Pluto

                                       Pluto              

In 1930, Pluto was classified as a planet. Around 1977, however, there were some critical voices who ensured the planet gederangeerd was to dwarf planet. Now scientists are re-walk the first path and Pluto would be called a real planet again (or at least approximately).

For space enthusiasts is one of their favorite topics of discussion: What is Pluto and is hell a planet or star may we forever belittle what? In 2006, established some guidelines at a major conference on the subject should clarify. A planet can only deserve the honorable title when it is in orbit around the sun, there is enough mass to achieve a hydrostatic equilibrium (a nice explanation to articulate that a planet should really be around) and the planet has its orbit swept clean of other debris.

The conference voted there: Pluto had to drop the title because the planet was not considered large enough. So Pluto faces competition from Eris, which is 27 percent larger. So much for the lot was settled.

Now it wants a division of Harvard once again organize an international conference to create once and for clarity. So like many scientists, the definition of a planet love to redefine as "a small fruit tree still is a fruit tree, and a baby hamster is an animal. "Even the smallest spherical lump of matter formed around stars and stellar remnants, is a planet," they claim.

Fans of the universe, so again cherish some hope, though Pluto will probably always have to live with the label of dwarf planet. The vote will be taken does not by science, but it can provide solace that a large proportion of respondents indeed find Pluto a planet.

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Stars

                                                        Stars

The color of a star you can see how hot he is. Yellow stars are around 6,000 degrees Celsius, red stars are around 3,000 degrees Celsius. Blue stars are hottest.

Because each star has a gravitational field, he draws everything that at a certain distance around it. Further away things go into orbit to orbit the star. This is when everything has a gravitational field so. Only the spheres in orbit around a star turn called planets. Globes in orbit around a planet called moons. 

Our own sun is a star, a medium. It is the star that is closest to the Earth. The planetary system where we live is called the solar system.

How is a star?

Stars form from gas and dust particles from space, or rather out of nebulae. Sometimes shapes that dust and gas together a big cloud. That cloud is billions of kilometers wide and called a nebula. They consist mostly of hydrogen and helium and icy particles of space dust. The haze particles are becoming more and sometimes it lumps. A clump may be increasing. And then the clot under the influence of its own gravity will shrink. The lump is getting hotter and gradually turns into a baby star! This shrinking gas cloud also called a protostar. 

Nebulae are very cold, but they therefore contain all the ingredients to form a star.

Stars give heat but how?

They split hydrogen and helium formed therefrom. In the fission heat is released.

Constellations:

A long time ago people were staring at the stars. And when they saw all figures. And those figures who gave them names: They thought of hey !, it looks like a Hunter. They knew a good hunter and named 'Orion'. And so they called the Orion constellation. Orion is one of the most beautiful constellations! And they thought hey !, it's like a big bear. That's in their language 'Ursa Major' The Great Bear is well known. You will see a saucepan, but the big bear is even greater.

If constellations put them there always drawn lines between. In total there are 88 constellations. But you can see not all at once, it depends on where you are on earth and what the time is. Then a star chart is useful. On this map you can see at what point you what part of the sky you can see.

When can you see the stars?

It has to be dark, and there must be little light of a city. For example, in the desert, there is no light from lampposts and houses. It is therefore very dark. And then you see a lot of stars.

It is also important that it is not cloudy.

It is best to look at a high place.

You can look at a star dome, but you can do even better in the mountains. In the mountains you are very high and there is little light of cities.

With the naked eye you can see a lot, but with binoculars you can see even more. And if you're a star or planet to view very well, then you better use a telescope. If you want to watch again stars with a telescope you can do that at an observatory.

Amorous stars:

The two stars in a binary are obviously not in love. But they always stay together, like a couple in love.

Moving stars?

The stars move, but compared to other stars they hardly will appear stars to stand still. The sun moves too. These moves at 230 km / s by the Milky Way, our own galaxy. This galaxy is moving again through the universe along with many other galaxies.

Habitable zone:

The habitable zone is the area between two specified distances from the star. Outside those distances are too hot or too cold and it naturally so that you'll be dying once. Optionally you at great distances from a star have a special heat source in order to survive, so that's why it is said here "naturally".

