Assignment 6: Modern Astronomy.

Immediately after World War II, the idea of observing from a telescope in space was initiated by a researcher and professor at Yale University in 1946. Lyman Spitzer explained the benefits of having such an instrument in space rather than on ground. His argument in support of this idea is evident in his paper, “Astronomical Advantages of an Extra-Terrestrial Observatory”. He states the drawbacks of a telescope such as the inability to accurately see the light being produced by the stars due to Earth’s atmosphere which causes it to be blurred and distorted. In addition, the earth’s atmosphere does allow the x-rays of stars and other celestial objects with high temperature to be identified. However, Spritzer argued that a space telescope would permit such observations.

It was not until 1990, the space telescope named Hubble Space Telescope was launched. With the support from the National Academy of Sciences in America (NASA), the project began in 1969. The delivery of the Hubble Space Telescope was delayed as a result of lack of funding from NASA after the lunar landing. The initial plans for the space telescope was altered by reducing the quantity of instruments, the size of the primary mirror and amount of spare parts. The design was specified to perform certain demands such being able to observe x-rays emitted from stars. The Hubble Space Telescope will enable scientists to observe a variety of wavelengths emitted from extraterrestrial objects without the diffusion of any wavelengths by Earth’s atmosphere. There was no clear single objective for the telescope apart from benefiting astronomers and scientists to observer the universe from another perspective and enable mankind to explore.

The Hubble Space Telescope would be launched into Earth’s orbit and remain there, where it will be able to record data without any interference from Earth’s atmosphere. The Hubble Space Telescope works by directing any forms of light, for example gamma rays, x-rays, and infrared through its lenses into sensors on board. After the light enters the Telescope the light is redirected by the main lens to the secondary lens that focuses the light source into the sensor. With the use of the extensive sensors scientists would be able to observe clear images in different wavelengths.

The Hubble Space Telescope faced a variety of difficulties when attempting to launch the telescope. Apart from the numerous delays the Hubble was launched on board the Discovery on April 24, 1990. The Hubble’s equipment’s consisted of the High Speed Photometer, Faint Object Spectograph, Faint Object Camera, Goddard High Resolution Spectograph, and the Wide Field/Planetary Camera. Following the launch of the telescope scientists began to notice slight distortions in the images sent back from the telescope. Even though the images delivered were clear enough for scientist to still study, they were not meeting their initial expectations. It was later discovered through investigations that the primary mirror had a spherical aberration, meaning that the edges of the mirror were flatter than they were supposed to be. Following the discovery of the flaw scientists were able to conceive a way to fix the problem by designing the Corrective Optics Space Telescope Axial Replacement. The COSTAR would fix the aberration by using multiple optics. A crew of astronauts were sent on a service mission to repair the Hubble in December 1993. The crew installed the COSTAR and also replaced the Wide Field/Planetary Camera with a new one that would compensate the problem caused by the mirror.

The Hubble Space Telescope has provided astronomers and scientists access to a great deal of images of the universe never seen before. The current state of the Hubble Space Telescope is in jeopardy due to the risks involved with servicing and maintaining the telescope along with the funds required. This risks involved have been displayed in the tragedy that occurred in 2003 when seven astronauts died during the reentry into the atmosphere which resulted in the administrative decision that all future missions will only be to the International Space Station. Eventually the Hubble Space Telescope will be retired by NASA and will fall off orbit towards Earth ending its journey.

The Hubble Space Telescope has contributed to the advancement of space exploration in the past years. One of these great observations that was provided by the observatory include, enabling scientists to observe galaxies that existed when the universe was only a billion years old. This was done by directing the telescope at an empty part of the sky for approximately 10 days. Although this was considered risky for the astronomers since they could be using the telescope for other research it ended up paying off. The image showed scientists over 3000 galaxies all shaped differently and was named the Hubble Deep Field. This method of observation was later used several times to continue to observe the initial galaxies in the universe and provide an insight into the early stages of the universe.

Another observation that the Hubble provided was images of Jupiter before and after a collision with a comet. The Hubble Space Telescope would allow scientists to observer the effects the comet collision has on Jupiter, how it affects the atmosphere and any changes of its satellites. With the use of the Hubble astronomers will be able study the impact more in-depth by being able to observer different spectrums and observe any variations which would have been not seen in the visible light.

