The Seven Wonders of the World

The first wonder of the world

Since the advent of satellites and space probes, our world has expanded, it now extends to the outer solar system.
For several decades now, our world view has been enriched with many images all as surprising as each other.
All objects in the solar system, from the same cloud, evolved together, following the same constraints, driven by the same forces, obeying the same laws and universal constants. Yet the planets, moons and asteroids, we show an extraordinary diversity. Astronoo chose the seven most amazing wonders known in 2015.
From space, the first of the Seven Wonders of the World is of course the Earth and its colors. This wonder of the world is the best, simply because life moved there and it shows its colors.
Numerous landscapes on Earth are magnificent, the Iguazu Falls, Niagara Falls, the Grand Canyon, Bora Bora, Annapurna, the Perito Moreno glacier, petrified dunes Paria Canyon, Halong Bay, Cappadocia, Hunan stone forest, Palawan islands, limestone pools of Pamukkale, but the Earth is beautiful overall, only in space.

Just look at from the outside, from any angle of view to find the original. Its shades of deep blue colors make it an exceptional object and it is these colors that betray the presence of biochemical life and just for its colors, I made the first of the Seven Wonders of the World.
We can easily understand the emotion felt by astronomers of the International Space Station when gravitate.
Note on the enlarged photo, frail membrane of air (oxygen and nitrogen) that protects living organisms.

NB: The original idea of the seven wonders of the world date Herodotus (≈484 - ≈425 BC.) and Callimachus (≈305 - ≈240 BC.), who established a list which included the lighthouse Alexandria, the Hanging Gardens of Babylon, Statue of Zeus chryselephantine in Olympia, the Temple of Artemis at Ephesus, the Mausoleum of Halicarnassus, the Colossus of Rhodes and the Great Pyramid of Cheops. Only the Great Pyramid of Cheops has survived until today.

Image: We are the first generation to see our planet from outside and in its entirety. The first image of the Earth was taken by Apollo 8 in December 1968 first mission to have carried men beyond Earth orbit. Image Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

The second wonder of the world

Everyone knows Saturn's rings but no one has seen up close. They are invisible to the naked eye from Earth but the Voyager and Cassini mostly sent us beautiful images of this amazing structure.
The round of Saturn's rings is one of the most beautiful sights offered by the solar system. The rings consist of billions of small ice beads of a few centimeters, each on its orbit, all contained on a disk gigantic, extremely fine. Despite the low sunlight, this disc appears and disappears in the shadow of Saturn as an outgoing sharp blade from its sheath.
Small mysterious icy moons, Atlas, Prometheus, Pandora, and Pan Mimas, a few tens of kilometers run on this ice belt unnoticed. All that ice gathered into a single object would only be a small moon of 150 km diameter. These rings could be a former moon which exploded under tidal forces from Saturn or disintegrated by the impact of a comet.
This wonderful too fragile and unstable structure to last, can only be to the recent astronomical scale.
The rings of the zone starts very close to Saturn, about 70 000 km and distinct bands of different colors, are stretched into the space on 500,000 km distance.

By comparison our Moon is about 385,000 km from the Earth and the diameter of Saturn is about 120,500 km.
The divisions between the rings are enigmatic because the gaps between the rings contain more dust than ice. This structural material can exist only near Saturn because it is the attractive forces on the smaller near rock particles, preventing accretion of the particles between them, now a ring structure.
Beyond a certain limit, called Roche limit, collisions cause the particles to append by accretion and to form a satellite.
Apart from their beauty, the origin of the rings is still one of the most difficult problems faced by astronomers. Especially since it is not a unique phenomenon, the planets Jupiter, Uranus and Neptune also have ring systems comparable, sculpted by gravity and made up of ice particles from aggregates that s' assemble and disperse constantly.

Image: The rings of Saturn have complex resonances with some satellites. The satellites 'shepherds' (Atlas, Prometheus and Pandora), roll the edge of the rings and are indispensable for the stability of these. The overall system is very fragile as this picture shows.