Outside the habitable area is for example 800 ° C or -150 ° C. Few planets located in the habitable zone. The only planets in our solar system that are in the habitable zone are the Earth and Mars. Hence, there are no plans for a manned space flight to Venus and Mars to be for (the two planets are the closest to the Earth).

If a planet is outside the habitable zone, you can say with all certainty that there is no finding on life.

A star at the end of his life

Stars die when the supply of nuclear fuel. First, burns the hydrogen, after that the helium. When the helium runs out, the nuclear energy disappears over quickly and then explode, shrink or cool them off. Stars burn a few million to many billions of years. The smallest stars but little fuel, but they eventually do it very sparingly and live longer than the big stars. A small star has enough gas to 10 billion years stay on.

When a star like our own Sun has no hydrogen in the core more, it becomes a red giant. In our own sun will occur over approximately 5 billion years. A star that is much larger and heavier than our sun turns into a supernova

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Galaxies

                                           Galaxies

With the Hubble Space Telescope, scientists have found a very old galaxy. Or very young, it's just how you look. The galaxy is 13 billion light years away.

This galaxy was formed 500 million years after the Big Bang. It is one of the first galaxies in the universe. Because the light has traveled 13 billion years to reach us, we see the galaxy in its infancy. But in reality this galaxy is 13 billion years older, and therefore probably one of the oldest galaxies in the universe.

The galaxy has a diameter of 850 light years. This makes this group of stars 500 times smaller than our Milky Way. The distant galaxy has a mass of only forty sunbathing million. In the system every three years there is a single star. 

Although there is a lot higher in the Milky this rate (one new star a year), scientists expect that the slow star formation process has to do with the fact that this is one of the first galaxies.

Gravitational Lens

What scientists have found this faint galaxy? The researchers have used the galaxy cluster Abell 2744. The cluster is for the distant galaxy and acts as a kind of cosmic lens. Because the cluster is so massive, it is able to bend light from underlying galaxies. Because of this we do not see one the same galaxy, but three times. In addition, the underlying galaxy ten times bigger and brighter than without the cosmic lens.

The first stars

The search for distant galaxies continues. Scientists hope this century watching the first stars. That way they can the story of the origin of the universe and the evolution of the first stars and galaxies further grinding. This requires new telescopes that can look further. There in the coming years many beautiful telescopes such as the James Webb telescope (the successor to Hubble) .

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Venus

                                                                   Venus

Venus is the second planet as seen from the sun, and it is "sister planet" Earth. Scientists assumed that the climate on

Venus would be very fruitful through their telescopes they just saw a huge thick cloud, so there would be water. Moreover 

Venus closer to the sun and is therefore comfortably warm, argued astronomers.

Upon the arrival of the first spacecraft to the planet would appear that these assumptions were all wrong.

Orbit and rotation

Venus rotates westward around its axis, unlike the other planets, running eastward. The sun is therefore important in the 

west! Moreover, Venus rotates very slowly, but they will do 243 Earth days to rotate once approximately itis axis. Because 

the planet orbits the sun at the same time, it takes a "day" (the time between two sunrises) yet only 117 Earth days.

Atmosphere and Climate

Venus was the first planet was visited by interplanetary spacecraft: the Russian Venerasondes. Who discovered that Venus 

did not appear on the earth. The planet has no water, the atmosphere is CO2, it rains sulfuric acid, the air pressure is 

100 times higher than the earth, and the average temperature is 350 ° C. That extreme conditions are not only due to the 

fact Venus is closer to the sun, the planet is the victim of a particularly strong greenhouse result , causing the 

temperature three times higher than normal.

The greenhouse effect on Venus is caused by the large amount of carbon dioxide (CO2) in the atmosphere 96% of the 

atmosphere consists of carbon dioxide. Carbon dioxide that forms dense clouds that hold the heat means heat rising from 

the surface of the planet in the form of infrared radiation is reflected back through these clouds to the surface.

The clouds of Venus rotate much faster than the planet itself: in 243 days while Venus rotates on its axis, the thick 

layer of clouds rotating in four days around the planet. This difference causes a huge wind speed up to 100 m / s.

