What are the specail features of earth?

Answer 1

Probably the most important is that it is just the right distance from the sun to use its energy, yet far enough away and protected so life can exist on it.

Another special feature has to do with its position in relation to the planet Jupiter. Jupiter is so close and so large, that many of the comets that would hit the earth and destroy all life end up getting sucked into her huge gaseous mass, or deflected out of the solar system, leaving us her on earth unharmed.

The next most important feature, and the one that is keeping us alive, is the molten core of iron. The core of the earth generates a magnetic field that keeps cosmic rays from entering our atmosphere. If it stopped doing that, our atmosphere would be blown away by the solar wind and the cosmic rays would kill every living thing on earth.

The next important thing is the ozone layer high up in the atmosphere. It keeps the harmful ultraviolet rays from also endangering life on earth.

Next item would have to be the seas and oceans that help keep us at a relatively stable temperature that is just right for supporting life.

Another important feature is oxygen. Though the earth does not produce it, it is vital for supporting life as we know it. Virtually all our oxygen comes from plants in the sea and on land. If we loose these important organisms, life on earth would not be possible. In 3 million years Earth will get sucked into the blackhole from the sun.

Answer 2

Mercury : The closest planet to the Sun, and has the highest extremes of surface temperatures. The lack of an atmosphere allowed extensive cratering as on the Moon.

Venus : The thick clouds of Venus form a hellishly hot atmosphere of carbon dioxide.

Earth : The Blue Planet, has a generally transparent atmosphere, and extensive water in all three phases.

Mars : A small, cold planet with a very thin atmosphere and a reddish, dusty surface.

Jupiter : The largest planet, with a powerful gravity and a thick atmosphere of mostly hydrogen and helium. Its small inner core is covered with a superheated layer of solid metallic hydrogen, covered by a dense, hot "sea" of liquid hydrogen.

Saturn : The Ringed planet, has visible orbiting rings of ice chunks and dust. Its moon Titan is a miniature planet bigger than Mercury, with a dense atmosphere, lakes of liquid methane, and "volcanoes" that spew liquid water and ammonia.

Uranus : Tipped on its side, the gas giant alternately points its poles toward, then away from the Sun.

Neptune : Like Uranus, has a hot slushy layer of water and ammonia under its cold cloud layers.

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Assorted details on the planets Mercury, Venus, Mars, and Uranus :

Mercury

The planet Mercury is the closest in the Solar System to the Sun. It is the second smallest planet in the Solar system after Pluto, and is about a third of the size of Earth.

The length of days and years on Mercury are vastly different to those on Earth. Mercury rotates on its axis once every 58.9 Earth days. It circles the Sun once every 87.9 Earth days. In other words, if you were to stay up from sunrise to sunset on Mercury, you would need to be awake for two Mercury years, or 176 Earth days!

Being the closest planet to the Sun, Mercury experiences the hottest surface temperatures out of all the planets in the solar system, but it also sees a broader range of temperatures too. The lack of any substantial atmosphere contributes to this range in temperatures. The atmosphere is very thin and is made up of helium and sodium.

The side of the planet nearest to the sun has temperatures reaching up to 427C. In comparison, the side in night time experiences temperatures which fall as low as -183C.

Although closest to the Sun, Mercury's slow orbit means it also experiences extreme coldness. Radar imagery which is used to study Mercury from Earth, shows reflectivity near the north and south poles. It is suggested this could be an indication that ice has formed there. If the areas are shadowed, possibly by a crater, it is thought this could be the case. There are two suggestions about where the ice has come from; one is from meteorite bombardment, the other is planetary outgassing. Meteorites were thought to carry vast quantities of water in the past.

As Mercury is so far away, very little exploration has been carried out. The only spacecraft to travel there was in 1974, by the Mariner 10. Over three trips it imaged around half of the planet. To date the other half is still untouched, so a true picture of the planet, or its weather, is not known.

Mercury does not have a moon and its gravity is about a third of that of the Earth. Its diameter is 3,025 miles.

Venus

Often called Earth's "sister" planet, Venus is the second planet from the Sun and is the sixth largest in the Solar System. It has no significant magnetic field and no satellites.

Venus spins very slowly in comparison to us - one day is the same as 243 days on Earth. However, it circles the Sun in less time than this, making a Venus year 224 days. In addition Venus spins the opposite way to us, which would mean the Sun rising in the West and setting in the East. Venus is a similar size to Earth, but is closer to a perfect sphere than our planet.

The atmosphere surrounding Venus is incredibly dense and is made up predominantly of carbon dioxide. The pressure on the surface of the planet is immense and is about 100 times that of Earth. As well as carbon dioxide, which makes up about 96% of the composition, Venus' atmosphere has had some other gases detected - hydrochloric and hydrofluoric acid were discovered in 1967, carbon monoxide was noticed in 1968, water in 1972, and sulphuric acid was found six years later. In addition small amounts of oxygen, argon and neon have been detected too.

Venus is covered in a mass of clouds which are thought to be a couple of miles thick and made up of sulphuric acid. These clouds move in both East and West directions, but move extremely fast - about three times faster than hurricane winds. In one examination at least four distinct cloud and haze layers were found at different levels.

