Astronomy Final

The age of the cluster can be estimated by viewing a cluster of stars on the HR diagram in reference to where they end on the main sequence. 2. Seasonal variation of a planet depends on the frequency with which any given side of the planet changes it's position with respect to the star. For a planet like Uranus, which has a high tilt (73 deg), the same side always faces the sun and hence it's always summer on one side and winter on the other. Thus we can conclude that seasonal variation is directly related to the tilt of the planet. 3. a.Among the given planets, D has the minimum tilt – So the answer is D, which shows max seasonal variation. b. A planet will be geologically active if it has a high density, since that would assure wide vvariety of rocks and minerals and ores and less amount of hot gases; so among the planets, A has the highest density and is the most geologically active. 3. The younger surface would go to Moon A due to the fact that Moon B possesses many crater s, which are clearly visible as the picture represents (this is clearly shown by the illuminated spots).Genesis shows that the craters were developed over time. Since moon A has far less craters, this mearns it was recently formed thus making it the younger moon. 4. a. The Hubble Expansion: As the distance increases, the apparen't brightness of the object decreases meaning it becomes darker the farther away it gets. This technique determines the relative distances of ssimilar objects. In addition, a phenomenon called the Doppler effect can be used to determine the velocity of an object.The sonic Doppler effect is caused by compression of sonic wave fronts, which can be generalized to electromagnetic radiation and other wavelike phenomena. The magnitude of an object's Doppler shift is a function of its radial velocity relative to the observer. Velocities of various objects, such as stars and galaxies, have been tabulated in our vicinity. An almost straight line with positive slope wa s obtained when the distance was plotted for various galaxies against their velocities. This shows us that the farther away an object is, the greater the velocity.This lends support to the Big Bang theory–if the universe does indeed expand in a manner consistent with the Big Bang model, then two objects that are close to each other should have smaller relative velocities than in comparison with distant objects. b. Cosmic Microwave Background (CMB): This is the result of theorized energetics, which was discovered in 1965 by Penzias and Wilson. Their discovery showed microwave radiation emanating from all directions in our observable locality of the universe. As predicted by the Big Bang Model, the universe is filled with plasma at high temperatures.As a result, hydrogen can only exit as plasma with an ambient temperature of about 3000K. c. Primordial abundance of light elements: This is the observed abundance of elements in the universe. Examinations through the spectra of var ious objects shows us that helium makes up about 23% of observable mass in the universe, which is entirely too large to be accounted for by stellar fusion. Since stellar nucleosynthesis makes the abundance of lighter nuclei hard to explain, the Big Bang model theorizes that the nuclei were created during the fierce explosion. . Due to the numerous negative effects on the body, human space travel remains physiologically difficult. Many of these affects are due to long-term weightlessness. Examples include: muscle atrophy, skeletal deterioration, slowing of cardiovascular functions, red blood cell production decrease, balance disorders, and weakening of the immune system. In addition, without the appropriate protection, space exposure becomes a sever threat due to the environmental differences between space and earth – especially the lack of oxygen and pressure.Interstellar space travel consists of many problems, which makes human travel extremely difficult – even in the future. One problem is the amount of fuel needed for long-duration flights. In addition, we have to worry about the damaging effects of galactic radiation. Also consider the loneliness and boredom of generations of humans spending their entire lives aboard a spacecraft. In order to get to the nearest star system beyond our Solar System (Alpha Centauri), we would have to travel 4. 3 ly with a constant flight velocity of 50 km/s; which is roughly about 25,000 years.Although that velocity would allow us to escape the Solar System, it would still take 250 centuries to reach our closest star system. It is very unlikely that humans will be able to equip themselves with the technology, at least anytime soon, to make contact with extraterrestrial life. Even if we took into account the many factors in the Drake equation, galactic civilizations are probably spread out like small islands tthroughout space. Even if the average lifetime of extraterrestrial civilizations is 1 million years, our most optimistic estimates suggest that each is separated by ~300 ly.Additionally, thousands of sorties would have to be launched toward candidate star systems for any hope of successful extraterrestrial contact. In summary, although it may never become feasible, interstellar space flight is both uneconomical and impractical now and anytime in the foreseeable future. 6. Galileo Galilei was a very influential astronomer because he defended his beliefs in a time when the Roman Inquisition was in power. Galileo defended his idea of heliocentrism against the Inquisition and was put on house arrest. This did not stop him from doing what he loved.While on house arrest, he made observations and continued his work. His contributions to astronomy include the discovery of three moons of Jupiter, the idea that the nature of each planet is unique, identification of sunspots, and his continued examinations of the Milky Way and sea tides. 7. As of March 23, 2012, 763 exoplanets (extrasolar) within our Milky Way have been discovered by satellites such as the Kepler. Consequently, these satellites have been flying through space, uncovering hundreds of new planets within our galaxy.Recently, two planets (Kepler 62e and 62f) have been discovered, which orbit a sun ssimilar to ours but cooler. These planets are at just the right distance that allows water to remain liquid – an essential must for a planet to support life. In addition, these planets are very ssimilar to the size of Earth. Because of their size and orbits, it is highly likely that they are either rocky or watery. The two planets are located 1,200 light-years away in a five-planet system orbiting a star dubbed Kepler-62. 8. The milky is a flat disk surrounded by a halo with a bulge at the center.Within the disk, lay clouds of gas and dust that amount to around 15% of the mass of stars. Although we cannot see the nucleus due to all the scattered dust – radio, infrared, and x-ray telescopes allow us to se e through the dust and show us that the core contains a dense swarm of gas and stars and a massive black hole. A majority of the gas and dust clouds lie within the disk. In addition, bright stars gather into spiral arms winding in an outward direction. The location of our solar system is about 26,000 ly from the center, lying on the inner edge of the spiral arm. 9. D C B A