Another breakthrough made possible by the Hubble Space Telescope was the discovery of organic molecules. The Hubble was able to detect methane molecules in the atmosphere of a planet orbiting another star. This is a significant breakthrough since it proves to astronomers that with the use of spectroscopy, space telescopes will be able to observe organic molecules in planets in different solar systems. This will enable scientists to search for planets in the habitable zone with prospects of life using space telescopes. It also provides scientists to be able to examine conditions such as temperature using spectroscopy.

Reference

http://history.nasa.gov/hubble/

http://www.nasa.gov/mission_pages/hubble/story/index.html#.VRtge5N37jl

http://hubblesite.org/hubble_discoveries/breakthroughs/cosmology

http://www.nasa.gov/mission_pages/hubble/science/hst_img_20080319.html

http://www2.jpl.nasa.gov/sl9/hst.html

http://hubblesite.org/newscenter/archive/releases/solar-system/comet/1994/46/results/50/

 http://www.nasa.gov/sites/default/files/images/345535main_hubble1997_hi.jpg

Assignment 5: Discoverer of Expanding Universe

The Life of Alexander Friedmann

Alexander Friedmann was born on June 16, 1888 in Saint Petersburg, Russia. He was born to a ballet dancer and pianist. Early on his life, he witnessed the separation of his parents’ marriage. Thus growing up, he lived with his father. In 1897, Friedmann attended Second St Petersburg Gymnasium where he initially had a standard academic standing. Although, before long, he became one of the top students. Included amongst the top academic students, was Alexander’s friend Yakov Tamarkin. The two remained friends throughout school and university. As mathematicians, in 1905, Friedmann and Tamarkin wrote about Bernoulli numbers and in 1906 it was published in Mathematische Annalen. During this year, Friedmann and Tamarkin became interested in politics. This was evident in his participation as a leader of strikes at school and protested the government’s oppression for education. Following his graduation, in 1906, Friedmann enrolled in the University of St Petersburg later that year. During his time at the university, he had the opportunity to participate in a seminar on physics in 1907. It was organized by Ehrenfest and the topics discussed are quantum theory, statistical mechanics, and relativity. After completing his undergraduate degree in 1910, Friedmann continued his studies to obtain a graduate degree. After receiving the degree in 1913, Friedmann was hired by the Aerological Observatory in Pavlovsk. His position required him to study meteorology. Following this, in 1914, Friedmann travelled to Leipzig to study with the well-known meteorologist, Vilhelm Bjerknes. That same year, World War I began and Friedmann voluntarily joined and became a pilot of the Russian Air Force. During the war, he remained passionate about mathematics and shared this thoughts with Steklov by writing letters. In addition, it was at this time when Friedmann received the award, George Cross for his courage. He was then sent to Kiev in 1915 and was employed as the head of the Central Aeronautical Station. In 1917, the Central Aeronautical Station was relocated to Moscow and Alexander decided to move as well. After being stopped to work here, Friedman became a professor at the University of Perm. He was a part of both the Department of Mathematics and Department Physics and founded an Institute of Mechanics at the university. Additionally, Friedmann was a part of the Journal as an editor for the Physics-Mathematical Society of University of Perm. As a result of the civil war, he went back to St Petersburg and worked at the Main Geophysical Observatory. Later, Friedmann took several other positions related to his field of expertise. These include, professor in Petrograd University, teaching mechanics, physics and mathematics meanwhile worked at the same Institute of Railway Engineering, and the Naval Academy and researched at the Optical Institute. Near the end of his life, Friedmann constructed a remarkable balloon flight in order to make observations. Near the end of August in 1925, he was detected to have typhoid and within two weeks of being hospitalized, Friedmann passed away.

