Aarushhh/wikipedia-simple-splitted huggingface dataset:
MESSENGER

The second satellite to visit Mercury is NASA's MESSENGER. It stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging. It was launched on August 3, 2004. It made a fly-by of Earth in August 2005. It made another fly-by of Venus in October 2006. It made its first fly-by of Mercury happened on January 14, 2008, a second on October 6, 2008, and a third on September 29, 2009. It made a map of most of Mercury that Mariner 10 didn't map. The first image of Mercury orbiting the Sun was gotten on March 29, 2011.

MESSENGER was made to study Mercury's high density, the history of Mercury's geology, its magnetic field, the structure of its core, if it has ice at its poles, and where its thin atmosphere comes from. MESSENGER crashed into Mercury's surface on April 30, 2015.

Bepicolombo
Bepicolombo

The European Space Agency and the Japanese Space Agency made and launched a spacecraft called BepiColombo. It will orbit Mercury with two probes: one to map the planet and the other to study its magnetosphere. It was launched on October 20, 2018. BepiColombo is expected to reach Mercury in 2025. It will release the probe that will study the magnetosphere into an elliptical orbit. It will then release the probe the will make a map of Mercury into a circular orbit.

Related pages 
 List of planets

References

Other websites 
 
 SolarViews.Com
 www.planetfacts.net
Mars is the fourth planet from the Sun in the Solar System and the second-smallest planet. Mars is a terrestrial planet with polar ice caps of frozen water and carbon dioxide. It has the largest volcano in the Solar System, and some very large impact craters. Mars is named after the mythological Roman god of war because it appears of red color.

Space probes such as the Viking program landers are the main tools for the exploration of Mars.

Appearance
Appearance 

Mars is a terrestrial planet and made of rock. The ground there is red because of iron oxide (rust) in the rocks and dust. The planet's atmosphere is very thin. It is mostly carbon dioxide with some argon and nitrogen and tiny amounts of other gases including oxygen. The temperatures on Mars are colder than on Earth, because it is farther away from the Sun and has less air to keep heat in. There is water ice and frozen carbon dioxide at the north and south poles. Mars does not have any liquid water on the surface now, but signs of run-off on the surface were probably caused by water.

The average thickness of the planet's crust is about 50 km (31 mi), with a maximum thickness of 125 km (78 mi).

Moons 
Mars has two small moons, called Phobos and Deimos.
The origin of Mars' moons is unknown and controversial. One theory is that the moons are captured asteroids. However, the moons' near circular orbits and low inclination relative to the Martian equator are not in agreement with the capture hypothesis.

Estimates of the mass ejected by a large Borealis-size impact vary. Simulations suggest that a body about 0.02 of Mars mass (~0.002 Earth mass) in size can produce a sizable debris disk in Martian orbit. Much of the material would stay close to Mars. There are several other large impact basins on Mars that could also have ejected enough debris to form the moons.

Physical geography
Physical geography

Lack of magnetic field 
Mars does not have a global magnetic field. Despite this, observations show that parts of the planet's crust have been magnetized. This suggests that polarity reversals have occurred in the past. This paleomagnetism  is similar to the magnetic striping found on Earth's ocean floors. One theory is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo stopped working and the planet's magnetic field faded.

Rotation 
A Martian day is called a sol, and is a little longer than an Earth day. Mars rotates in 24 hours and 37 minutes. It rotates on a tilted axis, just like the Earth does, so it has four different seasons. Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to their similar axial tilt. The lengths of the Martian seasons are almost twice those of Earth's, as Mars's greater distance from the Sun leads to the Martian year being almost two Earth years long.
Martian surface temperatures vary from lows of about  (at the winter polar caps) to highs of up to  (in equatorial summer). The wide range in temperatures is due mostly to the thin atmosphere which cannot store much solar heat. The planet is also 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.

Water 

A 2015 report says Martian dark streaks on the surface were affected by water.

Liquid water cannot exist on the surface of Mars due to its low atmospheric pressure (there's not enough air to hold it in), except at the lowest elevations for short periods. The two polar ice caps appear to be made largely of frozen water. The amount of ice in the south polar ice cap, if melted, would be enough to cover the entire planet's surface 11 meters deep. A permafrost mantle stretches from the pole to latitudes of about 60°.
Geological evidence gathered by unmanned missions suggest that Mars once had much liquid water on its surface. In 2005, radar data revealed the presence of large quantities of water ice at the poles, and at mid-latitudes. The Mars rover Spirit sampled chemical compounds containing water molecules in March 2007. The Phoenix lander found water ice in shallow Martian soil in July  2008.
Landforms seen on Mars strongly suggest that liquid water at some time existed on the planet's surface. Huge areas of ground have been scraped and eroded.

Polar caps
Polar caps 

Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice). When the poles are again exposed to sunlight, the frozen CO2 sublimes (turns to vapor), creating enormous winds that sweep off the poles as fast as 400 km/h. Each season this moves large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds and dust storms. Clouds of water-ice were photographed by the Opportunity rover in 2004.