The third wonder of the world

Io is closest moon of Jupiter, it toured in just 40 hours. It is the fourth largest moon in the solar system, slightly larger than our moon. Io is mainly composed of rocks and not of ice as the other moons, there is no water on Io.
Io is unique in its beauty, it has an incredibly active area and so young that it lacks impact crater. With over 400 active volcanoes is the most active object in the solar system.
This geological activity is due to its proximity to the giant, which continuously deforms crust and mantle made soft and warm by tidal forces and its orbital resonance with its neighbors, Europa and Ganymede.
The show must be seen up close breathtaking because volcanoes reject huge silicate lava projected volumes and at great altitudes up to 500 km height, sulfur and sulfur dioxide.
All plains are covered and that gives him amazing hot colors, red, yellow, white, black and green, changing the appearance of Io in the space of a few months.

His intense activity carved a beautiful landscape of a hundred mountains, some of which are taller than Everest. In the colorful plains, we see lava flows rich in sodium and magnesium, many yellow and red lakes of molten sulfur and white and green calderas, several kilometers deep.
Io also has a small atmosphere produced by the gas that rises to the surface and break. This gas is composed mainly of sulfur dioxide (SO2).
The very low gravity Io cannot retain a dense atmosphere, however, at the equator, where volcanoes are concentrated, the atmosphere is thicker. In these hot spots, glowing auroras were seen from Earth.
The hottest areas, those where there are lava, reach temperatures of 1700 ° C, in these regions, the average temperature is 27 ° C.
Through these local temperature Io could be a promising location for the search for signs of life. However the average temperature of the moon is icy, in the range of -143 ° C.

Image: Credit Voyager 1 (1979) and the Galileo mission (1995) NASA.

The fourth wonder of the world

Enceladus, the sixth largest moon of Saturn, has despite its small size of 500 km in diameter, amazing features, Enceladus is alive. View from its surface, Saturn is huge, 60 times larger than the Moon in our sky, while the Sun it is 10 times smaller.
It is this proximity that by Saturn tidal effect it brings a little warmth.
Indeed Enceladus is covered with a layer of snow "recent" to bluish, about a hundred meters. Enceladus also has a difficult to explain geological activity for such a small body. Enceladus has a huge subsurface liquid water ocean, 150 km depth.
Its surface is of tectonic fractures, as great rift roughly parallel grooves 200 km long and 10 km wide and deep than 1 km.
From these narrow fractures out of the ice plumes that sprinkle its orbit.

Geysers constantly exploding in all directions, by ejecting ice particles 500 km height and fall on the surface. These geysers of ice as salt spreading a thin swirling trail in the wake of the moon. This feeds drag the ring outermost and largest of Saturn and the solar system.

NB: A geyser projected at high temperature and high pressure water. The activity of geysers is related to the presence of water at depth. The water is heated by meeting a rock, itself hot. This pressurized water, then springs towards the surface by convection effect. The surface is generally narrow orifice, connected to conduits for leading to extensive underground water reservoirs. The largest active geyser on Earth, the Steamboat geyser in Yellowstone National Park in the United States, measuring barely a hundred meters.

Image: Enceladus, moon of Saturn, has despite its small size of 500 kilometers in diameter, intense geological activity.

The fifth wonder of the world

Olympus Mons, is an exceptional shield volcano on Mars, for astronoo, it is also one of the Seven Wonders of the World.
This beautiful yellow volcano, 648 km wide, rises to an impressive height, 21,229 meters above the Martian baseline.
Compared to the surrounding plains, the giant rises to 22.5 km, piercing the red sky of Mars. Olympus Mons is surrounded by huge white cliffs, in the image of this great uprising.
This cliff extending over the entire circumference, achieved by spot 6 km high.
Its caldera is 85 km long and 60 km wide and 3 km deep, a huge hole in which one can still admire six of collapse craters entangled, smaller.

The exceptional size of Olympus Mons is certainly due to the fact that Mars does not have plate tectonics and it seems that all the lava depths accumulated for billion years in the same place, until achieve an incredible height, beyond the ceiling aviation aircraft lines.
Olympus Mons is the largest volcano in the solar system. Placed on France, it would cover an area from Paris to Montpellier and Bordeaux at the Swiss border.

NB: A shield volcano is the result of very fluid lava emitted by stacking volcanic pipes of a vast volcano, over a very long period of time.

Image: Olympus Mons is the largest volcano in the solar system, it sits on a vast plateau of 22.5 km in height.

