The Doppler shift.

The Doppler shift also known as the Doppler Effect refers to the change waves frequency where the observer of the wave is moving towards the source of the wave. It is most common when a vehicle that has a siren passes and goes at a far distance from the observer. In this particular case the frequency that is received is a lot higher than the actual emitted frequency when the vehicle is approaching. When the vehicle is passing by, the frequency is identical to the emitted frequency and when the vehicle rescinds the frequency is lower that the emitted frequency.

Sound waves which pass through mediums, the velocity of both the source of the sound and that of the observer depend on the medium of propagation of the waves. The Doppler Effect thus results from motion of the medium, the observer and the source of the wave.

The Doppler Effect is applied in various areas of everyday life. This effect is applied in emergency vehicles that use sirens so that it appears to start on a high note becomes gradual and finally fades when the vehicle has finally passed. According to John Dobson if the siren approached an observer directly then the frequency would remain constant throughout.

In astronomy this effect is used in electromagnetic waves like the light waves. It is used to measure the speed at which galaxies and stars either approach or move away from the earth. This effect is also used in measurement of vibrations. This is done by the use of a gadget known as a Laser Doppler Vibrometer.

Black Holes.

The universe comprises everything from the smallest particles to the biggest galaxies, as well as the entirety of both time and space. While many are familiar with stars, planets, and other visible objects from space, the universe contains stranger objects that have fascinated and puzzled experts for years. Black holes are just one of the many objects in the universe that embody mysteries some have been solved, while others are yet to be discovered. As its name implies, black holes are known for their dark faade and interiors, making them hard to be seen by the naked eye. Although recent developments in technology made it possible to understand this region of the universe, black holes still remain as one of the strangest and puzzling objects found in space.
Black Holes An Overview
    Black hole is an object of high density that has a very strong gravitational force, which makes it impossible even for light to pass through. Because nothing else can travel faster than light, it is also impossible for other matter and energy to escape from this region in space. This implies that experts can never directly observe what happens inside a black hole, except by entering in it. Yet, as it has been stated earlier, such object is a point of no return. Thus, one could never come back to report findings (Freudenrich).
    The existence of  black holes was first proposed during the 18th century on the basis of known laws of gravity at that time. That is, the more massive an object or the smaller its size is, the stronger or larger gravitational pull can be felt on its surface. This idea was supported by geologist John Michell and Pierre-Simmon Laplace, who both independently contend that if an object were either extremely massive or small, it is impossible to escape from its gravity that even light can be captured inside that object forever. However, the object of such observation was not named until 1967 when John Archibald introduced the term  black hole  for the proper identification of the object that Michell and Laplace theorized. Since then, black hole has become a common term for any type of mysterious bottomless pits found in outer space ( Black Holes ). The first object of this type was the Cygnus X-1, which was detected during the 1970s. After such discovery, a dozen more possible black holes have been identified such as that of the stellar black holes, which are left when super giant stars, at least 25 times more than the mass of the sun, explode (Parker 31). 
Formation of Black Holes
    Aside from the excessive gravitational force which primarily causes the formation of black holes, there are two other ways through which these objects develop. First is that, if a large star (probably more than nine solar masses) has burnt all its fuel, it then explodes into a supernova. Excessive stuff from the collapse turns to an extremely dense object known as neutron stars. The only thing that holds a neutron star from collapsing is due to the strong nuclear force that keeps the center of an atom from exploding. However, if a neutron star is so massive, its gravitational force is too strong that it overwhelms the nuclear force protecting the atom, allowing it to collapse. As the neutron star continues to shrink, it eventually becomes a black hole. The last means of black hole formation was proposed by Stephen Hawking. He theorized that trillions of black holes were formed during the Big Bang, with some still existing today. However, unlike the first two means, Hawkings theory is not widely accepted by the scientific community (Mihos).
Anatomy of Black Holes
    Black holes have very simple structures. However, some of their parts can only be found in certain types of black holes, while others do not have all of the parts that are to be discussed here. The very core of a black hole is called singularity. It is situated at the center of the black hole, and this is where the mass of the original star is said to be found, along with other matters acquired by the black hole. To date, nobody really knows what a singularity is really like. Some believe that it appears like a quantum foam, while others hold that it is more solid. No one knows what happens once an object is drawn from the singularity whether it smashes, becomes a part of the singularity, or if it travels through, which is commonly depicted in science fiction. Even current theories of physics do not apply to the premise of a singularity (Mihos).
    Just outside the singularity is the inner event horizon. It has been believed that between the singularity and the inner event horizon, space is relatively normal only that all objects are directly trapped in the singularity, and there is no means of escape. Outside the inner event horizon is the outer event horizon, which serves as the boundary through which the so-called escape velocity is much greater than lights speed. This also marks the holes outer edge, and the part of the object where other objects are drawn towards the hole. The outer event horizon is not visible to the eye as from this point of the hole inward, no known radiation escapes due to the extreme gravitational pull (Mihos).
