot bright stars that reveal its position. The spiral arms are an illusion. They trace the passage of a ‘sound wave’ through the disk of the galaxyFaster than light?: Faster than light?Many radio-objects have expanding lobes This is a double-lobed radio galaxy, observed with the ATNF, super-imposed on a visible-light photograph.: Many radio-objects have expanding lobes This is a double-lobed radio galaxy, observed with the ATNF, super-imposed on a visible-light photograph.Twin jets of material from a binary star in our Galaxy The expansion took place during the course of a few days in late-1997. : Twin jets of material from a binary star in our Galaxy The expansion took place during the course of a few days in late-1997. Faster than light…?: Faster than light…? By the time the jet reaches HERE light from the outburst is only HERE giving the appear- ance from Earth of material moving at superluminal velocity.Gravity’s lens: Gravity’s lensThe discovery of gravitational lenses: The discovery of gravitational lensesGravitational lensing: Gravitational lensingAn Einstein Ring…: An Einstein Ring… B0047-2808: zlens = 0.485; zsource = 3.595Gravitational lens in Abell 2218: Gravitational lens in Abell 2218Is there a Cosmic Illusionist?: Is there a Cosmic Illusionist?The laws of physics create the illusions…: The laws of physics create the illusions… but they also allow us to see behind them!Slide40: The End You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
watson7 Tirone Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 17 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: January 14, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide1: This page is intentionally blankA new view of the Universe VII Fred Watson, AAO April 2005: A new view of the Universe VII Fred Watson, AAO April 2005In the Universe, things aren’t always what they seem… : In the Universe, things aren’t always what they seem… …in fact, they hardly ever are!Building-blocks of illusion…: Building-blocks of illusion… Natural (stereoscopic) depth perception is limited. Understanding Solar System dynamics extends our perception of depth to more than 10 billion km. Stellar parallax extends depth perception to a thousand or so light-years. A 2-dimensional view of the sky Stellar parallax: Stellar parallax Earth Earth 6 months later Star appears to move against background SunBuilding-blocks of illusion…: Building-blocks of illusion… A fixed vantage-point Building-blocks of illusion…: Building-blocks of illusion… Natural sensitivity only to visible light Building-blocks of illusion…: Building-blocks of illusion… Lookback times: Moon… 1.3 seconds Sun… 8 minutes Jupiter (this evening)… 35 minutes Nearest star… 4.2 years Large Magellanic Cloud… 165,000 years Andromeda Galaxy… 2.2 million years Finite speed of lightThe Moon Illusion: The Moon IllusionSpot the Moon…: Spot the Moon… What’s that beside your head, Liam? Only my love for you, my sweet. Oh, Yukkk!!! Our perception of the sky—not a hemisphere, but an inverted dish: Our perception of the sky—not a hemisphere, but an inverted dishAre we at the centre of our Galaxy?: Are we at the centre of our Galaxy?The Milky Way— relatively uniform.: The Milky Way— relatively uniform.Are star-counts telling the truth?: Are star-counts telling the truth? No—they ignore the presence of dustGlobular clusters: Globular clusters About 150 known in our Galaxy Most are in one part of the sky (Sagittarius) Many are above or below the plane of the Galaxy—no dust In 1919, Shapley measured their distances from the SunDeductions: we are in the galactic suburbs— and the Galaxy is much bigger than anyone thought: Deductions: we are in the galactic suburbs— and the Galaxy is much bigger than anyone thought The Galaxy’s halo of globular clustersSupernovae: SupernovaeVela supernova remnant: Vela supernova remnantSupernova 1987a photographed 6 Feb 1989: Supernova 1987a photographed 6 Feb 1989Supernova Light Echo: Supernova Light Echo Earth Supernova Light Echo: Supernova Light Echo Earth Dust sheetsWhat puts the spirals into spiral galaxies?: What puts the spirals into spiral galaxies?What are the spiral arms?: What are the spiral arms? Just strings of stars? No, because they would be tightly wound up. Suppose the age of the galaxy is 10 billion years. Its inner regions rotate once in 200 million years… Therefore, we’d expect about 50 turns. The galaxy would look like a clock spring.Slide28: This density wave triggers star-formation, producing masses of hot bright stars that reveal its position. The spiral arms are an illusion. They trace the passage of a ‘sound wave’ through the disk of the galaxyFaster than light?: Faster than light?Many radio-objects have expanding lobes This is a double-lobed radio galaxy, observed with the ATNF, super-imposed on a visible-light photograph.: Many radio-objects have expanding lobes This is a double-lobed radio galaxy, observed with the ATNF, super-imposed on a visible-light photograph.Twin jets of material from a binary star in our Galaxy The expansion took place during the course of a few days in late-1997. : Twin jets of material from a binary star in our Galaxy The expansion took place during the course of a few days in late-1997. Faster than light…?: Faster than light…? By the time the jet reaches HERE light from the outburst is only HERE giving the appear- ance from Earth of material moving at superluminal velocity.Gravity’s lens: Gravity’s lensThe discovery of gravitational lenses: The discovery of gravitational lensesGravitational lensing: Gravitational lensingAn Einstein Ring…: An Einstein Ring… B0047-2808: zlens = 0.485; zsource = 3.595Gravitational lens in Abell 2218: Gravitational lens in Abell 2218Is there a Cosmic Illusionist?: Is there a Cosmic Illusionist?The laws of physics create the illusions…: The laws of physics create the illusions… but they also allow us to see behind them!Slide40: The End