Conservapedia - User contributions [en]

Science

2010-06-26T20:53:06Z

BH1:

[[Image:Cassini-science-289.jpg|right]]
'''Science''' consists of three aspects: first, it provides systematic descriptions of everything in the world and all of human experience, generally considered as scientific [[knowledge]]. Second, there are the men (and a few rare women) of science who have amassed these descriptions and communicate them to everyone else. Third, there are the methods by which they carry out this work (see [[scientific method]]).
Science can be divided into two areas: [[natural science]], dealing with the [[physical]], [[natural]] world,<ref>Soanes and Stevenson called science "the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment."Soanes,C. and Stevenson, A. (eds.) (2005) 'The Oxford Dictionary of English (revised edition)' Oxford University Press, Oxford, U.K.</ref> and [[social science]], dealing with society and human nature. It is very important for an intelligent person to be able to distinguish real science from [[junk science]]

Science differs from other methodologies of classifying knowledge in that a scientific theory is a description of the world which in principle is cabable of being disproved; this is known as [[falsifiability]]. It is this property which distinguishes science from other possible methods of discovering knowledge such as religion.

[[Epicurus]] is an important figure in the development of the [[scientific method]]. He insisted that nothing should be accepted except that which has been sufficiently tested through direct observation and logical deduction. [[Roger Bacon]] is hailed by many as the father of modern science. His focus on empirical approaches to science was influential. He wrote an encyclopedia, his ''Opus Majus''.

People who study science are called [[scientist]]s. Most of the early scientists who started many of the scientific fields, and some of history's greatest thinkers, such as [[Galileo Galilei]] and [[Isaac Newton]], believed in [[God]], or some other higher power, and many were [[creationists]] although the ideas of [[evolutionism]] or [[Darwinism]] had yet to be conceived.
In addition, [[Christianity]] played a pivotal role in the development of modern science (see [[Christianity and Science]]). However, in recent years, American scientists have deviated, and been much more [[atheism|atheistic]] as a group than the general public. <ref>http://www.atheists.org/flash.line/atheism1.htm</ref>

== Principles of science ==

The basis of modern science is observation and hypothesis. It involves constructing the best theory to explain an occurrence based on the evidence at the time and predict further observations.

Economist [[Milton Friedman]] said, "In all of science, progress comes through people proposing hypotheses which are subject to test and rejected and replaced by better hypotheses." [http://www.pbs.org/wgbh/commandingheights/shared/minitext/int_miltonfriedman.html#10]

The [[scientific method]] consists of two stages, theory formation and theory testing. In the early 20th Century the scientific method was commonly understood to follow the inductive procedure, whereby general statements are derived from a collection of singular observations. It was thought that through this method theories were constructed; a collection of observations led to the formation of a general theory to explain them. Secondly, at the testing stage, it was considered that a hypothesis could be verified through a collection of singular observations.

[[Karl Popper]], considered by many to be the most important contributor to the philosophy of science in recent times, put forward a damning critique of induction, going so far is to claim that it did not exist. Popper argued that general theories cannot ever be conclusively verified by singular observations, but that such a theory could be conclusively [[Falsifiable|falsified]] by such means.

The consensus today is based in large part upon the work of Popper, although in general induction is believed to play a part. The modern view is that the scientific method employs both inductive and deductive methods and is characterised by the principle of falsification:

* A theory is put forward (Popper argues that this is not inductive, but the consensus is that people are led to invent theories based upon previous observations)
* This theory is provisionally assumed to be true for the purposes of testing it.
* Assuming the theory is true, we can logically follow it through to a specific and inevitable outcome, a prediction, which becomes the hypothesis. In order for the hypothesis to be considered scientific it must be falsifiable.
* The hypothesis is repeatedly tested empirically.
* If the observations do not falsify the hypothesis then we accept the theory provisionally (note, we cannot say that it is now 'fact', nor that is has been 'proven')
* If the observations do falsify the hypothesis then we reject it in its current form.
* The theory, or at least parts of it, can then be modified, or a new theory proposed, which takes us back to the beginning of the process.

Since verification of general theories is logically impossible, science is not, as many believe, a body of accumlated 'facts', but rather a collection of theories that have yet to be falsified. Via falsification we can move closer and closer to the truth, but since verification is not possible, we can never know if we ever reach the goal of 'ultimate truth' itself.