Surface

The very dense clouds of Venus has long prevented scientists to see something of the surface of the planet. Since the 60s 

were attempts with radars from Earth by watching the clouds.

However, this yielded little results. The Russian Venera's 15 and 16, that same tried in orbit around Venus, all gave 

better resolution, but it was the US Magellan probe, which ran between 1992 and 1994 around the planet, which gave us a 

very detailed image of the surface.

The Russian Veneralanders sent by pictures of on the surface of Venus. Which showed that the surface consists of flat, 

basaltic rock similar to basalt sometimes produce Earth's volcanoes.

Old radar had shown a large number of craters, so they went out that the surface of Venus was pretty older . so, the 

Magellan images showed that the mostly volcanic craters dominate the surface. Impact craters of meteors were hardly found. 

This means that the surface of Venus is just very young: up to 500 million years. Magellan even found some places where 

the surface changed over the 2 year period in which the probe took pictures. Venus is still geologically active!

Origins and evolution

Since the surface of Venus is so young, we know nothing about the origin and early history of the planet. maybe that 

compare with the early history of the other terrestrial planets: in the vicinity of the sun arise rocky planetesimals, 

which clump together to proto planets and planets. The opposite rotation of Venus suggests that the planet was ever handle 

a very heavy impact, as with Mercury and the Earth happened more than once. However, any geological evidence thereof is 

obliterated by volcanism.

Composition

Just as the earth Venus has an iron core around there a liquid stone mantle. The magma in the mantle, some places may 

break the crust and cause different types of volcanic activity.

Venus shows no signs of plate tectonics. Venus has no magnetic field, and by the high temperatures is any indication of 

any previous magnetic field disappeared. Therefore, many scientists believe that the core of Venus is not liquid. Others, 

however, think that the core is still liquid, such as on the earth, but is slow to solidify. It is indeed difficult to 

explain why the core of Venus it would be solidified, and not of the earth.

Exploration

Like Mars Venus has long been regarded as a sister planet earth. In the beginning of the space age were also numerous 

missions to the veiled planet, hoping to discover more of its enigmatic surface.

The first probe who managed to reach the planet was the American Mariner 2, 1962. The earlier probe Mariner 1was lost 

shortly after launch. Mariner 2 discovered the retrograde movement of Venus, studied the atmosphere and climate and found 

no magnetic field.

Five years later the probe Mariner 5 was sent to Venus. Mariner 5 was a backup probe Mariner 4, which was sent to Mars. 

The Mariner 5 investigated especially the effect of the absence of a magnetic field around Venus. A third Mariner who 

visited the planet Venus, Mariner 10 was on his way to Mercury. This probe, however, yielded little new information about 

Venus.

Meanwhile, since 1961 the USSR had tried to reach Venus. Only in 1967 the Venera 4 managed to reach the planet. Venera 4 

dived into the atmosphere and took direct measurements of temperature, pressure and wind speeds. Successive Veneras 5 and 

6 went down into the Venus atmosphere. The logical next step was the Venera 7 who first performed a successful landing on 

Venus. For 23 minutes, sent the landing capsule measurements from the planet's surface by. Venera 8 held the 50 minutes, 

and in 1975 became the first probe Venera 9, which provided us pictures of the Venus surface. Venera 10 did exactly the 

same. The USSR launched until 1983 probes to Venus. The Venera 13 sent color images of the surface. Venera 15 and 16 were 

equipped strong radars which brought the surface of the planet roughly in card.

The sequel to the Venera probes were the Vega 1 and 2 which in 1985 flew past Venus on its way to the comet called Halley. 

During their passage past Venus they left two probes descent down which did extensive measurements of the atmosphere and 

after their landing investigated a soil sample.

Meanwhile, NASA had launched a new Venus mission in 1978, the Pioneer Venus. This probe consisted of an orbiter, which the 

atmosphere, magneto atmosphere and examined the surface of the planet, and four descent modules did detailed measurements 

of the Venus Clouds while flying on a parachute through the atmosphere.

The Pioneer Venus orbiter was reactivated in 1991 to explore the south pole of the planet and the probe in 1992, burned up 

in the atmosphere of Venus.

