Prob01_sol1 - deuterium will not This suggests that Venus...

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Page 1/1 UGEB 2401B Astronomy Problem Set 1 (Suggested answers) 1. (a) The flaws were: (i) Stars collide very infrequently because their sizes are small compared to their separation. ( 2 marks ) (ii) The gas pulled from the sun and the star would be much too hot to condense to make planets. ( 2 marks ) (iii) Even if planets form, they would not go into stable orbits. ( 2 marks ) (b) According to the nebular hypothesis, the sun should be spinning very rapidly. The sun should have most of the angular momentum of the solar system. However, astronomers found that the sun rotated slowly and the planets moving in their orbits had most of the angular momentum of the solar system. ( 4 marks ) 2. (a) Evidence of water on Venus is indicated by the relatively large abundance of deuterium in the atmosphere. Ultraviolet radiation will dissociate water and the hydrogen can be found in two forms, normal and heavy hydrogen (i.e., deuterium). Normal hydrogen will have speeds sufficient to escape Venus but
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Unformatted text preview: deuterium will not. This suggests that Venus once had more water than at present. ( 5 marks ) (b) One way that Earth may have escaped developing such a thick atmosphere of carbon-dioxide is that the large amount of liquid water on Earth absorbed much of the carbon-dioxide. ( 5 marks ) 3. (a) Images of dry river channels and eroded craters, along with chemical analysis of Martian rocks, all show that water once flowed on Mars. ( 5 marks ) (b) That period ended at least 2-3 billion years ago. ( 5 marks ) 4. (a) Occultation. ( 2 marks ) (b) Kepler-10b should be considered as a terrestrial planet. Its density is about 8.8 times that of water, meaning it must be made mostly of rock and metal, like Earth. ( 5 marks ) (c) Kepler-10b cannot support life. It orbits its host star at less than 4 per cent of Mercury’s distance from the sun, making the planet’s surface too hot to support life. ( 5 marks )...
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