Cosmological Works: Einstein and Three Types of Universe Models

Albert Einstein in his paper on the General Relativity, believed in the theory that the universe was in fact static. Einstein had incorporated the cosmological constant into his calculations to account for the static model of the universe. This cosmological constant was viewed to him as a repulsive force in the universe that kept the universe from collapsing within itself. Alexander Friedmann had confronted the use of the static universe model that was accepted by many scientists at the time along with Einstein. He proposed substituting the cosmological constant with other values and developed different models of the universe, these models that he proposed were dynamic in nature. Friedmann proposed three models of the universe closed, open, and Einstein-deSitter. The first closed model of the universe proposed that the universe was expanding. At a point in time this model of the universe will stop expanding and eventually collapse on itself. The closed model is represented as a spherical universe and is assumed to have a high density. Another model proposed was the Open Model of the universe. In this model the universe is expanding and will continue to expand forever. The open model is assumed to have a low density. The third model, Einstein-deSitter was a combination of both the closed and open models of the universe. In this model it was theorized that the universe will expand to a point then collapse on itself but never fully expand or collapse. All the models that Friedmann presented had one thing in common, which was that the universe was not static. This proposal lead on to many advancements in the study of cosmology. After the publication of Friedmann’s theory, many scientists opposed his findings. Albert Einstein had responded to Friedmanns work and stated that there must be miscalculations in his work. Friedmann replied to Einstein’s statement by sending him a detailed letter including extensive calculations explaining his theory. Friedmann requested Einstein to retract his prior statement if Einstein could discredit his calculations. When Einstein later read this letter, he accepted Friedmann’s theory and revised his statement by accepting Friedmann’s work. Einstein eventually removed the cosmological constant and credited Friedmann for his contribution towards General Relativity.

George Gamow: Friedmann’s Student

At Friedmann’s time working at the University of St. Petersburg, he had a student named George Gamow. Gamow was also born in Russia in 1904 and is recognized as a cosmologist, nuclear and theoretical physicist. He known for his work contributing to radioactivity and was working on his own theory. His biggest contribution to his field of study was his theory about the alpha particle decay of atomic nuclei. In 1948, George Gamow with his colleague Ralph Alpher published “The Origins of Chemical Elements”. In this paper they pointed out that the current universe is the aftermath of the chemical reactions that occurred during the Big Bang, and the composition of hydrogen and helium in the universe can be accounted for in their theory. Additionally Gamow had estimated the strength of the cosmic microwave background radiation. He predicted that the Big Bang would have resulted in an afterglow that would cool down billions of years later and fill the universe with radiation that was approximately 5 degrees above absolute zero. George Gamow’s theory was the foundation for further scientific contributions from other advocates of the Big Bang theory. In the year 1965 in America, Arno Penzias and Robert Wilson accidently found the existence of cosmic microwave background. They determined that its temperature was approximately 2.7K, as a result proving Gamow’s theory.

References

George Gamow - Important Scientists - The Physics of the Universe. (n.d.). Retrieved March 25, 2015, from http://www.physicsoftheuniverse.com/scientists_gamow.html

Alexander Friedmann: Unsung Hero of Modern Cosmology. (2012, October 31). Retrieved March 25, 2015, from http://www.decodedscience.com/alexander-friedmann-unsung-hero-of-modern-cosmology/19423

Alexander Friedmann - Important Scientists - The Physics of the Universe. (n.d.). Retrieved March 25, 2015, from http://www.physicsoftheuniverse.com/scientists_friedmann.html

Aleksandr Aleksandrovich Friedmann. (n.d.). Retrieved March 25, 2015, from http://www-history.mcs.st-and.ac.uk/Biographies/Friedmann.html

The Friedmann Equation for the Expanding Universe. (n.d.). Retrieved March 25, 2015, from http://www.einsteins-theory-of-relativity-4engineers.com/friedmann-equation.html

http://friedmannlab.ru/Img/friedmann.jpg

http://phys.colorado.edu/sites/default/files/gamowmain.jpg

http://www.phys-astro.sonoma.edu/PEOPLE/FACULTY/TENN/FriedmannModels.jpg

Assignment 4: The changing Pluto.

Pluto was once thought to be one of the nine planets of our solar system, however it was reclassified as a dwarf planet in 2006. Pluto is the furthest planet from the sun and is unique from the other outer planets. Pluto is composed of primarily rock with an outer layer of frozen water. This is vastly different compared to the gaseous composition of the outer planets in the solar system. Pluto is known as one of the largest celestial object in the Kuiper Belt, amongst its vast population of comets.