In 1990, the Galileo Jupiter probe flew past Venus. The probe took some photos but was not equipped for scientific 

observations of Venus.

The latest Venus Mission was Magellan, who also arrived in 1990 and aimed the surface of the planet had to make very 

detailed map. Before the probe had a very strong radar on board, who could see through the clouds. In 1994, it lost 

contact with Magellan, but in the meantime had the probe us know a whole new dynamic planet with active volcanism and a 

very young surface.

Venus Express:

Venus Express is an unmanned spacecraft sent by the European Space Agency to the planet Venus.

The launch took place at the Baikonur cosmodrome in Kazakhstan on November 9, 2005 4:33 pm with a Russian Soyuz rocket 

equipped with a Fregat "upper stage. After peeling the third state brought a first ignition of the Frigate spacecraft in a 

circular 'parking orbit' around the Earth. 82 minutes later made a second ignition sure the spacecraft began its 

interplanetary journey. 1 hour and 36 minutes after launch, the spacecraft Frigate was disconnected. Interplanetary voyage 

lasted 153 days. The operational orbit of Venus Express is a 24-hour, highly elliptical polar orbit. The lowest and 

highest point of the at resp. 250 and 66 000 km from the surface of the planet.

The surface of Venus is invisible because it always hides under a thick cloud, but Venus Express will also explore the 

planet's surface. This is done by observing in the infrared: the cloud appears to let certain wavelengths in the infrared 

range.

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Planets

                                                                                Planets

Asteroid Belt:

On the border between the stony planets and gas giants we find the asteroid belt, a zone where no single planet but a lot miniplaneetjes through the solar system move.

There are many thousands of these planets (planetoids or asteroids), which all have their own name. To cataloging them easier, they all get a number, in order of their 

discovery. The first discovered asteroid Ceres is one example.

View and surface:

Asteroids are very small. 1 Ceres, the largest of all, it is 930 km wide. 2 Pallas and 4 Vesta is about 500 km wide. Most measure only a little kms. but  the very 

largest asteroids are not around: most are vaguely oval or "potato-shaped".

Meanwhile, there are further away in the solar system discovered a number of objects that are larger than Ceres, and almost as large as Pluto. These are cooper 

objects, the icy brothers of the stony, metallic or carbonaceous asteroids.

NEAR discovered that the asteroid Eros is covered with a thick layer of fine regolith, as the moon is the case. Perhaps partly consists of micrometeorites and partly 

of debris from the asteroid was loosened by smashing these micrometeorites.

Recently it has been discovered that an asteroid sometimes consists of several pieces of stone that just float together, such as 4769 Castalia. Sometimes it to two or 

three large boulders that will revolve around each other, but sometimes an asteroid also consists of a large lot of small stones, as might be the case in 1620 

Geographos. The Galileo probe found that the planetoide243 Ida has a small moon, Dactyl that was baptized. That moon is no extra  than 1.5 kilometer wide.

The Hubble Space Telescope has discovered large color contrasts on asteroid Vesta, similar to the dark areas on the Moon (lava plains are called "seas"). That means 

that on Vesta magma must have flowed from the interior of the asteroid. This cast a totally new light on asteroids, once thought that the blocks of stone were extinct 

since the birth of the solar system hardly had changed. For now, however, Vesta is the only asteroid which found traces of geological activity that are related to 

impact features.

Vesta was probably hit about 4 billion years ago by a slant that rending away part of its crust, and so brought the dark (liquid) mantle to the surface. So as Vesta 

offers us actually look at her inner. Moreover, a number of terrestrial meteorites exhibit many similarities with Vesta, scientists assumed that dare assume that they 

are dealing with original pieces of the crust associated with that collision come loose, and after a journey through the solar system on earth crashed. Even those 

meteorites (found in 1970) indicate volcanic activity. Finally, an entire family were also smaller asteroids discovered near Vesta, which probably also originally part 

of the mantle of the asteroid.