    The ergosphere is a part that can only be found in a spinning black hole. This is an area where all particles are drawn and go parallel to the rotation of the hole. Contrary to the outer event horizon where matter and energy are trapped, within the ergosphere these objects can still escape the holes grasp. The outer edge of the ergosphere is known as the static limit, which is also the boundary between normal space and the ergosphere. This is the distance that any matter in space should maintain to have a stable orbit so as not to be trapped from the black hole. Other parts that are only apparent in some forms of black holes include that accretion disk, which is identified as a matter trapped in orbit around the black hole. This matter is gradually pulled into the hole. As it gets closer, it increases in speed, gains energy, and eventually emits light, which in turn astronomers use in order to determine the weight of the black hole. Through the use of doppler effect, astronomers are able to know how fast the accretion disk is revolving inside the black hole (Mihos). 
Types of Black Holes
    There are two basic types of black holes. First is the Schwarzchild black hole, which was named after German physicist, Karl Schwarzchild, who discovered the said holes size of event horizon during the First World War. This type of black holes have stationary core meaning, it does not rotate. Hence, it only has two parts, the singularity and an event horizon. The Kerr black hole is considered as the most common form of black holes. Unlike the Schwarzchild black hole whose core does not rotate, the core of the Kerr black hole rotates due to the fact that the star from which it was formed was rotating as well. Once the rotating star collapses, its core continues to rotate (angular momentum),  thereby forming the Kerr black hole (Freudenrich).
Measuring and Detecting Black Holes
    It is noteworthy that no black hole has been actually imaged in a telescope. In fact, doing such would also be impossible as one simply cannot see nothing. However, although people cannot see a black hole, it does have three properties that make it possible to be measured mass, electric charge, and the rate of rotation (angular momentum). As of the moment though, it is only the mass of black holes that can be measured reliably through the movement of objects surrounding it. For instance, if a black hole has a companion such as the accretion disk, it is then possible to measure the radius of the holes rotation or the orbiting speed of the materials surrounding the invisible black hole. The mass of the black hole is then calculated using Keplers modified third law of planetary motion, or through rotational motion (Freudenrich).
    Just like its measurement, the detection of black holes presence can be done by measuring the effects of the materials or objects surrounding it. These effects include estimation of the mass of objects that orbits a black hole or those that spiral into the core gravitational lens effects and emitted radiation.
    Mass many black holes have various objects surrounding them. By looking at the behavior of these objects, experts are able to detect the presence of black holes. Usually, scientists look for stars or disk gas that behaves as though a large mass is nearby. For instance, if a visible star wobbles or spins without any visible reason, and the invisible reason has effects as if it is caused by an object greater than three solar masses, then it is possible that a black hole is what causes such motions. The movements of the objects surrounding the black hole is then used to calculate the mass of the black hole (Freudenrich).
    Gravity Lens This system of detection is based from Einsteins General Theory of Relativity which predicted that gravity is capable of bending space. Therefore, an object that has immense gravity (black holes), between earth, and a distant object could bend the light from the distant object within a focus, just like a lens. For instance, the star named Macho-96-BL5 brightened when a gravitational lens passed between it and earth. Images from the Hubble Space Telescope showed two objects close together, which was a clear indication of the gravitational lens effects. Hence, the intervening invisible object that passed between the earth and the object was ruled as a black hole (Freudenrich).
    Emitted Radiation when materials fall into a black hole from a surrounding star, they are then heated and accelerated. These superheated materials then emit X-rays, which in turn are detected by x-ray telescopes like the Chandra X-ray Observatory. Other than this, black holes also eject materials at high speed which form jets. This, along with the x-rays, is used to detect the existence of black holes (Freudenrich).
Significance of Black Holes
    There has been much speculation about the real significance of black holes. Some propose that black holes may be a manifestation of what other universes look like, and that a hyperuniverse exists much bigger than the universe that people know about. However, at present, there is still no known way of proving whether these assumptions are real or not. Yet, black holes tell something important about the universe and galaxies that humans are aware of. As the density of black holes are so immense, the gravitational forces they exert generate a large amount of energies than those of the stars. Nevertheless, their existence made scientists aware of the constellation Sagittarius, which was identified through the use of Sagittarius A.
    Aside from this, the existence of black holes at the center of many galaxies can also help explain the presence of another strange object known as the quasar or quasistellar radio source. It should be taken into consideration that the first quasars detected in 1962 were considered as the brightest objects known to modern astronomy. This was made possible through the existence of black holes. Most quasars are more than 10 billion light-years away, and none are closer than two billion light-years from earth. Hence, it has been inferred that quasars existed early in the life of the universe and that it can be considered as the astronomical equivalent of dinosaurs. Basically, quasars are consisted of black holes, which also serve as their food. They were particularly numerous during the early universe because galaxies were still crowded, which in turn feed the black holes really well. However, as the universe expanded and galaxy clusters moved far apart from each other, the pickings of star foods decreased for galactic black holes. Though most galaxies still have black holes in their centers, few of these objects consume enough to be able to create quasars. Because most quasars do not live for more than a few million years due to their voracious appetite for star dusts, they are considered rare in modern universe (Christian 46-47).
Conclusion
    From the given perspectives above, it can be inferred that black holes are indeed strange objects found in space due to their mechanisms. Though simple in structure, they remained as one of the most difficult astronomical bodies to be studied. However, the advancement in technologies have made it possible to somehow understand some of the aspects about these objects. Yet, there are still a myriad of things to be discovered about this  phenomena, as what humans already know about black holes may constitute only a bit of what these strange objects really have and can offer.

