Hubble Space Telescope

        The Hubble Space Telescope is a joint project between NASA and the European Space Agency. The telescope was launched into low Earth orbit in late 1990, and remains into operation. (1)Since its operation, the telescope has provided scientists and the public with spectacular images of deep space. It is one of the most technologically advanced pieces of equipment humans have put into orbit. Until now, the Hubble Space Telescope has helped researchers make countless discoveries about the universe, ranging from planets and stars to galaxies and cosmology.(2)

The Design of the Hubble Space Telescope

        Although the telescope was launched into the orbit in late 1990, the origin date of the project is far before that. In 1946, Lyman Spitzer, a professor and researcher at Yale University, explained that  the Earth's atmosphere not only blurs and distorts light coming from stars, but also blocks X-rays emitted from high-temperature phenomena in stars and other objects in his paper Astronomical Advantages of an Extra-Terrestrial Observatory.(2) He argued that a space telescope would offer great advantages over ground-based observations and allow scientists to accurately measure these X-rays as well. While teaching at Princeton University, Spitzer was asked to head a National Academy of Science Ad Hoc Committee on the Large Space Telescope. In 1969, the committee published Scientific Uses of the Large Space Telescope, in which the National Academy of Science urged the construction of Space Telescope.(2) At that time, the only agency likely to execute the National Academy's recommendation was NASA, and the main block of implementing the Large Space Telescope program is how to obtain the federal fund. The total cost of the large space telescope was roughly estimated at $400 to $500 and the motion of funding was rejected by the House Appropriations Subcommittee in 1975.(2) However, due to a large-scale lobbying effort by NASA and the European Space Agency's participation, the cost of the project down to about $200 million. The proposal was accepted by Congress, which granted the Large Space Telescope program funding in 1977.  (2) The Large Space Telescope was renamed the Hubble Space Telescope in honour of Edwin Hubble, an American astronomer who determined that the universe extended beyond the borders of Milky Way.(1)
        NASA orginally planned to launch the telescope in 1983, but the program experienced a considerable delay. Because the construction of mirror and optical assembly was handed over to Perkin-Elmer Corporation, the construction of the spacecraft and its support systems belonged to the Lockheed Missiles and Space Company. The mirror was completed in 1981, but the entire optical assembly was not put together until 1984. Subsequent final assembly of the spacecraft did not take place until 1985.(2) With all the pieces in place by December 1985, NASA planned the launch on October 1986. However, on January 28, 1986, when the Space Shuffle Challenger lifted off into the sky, in what appeared to be a routine launch, the vehicle exploded into a ball of smoke and flame. The accident stops the shuffle flights until 1988 and delayed the launch of the Hubble Space Telescope to April 24, 1990.(2)

Fuzzy Photos and Spectacular Repair
        Hubble was finally launched aboard Discovery on April 24, 1990. The telescope's original equipment package included the Wide Field/Planetary Camera, Goddard High Resolution Spectograph, Faint Object Camera, Faint Object Spectograph and High Speed Photometer. (2) After a few weeks of operation, scientists noticed that the images being sent back by Hubble were fuzzy- close to useless. An investigation finally revealed Hubble's main mirror had a major defect, a spherical aberration caused by a manufacturing error. The flaw was just 1/50th the thickness of a sheet of paper.(1) In December 1993, the crew of STS-61 embarked on a service mission to replace a number of Hubble's parts. Two teams of astronauts completed repairs during a record five back-to-back spacewalks. During the repair, COSTAR was installed and the Wide Field/Planetary Camera was replaced with the Wide Field/Planetary Camera 2, which was designed to compensate for the mirror problem. The first new images from Hubble reached Earth were breathtaking.(1)
       Hubble Space Telescope had already been serviced 5 times, in 1993, 1997, 1999, 2002, 2009 respectively. After its final serving mission took place in 2009, the telescope is expected to continue working until 2014. NASA plans to replace it with the James Webb Telescope, scheduled to launch in 2018.(2)
     