The polar caps at both poles consist primarily of water ice.
Atmosphere 
Mars has a very thin atmosphere with barely any oxygen (it is mostly carbon dioxide). Because there is an atmosphere, however thin it is, the sky does change colour when the sun rises and sets. The dust in the Martian atmosphere makes Martian sunsets somewhat blue. Mars's atmosphere is too thin to protect Mars from meteors, which is part of the reason why Mars has so many craters.
Meteorite craters 
After the formation of the planets, all experienced the "Late Heavy Bombardment". About 60% of the surface of Mars shows a record of impacts from that era. Much of the remaining surface is probably lying over the immense impact basins caused by those events. There is evidence of an enormous impact basin in the northern hemisphere of Mars, spanning , or roughly four times larger than the largest impact basin previously known. This suggests that Mars was struck by a Pluto-sized body about four billion years ago. The event is thought to be the cause of the difference between the Martian hemispheres. It made the smooth Borealis Basin that covers 40% of the planet.
Some meteorites hit Mars with so much force a few pieces of Mars went flying into space  even to Earth! Rocks on Earth are sometimes found which have chemicals that are exactly like the ones in Martian rocks. These rocks also look like they fell really quickly through the atmosphere, so it is reasonable to think they came from Mars.

Recent hits 
Spacecraft Insight detected seismic waves made by the biggest meteorite impacts ever seen on Mars.

Geography 
Mars is home to the highest known mountain in the Solar System, Olympus Mons. Olympus Mons is about 17 miles (or 27 kilometers) high. This is more than three times the height of Earth's tallest mountain, Mount Everest. It is also home to Valles Marineris, the third largest rift system (canyon) in the Solar System, 4,000 km long.

Observation of Mars 

Our records of watching and recording Mars start with ancient Egyptian astronomers in the 2nd millennium BC.
Detailed observations of the location of Mars were made by Babylonian astronomers who developed methods using math to predict the future position of the planet. The ancient Greek philosophers and astronomers developed a model of the solar system with the Earth at the center ('geocentric'), instead of the sun. They used this model to explain the planet's motions. Vedic and Islamic astronomers estimated the size of Mars and its distance from Earth. Similar work was done by Chinese astronomers.

In the 16th century, Nicholas Copernicus proposed a model for the Solar System in which the planets follow circular orbits about the Sun. This 'heliocentric' model was the beginning of modern astronomy. It was revised by Johannes Kepler, who gave an elliptical orbit for Mars which better fit the data from our observations.
The first observations of Mars by telescope was by Galileo Galilei in 1610. Within a century, astronomers discovered distinct albedo features (changes in brightness) on the planet, including the dark patch and polar ice caps. They were able to find the planet's day (rotation period) and axial tilt.

Better telescopes developed early in the 19th century allowed permanent Martian albedo features to be mapped in detail. The first crude map of Mars was published in 1840, followed by better maps from 1877 onward. Astronomers mistakenly thought they had detected the spectroscopic mark of water in the Martian atmosphere, and the idea of life on Mars became popular among the public.
Yellow clouds on Mars have been observed since the 1870s, which were windblown sand or dust. During the 1920s, the range of Martian surface temperature was measured; it ranged from 85 to 7 oC. The planetary atmosphere was found to be arid with only traces of oxygen and water. In 1947, Gerard Kuiper showed that the thin Martian atmosphere contained extensive carbon dioxide; roughly double the quantity found in Earth's atmosphere. The first standard naming of Mars surface features was set in 1960 by the International Astronomical Union.

Since the 1960s, multiple robotic spacecraft and rovers have been sent to explore Mars from orbit and the surface. The planet has remained under observation by ground and space-based instruments across a broad range of the electromagnetic spectrum (visible light, infrared and others). The discovery of meteorites on Earth that came from Mars has allowed laboratory examination of the chemical conditions on the planet.

Martian 'canals'
Martian 'canals' 

During the 1877 opposition, Italian astronomer Giovanni Schiaparelli in Milan used a  telescope to help produce the first detailed map of Mars. What caught people's attention was that the maps had features he called canali. These were later shown to be an optical illusion (not real). These canali were supposedly long straight lines on the surface of Mars to which he gave names of famous rivers on Earth. His term canali was popularly mistranslated in English as canals, and thought to be made by intelligent beings.

Other astronomers thought they could see the canals too, especially the American astronomer Percival Lowell who drew maps of an artificial network of canals on Mars.
Although these results were widely accepted, they were contested. Greek astronomer Eugène M. Antoniadi and English naturalist Alfred Russel Wallace were against the idea; Wallace was extremely outspoken. As bigger and better telescopes were used, fewer long, straight canali were observed. During an observation in 1909 by Flammarion with a  telescope, irregular patterns were observed, but no canali were seen.

Life on Mars 

Because Mars is the one of the closest planets to Earth in the Solar System, many have wondered if there is any kind of life on Mars. Today we know that the kind of life, if any, would be some simple bacteria-type organism.