==Naturalism and science==
Since the beginning of modern science, scientists have worked under the assumption that their subjects of study have been controlled by consistent natural laws.
There is good evidence that this assumption was based on the [[Christianity|Christian]] view that the laws were created by a consistent creator Who didn't change those laws on a whim.<ref>See [[Natural science#Beginnings]]</ref>
This assumption is seen as a prerequisite for logical deduction to act on the observations made. Without the assumption that the universe is consistent we cannot apply the lessons drawn from an observation to any area other than the observations themselves. If a [[chemical reaction]] occurs in a given solution in a laboratory in one city it is assumed that the same reaction can occur in a different laboratory in a different city on a different day because the chemical [[solution]] and situations will be the same.

If a capricious supernatural force was to enter the equation they could not be controlled for and could not be studied.

The physical sciences largely concern themselves with questions involving the natural, not the supernatural, but this is not the same as assuming that the supernatural does not exist. In addition, there are also the social sciences like [[history]]. [[Christian apologetics|Christian apologists]] maintain that history testifies to the supernatural existing and that the physical sciences (such as [[Biblical archaeology]]) can aid in historical determinations and testify to the existence of God and the truth of biblical Christianity.

Three broad philosophies have developed in the scientific community.
* "[[Methodological naturalism]]" adheres to [[naturalism]] insofar as it concerns scientific experiments and observations, but does not rule out a personal deity. It does, however, ''a priori'' rule out the supernatural being an explanation for observations.
* "[[Philosophical naturalism]]" adheres to the belief that there is no beings or forces beyond what can be observed; this [[atheism|atheistic]] view rejects the supernatural, or is skeptical of such beliefs.
* The third approach is to follow the inference to the best explanation regarding whether or not a supernatural or natural cause best explains a past or present observation.<ref>http://creationontheweb.com/content/view/1315/</ref><ref>http://www.cgst.edu/publication/journal/43/J43_203_Forum04Abstract.pdf</ref> For example, this third approach is advocated by [[creation science|creation scientists]] and [[intelligent design]] theorists when it comes to the origins of the natural world. Creation scientists and intelligent design theorists maintain the falsity of the [[evolution|evolutionary]] position given the lack of evidence for evolutionary position and the many lines of evidence against the evolutionary position. One common argument of creationists is the perceived contradiction between the laws of thermodynamics and the existence of an eternal universe <ref>[http://godevidences.net/space/lawsofscience.php Evidences for God From Space—Laws of Science]</ref><ref>Thompson, Bert, [http://www.apologeticspress.org/articles/2329 So Long, Eternal Universe; Hello Beginning, Hello End!], 2001 (Apologetics Press)</ref><ref>http://www.creationscience.com/onlinebook/AstroPhysicalSciences14.html</ref>. This is, however, a misrepresentation of the laws of thermodynamics. But in other respects, such as why [[Krakatoa]] exploded, a natural explanation would be considered the best explanation.

==Religious cultivation of early modern science==
''See also:'' [[Christianity and Science]]

According to the historian [[H. Floris Cohen]], there exists two distinct levels of argument along this line of historical scholarship. <ref> [http://books.google.com/books?id=wu8b2NAqnb0C The Scientific Revolution: A Historiographical Inquiry], [[H. Floris Cohen]], University of Chicago Press 1994, 680 pages, ISBN 0-2261-1280-2, pages 308-321 </ref> The first to be proposed was the [[Merton thesis]] in the late 1930's, which parallels the [[The Protestant Ethic and the Spirit of Capitalism|Weber thesis]] in suggesting that the rise of science was due, at first, to a [[protestant work ethic]] but later extended to a more general biblical ethic. The second to be proposed was that of [[Reijer Hooykaas]], who held the rise of early modern science was due to a unique combination of Greek and biblical thought. One of the main aspects of Hooykaas's argument was that the Greek disrepect for manual work prevented an experimental science from truly developing until the biblical view of honoring work with one's hands was socially sanctioned. Hooykaas reaches the conclusion that "Metaphorically speaking, whereas the bodily ingredients of science may have been greek, its vitamins and hormones were biblical." <ref> * [http://books.google.com/books?id=c6TEDHvAbXAC ''Religion and the Rise of Modern Science''], Regent College Publishing, 2000. ISBN 1-5738-3018-6 </ref>