Analytic Way Basic Physics.

The  9642  feet  high  Bighorn  Medicine  Wheel  has  an  80  diameter  and  a  wheel-like  pattern  of  stone.  This  Native  American  construction  is  believed  to  have  been  constructed  between  300-800  years  ago  in  the  period  between  1200  and  1700 A.D. At  the  centre  rests  a  cairn  connected  to  the  outer  circle  of  the  wheel  by  28  lines of  stones  representing  the  spokes  of  a  wheel.  The  significance  of  the  Bighorn Medicine  Wheel  lies  in  two  of  its  assumed  purposes.  Firstly,  the  number  28  is  important  because  it  represents  the  lunar  month  and  secondly,  it  represents  the  heliacal  or  dawn  rising  of  Rigel, 28  days  after  the  solstice  and  Sirius,  28  days  after  that.  One  characteristic  of  the  construction  has  been  believed  to  serve  as  points  for  the  rising  and  setting  place  of  the  Sun  at  summer  solstice,  as  pointed  out  by  Jack  Eddy.  Another  astronomer,  Jack  Robinson  found  that  a  cairn  pair  marked  Formalhauts  rising  point  28  days  before  the  solstice.  The  cairns  represent  according  to  him,  the  summer  solstice  sunset  and  also  points  out  where  Alderdan,  Rigel,  Sirius,  and  Formalhaut  rise  along  with  the  point  of  the  summer  solstice  sunrise.  The  determination  of  the  heliacal  point  of  a  star  signifies  the  date  a  star  is  first  seen  before  dawn  after  being  hidden  by  the  Sun  for  a  season.  The  four  stars   mentioned,  served  as  solstice  markers  for  the  native  Americans.
The  Stonehenge  dates  back  to  around  3000 B.C  and  is  one  of  the  most  important  constructions  that  was  used  for  purposes  of  astronomy  William  Stukuley,  in  the  18th  century,  discovered  that  the  horseshoe  of  great  Trilithons  and  the  horseshoe  of  19  Bluestones  of  the  Stonehenge  (which  comprises  broadly  of  three  sets  of  structures  Stonehenge I, Stonehenge  II, Stonehenge III)  faced  the  direction  of  sunrise  during  midsummer.  In  other  words,  the  sun  was  found  to  rise  directly  over  the  Heel  Stone  in  midsummer.  It  was  thus  concluded  that  since  the  alignment  signified  a  ritualistic  connection  with  Sun  worship,  it  was  probably  constructed  as  a  place  for  worship  of  the  Sun.  however,  more  recent  findings  indicate  that  this  ancient  construction  may  have  served  several  other  purposes  such  as  the  prediction  of  eclipses.  Although  the  great  stone  circles  and  horseshoe  alignments  were  later  additions  to  the  construction,  the  site  of  the  Stonehenge  no  doubt  has  special  astronomical  significance  since  the  stones  used  were  brought  from  great  distances  away.  It  has  also  been  claimed  that  the  Aubrey holes,  56  in  number,  were  used  to  keep  track  of  the  points  where  the  paths  of  the  Sun  and  the  Moon  intersected  in  the  event  of  an  eclipse.
The  ample  astronomical  evidence  provided  by  both  the  Bighorn  and  the  Stonehenge  show  that  the  people  of  those  times  had  astute  knowledge  of  astronomy  and  were  even  capable  of  predicting  solar  and  lunar  events  before  they  took  place.  It  is  also  thus  established  from  the  revelations  of  the  astronomical  alignments  of  these  two  ancient  sites  that  in  spite  of  the fact  that  the  people  lacked  the  technological  assistance,  their  knowledge  of  science  was  so  powerful  that  they could  do  without  the  technical  help  that  we  require  today.