 "Pillars of Creation", took by Hubble in 1995

Three  Astronomy Discoveries Using the Hubble Space Telescope
       Firstly, the Hubble Space Telescope helped astronomers discover dark energy, which prevades our universe. Dark energy comprise about 70% of the universe's energy, yet scientists know almost nothing about it. This mysterious energy exerts a repulsive force that works against gravity. The telescope also provided evidence that dark energy has been engaged in a tug of war with gravity for billions of years, which means dark energy pushing galaxies away from each other at an increasing speed, making our universe expand at an accerlerating pace. Hubble also traced dark energy back 9 billion years ago. During that epoch, dark energy was struggling with gravity for control of cosmos. Dark energy finally won the struggle with gravity about 5 billion years ago.((3) page 2)

"Distant Supernova"

       Secondly, Hubble help astronomers determine a precise age for the universe. Before Hubble was launched, astronomers used the expansion rate of universe to pin down the universe's age, the rate is named the Hubble constant. However, their values for the Hubble constant were highly uncertain, making their calculations for the universe's age ranged from 10 to 20 billion years. With the Hubble Space Telescope, astronomers used the telescope's keen vision to accomplish that goal. Astronomers measured the brightness of dozens of pulsating stars called Cepheid variables, they then calculated the stars' distance from earth. From this study and other related analyses, astronomers determined the Hubble constant and the universe's age to an accuracy of "about 5 percent"((3) page 2). By their calculation, the universe is about 13.75 billion years old.((3) page 2)
       Thirdly, astronomers used Hubble to make the first three-dimensional map of dark matter, an invisible form of matter that makes up most of the universe's mass and forms its underlying structure. The gravity of dark matter allows normal matter in the form of gas and dust to collect and build up into stars and galaxies.((3), page 3) Although dark matter is invisible, astronomers detect its influence in galaxy clusters by observing how dark matter's gravity bonds and distorts the light of more distant background galaxies, a phenomenon called gravitational lensing. According to Hubble's observation, astronomers using gravitational lensing to construct the three-dimensional map by studying the warped images of half a million faraway galaxies. The new map provides the best evidence to date normal matter accumulates along the densest concentration of dark matter. The map stretches halfway back to the beginning of the universe and reveals a loose network of dark-matter filaments. Astronomers also used Hubble to observe the dark matter's distribution in the titanic collision of clusters of galaxies. Astronomers used Hubble to discover that a ghostly ring of dark matter that formed long ago during a clash between two groups of massive galaxies((3) page3)

Reference

1. Nola Taylor Redd, "Hubble Space Telescope: Pictures, Facts & History", April 23, 2014, space.com, http://www.space.com/15892-hubble-space-telescope.html

2. Okolski, Gabriel. "A Brief History of the Hubble Space Telescope." A Brief History of the Hubble Space Telescope. National Aeronatautics and Space Administration. Web. 28 Mar. 2015. http://history.nasa.gov/hubble

3. Hubble Space Telscope Top Science Findings, .http://hubblesite.org/hubble_20/downloads/hubble_topscience_lo-res.pdf

Assignment 5

the Discovery of Expanding Universe

         Everyone knows Edwin Hubble discover the evidence that the universe is expanding at a faster speed. However, he is not the person who set up the model shows the universe is expanding. Alexander Friedman, a Russian cosmologist and mathematician, is the 1st person who applied Einsteins' equation and found that the universe is expanding.

Russian Mathematician and cosmologist Alexander Alexandrovich Friedmann. Image by Qwerk