Historian and professor of religion [[Eugene Marion Klaaren|Eugene M Klaaren]] holds that "a belief in divine creation" was central to an emergence of science in seventeenth-century England. The philosopher [[Michael B. Foster]] has published influential analytical philosophy connecting Christian doctrines of creation with empiricism. Historian William B. Ashworth has argued against the historical notion of distinctive mind-sets and the idea of Catholic and Protestant sciences in "Catholicism and early modern science."<ref> [http://books.google.com/books?id=hs2edDIGCqEC ''God and nature''], Lindberg and Numbers Ed., 1986, pp. 136-66; see also [http://cas.umkc.edu/history/faculty/AshworthW/pub.html William B. Ashworth Jr.'s publication list]; this is noted on page 366 of ''Science and Religion'', [[John Hedley Brooke]], 1991, [[Cambridge University Press]]</ref> Historians James R. Jacob and Margaret C. Jacob have published the paper "The Anglican Origins of Modern Science," which endeavors to show a linkage between seventeenth century [[Anglican]] intellectual transformations and influential English scientists (e.g., [[Robert Boyle]] and [[Isaac Newton]]).<ref> [http://www.compilerpress.atfreeweb.com/Anno%20Jacob%20&%20Jacob%20Anglican%20Fdn%20of%20Modern%20Science.htm The Anglican Origins of Modern Science], [[Isis (journal)|Isis]], Volume 71, Issue 2, June 1980, 251-267; this is also noted on page 366 of ''Science and Religion'', [[John Hedley Brooke]], 1991, [[Cambridge University Press]]</ref>

Two well-respected theological surveys, which also illustrate other historical interactions between religion and science occurring in the 18th, 19th, and 20th centuries, are [[John Dillenberger]]'s ''Protestant Thought and Natural Science'' ([[Doubleday]], 1960) and [[Christopher B. Kaiser]]'s ''Creation and the History of Science'' ([[Eerdmans]], 1991).

{{quotation|When natural philosophers referred to ''laws'' of nature, they were not glibly choosing that metaphor. Laws were the result of legislation by an intelligent deity. Thus the philosopher Rene Descartes (1596-1650) insisted that he was discovering the "laws that God has put into nature." Later Newton would declare that the regulation of the solar system presupposed the "counsel and dominion of an intelligent and powerful Being."<ref> [[John Hedley Brooke]], ''Science and Religion: Some Historical Perspectives'', 1991, [[Cambridge University Press]], ISBN 0-521-23961-3, page 19 </ref>
|Historian and [[Oxford University]] [[Science and Religion]] theologian [[John Hedley Brooke]]}}

[[University of California at Berkeley]]-educated historian [[Ronald L. Numbers]] has stated that this thesis "received a boost" from mathematician and philosopher[[Alfred North Whitehead]]'s ''[[Science and the Modern World]]'' (1925). Numbers has also claimed "Despite the manifest shortcomings of the claim that Christianity gave birth to science—most glaringly, it ignores or minimizes the contributions of ancient Greeks and medieval Muslims—it too, refuses to succumb to the death it deserves. The sociologist [[Rodney Stark]] at [[Baylor University]], a [[Southern Baptist]] institution, is only the latest in a long line of Christian apologists to insist that 'Christian theology was essential for the rise of science.'"<ref> ''Science and Christianity in pulpit and pew'', [[Oxford University Press]], 2007, [[Ronald L. Numbers]], p. 4, and p.138 n. 3 where Numbers specifically raises his concerns with regards to the works of [[Michael B. Foster]], [[Reijer Hooykaas]], [[Eugene M. Klaaren]], and [[Stanley L. Jaki]] </ref>

==Notes==

{{reflist}}

==See also==
* [[Scientific method]]
* [[Computing]]

[[category:science]]

Moon

2010-06-26T20:41:56Z

BH1:

{{Planet|image=Moon2.jpg
|caption=The Moon one week after [[full moon]]
|primary=Earth
|periapsis=363,300 km<ref name=moonfact>"[http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html Moon Fact Sheet]," [[NASA]], April 19, 2007. Accessed May 3, 2008.</ref>
|apoapsis=405,500 km<ref name=moonfact/>
|semimajor=384,400 km<ref name=moonfact/><ref name=ssdorbit>"[http://ssd.jpl.nasa.gov/?sat_elem Planetary Satellite Mean Orbital Parameters]." [[Jet Propulsion Laboratory|JPL]], [[National Aeronautics and Space Administration|NASA]]. Accessed March 25, 2008.</ref>
|orbitradius=378,000 km
|eccentricity=0.0549<ref name=moonfact/><ref name=ssdorbit/>
|sidereal=27.3217 da
|synodic=29.530588 da
|orbitspeed=1.023 km/s
|inclination=18.28°<ref name=moonfact/>
|siderealday=27.3217 da<ref name=moonfact/><ref name=ssdorbit/>
|solarday=29.530588 da
|mass=7.35 * 1022 (1.23% earth)<ref name=moonfact/>
|density=3350 kg/m³<ref name=ssdphys>"[http://ssd.jpl.nasa.gov/?sat_phys_par Planetary Satellite Physical Parameters]." [[Jet Propulsion Laboratory|JPL]], [[National Aeronautics and Space Administration|NASA]]. Accessed March 25, 2008.</ref>
|surfacegrav=1.62 m/s² (0.165 ''g'')<ref name=moonfact/>
|escapespeed=2.38 km/s<ref name=moonfact/>
|meanradius=1737.1 km<ref name=moonfact/><ref name=ssdphys/>
|equatorradius =1738.1 km<ref name=moonfact/>
|polarradius =1736.0 km<ref name=moonfact/>
|surfacearea=37,919,000 km² (7.434% earth)
|mintemp=100 K
|meantemp=250 K
|maxtemp=400 K
|albedo=0.12<ref name=moonfact/>
|pmdm=1.3 * 1015 N-m/T<ref name=Humphreys>Humphreys, D. R. "[http://www.creationresearch.org/crsq/articles/21/21_3/21_3.html The Creation of Planetary Magnetic Fields]." ''Creation Research Society Quarterly'' 21(3), December 1984. Accessed April 29, 2008.</ref>
|cmdm=1.73 * 1022 N-m/T<ref name=Humphreys/>
|mdt=364 a<ref name=Humphreys/>
|mhl=252.3 a<ref name=calc>Calculated</ref>
}}The '''Moon''' is a natural [[satellite]] orbiting the [[Earth]] at an average distance of about 238,000 miles (380,000 km).

Unlike most planets in the [[solar system]], [[Earth]] has only one moon. To those on Earth the Moon appears as a pale disc which goes through phases in which greater or lesser amounts of the side lit by the sun are visible from Earth.

==The Moon as God's creation==

The Earth's moon has several striking characteristics. To many Christians, these characteristics appear as "clues" or "hints" left by God for men to discover. <ref>http://www.math.nus.edu.sg/aslaksen/gem-projects/hm/0102-1-phase/CALENDARS.htm</ref>

===Size of its disc===

The Moon appears to have approximately the same size as the [[Sun]] when viewed from Earth. This creates a unique symmetry and phenomenal [[solar eclipse|solar eclipses]].
Coincidentally, the Moon is just far enough away from the Earth to appear the same size of the Sun.

===Rotation and revolution===

The Moon presents the same side to [[Earth]] at all times. That means that the rotation of the Earth offsets the separate effects of the revolution of the Moon. Physical explanations rely on [[tidal locking]], asserting that tidal forces on Earth caused a bulge on the Moon, thereby creating a drag on the rotation of the Moon until its same face always presents to the Earth.<ref> The same theory suggested that the planet [[Mercury]] had a similar locked rotation due to gravitational forces from the sun, such that the same side of Mercury always faces the sun. In fact, that is false. [[Mercury]]'s tidal locking is incomplete and it does not always present the same face to the sun.</ref> In fact, current tidal forces exerted by the [[Earth]] on the Moon cannot account fully for its bulge or egg shape.<ref>"[http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/AT308/HTML/AT30803.HTM Chapter 8, Section 3: The Rotation of the Moon]," "Astronomy Today", Department of Physics, Fort Lewis College, Durango, [[Colorado|CO]]. Accessed February 18, 2008</ref>

===Origin theories===

Most astronomers assert that the Moon originated from a collision early in Earth's history which created an orbiting ring of debris from the [[iron]]-poor surface of the planet which eventually coalesced into the moon.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=2198</ref> This theory is confirmed by the relatively low levels of [[iron]] in the Moon's crust.<ref>J. H. Jones: [http://www.lpi.usra.edu/meetings/origin98/pdf/4045.pdf Tests of the Giant Impact Hypothesis]</ref> Biblical history records the Moon being created on the fourth day of [[creation week]], along with the Sun.