Composition:

In terms of chemical composition, we distinguish three types of asteroids: C, S, and the smaller group M. The C-type state for carbonaceous asteroids while S stands 

for asteroids that predominantly contain silicates. Rare M-types are metallic. On the basis of observations of the color of asteroids and measurements of their 

reflectivity by the IRAS satellite could which three families are further divided into 14 subtypes, according to their composition.

The C group is the largest and contains about 3/4 of all asteroids. Asteroids of this group are very dark. Some contain compounds that indicate that they used to have 

that water has entered into connections with the minerals present. A small portion of the asteroids in the C group, especially those who are on the outside of the 

asteroid belt, are dark red. This suggests that their surface contains organic substances.

Approximately 1/6 of the asteroids is quite clear and reddish in color. This is the S-group. They consist of silicates with iron compounds.

The smaller M-group, finally, consists mainly of nickel and iron, without any trace of silicates. They exist so probably entirely of metal, and may be left over (parts 

of) iron cores of planetesimals that their older stone mantle are completely lost in a giant collision.

Also cooper objects and Centaurs are classified as asteroids, although they consist mainly of ice and thus more akin to comets. These objects are not discussed here.

Origins and evolution

The origin of the asteroid belt is quite easy to explain: while in the early solar system anywhere planetesimals collided, samenklonterden and shaped  planets, could 

not do that at the place between Mars and Jupiter. Probably is the great attraction of Jupiter here for something in between.

Jobs and families:

Most asteroids we find located in an elliptical orbit between Jupiter Marches, roughly in the plane of the ecliptic.

Although there are a lot of asteroids, they come very rarely together or a planet around: the space through which they float is very large, and the asteroids 

themselves are very small. Yet it must occasionally prevent two asteroids collide. Unless there is a large difference in mass, the two asteroids will usually break 

into pieces. Only at the very heavy collisions will all those little pieces in different jobs to reach the sun, and thus new asteroids. In several states, the remnants 

  together in the area, in what is called "Hirayama families". Such families are usually also characterized by a cloud of dust, resulting from the collision.

A large family of asteroids located on the orbit of Jupiter. These are called Trojans because every asteroid in this family is named after a hero of the Greek story of 

the Trojan War. By gravity, these Trojans divided into two families: one group is in orbit before Jupiter, the other group follows the planet.

There are also some asteroids that are in orbit near the Earth. This family is called "Near Earth Objects". 1 of this is the asteroid Eros(god of love), was from 

February 2000 until February 2001 that examined the spacecraft near.

The satellites of Mars, Phobos and Deimos, are probably asteroids captured by the Martian gravity. The gas giants have some irregular moons, which are captured asteroids.

Research:

In new  years there has been a transformed  focus on asteroids: the public interest was aroused by theories that the impact of an asteroid associated with the 

disappearance of the dinosaurs, or even an imminent catastrophe predicted that would put an end to our civilization. No matter how small the chances of such a 

devastating impact, still keeping an eye on asteroids space agencies who come too close to the earth. Other motives, however, the interest in these small planets been 

tightened at the scientific level, they can teach us more about the origins of the solar system. In economic terms, they may be suitable for future mining: they are 

rich in minerals.

The increased interest is particularly evident in the number of probes that can be output to asteroids. The most spectacular example so far is the NEAR probe, which in 

1997 first asteroid 253 Mathilde Visited and in February 2000 at the nature shearer 433 Eros arrived and from orbit around the asteroid for a year conducted extensive 

research. At the end of the NEAR mission was always closer to the asteroid, the probe crashed there in the end, and thus the first "landing" conducted on an asteroid. 

The latest photo NEAR sent it was taken from a height of 25 meters above the surface.

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Mars

History:

Since ancient times is Mars, the red planet, closely monitored by humans. His blood-red color made him many civilizations associated with war. Thus, the planet came

also to his name: Mars is the Roman god of war. In the 17th century, astronomers turned their first, self-built telescoopjes on Mars, and discovered they color spots 

that reminded them of the maria on the moon. In the course of time, they also discovered line systems, color changes, the mobile polar caps and clouds. Mars began more 

and more to the imagination.