          Alexander Alexandrovich Friedman wan born on 16 June 1888 in Saint Petersburg, Russia. His father was a ballet dancer and his mother was a planist. He was an excellent student in high school. He began studying mathematics from 1906 to 1910 at saint Petersburg state university. He was appointed the position in the Aerological Observatory in 1913 and got his master's degree in pure and applied mathematics in 1914. He went to Leipzig to study with Vilhelm Bjerknes, the leading theoretical meteorologist of the time. When the World War 1 broke out, Friedman volunteered to serve with the Russian air force as a technical expert and as a bomber pilot, he went to the Central Aeronautical Station but it was disbanded after 1917 Russian Revolution. He worked as a theoretical mechanics professor at Perm University from 1918-1920. Friedman back to Saint Petersburg in 1920 because the Red Army occupied Perm and civil war. He had several works at that time: a teacher of mathematics and mechanics at Petrograd University, a professor of physics and mathematics at Petrograd Polytechnic Institute, and as a researcher at the Petrograd Institute of Railway Engineering, the Navy Academy and the Optical Institute.(1)
         Scientists at that time thought our universe was static and eternal. Einstein hold that opinion too. In 1917 Einstein adjusted his field equations to model just such a static universe. He added the repulsive force of a cosmological constant to model just such a static universe. However, Friedman didn't know such change. He became familiar with Albert Einsteins' General Theory of Relativity. In 1922, Friedman published a set of remarkable solutions to Einstein's equations. He introduced a new universe model at that time,  a dynamic universe can change its size overtime. In fact, Friedman introduced the expression "expanding universe'. One of his solution even point out that the cosmos began in a singularity-an infinitesimally small point. The model had an expansion rate which increased overtime. These characteristics of his model all has been proved right through observation in the future.

Per the Friedmann equations, the geometry of the universe is determined by its overall mass/energy density. If equal to the critical density, Ω0 the universe has zero curvature (flat configuration). If less than critical, the universe has negative curvature (open configuration). If greater than critical, the universe has positive curvature (closed configuration). Image credit: NASA/GSFC (2)

        But, Einstein didn't believe such a result while Friedman wrote a letter showing his works. Einstein calling Friedman's non-stationary world 'suspicious'. Friedman immediately sent another letter to Einstein in which detailing his work and calculation. After reading the letter, Einstein wrote in the journal:
"...my criticism...was based on an error in my calculations. I consider that Mr. Friedmann's results are correct and shed new light."(2)
       In 1923 and 1924, Friedman travelled through Europe, discussing his areas of research with other scientists, particularly in German, Norway and the Netherlands. Then he returned to Saint Petersburg( named Leningrad at that time), where he was given the job of director of the Main Geophysical Observatory in Leningrad. In July 1925, Friedman attended a record-setting balloon flight, reaching an evaluation of 7400 meters. However, 2 months after this experiment, Friedman died from typhoid fever in September 25, 1925, at the young age of 37.(1)
       Friedman's model of universe has 3 types. The first one is called closed universe, in this type, the universe begins with a Big Bang and continue expanding. But after a long enough time, the mutual gravitational attraction of all the matter slows the expansion to a stop. The universe then starts to fall in on itself, replaying the expansion in reverse direction. Finally all the matter collapse back to a singularity, in what physicist John Wheeler likes to call the Big Crunch.

Close Universe: The Big Bang's momentum is offset by gravity, producing a Big Crunch. (3)

       The second one is called open universe, in which there is not enough matter to stop the expansion of universe in which the universe will expand forever, eventually all stars go out and the whold universe became dark and cold. The third one is called flat universe, the universe will expand forever but the speed at which the galaxies separate will eventually reach zero.(3)

Open Universe: There is not enough matter to stop the universe from expanding forever. (4)

Flat Universe: Expansion slows until the rate approaches zero. (3)

       As Friedman being the director of the Main Geophysical Observatory in Leningrad in 1924. George Gamow studied after him. Gamow gaining his PhD from the university of Leningrad in 1928.