===Rate of recession===

The Moon currently recedes from the Earth at a rate of 1.5 inches (3.8 cm) per year<ref>NASA [http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/ApolloLaser.html Measuring the Moon's Distance], LPI Bulletin, No. 72, August, 1994.</ref>, and is believed by mainstream scientists to be 4.6 billion years old <ref>NASA, [http://history.nasa.gov/SP-350/ch-15-2.html Apollo Expeditions to the Moon], Chapter 15.2.</ref>. The Moon could never have been closer than about 11,000 miles or it would have been broken up by tidal forces.<ref name="js">Sarfati, Jonathan, [http://www.creationontheweb.com/content/view/764/ The moon: the light that rules the night], ''Creation'' 20(4):36–39, September 1998.</ref> If the rate of recession stayed constant at 3.8 cm per year, it would take 9.6 billion years for the lunar distance to migrate from 11,000 miles to the present distance of about 240,000 miles. 

===Impact Craters===
Astronomers assume that crater impacts are a reliable indicator of the age of a celestial body. True to the form and principles of [[uniformitarianism]] (as applied to [[astronomy]] rather than to [[geology]]), any such estimation relies upon uniform constants and weather/erosion trends. Recent research into crater impacts on the moon suggests that many of the assumptions previously made are unwarranted. Bonnie Buratti of NASA's Jet Propulsion Laboratory has asserted that space weathering "takes place very rapidly on the Moon."<ref>David, Leonard. "[http://www.space.com/missionlaunches/lunar_impact_021214.html Lunar Crash of 1953: Impact Crater Identified]." <http://www.space.com>, December 14, 2002. Accessed January 16, 2008.</ref> Peter Brown of the University of Western Ontario insists that there is no absolute criteria for the dating of craters.<ref>Hecht, Jeff. "[http://www.newscientist.com/article.ns?id=dn3242 New crater revives Moon mystery]." <http://www.newscientist.com>, January 11, 2003. Accessed January 16, 2008.</ref>

===Creationist models===
Danny Faulkner of the [[Institute for Creation Research]] has observed that many of the lunar maria contain ''ghost craters'', or craters that the lava flow that produced the maria seem to have filled only partially. In the [[deep time]] scale required by [[uniformitarianism]], the ghost craters are the result of impacts that occurred as much as half a gigayear before the crust-fracturing impacts that caused the lava flows.<ref name=Henderson>Henderson, Thomas H. "[http://www.hal-pc.org/~tom/HeavyCratering.html Do heavily cratered planets and moons demand an old age for the solar system]?" ''Tom Henderson's Creation Resources'', July 25, 2003. Accessed March 25, 2008.</ref> This is not a reasonable assumption, because any impact strong enough to crack the crust should have obliterated any craters previously extant. Faulkner thus concludes that the impacts that formed the ghost craters, and those that let loose the lava flows that formed the maria, occurred within days of one another<ref name=Faulkner1>Faulkner, Danny. "[http://www.icr.org/research/index/researchp_df_r01/ The Current State of Creation Astronomy]." ''Proceedings of the Fourth International Conference on Creationism,'' Creation Science Fellowship, Pittsburgh, pp. 201–216, August 3-8, 1998. Hosted at ''[[Institute for Creation Research]].'' Accessed March 25, 2008.</ref> and were probably part of at least one system-wide catastrophe involving a narrow stream of meteoroids and/or comets that delivered a concentrated bombardment of the Earth and Moon in a short interval.<ref name=Faulkner2>Faulkner, Danny. "[http://creationontheweb.com/content/view/1637 A Biblically-based cratering theory]." ''Technical Journal'' (now ''Journal of Creation''), 13(1):100-104, April 1999.</ref>

Faulkner assumes that this system-wide catastrophe occurred during the year of the [[Great Flood]]. But in 1984, Russell Humphreys, then at the Sandia National Laboratories, developed evidence suggesting different dates entirely. Specifically, the [[Project Apollo]] exploration teams brought back many samples of [[basalt]] (an [[igneous rock]]) and [[brecchia]] (pulverized meteor-impact remains). Geologists analyzed both types of samples and found evidence that each type of rock had once been in a magnetic field far more powerful than that which the Moon has today. Using his model for the creation and decay of magnetic fields<ref name=Humphreys/>, Humphreys determined that the basalt had been laid down about 370 years after creation, and the brecchia had been laid down 1840 years after creation, or about 190 years after the Flood.<ref name=Humphreys2>Humphreys reasoned that the higher the magnetic dipole moment of the samples, the earlier in lunar history they were formed.</ref> These findings clearly suggest that the Moon, and presumably all other bodies in the solar system, have been subject to two separate system-wide bombardments, one occurring in the second or third generation after the [[fall of man]] and the other occurring well after the Flood.