Meteorites 
NASA maintains a catalog of 34 Mars meteorites, that is, meteorites which originally came from Mars. These assets are highly valuable since they are the only physical samples available of Mars.
Studies at NASA's Johnson Space Center show that at least three of the meteorites contain possible evidence of past life on Mars, in the form of microscopic structures resembling fossilized bacteria (so-called biomorphs). Although the scientific evidence collected is reliable, and the rocks are correctly described, what made the rocks look like they do is not clear. To date, scientists are still trying to agree if it really is evidence of simple life on Mars.

Over the past few decades, scientists have agreed that when using meteorites from other planets found on Earth (or rocks brought back to Earth), various things are needed to be sure of life. Those things include:
Did the rock comes from the right time and place on the planet for life to exist?	
 Does the sample contain evidence of bacterial cells (does it show fossils of some kind, even if very tiny)?
 Is there any evidence of biominerals? (minerals usually caused by living things)
 Is there any evidence of isotopes typical of life?
 Are the features part of the meteorite, and not contamination from Earth?

For people to agree on past life in a geologic sample, most or all of these things must be met. This has not happened yet, but investigations are still in progress. Reexaminations of the biomorphs found in the three Martian meteorites are underway.
The significance of water 
Liquid water is necessary for life and metabolism, so if water was present on Mars, the chances of life evolving is improved. The Viking orbiters found evidence of possible river valleys in many areas, erosion and, in the southern hemisphere, branched streams. Since then, rovers and orbiters have also looked closely and eventually proved water was on the surface at one time, and is still found as ice in the polar ice caps and underground.
Today 
So far, scientists have not found life on Mars, either living or extinct. Several space probes have gone to Mars to study it. Some have orbited (gone around) the planet, and some have landed on it. There are pictures of the surface of Mars that were sent back to Earth by the probes. Some people are interested in sending astronauts to visit Mars. They could do a better search, but getting astronauts there would be difficult and expensive. The astronauts would be in space for many years, and it could be very dangerous because of radiation from the sun. So far we have only sent unmanned probes.

The most recent probe to the planet is the Mars Science Laboratory. It landed on Aeolis Palus in Gale Crater on Mars on 6 August 2012. It brought with it a mobile explorer called 'Curiosity'. It is the most advanced space probe ever. Curiosity has dug up Martian soil and studied it in its laboratory. It has found sulfur, chlorine, and water molecules.

Popular culture
Popular culture 

Some famous stories were written about this idea. The writers used the name "Martians" for intelligent beings from Mars. In 1898, H. G. Wells wrote The War of the Worlds, a famous novel about Martians attacking the Earth.  In 1938, Orson Welles broadcast a radio version of this story in the United States, and many people thought it was really happening and were very afraid. Beginning in 1912, Edgar Rice Burroughs wrote several novels about adventures on Mars.

References 

Notes

Other websites 

 Mars at Space Wiki
 Mars at ESA/Hubble
 Mars Profile by NASA's Solar System Exploration
 Mars  - http://space.about.com 
 NASA's Mars fact sheet
 Mars Research News on https://www.sciencedaily.com
 Planets - Mars A children's guide to Mars.
 Mars  - http://stevechallis.net 
 Canals of Mars 
 New Papers about Martian Geomorphology 
 Mars (planet) -Citizendium
The Macintosh Operating System (Mac OS) is a program that allows a Macintosh computer to  operate and be used. Mac OS was first made by Apple Inc. in 1984. In those days Mac OS was called Macintosh System Software – which was shortened to System or SSW (System Software). The term "Mac OS" first appeared in the splash screen for System 7.5.1, but was not adopted as the new name until the release of Mac OS 7.6.

The latest version of Mac OS is macOS 14 Sonoma.

Related pages
 Apple Macintosh

References 

Operating systems
MacOS
The Apple Macintosh or just Mac is a line of personal computers made by the American company Apple Inc. The Macintosh was one of the first computers in which the people could use a mouse for pointing on a screen which had icons. This new way of working with a computer (interface) was known as graphical user interface. It was this feature of the Macintosh that made it so popular.

History

Processor history 
The Apple–Intel transition was when Apple changed the CPU of Macintosh computers from PowerPC processors to Intel x86 processors.  It was announced at the 2005 World Wide Developers Conference. Steve Jobs announced it.

Macintoshes were different than other personal computers for many years based on their central processor unit (CPU). At the start, Macs used Motorola 68000 chips instead of Intel chips. Later, Macs used PowerPC chips. In 2006, Macs started to use Intel chips. In 2020, Macs started to use Apple Silicon chips. Today, Macs are sold with Apple M1 chips.

Macintoshes
Macintoshes

Software 
The Mac does not have the Windows operating system installed on it. It has its own range of operating systems, known as macOS. The newest operating system is known as “Big Sur".  Macs can run both Windows and macOS at the same time with help of a program called “Boot Camp”, which comes on every Mac.

In general, Macintosh computers cost more than other computers of the same speed.

Related pages
 iMac
 MacBook
 MacBook Air
 MacBook Pro   
 Other popular products of Apple include iPod, iPhone and iPad.