George Gamow, Professor, University of Colorado (5)

He was invited to Niels Bohr's Institute for Theoretical Physics at the University of Copenhagen in Germany from 1928 to 1931, with a break in 1929 to work with Ernest Rutherford at the Cavendish Laboratory, Cambridge. Gamow backed to the USSR but after a short time he decided to flee Russia due to an increased oppression by Stalin. He successfully escaped while attending the 1933 Solvay Conference for Physicists in Brussels, Belgium. Gamow and his family moved to United States in 1934, and Gamow began working as Professor of Physics at George Washington University in Washington DC. In 1948, Gamow and his student Ralph Alpher produced a paper entitled "The Origin of Chemical Elements", which outlined how the present levels of hydrogen and helium in the universe could be largely explained by reactions occurred  during the Big Bang. This lent theoretical
support to the Big Bang theory. Gamow also estimate the strength of residual cosmic microwave background radiation in this paper. Gamow died on August 19, 1968 due to his excessive drinking habit, at age 64.(4)

References:

(1) Luke Mastin, Important Scientists: Alexander Friedmann (1888-1925), 2009. The Physics of the             Universe,   http://www.physicsoftheuniverse.com/scientists_friedmann.html

(2) Mark Edgall, Alexander Friedmann: Unsung Hero of Modern Cosmology, October 31, 2012. decoded Science, http://www.decodedscience.com/alexander-friedmann-unsung-hero-of-modern-cosmology/19423

(3) Friedmann Universe, PBS Organization,  http://www.pbs.org/wnet/hawking/universes/html/univ_fried.html

(4) Luke Mastin, Important Scientists: George Gamow (1904-1968), 2009. The Physics of the Universe,  http://www.physicsoftheuniverse.com/scientists_gamow.html

(5) The Distinguished Life and Career of George Gamow. Department of Physics, University of Colorado Boulder, http://phys.colorado.edu/public-outreach/distinguished-life-and-career-george-gamow

Assignment 4

The Changing Pluto

       The most detailed view to the date of  the ensure surface of the dwarf planet Pluto,

                                   by NASA Hubble Space Telescope took from 2002 to 2003.(1)   

         Pluto is a dwarf planet which is once considered as the ninth planet of the solar system. Its diameter is 2368 km, mass is about (1.305*10)^22 kilograms. Pluto locates in Kupier belt,  a shadowy disk-like zone beyond the orbit of Neptune populated by a trillium or more comets.(1)
It is primary made of ice and rocks and is relatively small, about 1/6 the mass and 1/3 the volume of Moon. Pluto's orbit is highly eccentric, distance between the Sun and Pluto is about 4.4 billium kilograms when is closest to the Sun, and it became 7.3 billium kilograms when Pluto is far from the Sun.(2) The average temperature on Pluto is roughly minus 225 degrees C. but because of it eccentric orbit, the temperature on Pluto also changes dramatically depends on its location, when Pluto is moving closer to the Sun, its thin, tenuous atmosphere expands; when Pluto is moving far away from the Sun, the atmosphere collapse. Pluto has 5 known moons, Charon, Nix, Hydra, Kerberos and Styx which was found in 1978, 2005, 2011, 2012 respectively.(3)

 

                               

Pluto and its five moons(2)

      The discovery of Pluto is largely due to 2 person, Percival Lowell and Clyde Tombaugh.

      Percival Lowell was born on March 13, 1855, in Boston. He entered Harvard University and graduated in 1876 with a Bachelor degree of Arts in Mathematics. After graduation, he worked in his family's textile business. In 1882, He served as a foreign secretary to the Korean special mission. In 1890s, Lowell learned the discovery of canals on Mars by Italian astronomer Giovanni Schiaparelli, which attracts Lowell's excitement, he built an observatory on Mars Hill in 1894 in order to prepare for Martian opposition, that is Lowell Observatory. Despite he insist on that canals exist on Mars and claims he found several pictures about it, his insistence was disproved by NASA in 1972. In 1905, Lowell put the work in searching for the missing planet. He calculated that the variations in the orbit of Neptune and Uranus were caused by a ninth planet, which he dubbed Planet X. However, he didn't really discover Pluto. On Nov, 12, 1916, Lowell died of a cerebral hemorrhage. But his Laboratory continued the search, and 24 years later, Clyde Tombaugh, an astronomer of Lowell Laboratory, found Pluto depends on Lowell's calculation.(4)

                                  Image of Percival Lowell, founder of Lowell Laboratory and the person greatly 
                                          the discovery Pluto.(4)