==Tides==

The gravitational force of the Moon causes the ocean [[tides]]; these tidal forces have other effects as well. These tidal forces have the effect of creating resistance which slows down the rotation of both objects. In the case of the Earth, the result is that the Earth's rotation slows on the order of one millisecond per century. The Moon's rotation is locked in to its period of revolution, and the same side of the Moon always faces the Earth.

==The "dark" or far side==

The phrase "the ''dark'' side of the Moon" is inaccurate because the Moon does rotate relative to the Sun, with the same period as its period of revolution, once every 29 days. Our view of the Moon from the Earth always shows the same side of the Moon, with the same markings and features. When the Moon is full, the entire side that faces us is experiencing lunar "day" and is lit by the Sun. Two weeks later, when the Moon is new, the side that faces us is experiencing solar "night" and is unlit (and virtually invisible).

The far side of the moon is far more heavily cratered than the near, and the predominant type of cratering is consistent with brecchia-forming meteor impact. This would suggest that the far side suffered its bombardment in the latter of the two catastrophes that Humphreys suggests that the Moon has suffered.

Due to a slight "wobble" in the lunar motion called ''libration,'' we actually see a little bit more than half of the Moon's surface; sometimes it is turned a bit one way and sometimes the other. However, nobody had any idea of what the far side of the Moon looked like until 1959, when a Soviet satellite photographed it and relayed pictures back.

[[image:oldmooninnew.jpg|200px|right|thumb|The "old Moon in the new Moon's arms"]]
In the old Scottish ballad ''Sir Patrick Spens''<ref>Child, Francis James (1860), ''The English and Scottish Popular Ballads,'' [http://www.sacred-texts.com/neu/eng/child/ch058.htm No. 58]; the ballad is thought to refer to an actual event of the year A.D. 1290.</ref>, a sailor cautions:

:"I saw the new moon late yestreen
::With the old moon in her arm;
:And if we go to sea, master,
::I fear we'll come to harm."

==Earthshine==

The effect known as "the old Moon in the new Moon's arms" can often be seen when the Moon is a narrow [[crescent]]. Within the intensely bright crescent, a dim and mysterious view of the entire circular moon is seen. The effect is also known as ''earthshine'' because it is light from the Sun reflected off the Earth to the Moon and back that lights up the darker portion of the Moon. The bright crescent is lit by the Sun and is in full daylight. The rest of the Moon is not lit by the Sun; but an [[astronaut]] standing in this area would see a "full Earth" dominating the nighttime sky, lighting it up by its earthshine. The brightness of Earthshine, and hence the visibility of the old Moon in the new Moon's arms, varies. When the Earth is covered with clouds, or when there is a lot of snow-pack on the side of the Earth facing the Moon, the Earth is a white and bright and the Earthshine is intense. When the Earth looks like a "big, blue marble," it is less intense.

==Lunar calendars==

Throughout history, many calendar systems have been based on the phases of the moon.

The months of the [[Islam|Muslim]] [[calendar]] are determined by observations of the [[hilal]], the moment at which the thin crescent moon first becomes visible. This marks the start of a month. Traditionally, and today in [[Pakistan]] and [[Jordan]], hilal is determined by actual observation and can be affected by weather and other factors. When following the traditional method, it is not actually possible to be certain precisely when future months will begin. In most Muslim countries, actual observation has been replaced by [[astronomy|astronomical]] rules.

==The moon in culture==

"The Old Moon in the New Moon's Arms" is the title of a poem by [[Ella Wheeler Wilcox]], in which she interprets the effect as the New Moon wishing that her lost love, the Old Moon, be in her arms one last time; Venus grants the wish, and:

:Swift thro' the vapors and the golden mist— 
::The Full Moon's shadowy shape shone on the night, 
:The New Moon reached out clasping arms and kissed 
::Her phantom lover in the whole world's sight. 