Part II Answers

Since  light  takes  time  to  travel  and  its  wavelength  changes  through  different  media,  we  do  not  see  any  object  in  real-time. The  fundamental  forces  of  nature  can  explain  everything,  even  thought  processes  and  muscle  movement  which  have  been  regulated  by  remote  viewing  and  telepathy  for  years.
The  fundamental  force  of  nature  responsible  for  light  is  the  electromagnetic  force  while  the  weak  force  is  responsible  for radioactivity.
An  element  is  the  simplest,  essential  and  fundamental  component  of  which anything  consists.
The  end  of  the  oceans  would  represent the  end  of  the  earth  and  Rome  would  be  the  centre  in  that  case.
It  is  the  intersection  of  the  equatorial  and  ecliptic  plane  that  results  in seasonal  changes,  if  the  earth  was  not  tilted,  there  would  no  such  alteration.
In  order  for  a  solar  eclipse  to  take  place,  the  moon  has  to  come  in  a  position  exactly  in  between  the  sun  and  the  earth. Since  there  are  orbital  variations  of  the  earth  and  the  moon,  a  solar  eclipse  can  take  place  only  during  a  new  moon  and  not  every  month.
It  is  dusk  when  the  moon  is  full  on  the  western  horizon.
Mercury  and  Venus  are  seen  from  the  earth  in  phases  because  these  planets  pass  between  the  sun  and  the  earth.
 If  the  same  speed  is  maintained  while  turning  right,  then  no  acceleration  is  required.
Since  I  have  lifted  my  feet  from  the  accelerator,  I have  decelerated  and not  accelerated. Since the weight of objects of the moon decreases to around 14th   of  their  actual  weight,  one  pound  of  chocolate  on  the  moon  will  be  more  in  quantity  than  a  pound  of  chocolate  on  earth.
There  is  no  gravity between  the  earth  and  a  space  shuttle  orbiting  the  earth  since  space  is  composed  of  vacuum.
The  basic  difference  between  light  waves  and  all  other  wave  phenomena  is    that  light  can  pass  through  vacuum  while  other  wave  phenomena  cannot.
Light traveling  glass,  air  or  water  gets  slowed  down  because  of  molecules  that  bend  light  rays  and  hence  slows  its  progress.
Sound  cannot  travel  through  vacuum  and  space  is  composed  of  vacuum,  therefore  there  is  no  sound  in  outer  space.
 Since 10,000K  is  the  black-body  temperature  of  an  object,  if  the  original  color  of  the  jacket  is black,  in  a  precise  spectrum  it  might  appear  blue  at  a  temperature  of  10,000K.  The  jacket  may  also  appear  blue in  daylight  if  it  reflects  the  white  hot   color  temperature  of  the  sun  and  also  under  fluorescent  light.
 A  4m  radio  telescope  is  more  powerful  than  a  4m  optical  telescope  because  optical  telescopes  cannot  detect  radio  waves.
 Stars  twinkle  because  we  see  them  through  the  various  layers  of  the  earths  atmosphere  where  various  particulate  matter  cause  the  light  from  stars  to  get  refracted.