      Clyde Tombaugh, who was born in 1906 in Streator, Illinois. He build his own telescope by himself in 1926, and built another 2 in the next two years. He used his telescope to observe Mars and Jupiter and sent the drawings of them to Lowell Observatory. The astronomers in Lowell was impressed by the power of observation of Clyde, they invited him to work at the Observatory. He stayed at Lowell Observatory for nearly 14 years. In 1932, he entered the university of Kansas and got Bachelor degree of Science in 1936. In 1938, he earned his master's degree in 1938 and returned to Lowell Observatory as a full-time astronomer. During his time in Lowell Observatory, he discovered hundreds of new variable stars, asteroids and counted over 29000 galaxies. He worked at Lowell until being called to service during World War 2. After the war, Lowell Observatory unable to rehire him due to a funding shortfall. He then worked for the military at the ballistics research laboratories of the White Sands Missile Range in Las Cruces, New Mexico. He left the missile range in 1955 and being awarded the medal of the Pioneers of White Sands Missile Range. He entered the faculty of New Mexico State University in Las Cruces until retired in 1973. He died in 1997, shortly before his 91th birthday at his home in Las Cruces, New Mexico.(5)

Clyde Tombaugh, the discoverer of planet Pluto(5)

     When Pluto was found in 1930, astronomers considered that Pluto was a big planet with a huge mass and size. However in 1978, as Pluto's moon Charon was found, astronomers was able to found the mass and size of Pluto. Pluto's mass is only 0.0021 mass of the Earths, its diameter is 2368km, despite Pluto's tiny size, astronomers believe that it is larger than any other planets pass the orbit of Neptune. Over the last few decades, with powerful new ground and space-based observations, astronomers realized Pluto is only a big example of a collection object named Kupier Belt. Astronomers found other objects in Kupier Belt which size is similar to Pluto. In 2005, Eris, an object in Kupier Belt which mass is 25% more than Pluto, and its diameter is about 2600 km- 200 longer than Pluto's. The foundation of Eris pushed the concept that solar system has nine planets began to fall apart. During the 26th General Assembly of the International Astronomical Union, which held from August 14 to August 26th, 2006 in Prague, Czech Republic, IAU redefine the definition of Planets in solar system:
      (1)It needs to be in orbit around the Sun.
      (2)It needs to have enough gravity to pull itself into spherical shape.
      (3)It needs to have "cleared the neighbourhood" of its orbit.
Because Pluto doesn't match the third one, IAU moved Pluto down to the new classification-"dwarf planet".(6)

Examples of Plutinos(6)

      Plutinos , means "little Plutos", is a generic name of the class of Kupier Belt members with orbits that very close or even cross the orbit of Neptune. Despite the close distance between the orbits of Plutinos and Neptune, Plutinos will not encounter Neptune. The orbital periods of Plutonis compared to Neotune's are in the ratio about 2 small numbers.(7)

References

     (1)Charles Q. Choi, Dwarf Plant Pluto: Facts About the Icy Former Planet, Nov 03, 2014. Purch http://www.space.com/43-pluto-the-ninth-planet-that-was-a-dwarf.html
     (2)Karl Tate, Pluto's 5 Moons Explained: How They Measure Up (Infographic), July 11, 2012 SPACE.com,
http://www.space.com/16538-pluto-moons-explained-infographic.html
     (3)Solar System Exploration,
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Pluto
     (4)Nola Tayler Red, Percival Lowell Biography, Feb 13, 2013, SPACE.com, 
http://www.space.com/19774-percival-lowell-biography.html
     (5)Clyde Tombaugh Biography, Dec 10, 2013, Academy of Achievement,
http://www.achievement.org/autodoc/page/tom0bio-1
     (6)Fraser Cain, Why Pluto is No Longer a Planet, Jan 5, 2012, Universe Today,
http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/
     (7)Plutinos, June 6, 1997, SKY & TELESCOPE NEWS BULLETIN,
http://carlkop.home.xs4all.nl/plutino.html

ASTB03-3836 The Copernican Revolution

ASTB03-3836

The Copernican Revolution

           Copernicus is a mathematician and astronomer in the 16th century. His book, De revolutionibus orbium coelestium, post the Heliocentric theory for the first time, give an alternative model of the universe to geocentric system.

