Question by olibobwa: Done with ASTRONOMY HOMEWORK need someone to check behind me PLEASE!!!?
Chapter 5 Homework
1. Why was Pluto recently closer to the Sun than Neptune?
•For most of its orbit, Pluto is more distant than Neptune, reaching out as far as 49 astronomical units (49 times the distance from the Earth to the Sun). But it has such an eccentric, elliptical orbit that it gets much closer, reaching a mere 29 AU. And during that time, it’s actually orbiting within the orbit of Neptune. The last time Pluto and Neptune made this switch was between February 7, 1979 and February 11, 1999. And give it another couple of hundred years and it’ll happen again
2. Why do astronomers believe that the solar nebula was rotating?
•Rotation occurred because the formation of nebulae is turbulent, meaning that they are created with many slowly swirling regions, like so much smoke rising for a fire.
3. To test your understanding of the formation of the solar system, do Interactive Exercise 5-1 on the Web site. Explain what is happening in each figure. You can print out your results, if required.
4. Describe four methods that exist for discovering extrasolar planets.
•A) A planet and its star both orbit around their common center of mass, always staying on opposite sides of that point. The planet’s motion around the center of mass often provides astronomers with the information that a planet is present.
•B) As a planet moves toward or away from us, its star moves in the opposite direction. Using spectroscopy, we can measure the Doppler shift of the star’s spectrum, which reveals the effects of the unseen planet or planets.
•C) If a star and its planet are oving across the sky, the motion of the planet causes the star to orbit its center of mass. This motion appears as a wobbling of the star across the celestial sphere
•D) If a planet happens to move in a plane that takes it across its star as seen from earth, then the planet will hide some of the starlight, causing the star to dim. This change in brightness will occur periodically and can revel the presence of a planet.
5. What two properties of a planet must be known in order for its average density to be determined? How are these properties determined?
•Total mass and total volume.
•Kepler’s laws enable us to determine the mass of each planet from the periods of their moons’ orbits.
•The measured diameters of the planets (determined from their distance; from Earth and angular sizes in the sky) yield their volumes
6. How can Neptune have more mass than Uranus but a smaller diameter? Hint: See table 5-2
•It’s made up of different elements.
7. The Earth had formed around the of the first generation stars created in the universe? What chemical elements would the Earth then be composed of? Could we humans exist on that version of Earth? Why or why not?
•Carbon, silocone, & Iron. Yes. We are carbon based life forms
9. The accretion process of planet formation was still going on? How would life in general on Earth be different and how might we be different?
•Earth would be bombarded by other pieces of rock collecting together which would create a hostile environment. We would probably be subterranean.
10. The solar system passed through a cloud of gas and dust that was beginning to collapse to form a new star and planet system? What might happen to the Earth and how would the passage affect the appearance of the sky?
•The Earth might heat up and the sky would turn the color of the nebula.
11. Search the Web for information about recent observations of protoplanetary disks. What insights about the formation of the solar system have astronomers gained from these observations? Explain the evidence astronomers have, from these observations, that planets are forming in these disks.
•As accretion continues within a protoplanetary disk, sizable objects known as planetesimals form which, after several million years, give rise to small, rocky planets close to the host star. Further out, where it is cold enough for ice to form in the disk, more solid material is available for world-building. Gas giants, like Jupiter and Saturn, may start with cores of rock and ice of about 10 Earth-masses and then sweep up large quantities of light gases to form thick atmospheres. This should result in the creation of a central cavity within the circumstellar disk, similar in size to the solar system, and a drastic depletion of the disk’s gas content. Recent observations, for example of the 10-million-year-old star HR 4796A, provide evidence for this view.
13. Search the Web for information about the planet orbiting the star HD 209458. This planet has been detected using two methods. What are they? What have astronomers learned about this planet?
•By transit and Spectroscopic studies.
•The atmosphere is at a pressure of one bar at an altitude of 1.29 Jupiter radii above the planet’s center
•on November 27, 2001 the Hubble Space Telescope detected sodium, the first planetary at
Answer by chrislove718
google it. and if your in high school i dont think your teacher would mind if you get questions wrong as long as you attempted to do it and made it look like you put more than 15 min of effort in it
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