In 1905, Percival Lowell, an astronomer observed deviations between the orbits of Neptune and Uranus hence predicting the existence of a ninth planet. He later died without ever finding the planet. Pluto was discovered by Clyde William Tombaugh in 1930 at the Lowell Observatory in Flagstaff, Arizona. Tombaugh was born on February 4, 1906 in Illinois. He was not from a wealthy family and thus was not financially capable to attend college, although, he did graduate High School in 1925. Throughout his early life he had an interest towards astronomy, thus using his uncle’s telescope, he would observe the night sky. Later in 1926, he constructed a telescope by following the guidelines provided in an article published in the magazine Popular Astronomy. This fascination led him to construct two more telescopes and using these, Tombaugh was able to make drawings of Mars and Jupiter. He later sent these drawings to the Lowell Observatory in 1929. His intention was to receive feedback about his work but rather he was offered a job at the observatory. This job required him to photograph the night sky using a 13 inch telescope and to look for any differences in the sky by comparing the images. The intention of his work was to locate Planet X. It was on February 18, 1930, Tombaugh discovered the ninth planet, later named Pluto. It was declared as the ninth planet on March 18, 1930. After this discovery, he was able to pursue an education with a scholarship to earn an undergraduate degree at the University of Kansas. Later he continued his education and received a Master’s degree in astronomy in 1939. Meanwhile, he continued working at the Lowell Observatory and made additional contributions to astronomy by discovering more than thirty thousand objects in the sky. Additionally, he had an interest for the planet Mars and provided in depth observations about its surface and provided an explanation for the presence of craters on Mars. During World War II, he was hired by the Navy to teach navigation at Arizona State College until the end of War. Following the War, he obtained another job at the University of California as a visiting assistant professor because Lowell laboratory wasn’t able to employ him. Clyde William Tombaugh later died in 1997, and his ashes are to be sent on a probe to Pluto in 2015.

The existence of another planet after Neptune was first proposed by Percival Lowell. Lowell founded the Lowell Observatory, which was used by Tombaugh to find Pluto. Lowell first noticed that Neptune and Uranus orbits were being affected by an external force from beyond them. These observations led him to believe of another planet that was yet to be discovered. He dedicated his life to finding this mysterious planet and spent countless hours predicting the location using various mathematical calculations. Lowell was never able to find this planet. Tombaugh was later set with the task of finding the planet. He had used a blink comparator to find Pluto. A blink comparator enables one to observe two pictures simultaneously by switching between them quickly this allows the user to notice any variations in the pictures. Hence able to identify any movement in celestial objects. Tombaugh was able to find Pluto using the blink comparator in 1930.

Pluto was discovered by Tombaugh by complete accident. Tombaugh was looking for the proposed planet by Lowell based on Lowell’s calculations, which were found to be completely wrong. Tombaugh was able to locate Pluto, which was miniscule compared to Lowells’ predictions. Lowell believed that Neptune and Uranus were being greatly affected by this mysterious planet, however Pluto’s gravity would have minimal impact on the other planets due to its sheer size.

The discovery of Pluto lead to a lot of controversy in the astronomical field. The sheer size of Pluto made scientists question the meaning of the word planet. This is due to the fact that Pluto is smaller the many of the moons found in our solar system. In addition, Pluto unlike the other outer planets has a rock core. In addition, the existence of more icy celestial objects beyond Pluto were proposed by Gerard Kuiper. This was discovered in 1992 and was given the name Kuiper Belt. Which now holds Pluto as one of the largest members amongst the Kuiper Belt. Due to the controversy regarding classifying Pluto as a planet, the International Astronomical Union classified Pluto as a dwarf planet. In addition, the International Astronomical Union classified any objects orbiting the sun beyond Neptune to be classified as plutoids.

Plutinos are celestial objects that orbit the sun in our solar system that are at a greater distance than Neptune. These minor planets must be further than 30 astronomical units from the sun.  Plutinos orbit 2 times for every 3 times that Neptune orbits. They were named after the dwarf planet, Pluto. Plutinos occupy a great amount of the known Kuiper belt objects.

Sources:

http://www.space.com/43-pluto-the-ninth-planet-that-was-a-dwarf.html

http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-pluto-k4.html

http://www.space.com/19824-clyde-tombaugh.html

http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs

http://cseligman.com/text/planets/plutoid.htm

Pictures:

http://en.wikipedia.org/wiki/File:ThePlutinos_Size_Albedo_Color2.svg

http://en.wikipedia.org/wiki/File:TheKuiperBelt_60AU_LargePlutinos.svg

http://www.plutopark.info/images/Clyde-Tombaugh.jpg

http://twanight.org/newTWAN/photos/3003984.jpg

http://i.space.com/images/i/000/018/506/i02/kuiper-belt.jpg?1339696229