The Planet Venus

    Venus, the second planet from the sun, is almost the size of the earth (diameter of 12104 kilometers compared to the earths 12756 kilometers), and has an average density of 5.2 gramscc, which is slighter lesser than the earths.  It is the hottest planet in the solar system, with temperatures about 450 to 550 degrees C throughout the planet.  As the planet is inclined at 3 degrees to its axis compared to the earths 23 degrees, Venus does not have any seasons, and throughout the year the planet is hot in all areas including the poles (Randy Russell 2009).  The planets internal structure is similar to that of the earth and is basically made up of an iron core.  The planet has an orbital period of 225 days around the sun, and it has a slow rotational velocity making its magnetic field very week.  The planet is intensely covered by a thick layer of clouds.  This makes it very difficult to view the surface of the planet.  As the surface takes 8 months for one rotation, and the clouds can move around the planet within 4 days, there are chances that the winds reach a very high velocity in the upper portions of Venuss atmosphere (University of Tennessee at Knoxville 2009).  Venuss rotates and revolves around the sun in such a way that the same side faces the earth when they are closest to each other (Bill Arnett 2009). 

Atmosphere of Venus
    The clouds that cover Venus begin at a height of 50 kilometers above the surface and are mainly composed of sulphuric acid.  Winds in the upper portion of the atmosphere can reach speeds of about 300 kilometers per hour.  They may spread to large areas of Venus, and it is still not understood of the exact phenomenon of such winds.  The atmosphere of Venus may not contain water vapor and there is little or no evidence of any water on the surface of Venus.  The exact reason as to why water or water vapor may be absent on Venus is not understood clearly, but scientists feel that the high temperature of Venus would have made the water to evaporate to the upper atmosphere, where it would have disintegrated into hydrogen and oxygen.  This would have been lost into the outer the space beyond the outer layer of the planets atmosphere.  Venuss atmosphere is contains 96 carbon dioxide and 4  nitrogen, and traces of other gases (University of Tennessee at Knoxville 2009).  The lower layers of Venuss are clear, and clouds begin to accumulate at 50 kilometers above.  It has been found that the atmospheric pressure of Venus is 90 times the Earths atmosphere and the temperature is around 450 degrees, at which several metals would melt (University of Tennessee at Knoxville 2009).  Venuss atmosphere is known to trap sunlight and that leads to intense heating of the planets surface.  The clouds present 50 kilometers high from the surface move at a very high speed, but at the surface the winds are weak.  However, reason for the high velocity winds that occur at the upper atmosphere and the low speed winds that occur at the lower atmosphere are really not understood by the scientists. 