References

Macintosh
A metre (US spelling, meter) is the basic unit of length in the SI measurement system. The symbol for the metre is m. The first meaning (in the French Revolution) was one ten-millionth of the distance between the Earth's equator and the North Pole along the Paris meridian. The metre is now defined as the distance light travels in a vacuum in 1/299,792,458 of a second.

In the imperial system of measurement, one yard is 0.9144 metres (after international agreement in 1959), so a metre is very near to 39.37 inches: about 3.281 feet, or 1.0936 yards.

Units multiples
0.000 000 000 000 000 000 000 001 Ym (yotametre) = 1 m
        0.000 000 000 000 000 000 001 Zm (zetametre) = 1 m
            0.000 000 000 000 000 001 Em (exametre) = 1 m
                0.000 000 000 000 001 Pm (petametre) = 1 m
                    0.000 000 000 001 Tm (terametre) = 1 m
                        0.000 000 001 Gm (gigametre) = 1 m
                            0.000 001 Mm (megametre) = 1 m
                                0.001 km (kilometre) = 1 m
                                 0.01 hm (hectometre) = 1 m
                                  0.1 dam(decametre) = 1 m
                                  1 m  (metre)
                                 10 dm (decimetres) = 1 m
                                100 cm (centimetres) = 1 m
                               1000 mm (millimetres) = 1 m
                          1 000 000 μm (micrometres) = 1 m
                      1 000 000 000 nm (nanometres) = 1 m
                   1 000 000 000 000 pm (picometres) = 1 m
1 000 000 000 000 000 fm (fermi or femtometres) = 1 m
             1 000 000 000 000 000 000 am (attometres) = 1 m
         1 000 000 000 000 000 000 000 zm (zeptometres) = 1 m
     1 000 000 000 000 000 000 000 000 ym (yoctometres) = 1 m
Related pages
Metre Convention

References

SI units
Units of length
A magnifying glass is a lens through which can be used to make things appear bigger, so you can see them better. It is used in many applications and manual operations, e.g., for examining postage stamps in philately.

The magnifying glass consists of a piece of convex-shaped glass or plastic. It has to be held at the right distance between the eye and the object for the object to be in focus. The magnifying glass usually comes with a handle. A telescope is a more advanced kind of magnifying glass and consists of at least two glass lenses. 

A pair of binoculars is like a telescope for each eye. Spectacles or eyeglasses also use lenses to correct a person's vision.

Related pages 
 Binoculars
 Stamp album
 Telescope

References

Other websites

 

Tools
Philately
A molecule is the smallest amount of a chemical substance that can exist. If a molecule were split into smaller pieces, it would be a different substance.

Molecules are made up of atoms that are stuck together in a particular shape or form. Not all combinations of atoms are equally possible; atoms make certain shapes in preference to others.  Also, they have different valency.  For example, oxygen atoms always have two bonds with other atoms, carbon atoms always have four bonds with other atoms, and nitrogen atoms always have three bonds with other atoms.

In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are in fact monoatomic molecules.
In gases like air, the molecules are just flying around. In liquids like water, the molecules are stuck together but they can still move. In solids like sugar, the molecules can only vibrate.  In the fourth state of matter known as plasma, the atoms are ionized and cannot form molecules.

With a molecular formula, you can write down the numbers of all atoms in a molecule. For example, the molecular formula of glucose is C6H12O6. That means that one molecule of glucose is made up of six carbon atoms, twelve hydrogen atoms and six oxygen atoms.

Bonding 

For a molecule to exist, atoms have to stick together. This happens when two atoms share electrons. Instead of circling just one atom, the electron now circles around two. This is called a covalent bond.  Sometimes, more than one electron is shared. The more electrons are shared, the stronger the bond gets and the stronger the atoms stick together.
Bonds can also be broken apart. Since most bonds require energy to form, they also give off energy when they are broken. But before most bonds break, the molecule has to be heated. Then the atoms start to move, and when they move too much, the bond breaks. Molecules that require less energy to break than they give off when broken are called fuels. For example, a candle will just sit there and nothing happens. But when you use a match to light it, it will burn for a long time. The match brings the energy to break the first bonds, which release enough energy to break the bonds below them, until the candle has burned down. There are also ionic bonds.

References

Other websites 
 Molecule of the Month - School of Chemistry, University of Bristol
 Antibody Molecule - The National Health Museum
 Data Book of Molecules - Home Page for Learning Environmental Chemistry

Chemistry
Moral reasoning is a topic studied in psychology and in moral philosophy. It studies how people think about moral issues, problems, and questions. Psychologists who have studied it include Lawrence Kohlberg and Elliot Turiel. Kohlberg said that moral understanding develops in three main stages as a person gets older, but Turiel said that there are three domains of moral understanding that develop at the same time as a person gets older.