In 1877, the Italian astronomer Giovanni Schiaperelli published a map of Mars, based on his many years of observations of the planet. Schiaperelli gave the lines that 

he saw the name canali, an Italian word for natural water channels. Due to a translation error, there was the English version of the maps canals, which refers to 

artificial canals (the English word for natural channels is "channels"). This translation error occurs in the American fantasist Percival Lowell, the idea emerged that 

there was a high civilization on Mars, which by means of giant channels trying to irrigate its desert planet with water from the polar caps. The step to Martians has 

put it. Still there are people who believe that Mars once great civilizations have existed, despite an obvious lack of any convincing evidence.

Even when scientists Mars remains a popular planet: after our earth and moon she is the most studied object in the solar system. The conditions on Mars sometimes 

resemble those on Earth. Some scientists even think that there is life on Mars ever created, which has since disappeared. The recent discovery of large amounts of 

water ice and possible liquid surface water on Mars make the planet more interesting. Since the 60s though she is the target vantalloze space missions. Perhaps it will 

not be long before even the first astronauts our neighboring planet visit, the US space agency NASA has had to abandon the ambitious plans of President Reagan, so a 

manned flight is at a standstill the aim , albeit using commercial partners. Other countries such as Russia and ESA investigate long-term stay in space.

Orbit and rotation:

Mars rotates in 687 Earth days to the sun. Mars axis is slightly tilted (23 ° 30 ', similar to the caster of the earth 23 ° 59' is) so the seasons are very similar to 

those of the Earth.

A day on Mars (since the landing of the popular Mars Pathfinder often 'sol' called) takes 24 hours and 37 minutes. That is very similar to the Earth day. All these 

similarities make that future colonists will have it very easy to adapt to the rhythm on Mars.

Origins and evolution:

Mars must have occurred about the same time the earth, and initially had perhaps a more or less similar evolution. The biggest difference is that Mars because they 

only half as large as the earth could cool much faster. That made for a much more limited than volcanism on Earth, and the total absence of plate tectonics, the outer 

layer of Mars is a single plate. Therefore, there are no high mountain ridges, dieptetroggen or volcanic ridges. Where the crust was thin enough to be penetrated by 

magma, emerged very high volcanoes.

Composition:

Like Earth and Mars Venus consists of a crust, a mantle rocks and an iron core. The fact that Mars has only a very weak magnetic field, indicates that this core is 

completely fixed. The little magnetism that space explorers detected is probably a relic from the earliest period of the planet, when that iron core was still liquid. 

Some rocks can indeed retain magnetism.

Surface:

The surface of Mars is quite young: contrary to what had been expected, there are on the planet but find few large impact craters. The southern hemisphere of Mars is 

the oldest (about 3.8 billion years), and consists of heavily cratered mountains, similar to the crater field of the moon. The northern hemisphere consists mainly of 

plains young (younger than 3.5 billion years), intersected by valleys. The region Tharsis region, which is also the volcano Olympus Mons, is not older than 500 million 

years!

The separation between the old and the young southern terrain northern area happens quite abruptly, with a sudden altitude of several kilometers. Possible Mars in its 

early history experienced a severe impact on the northern hemisphere, making it half the planet was largely renovated. Mars Global Surveyor also generated data showing 

that the crust in the northern hemisphere 35 km thick, as opposed to 80 km in the southern hemisphere.

Volcanoes:

One of the most spectacular relief units on Mars is the volcano Olympus Mons, the bigest shield volcano in the solar system: it is 24 km high and has a base diameter 

of 500 km. The volcano is surrounded by a steep cliff 6 km high. Besides Olympus Mons are also in the same area there is Alba Pathera (1500 km wide) and three smaller 

volcanoes Arsia, Pavonis and Ascraeus. There are on Mars prevent two other areas where smaller volcanoes Elysium regioen the Hellas impact basin. 

Because there is no plate tectonics on Mars as on Earth the lava continues to flow through the same place the crust. On Earth, the Earth's crust shifts over time, so 

that the volcanoes are positioned next to each other (eg, the archipelago of Hawaii).

There is evidence that Mars 150 million years ago, a volcanic eruption witnessed; geologically speaking it is very recent, so it is believed that Mars today is still 

volcanically active. However, volcanism is very limited and dormant, and the likelihood that we will soon see an eruption is extremely small.