    One phenomenon that has been operational in Venus is the Runaway Greenhouse Effect.  This is caused by the greenhouse effect really going out of control due to the suns radiation incident on the planet or the huge amounts of greenhouse gases that are present in the atmosphere.  When the sunlight is incident on the planet, greenhouse gases such as carbon dioxide (which is present in excess of 96  on the planet) absorb the radiation and get heated up.  On the earth, the a major portion of the greenhouse gases including carbon dioxide and water vapor do not remain in the atmosphere but are found in the rocks as carbonates or in the oceans as water vapor respectively (which assures some amount of control over the greenhouse effect).  However, in Venus, the greenhouse effect has gone out of control as the water vapor in its oceans has evaporated and the carbonates present in the rocks have sublimated.  The oceans were slowly heated that they reached the boiling point of water resulting in evaporation and the rocks would get heated up resulting in chemical processes that result in the carbon dioxide escaping into the atmosphere.  Finally, the atmosphere has settled at a higher temperature and density.  Experts feel that a disaster may have taken place in the atmosphere of Venus, which has led to its climate today (University of Tennessee at Knoxville 2009).  The same can be a concern to the earth today due to the looming crisis of global warming. 

Surface of Venus
    The surface of Venus especially near the poles is rugged, contains of a few mountain ranges with several islands, volcanic eruptions and craters (University of Tennessee at Knoxville 2009).  There are 2 relatively large areas on the surface of the planet that are higher than the normal ground and are known as continents.  The continent near the north pole is known as Ishtar Terra (about the size of the US), and the other continent known as Aphrodite Terra is near the equator and measures about 50 that of Africa.  There are several mountain ranges on the planet including the 4 major ones  Maxwell Montes, Frejya Montes, Akna Montes and Danu Montes (Windows Team 2000).  All these 4 major mountain ranges are found in the Ishtar Terra region and are created due to the folding of crust from the volcanic activity.  Many of the features that are present on the mountain ranges of Venus are similar to that of the earth including the faults and the folds.  The highest peaks present on the Maxwell Montes ranges is about 11000 meters high (University of Tennessee at Knoxville 2009).  Venus has large number of craters strewn on its surface that the ground near the crater may melt.  The number of craters present on Venus is about 900 similar to the number present on earth.  Venus seems to have craters that are evenly distributed throughout the planet.  Most of the craters that are formed are from meteors (Windows Team 2000).

    Volcanic and lava flows are common on the surface of Venus.  The surface of Venus is a single crustal plate with little horizontal motion of the crustal plate.  On the other hand, the earths crust consists of moving tectonic plates and evidence is present that with time, the tectonic activity may begin on Venus.  The surface age of Venus may be around 300 million years (University of Tennessee at Knoxville 2009).  Around the poles, the surface of Venus is rugged and rises several kilometers higher.  Often these ridges run for thousands of kilometers and are hundred kilometers wide (Windows Team 2000).

Space Missions to Venus
    There have been many space missions to Venus that were organized by the USA, USSR and the European Union.  In Began in the year 1961, when the USSR launched the Venera 1 satellite to study Venus.  The USA launched the Mariner 2 in August 1962 which reached a distance of 35, 000 meters to the planet.  In 1967, the Venera 4 satellite was able to relay back atmospheric information about Venus.  In August 1970, Venera 7 was able to land on the surface of Venus and could relay data for about 23 minutes.  In 1972, the Venera 8 satellite was able to relay data for about 50 minutes after landing.  In 1973, Mariner 10 planned a dual mission to mercury and Venus.  In 1975, Venera 10 was able to relay back images of the Venus terrain.  In 1984, Vega 2 from USSR was able to drop a lander on Venus and conduct experiments on soil (Randy Russell 2009).  Magellan was launched by the USA in 1989 was able to use Radar images to demonstrate the lava flows on the planet.  More recently, findings have shown that the planet may actually be quiet in several areas except for a few areas having active volcanoes (Windows Team 2000).   