The sixth wonder of the world

Triton, with its 2700 km in diameter, is the largest moon of Neptune, the seventh largest moon in the solar system, our moon is the 5th with its 3470 km in diameter.
Triton has a unique feature, this is the only large moon in the solar system that orbits in the opposite direction to the direction of rotation of the planet. Triton could therefore not form around Neptune and its composition is reminiscent of a distant solar system object like Pluto.
Its retrograde orbit is all the more surprising that Triton is very close to his planet to ≈355 000 km and revolves around Neptune in 5 days and 21 hours on a perfectly circular orbit.
But Triton is also noted for his fairly recent significant geological activity. This activity would explain why its surface was not great terrain and few impact craters.
In addition, Triton has very distinct seasons because its revolution plane is inclined to the orbital plane of Neptune around the sun. Each season on Triton lasts about 41 years.
The southern hemisphere ice Triton, which appears in the picture, is seen by Voyager 2 in 1989, i.e. in the spring. But Triton is the most distant moon the sun and the south entered the summer will be sunny and in 2000 for 40 years.

Triton receives very little heat, its surface temperature is extremely cold, -235 ° C.
However, the action of sunlight on the southern polar cap will sublimate the frozen nitrogen and generate a light breeze on the surface.
In the tenuous atmosphere of Triton, you can see in the sky clouds nitrogen purposes. Its surface exhibits beautiful pastel shades, the southern hemisphere is the highly reflective region tinged with pink and yellow, marked by small dark streaks likely nitrogen geysers demonstration sublimated under the surface and out under pressure, causing particles dark dust.
Above, we see another smoother region, in whose land melon skin, gray-green tone reflected stained dark spots haloed in white.
The darkest area is the satellite back region, which is opposite to the direction of travel, and thus protected from meteorite impacts. This area has a gray tint bluish, possibly Neptune's highlights. In this region, craters seem to belong to cryovolcanoes that instead of washing, reject volatiles, water, ammonia or methane.

Image: Triton is a big satellite 2706 km in diameter but its orbit is retrograde i.e. that its rotation direction is opposite to that of rotation of Neptune, this feature reveals that Triton is an object of the distant solar system, captured by the giant planet. Triton is also noticed by its geological activity and its seasons. Each season on Triton lasts about 41 years.

The seventh wonder of the world

Europa is a moon of Jupiter, the sixth largest moon of the solar system just after our Moon. Its surface is smooth and shiny and just the beauty of Europa comes from its enigmatic surface fractured.
Europa have a gigantic ocean of salt water, kept liquid, hidden under a frozen surface of several kilometers.
Fractures of ice crust show the friction generated by the enormous tidal forces of Jupiter. In places, cracks allow the upwelling groundwater '. These cracks open and close constantly hiding inside a "hot". Moreover, its atmosphere contains little oxygen and the surface of Europa seems to harbor organic elements.
The ice crust is torn by long and wide dark bands that show a deformation of the surface. This surface takes the form of a vast network of interwoven fractures, sprinkled with hydrated magnesium and sodium sulfates and possibly sulfuric acid. These traces betray the presence of underground water. Europa like Earth consists of an iron core, a rocky mantle and a saltwater ocean beneath its icy crust.

As far from the sun, the ocean would be completely frozen. But Europa orbits Jupiter in 3.5 days, and the moon is locked by gravity, always showing the same face to Jupiter.
Its proximity to the giant Jupiter creates tides that stretch and relax its surface. Tides provide energy to the ice moon envelope, creating linear fractures visible through its surface. If the ocean of Europa are the tides could also create volcanic or hydrothermal activity on the seafloor, providing nutrients. From there, everything is possible, even the ocean could harbor life.
In 2013, the Hubble Space Telescope spotted plumes of water into space, which generated considerable excitement among scientists, because it proves that the moon is still geologically active.
These feathers of liquid water will be studied by future missions to Europa, particularly that NASA will start in 2020 and that already fascinate the scientific world.
Europa is the most promising place in the solar system for the search for life.

Image: Color photography interpreted, taken between 1996 - 1997 by the Galileo spacecraft, at a distance of 671,880 km. Europa cracks open and close constantly with the tides, leaving glimpse of water vapor plumes. The red-brown color represents non-frozen areas of the crust, painted by minerals transported and distributed by the water vapor released from below. Blue represents the icy areas. White describes the fields covered with ice particles ejected during the formation of craters in the visible region. Credit: NASA Galileo Mission (1989-2003).