Moral philosophy, or ethics, is a major branch of philosophy. It is the study of value or quality. It covers the analysis and use of concepts such as right, wrong, good, evil, and responsibility.

ethics
psychology
philosophy
A mosque is a place where Muslims worship. The word mosque comes from the Arabic word masjid.  A larger, 'collective', mosque is called a masjid jāmi. Larger mosques offer more services to their community.

For many Muslim people, a mosque is more than a place of worship. Muslims worship, study and discuss Islam, and do many other things in a mosque and its compounds. In the United Kingdom, many mosques are used as community centres. They are also used to teach about Islam. Religious festivals and gatherings are held in mosques. Weddings are one example. Mosques have rules to control what people do inside. One of these is that it is disrespectful to disturb another person who is worshipping.

Many mosques are known for their Islamic architecture. The earliest mosques, opened in 7th century were open-air spaces. They are the Quba Mosque and Masjid al-Nabawi.  Later Mosques were buildings that were specially designed. Nowadays, mosques are in every continent, except Antarctica.

Architecture
Architecture 

Many mosques are famous works of architecture. They are often built in a style that has stayed the same for many centuries. Many mosques have prayer halls, domes, and minarets. They may also have a courtyard. Mosques are often built with patterned walls.

Mosques were first built on the Arabian Peninsula. The Muslims who built them used old architectural styles. They also combined these styles in new ways. A major influence was the palaces built during the Parthian and Sassanid dynasties of Persia. The Sarvestan palace from the Sassanid era is a good example of this. It has an arched entrance and a central dome. These features already existed in Persia before Islam.
After the Arab invasion of Persia, the new style, with its Sassanid influence, was used for the new Islamic world. Many forms of mosques have developed in different regions of the Islamic world. Important mosque types include the early Abbasid mosques, T-type mosques, and the central-dome mosques of Anatolia. In the 20th century, many countries that grew rich from oil paid for the building of many new mosques. The rulers of these countries often hired leading architects to design these mosques. They included non-Muslims.

Arab plan 

Many early mosques have a square or rectangular plan. They also have a prayer hall and an enclosed courtyard. This is known as Arab-plan. The first mosques of this type were built during the Umayyad Dynasty.

The flat roof of the prayer hall was supported by columns. Many rows of columns were needed to support such roofs; this is called "hypostyle architecture". One of the most famous hypostyle mosques is the Mezquita de Córdoba in Spain. It is supported by over 850 columns.
In the warm Mediterranean and Middle Eastern climates, the courtyard served to hold the large number of worshippers during Friday prayers. Often, hypostyle mosques have outer arcades. They allow the visitors to enjoy the shade. Arab-plan mosques were built mostly during the Umayyad and Abbasid dynasties. The Arab plan was very simple, which did not allow for much further development. This caused that style of mosque to fall out of favour.

Central dome 
The Ottomans began building central dome mosques in the fifteenth century. These mosques have a large dome centered over the prayer hall. There may also be smaller domes, which are off-center over the prayer hall or the rest of the mosque. This style was heavily influenced by the Byzantine religious architecture with its use of central domes.
Iwan 
Iwan mosques are famous for their domed rooms and iwans. Iwans are spaces with an arched roof. They have an opening at one end. One or more iwans face a central courtyard that serves as the prayer hall. The style borrows from pre-Islamic Iranian architecture. Most mosques with this style are in Iran.

Parts of Mosques

Minarets 

Most mosques have minarets. Minarets are tall towers. Usually they are at one of the corners of the mosque. The top of the minaret is the highest point in the mosque, and usually the highest point in the area around the mosque. The tallest minaret in the world is in the Hassan II Mosque in Casablanca, Morocco.
The first mosques had no minarets. The most conservative Islamic groups, like Wahhabis, still avoid building minarets. They see them as simply a fancy decoration and unnecessary. The first minaret was built in 665 in Basra during the reign of the Umayyad caliph Muawiyah I. Muawiyah encouraged the building of minarets, as they were supposed to be the same as bell towers on Christian churches. Because of this, mosque architects used the shape of the bell tower for their minarets. Both the minaret and the bell tower serve the same purpose — to call the faithful to prayer.

Before the five required daily prayers, a muezzin calls the worshippers to prayer from the minaret. In many countries like Singapore where Muslims are not the majority, mosques are stopped from loudly playing the call to prayer. The main problem is the use of electronic amplification of the call, which is now widely used by mosques.

Domes
Domes 
 

The domes were often placed directly above the main prayer hall. They represent the universe that Allah created. At first, these domes were small. They only took up a small part of the roof near the mihrab. Later, they took the whole roof above the prayer hall.
Domes normally have the shape of a hemisphere. The Mughals in India popularized onion-shaped domes in South Asia and Persia. Some mosques have several domes, as well as the main large dome. The other domes are often smaller.

Domes would help the imam be heard, as the sound waves would bounce in and then out of the dome making the voice louder.

Prayer hall 
All mosques have a prayer hall, which is also called musalla. Normally, there is no furniture in it except for prayer mats or rugs. These are necessary, as Islamic prayer is usually done kneeling.