    Overall, there are no chances of life to survive on Venus, due to the high temperatures and pressure of the atmosphere.  There was some hope initially, as Venus has similar characteristics as the earth including similar composition of the core, similar diameter, similar surface characteristics etc.   Venus was often known as the sister planet of the earth.  However, there are also several differences existing in the planets and Venus is much more hostile and uninhabitable.  Venus has a much slower rotational speed than the earth but a faster year (rotation around the orbit).  Venus is composed of a single plate surface than the multi-plate surface of the earth, mainly because Venus may be younger than the earth.  Venus does not have any satellite and the magnetic field of the planet is poor.  Venus lacks water on its surface and in its atmosphere.  The atmosphere is filled with clouds of sulphuric acid, and gases such as carbon dioxide and nitrogen which cannot sustain life.  The temperatures of Venus at is surface is about 450 to 550 degrees centigrade at which life cannot survive.

Module 8

1. This idea is that of the cosmological principle. The evidence is within the spatial distribution of galaxies, the distribution of radio sources and the cosmic microwave background radiation. All three of these things support the idea that the universe is homogeneous and isotropic.

2. The cosmological principle is the assumption that on large spatial scales the universe is homogeneous and isotropic.

3. Oblers paradox is the argument that the darkness of the night sky is at odds with the assumption of an infinite and static universe. The idea is that at any angle from the Earth the sight line will end at a star. This was solved because of the discovery that the speed of light is finite. At some point the light would not have reached us yet and so we could not see the star. This gives a finite observable universe.

6. The expansion of the universe is not the matter its self moving away but the stretching of space. This leads to not the galaxies flying outward into empty space because it is the space expanding and carrying the galaxies with it.

9. The main property that will determine the fate of the universe is the mass density. One mass leads to a mass freeze or heating another leads to a big crunch where everything falls back into its self. One of the most common ideas is that the universe will continue to expand into infinity because of the mass.

Ch 27 
3. Due to the fact that there is not an accepted way to combine quantum mechanics and relativity science can not currently make predictions about intervals less than the Planck limit. This means that scientists dont know what happened in that period at the beginning of the universe.

13. During this time the early universe underwent a period of extremely rapid expansion. This expansion increased the linear dimensions of the universe by a factor of at least 1026. This started at the end of the grand unification epoch.

19. The COBE explored the cosmic microwave background radiation and thus provided strong evidence to support the big bang theory.

20. WMAP measurements provided the underpinning for the current standard model of cosmology. The data fits a universe that is dominated by dark energy in the form of a cosmological constant.

Ch 28 
1. Life is difficult to define because there are very few basic constants in what constitutes something that is living, and even in those there are exceptions. This leads to a gradient between living and nonliving that is hard to put a point on.

3. This experiment started with non-living compounds that would have been present on early Earth and with simple chemical reactions produced organic compounds that are required for life including amino acids.
5. Carbon, Hydrogen, Oxygen and Nitrogen are the basis for nearly all biological molecules.

9. Organic molecules can be found in comets, in the clouds of Saturns moon Titan and even in an eight-million year old star in the constellation Centaurus.

10. Europa, one of Jupiters moons is an ocean-like moon and has a high possibility of life. Possibly life may exist in the methaneethane lakes of Titan as well.

12. Life as we know it is life like that found on Earth. Carbon based, oxygen breathing etc. The other options for life are many and varied. Maybe life exists on Titan that uses Methane like humans use water and many more options.

13. There are estimations for each of the parameters for the drake equation to varying degrees of certainty. The fraction of planets with life that is intelligent is the least well known of all because as far as we known, only Earth has intelligent life. This sample gives us no evidence of the proportions. The only ones that have evidence to support them are the rate of star creation, the fraction of stars with planets and the average number of planets.