There has been quite a lot of research into the presence of thunder and lightning on Venus. Many researchers believe the activity they see is similar to what we experience on Earth. They think the storms possibly occur in the afternoon, like here, and is probably related to clouds on the surface. There are some experts though who stress that not all the activity is related to thunder and lightning, but possibly due to something else entirely - one suggestion is that it could be related to volcanic activity.

Venus has only very weak winds near the surface (just a couple of miles per hour), however at higher altitudes, near the tops of the clouds, they believe the winds reach speeds of around 220mph. For an unexplained reason, evidence shows the solar winds are disturbed quite notably as they flow past the planet.

Temperatures on Venus are quite extreme - at the surface they are hot enough to melt lead - 484C! This is because a significant amount of sunlight reaches the surface. Venus is in fact hotter than Mercury, even though it is twice as far away from the Sun.

It is thought that at one time Venus had seas, similar to on Earth, however there are none now and it is believed they probably boiled away due to the extreme heat. The planet has been studied for quite some time now, both from Earth via telescopes and by explorations in space. The similarities with Earth make things interesting, because if we were any closer to the Sun, similar affects could have occurred to our planet.

Venus is visible with the naked eye from Earth - it appears as the brightest "star" in the sky.

Mars

Mars is the fourth planet in the solar system from the Sun and it is the other neighbour to Earth (Venus being the other). It has a radius at its equator of about 2110 miles and is around 141,634,937 miles from the Sun.

Mars' atmosphere is very different to ours, and weighs less than 1 percent of Earth's, as it is made up principally of carbon dioxide with small amounts of other gases, including neon, water, nitrogen, argon and oxygen.

The water on Mars is not very plentiful, but it can still form clouds when it reaches certain heights. Explorations of Mars have also seen evidence of fog, frosts and snow. The snow appears to fall in the polar caps during winter.

Temperatures on Mars are quite a bit colder than here on Earth, with an average ranging from -140C to 20C. It is therefore cooler than Earth, even though the carbon dioxide in its atmosphere creates a greenhouse like effect. This CO2 though is so thin its influence is minimal.

Mars rotates on its axis with a similar tilt to that of Earth (about 25 degrees) and therefore has seasons like we have - summer, winter, spring and autumn. Like our planet, these seasons are opposite depending on whether you are in the north or southern hemispheres. Mars' rotation around the Sun takes about twice as long as ours and therefore the length of a season is about double the length of ours.

The orbit of Mars is a lot more oval than Earth's which means it varies in distance from the Sun, varying from 128 million miles to 154 million miles. This also has an effect on the length of its seasons. At the moment Mars is nearest to the Sun when the Southern Hemisphere is experiencing summer, which means they are currently shorter but warmer than those which are in the northern hemisphere.

Mars usually appears quite cloudless, however there are occasionally clouds which are made up of ice crystals made up from water, or more usually, carbon dioxide. Large dust storms which can occur on Mars for several months at a time can turn the clouds a yellow or red colour.

Winds on Mars are fairly light (rarely more than 15 miles per hour). However during dust storms or in sudden gusts, they can reach over 300 miles per hour. The lower pressure on Mars though, would mean such strong winds would actually feel lighter over there than on Earth.

Uranus

The third largest planet in our solar system is Uranus, which is the seventh in line from the Sun. Very little was known about the planet until a visit by NASA's Voyager 2 spacecraft in January 1986, where it got within 50,600 miles of it. Now, information about its atmosphere, temperature, winds and rings has been collated.

A day on Uranus lasts 17 hours and 14 minutes whilst its year, one circulation around the Sun, takes a massive 84 years - the long duration due to Uranus being so far away from it. One puzzling thing about Uranus is that it appears to be tipped on its side. Unlike the other ringed planets, the rings go vertically rather than horizontally, and the poles are on the sides rather than at the top and bottom! This means the northern and southern polar regions are either exposed purely to sunlight, or purely to darkness.

Uranus' atmosphere is principally made up of hydrogen (83%) and helium (15%). The investigations by Voyager 2 discovered this, going against prior beliefs that its helium content would be a lot higher. Other gases detected in its atmosphere include methane, acetylene, and other hydrocarbons. Although scientists at first thought Uranus was a fairly bland looking planet, recent close-up studies show that it actually has a blue/green colour which is formed in its atmosphere as a result of the methane absorbing red light.

A high layer of haze has been detected around the pole which faces the Sun and that whole hemisphere has what is known as 'dayglow' which is where the planet radiates ultraviolet light. Little is known about the clouds around Uranus, although it is believed they are made up of methane crystals which condense as warm bubbles of the gas surge upwards from further within the atmosphere.

Temperatures on Uranus are, not surprisingly, very cold with an average of -213C. However what did surprise scientists was that even though Uranus' winters and summers last the equivalent of 21 Earth years, there is not a drastic temperature change between the lit and darkened sides of it. This is put down to the fact that Uranus is so far from the Sun's energy source that it doesn't get very much heating as a result.

There isn't a lot of information about the winds on Uranus, but those monitored travel at speeds of between 90 and 360 mph, which is generally faster than the average speed of a jet stream here on Earth.

One of the similarities between Uranus, Jupiter and Saturn, is that they all have a number of rings which circle them. In the case of Uranus, there are believed to be eleven rings around it, however they appear to be very unstable and quite "wobbly".

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Answer 3

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