Some mosques have Arabic calligraphy and Qur'anic verses on the walls to help worshipers focus on the beauty of Islam and its holiest book, the Qur'an, as well as for decoration.
The qiblah wall is usually at the other side of the entrance to the prayer hall. This wall is specially decorated. In a properly sited mosque, it will be set perpendicular to a line leading to Mecca. People pray in rows parallel to the qiblah wall. They arrange themselves so they face Mecca. In the qiblah wall, usually at its center, is the mihrab, a niche or depression showing the direction of Mecca. The mihrab serves as the place where the imam leads the five daily prayers.

Washing (wudhu) 
All people must wash themselves before they pray. Mosques often have fountains or other facilities for washing in their entrances or courtyards, so that people can perform the washing ritual before prayer.
At very small mosques, worshippers may use restrooms for their ritual washing, or wu'du. In traditional mosques, there is often a building specially for washing. This is often in the center of the courtyard. In the prayer halls, people must not wear shoes for much the same reason.
Modern features 
Modern mosques should appeal to the community they serve. For this reason, other facilities may also be available at the mosque, like health clinics, libraries, and sports halls.

The inside of mosques 

There may be decorative tiles, plaster or coloured mosaics on the walls. There are no pictures or statues.

Religious functions

Prayers 

Adult Muslims are expected to pray five times a day. Most mosques have formal prayers for each of these times. If performing the prayer is difficult, for example for ill people, then exceptions are made.

Mosques also hold a special prayer service, called jumuah. This is done once a week. It is a form of Sabbath and replaces the Friday prayers at the mosque. Daily prayers can be done anywhere. However, Muslims are expected to do their Friday prayer at the mosque.
When a Muslim dies, a funeral prayer is normally held. It is held outdoors in a courtyard or square close to the mosque. The prayers have all the worshippers present, including the imam, taking part. During eclipses, mosques will host special prayers called eclipse prayers.

There are two large holidays (Eids) in the Islamic calendar. During these days, there are special prayers at mosques in the morning. Larger mosques will normally hold them for their own communities as well as the people from smaller local mosques. Mosques, especially those in countries where Muslims are the majority, will also host Eid prayers outside in courtyards or town squares.

Ramadan events
Ramadan events 

There are many events in Ramadan, Islam's holiest month. During Ramadan, Muslims must fast during the day. Mosques organise iftar dinners after sunset. These are done after the fourth required prayer of the day. Part of the food is given by members of the community, which creates nightly potluck dinners. The community contribution to these dinners is required. For this reason, mosques with smaller communities may not be able to hold the iftar dinners daily.

Some mosques will also hold meals in the morning before dawn. Mosques will often invite poorer members of the community to these meals. Islam sees giving charity during Ramadan as good acts.
Larger mosques sometimes offer special, optional prayers. They are done after the last required prayer of the day. During each night of prayers, one member of the community who has memorized the entire Qur’an will recite a part of the book. It can last for up to two hours. Sometimes, several such people (not necessarily of the local community) take turns to do this. During the last ten days of Ramadan, larger mosques will host all-night programs to observe Laylat al-Qadr. It is the night Muslims believe that the Islamic prophet Muhammad first received Qur'anic revelations. On that night, between sunset and sunrise, mosques employ speakers to teach the worshipers about Islam. Mosques or the community usually provide meals at times through the night.

Political functions
During the late twentieth century, more and more mosques have been used for political purposes. Modern-day mosques in the Western world want to educate good citizens. The details differ greatly from mosque to mosque and from country to country.

Advocacy 
Countries with small Muslim populations use mosques as a way to support civic participation. They are more likely to do this than Muslim-majority countries of the Greater Middle East. American mosques host voter registration and civic participation drives. In the United States, Muslims are often immigrants, or the children of immigrants. Mosques want to interest these people for politics. They also want to keep them informed about issues that concern the Muslim community. People who attend the services at the mosque regularly are more likely to take part in protests, to sign petitions, and to involve themselves in political matters.
A link between political views and mosque attendance can still be seen in other parts of the world. After the al-Askari Mosque bombing in February 2006, imams and other Islamic leaders used mosques and Friday prayers to call for calm and peace during the widespread violence.

Beginning in the late twentieth century and continuing into the early twenty-first century, a small number of mosques have also become a base for extremist imams to support terrorism and extreme Islamic ideals. Finsbury Park Mosque in London is a mosque that has been used in this manner.

Social conflict 

Like other places of worship, mosques can be at the center of social conflicts.
Babri Mosque was the centre of such a conflict up until the early 1990s when it was demolished. Before a solution could be found, the mosque was destroyed by about 200,000 Hindus. It took place on 6 December 1992. The mosque was built by Babur to mark the birthplace of Ram. It was believed to be on a site of an earlier Hindu temple. The conflict over the mosque was directly linked to rioting in Bombay (present-day Mumbai) as well as bombings in 1993 that killed 257 people.

In February 2006, a bombing seriously damaged Iraq's al-Askari Mosque. This increased the existing tensions. The conflict between two Muslim groups in Iraq had already led to other bombings. However mosque bombings are not limited to Iraq. In June 2005, a suicide bomber killed at least 19 people at an Afghan mosque. In April 2006, there were two explosions at India's Jama Masjid.