1) The Earth is spinning around its axis every day, while the immense distant world of stars is motionless.

     This is one of the characteristics of Heliocentric theory. Supporters of Geocentric supporters argued that  "if Earth moved man would have some sort of perception of that movement. If Earth were moving at the speed required to explain movements observed in the heavens, a strong wind would continually,  blow in the direction opposite to the motion of Earth. In addition, if one were to throw a stone straight up into the air, a moving Earth would cause the stone to fall some distance behind its original position."(1) However, Geocentric theory can't make an illustration about why Sun rises in the East everyday and sets in the West, and Heliocentric theory can easily illustrate such phenomenon by stating the Earth's rotation. Like copernicus said,

"Such in particular is the daily rotation, since it seems to involve the entire universe except the earth and what is around it. However, if you grant that the heavens have no part in this motion but that the earth rotates from west to east, upon earnest consideration you will find that this is the actual situation concerning the apparent rising and setting of the sun, moon, stars and planets. Moreover since the heavens, which enclose and provide the setting for everything, constitute the space common to all things, it is not at first blush clear why motion should not be attributed rather to the enclosed than to the enclosing, to the thing located in space rather than to the framework of space."(2)

2) the Earth is a planet orbiting the Sun once a year like the other planets, so it is not in the center of the universe.

    It's the greatest difference as well as most well_known point in the whole Heliocentric theory. The Geocentric theory points out the Earth is the centre of the universe, ignoring that the same planet may nearer than the Earth at one time and far away from the Earth at another time. Copernicus insist, if the Earth is the centre of the universe, at anytime distance between the Earth, Sun and other planets in the solar system should unchanged. He regard this as same important characteristic of his theory as daily rotation. 

" It will occasion no surprise if, in addition to the daily rotation, some other motion is assigned to the earth. That the earth rotates, that it also travels with several motions, and that it is one of the heavenly bodies are said to have been the opinions of Philolaus the Pythagorean."(3)

(iii) the Sun does not orbit around the Earth, but remains motionless in the center of the planetary system.

In his book,   De revolutionibus orbium coelestium,  Copernicus points out that the Earth isn't the centre of the planetary system. so who's the centre? Copernicus first stated that the centre of the system should have the same characteristics as the Earth, Sun, Moon etc. It should have gravity, should rotate as other planets do. As well, it should have the same motion which can be seen not only from the Earth, but can also be seen from Moon and other planets. Copernicus thinks that the scenery we see everyday in the morning and evening---the rising and setting of Sun, can also be seen from other planets in the system, he also make sense that Sun is so large, as well as which is the evidence showing that Sun should be the centre of the planetary system and remains motionless.

Heliocentric theory of the solar system in Copernicus' Manuscript(4)

Though Aristarchus, Greek astronomer who is the first person put Sun into the centre of the solar system and describe the heliocentric theory, Copernicus is the first one who use the evidences and proofs to illustrate Heliocentric theory such systematic. He also the first one who publish a book which statement is fully against the Catholic Church's statement. Help Science make the first step to get rid of control from the Catholic Church. Just like Friedrich Von Engels said " the dictatorship of the Church over men's minds was shattered', the 'greatest progressive revolution that mankind had so far experienced'"(5).

Citations:

(1) Historic Dispute : Is Earth the center of the universe?,    http://www.scienceclarified.com/dispute/Vol-2/Historic-Dispute-Is-Earth-the-center-of-the-universe.html

(2),(3) Nicholas Copernicus On the Revolutions, translation and commentary by Edward Rosen. The Johns Hopkins University Press, Baltimore and London.

(4) Copernicus' manuscript: "De revolutionibus", Book One, Chapter 10: The Order of the Heavenly Spheres.

(5) F. Engels, The Dialectics of Nature in Marx, Engels, Collected Works (MECW), Vol 25 (London, 1987), P319