Valleys:

Another striking element of the Martian geography are the countless valleys especially in the older southern hemisphere to see. Since the photographs of the first 

Mariner scouts is the most accepted hypothesis that these valleys are actually dried out riverbeds. That means there must have once been on Mars large amounts of 

water. For years, scientists have wondered where that water or went there: Today Mars is a dry desert. Measurements have shown that it is probably in the form of 

permafrost is incorporated into the soil on Mars. It would be exceptionally large amounts of water ice that is stored on a few meters depth below the surface.

Vallis Marineris:

The gigantic canyon structure Vallis Marineris, a fault line of 4000 km long, is not caused by water erosion: it is a great crack in the crust caused by stresses due 

to the bulging of the Tharsis plateau on the other side of the planet. That plateau, 10 km higher than the average level Mars, was created by the upwelling of lava 

from the mantle of the planet. Because the crust in that place too thick to break through, the material piled up. On the other side of the planet tore the crust 

thereby open

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ozone layer

Ozone depletion: causes and effects

The ozone layer protects the earth from excessive irradiation of ultraviolet (UV) light. Influenced by the emission of

substances such as chlorofluorocarbons (CFCs) and halons has decreased the thickness of the ozone layer since 1980. The 

resulting increased UV radiation has harmful effects on humans and nature.

The ozone layer

The stratosphere is the layer of air between about 15 to 40 km altitude. This naturally has a high concentration of ozone 

and is therefore also called the ozone layer. Ozone protects the earth from excessive irradiation of ultraviolet (UV) 

light from the sun. When talking about a decrease in the thickness of the ozone layer (or over the hole in the ozone 

layer), then becomes a (strong) the reduction of the ozone concentration referred to in the stratosphere.

Above the Antarctic is the decrease of the ozone concentration much stronger than average on earth. This happens 

especially during the spring season there. This has to do with the extremely low temperatures which prevail there in the 

stratosphere in the winter, in combination with the presence of ozone-depleting substances (chlorine and bromine 

compounds). This low temperature leads to the formation of polar stratospheric clouds (PSCs). On the surface of the cloud 

droplets reactions occur with the chlorine and bromine compounds which ozone can be accelerated aborted when sunlight 

returns in spring. Even in the Arctic occurs in this process, but to a lesser extent than in the Antarctic. The gap in 

the ozone layer is therefore particularly in the Antarctic large. The gap varies greatly in size during a year and is 

maximum in the spring season (September to November) there.

The thickness of the ozone layer over the last years not continue down

From about 1980 has decreased the thickness of the ozone layer, especially during the eighties and early nineties of the 

last century. The reduction amounts to about 3% compared to the period before 1980. Around the mid-latitudes (35-60) is 

the decrease about 3.5% in the northern hemisphere and about 6% in the southern hemisphere .

The decrease has not put further in recent years, and stabilizes so now more-or-more on this lower level. This is due to 

the fact that the peak in the concentrations of substances that deplete the ozone layer is reached. This is because the 

global production and use of ozone-depleting materiales under the influence of the internationally agreed Montreal 

Protocol was strongly reduced. The concentrations of the major ozone-depleting substances are therefore declining.

By further decline may occur in time recovery of the ozone layer. The ozone hole over the Antarctic will persist for many 

decades. A full recovery of the ozone layer will take more than 50 years.

UV radiation increases

The thinning of the ozone layer results in an increase of the UV radiation on the earth's surface. In the Netherlands, the 

total skin cancer relevant UV radiation since 1980 increased by about 10%.

Effects of the increase in UV-load

An increase in UV radiation causes numerous adverse effects on health and the environment, including additional cases of 

skin cancer. Based on the average UV irradiation in the period 2004-2006, in time the annual number of people with skin 

cancer in the Netherlands increased by 150-200 per million inhabitants. In total there will be over 2400 additional cases 

compared to 1980. Of these extra cases per year is estimated about 40 people died. As the ozone layer recovers, will be in 

the Netherlands the additional number of annual cases of skin cancer from ozone depletion around the middle of the 21st 

century come in at around 1500 per year.

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