After the September 11 attacks, several American mosques were targets of attacks. These ranged from simple vandalism to arson.
The Jewish Defense League was suspected of plotting to bomb the King Fahd Mosque in Culver City, California. There were similar attacks in the United Kingdom after the 7 July 2005 London bombings. Outside the Western world, in June 2001, the Hassan Bek Mosque was the target of attacks. The attacks involved hundreds of Israelis angry at Arabs for a previous attack.

Saudi influence
Saudi involvement in building mosques around the world only goes back to the 1960s.
In the 1980s, the Saudi Arabian government began to pay for the building of mosques in countries around the world. An estimated US$45 billion has been spent by the Saudi Arabian government for mosques and Islamic schools in foreign countries. Ain al-Yaqeen, a Saudi newspaper, reported in 2002 that Saudi money may have helped to build as many as 1,500 mosques and 2,000 other Islamic centers. Saudi citizens have also given a lot of money to mosques in the Islamic world, especially in countries where they see Muslims as poor and oppressed. Following the fall of the Soviet Union, in 1992, mosques in Afghanistan received money from Saudi citizens. The King Fahd Mosque in Culver City, California and the Islamic Cultural Center of Italy in Rome are two of Saudi Arabia's largest investments in foreign mosques as former Saudi king Fahd bin Abdul Aziz al-Saud gave US$8 million and US$50 million to the two mosques, respectively.
Rules and behaviour in mosques 

In a mosque, people should keep focused on worshiping Allah. For this reason, there are a number of rules about the correct behaviour in a mosque. Some of these rules are the same all over the world, such as no shoes should be worn in the prayer hall. Other rules are different from mosque to mosque.

Prayer leader 
It is generally seen as good to have someone who leads the prayers, though this is not strictly necessary. The person who usually leads the prayers is called imam. He must be a free and honest man. He should also be an authority when it comes to answering questions on religion. In mosques that were built or that are kept up by the government, the imam is selected by the ruler. In private mosques, the community selects the imam, through majority voting.

Only men may lead prayers for men.  Women are allowed to lead prayers for congregations where there are only women.
Attending a mosque 
In addition to washing, there are other rules that also apply to those who enter the mosque, even if they do not wish to pray there. It is forbidden to wear shoes in the carpeted area of the prayer hall. Some mosques also do not allow wearing shoes in other parts, even though these may not be devoted to praying.

Islam requires that its believers wear clothes that show modesty. As a result, both men and women must follow this rule when they attend a mosque (though mosques may not always enforce the rules). Men are supposed to come to the mosque wearing loose and clean clothes that do not show the shape of the body. Similarly, women who come to the mosque are expected to wear loose clothing, shirts, pants that cover to the wrists and ankles and cover their heads such as with a hijab. Many Muslims, regardless of their ethnic background, wear Middle eastern clothing associated with Arabic Islam to special occasions and prayers at mosques.
Mosques are places of worship. For this reason, those inside the mosque should be respectful to those who are praying. Loud talking or discussion of topics that could be disrespectful, is forbidden in areas where people are praying. It is also considered as rude to walk in front of Muslims in prayer or otherwise disturb  them.

Men and women pray in different parts 

Islamic law requires men and women to be separated in the prayer hall. Ideally, women should pray behind men.  The second caliph Umar at one time stopped women from attending mosques, especially at night, because he feared they may be teased by males, so he made them to pray at home. Sometimes a special part of the mosque was railed off for women; for example, the governor of Mecca in 870 had ropes tied between the columns to make a separate place for women.
Many mosques today will put the women behind a barrier or partition or in another room. Mosques in South and Southeast Asia put men and women in separate rooms, as the divisions were built into them centuries ago. In nearly two-thirds of American mosques, women pray behind partitions or in separate areas, not in the main prayer hall; some mosques do not admit women at all. Although there are sections only for women and children, the Grand Mosque in Mecca is desegregated.

Non-Muslims in mosques 

A few scholars of Islamic law believe that non-Muslims may be allowed into mosques, as long as they do not sleep or eat there. Followers of the Maliki school of Islamic jurisprudence disagree. They say that non-Muslims may not be allowed into mosques at all.

Different countries have different opinions on the question. Nearly all the mosques in the Arabian Peninsula as well as Morocco do not allow non-Muslims. The Hassan II Mosque in Casablanca is one of only two mosques in Morocco currently open to non-Muslims.
In modern-day Saudi Arabia, the Grand Mosque and all of Mecca are open only to Muslims. Likewise, the Masjid al-Nabawi and the city of Medina that surrounds it are also off-limits to those who do not practice Islam. For mosques in other areas, it has most commonly been taken that non-Muslims may only enter mosques if granted permission to do so by Muslims and if they have a proper reason.