Module 7

Ch 23 
2. It is difficult to map out our Galaxy because our position in a spiral arm makes it difficult to see across the galactic bulge. The amount of dust in the center of the galaxy obscures what is on the other side.
4. Globular clusters are found in the halo of the galaxy. This is the spherical bulge seen clearest in spiral galaxies like the Milky Way.
5. Cepheid variables are precise time clocks, the variability of there luminosity and pulsation period is precise enough that they can be used as a standard candle. As the Cepheids are very bright they are usually the first thing to be seen in other galaxies.
11. Spiral arms are rich in O and B stars and in emission nebulae. O and B stars live only a few million years, so these stars must have formed recently. And because the stars dont move fast enough in their orbits to have moved out of the spiral arms in a few million years, we know that they must have been born in the arms. Emission nebulae are powered only by hot stars (again, O and B stars) that have relatively short lives, so emission nebulae also indicate recent star birth.
16. The idea of dark matter is one that is a hypothetical placeholder because of observations made of the gravitational effects seen on visible matter that are unexplainable. Dark matter is the name given to the apparent missing mass of the universe this is seen in the rotational speeds of galaxies, temperature distribution of hot gas, and more.
Ch 24 
4. The local group contains about 30 galaxies and is around 10 million light years in diameter. The mass of the local group is around 1.3 x 1012 M. The local group is a part of the Virgo Supercluster. The Milky way in comparison is only 100,000 light years in diameter and has a mass of around 5.8 x 1011 M.
5. Standard candles are objects that have a known brightness. Astronomers use the luminosity and compare that to the brightness to find a precise measurement of distance. This measurement can then be used as a measuring stick to find the distances to objects around the standard candles.
8. Hubbles law says that the velocity that various galaxies are receding from Earth is proportional to their distance from Earth.
11. Normal galaxies are made of stars emitting visible light whereas active galaxies are much brighter and have a different non-stellar spectrum which falls more into the radio waves more than visible.
13. Seyfert galaxies have bright nuclei and have high velocities. They have strong emissions in the radio, infrared, ultraviolet and x-ray portions of the spectrum. These galaxies are thought to have supermassive black holes in the center. 
17. Red shift is used because it gives additional information that distance does not. A red shift not only gives astronomers information regarding the orbit of the object (via the Doppler Effect) but can be used to calculate the approximate distance as well. 
Ch 26 
1. The Orbital method uses the same equation used to calculate the mass of the sun. Because the equation can calculate the mass in any spherically symmetric distribution of mass it applies to a galaxy as well as the sun. The brightness method uses the distribution of light within a galaxy to calculate the galaxies total apparent brightness within a given radius. Then that brightness and the distance to the galaxy are used to calculate the actual brightness. Then the actual brightness is used to convert brightness to mass.
2. When looking at how fast a galaxy is rotating, how they are moving and how the light coming past the galaxies is focused the mass can be measured. Each method of measuring mass gives a different answer. The brightness method shows a much smaller number than others and thus there must be matter in the galaxy that does not emit light.
5. Galaxy collisions lead to a number of things, one of the factors is that when a small galaxy collides with a larger one, the larger galaxy eats the smaller. This leads to larger and larger galaxies. Each collision also adds to the star formation in a galaxy because there is more gas and dust in the galaxy to condense into stars than usual.
6. Spiral or disk galaxies are thin and rotate rapidly, this leads to a spiral structure in many cases. These galaxies are fragile and mergers will often destroy the disks. These discs are thought to be the form that galaxies begin in. Smaller galaxies being merged into a large spiral galaxy doesnt result in a collapse of the spiral structure in many cases. When the galaxies get really large they end up as elliptical galaxies. These are the most massive galaxies and they are not rotating like there spiral cousins.
8. We have a plethora of evidence that the Milky Way has collided with other galaxies in the past because we can see the remains of the cannibalized galaxies in the core of the Milky Way. We can also see the Milky Way currently eating neighboring dwarf galaxies.
11. Scientists use measurements of the Doppler shift in the nucleus of nearby galaxies to see what may be in them. This look into the center reveals that the nuclei are moving very fast, this motion can only be explained by a large concentration of mass in the center of the nuclei. The only objects known to have the amounts of mass needed are black holes.
17. Voids are enormous holes in the universe which are empty of any type of matter from stars to dark matter.
18. The universe seems to be clumped together into galaxies of various sizes. The galaxies are clumped together in groups which are gathered into clusters. It also seems that these clusters are grouped into super clusters. The distribution of matter is uneven with large voids separating matter. Most of the universe is empty space.
20. Astronomers see dark matter by its gravitational effect on the visible matter around it.