== Trivia==
Although the Moon is often described as revolving around the Earth, this is slightly inaccurate: the Earth and the Moon ''both'' revolve around their ''barycenter'', their common [[centroid|center of mass]]. This point is 1,700 below the earth's surface, which is about 1/4 of the earth's [[radius]].<ref> The radius of the Earth is 6,378 kilometers, so that means that the barycenter is located INSIDE the Earth about 1707 kilometers below its surface. [http://www.astronomycafe.net/qadir/q665.html] </ref>

The combined motion is like an athlete performing an [[Olympics| Olympic]] hammer throw: one object swings in a large circle, the other almost pivots around a fixed point but actually performs a small opposing circle of its own. <ref>The Earth and the Moon orbit each other around a gravitational midpoint called the ''barycenter.'' This point is, however, actually inside the Earth, about 3/4 of its radius from its center. It is not the Earth, but the barycenter of the Earth-Moon system, that orbits the [[Sun]] in a near-perfect ellipse. Relative to this ellipse, Earth is 3,000 miles closer to the Sun at full moon and 3,000 miles further from the Sun at new moon.</ref>

When speaking of things having to do with the moon, the adjective ''lunar'' is used. The Greek-derived prefixed root ''selen-'' followed by the morpheme ''-o-'' is used as well; for example, the [[science]] of mapping the moon is called ''[[selenography]]'' (morphemes: ''selen-o-graph-y''). (Note, however, that the apsides of the orbits of the [[Project Apollo]] spacecraft were always called ''pericynthion'' and ''apocynthion'', not "periselene" and "aposelene.")

== Other moons ==
[[Image:Many_Moons.jpg|250px|left]]
While the Moon of [[Earth]] is the best-known satellite of any [[planet]], other planets in our solar system also have moons. Earth has the least number of moons (one), while [[Jupiter]] has sixty-two. The first extraterrestrial moons to be discovered were the four Galilean moons ([[Io]], [[Europa (moon)|Europa]], [[Ganymede]], and [[Callisto]]. Next to these, Earth's Moon is one of the largest, but Jupiter and [[Saturn]] have moons in orbit about them that might qualify as planets if they orbited the [[Sun]] instead.

=== Sizes of moons ===
Most moons in the solar system are no larger than typical asteroids. They are of irregular shape, have light and variable surface gravities, and are often unstable in their orbits. [[Phobos]] and [[Deimos]], the moons of [[Mars]], fall into this category.

Earth's own moon is an example of a [[dwarf planet]]-sized moon. These moons are so large that their own self-gravity forces them to collapse into spheres or spheroids. Some of them, like [[Ganymede]] and [[Titan (moon)|Titan]], are larger even than the planet [[Mercury]]. Earth's moon was, of course, known to the ancients, but the remaining dwarf-planet-sized moons were generally the first to be discovered in orbit around any given primary. [[Galileo Galilei]] discovered the first four of these in orbit about [[Jupiter]] early in the seventeenth century; [[Christiaan Huygens]] then discovered Titan of [[Saturn]] later in that same century.

== Symbolic Importance in Islam ==
The crescent moon is an internationally recognized symbol of [[Islam]]. It appears on the flags of several Islamic nations. It also forms part of the official emblems of the International Red Cross and Red Crescent Societies. <ref>http://islam.about.com/od/history/a/crescent_moon.htm</ref>

== See also ==
*[[Origin of the Moon]]
== External links ==

*[http://www.solarviews.com/eng/terms.htm Glossary]
==Further reading==
* Donna Henes. ''The Moon Watcher's Companion: Everything You Ever Wanted to Know About the Moon, and More'' (2004) [http://www.amazon.com/Moon-Watchers-Companion-Everything-Wanted/dp/1569244669/ref=sr_1_11?ie=UTF8&s=books&qid=1241592218&sr=1-11 excerpt and text search]
* David Schrunk et al. ''The Moon: Resources, Future Development and Settlement'' (2007) [http://www.amazon.com/Moon-Resources-Development-Settlement-Exploration/dp/0387360557/ref=sr_1_12?ie=UTF8&s=books&qid=1241592379&sr=1-12 excerpt and text search]
* Seymour Simon, ''The Moon'' (2003) [http://www.amazon.com/Moon-Seymour-Simon/dp/0689835639/ref=sr_1_1?ie=UTF8&s=books&qid=1241592218&sr=1-1 excerpt and text search]

== Notes and References ==
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[[Category:Astronomy]]