In modern Turkey non-Muslim tourists are allowed to enter any mosque, but must obey the rules of decorum. Visiting a mosque is allowed only between prayers; visitors must wear long trousers and take off their shoes; women must cover their heads; no photos; no loud talk is allowed. No references to other religions are allowed (no crosses on necklaces, no cross gestures etc.).
However, there are also many other places in the west as well as the Islamic world where non-Muslims are welcome to enter mosques. Most mosques in the United States, for example, report receiving non-Muslim visitors every month. Many Mosques throughout the United States welcome non-Muslims as a sign of openness to the rest of the community and to encourage conversions to Islam.

Dogs 
Dogs are usually banned from entering mosques, but on 24 September 2008, the Muslim Law Council UK made special ruling, called a fatwa, which granted a blind Muslim permission to take his guide dog into the mosque.
Mosques as hostels 
It is common for a smaller mosque to serve as a hostel for Muslims on haj (pilgrimage to Mecca). Sometimes mosques are used for refugees, or as temporary homes for homeless people. Obligations to neighbours in Islam are very strict, and specific. In the Qur'an Mohammed said that a person who helps others in the hour of need, and who helps the oppressed; that person God will help on the Day of Travail (agony). There are other commands, such as helping the poor and being nice to people. An important part of being Muslim, or just being part of the mosque, is taking care of people who need help. A mosque is a social, as well as a religious, group.

A madrassa is a little different from a mosque. A madrassa focuses on teaching Islam, usually to children and young people.

Mosques in Spain
Mosques in Spain 

When Spain was under Muslim control, some of the most beautiful buildings were mosques. After 1491, Spain was under Christian control. However, the Christians did not tear down the mosques. They simply put a crucifix in them to make them into churches. These mosques influenced the Renaissance architecture (way of building) in Europe.

References
Mammals are animals which form the class Mammalia (from Latin , 'breast'). They are a group of vertebrate animals. They have fur or hair and a very precise kind of temperature regulation.

With the exception of the monotremes, all mammals bear live young. Unlike other vertebrates, they are the only animals that produce milk for their young through their mammary glands. Parental care of the young is universal among mammals, sometimes for extended periods.

Mammals became the dominant land animals after non-bird dinosaurs were eliminated. Recent work helped to explain their success: epigenetics seems to have started in early mammals.

Main characteristics
Reproductive cycle 
Most marsupial and eutherian mammals have a reproductive cycle known as the oestrous cycle (U.S: estrous cycle). Females are sexually active only during the oestrous stage, when they are 'on heat' for a few days each month. If an ovum is not fertilized, the endometrium (uterus lining) is resorbed. Oestrus cycles may occur once or twice a year, or many times a year. Each group of mammals has its own frequency.
Skeleton 
One diagnostic feature of mammals is the lower jaw. Unlike earlier forms, it is a single bone, the dentary. This is one feature which can be seen in fossils, or at least those which are complete enough to have the lower jaw. Another diagnostic feature is the ear ossicles. Mammals have three little bones in their inner ear. These ear ossicles are bones which were, long ago, part of the lower jaw in early proto-mammals.

There are quite a number of other features in the skull and limbs, so that it is usually possible to identify and describe a mammal from its skeleton alone, or even a partial skeleton.
Neocortex and behavior 
Another diagnostic feature is the neocortex of the brain, which no other vertebrate has. This is involved in the kind of flexible behavior and learning typical of mammals. Reptiles and birds have much of their behavior controlled by "inherited behavior chains", which roughly translates as "instincts". Almost all animals can do some learning, but mammals do far more than other vertebrates. Their behavior is much more flexible than lizards, for example, and that is made possible by their neocortex.

Other things in the life of mammals seem to be connected with this flexibility and learning. Play is a kind of early learning period in which, according to one theory, mammals develop skills which they will need in life. All mammalian young play, and this is very obvious in the more intelligent mammals (primates, cats).
Other items
There are about 50 characters which are typical of mammals: some of the most important are discussed above. A few more examples will make it clear that mammals are very different from reptiles and birds:
Sweat glands
Tooth replacement: two sets, and no continuous replacement. Enamel on the tooth surface. Reptile teeth are all alike (apart from size); mammal teeth follow a set pattern (starting at the front): incisors, canines, premolars and molars.
Occipital condyles. Two knobs at the base of the skull fit into the topmost neck vertebra; most tetrapods have only one such knob.
With the exception of the five monotreme species, all other mammals have an outlet for food waste which is separate from the urinogenital outlet. Monotremes, reptiles and birds have a common cloaca at the rear.
Mammals excrete urea; reptiles and birds excrete uric acid.
Colour vision is defective or absent in almost all mammals. Primates are the exception, but we know their colour vision re-evolved from ancestors which lacked it.
In reptiles and birds the blood vessel which carries oxygenated blood from the left ventricle of the heart is on the right side of the body; but in mammals it is on the left side.
There are many features of the skeleton that mammals share:
Their neck almost always has seven vertebrae, no matter how long it is.
Their lower jaw is made of just a single bone on each side, the dentary.
Their inner ear has three tiny bones, the ossicles: malleus, incus and stapes.