Mercury Fact Sheet

Mercury Fact Sheet

Mercury is the first planet in our solar system and the closest to the sun. It completes a revolution around the sun in just 88 days while it takes the Earth 365 days. Wow that means that for every year we have here on Earth four years goes by on Mercury! That's probably why Mercury was named after the Roman god of speed.

Although it's fast it also happens to be the smallest planet in our Solar System. Mercury is so small and so close to the sun that it is almost impossible to see. With telescopes, just after dawn or before sunset, the planet can be seen as a small spot in front of the Sun's surface. Mercury's surface also looks a lot like our Moon's, because it’s covered in craters.

Life on Mercury is impossible. Temperatures on the planet can be extremely hot or extremely cold depending on which side of it is facing the Sun (From 100 K to 700 K). Mercury spins on its axis very slowly (each rotation lasting 59 Earth days), so one side of the planet can be in complete frozen darkness for days. The planet is also very heavy for its size. Astronomers believe that it has a large iron core which may explain why the planet weighs so much.

Mercury is composed of 42% molecular oxygen, 29% sodium, 22% hydrogen, 6% helium and 0.5% potassium. Mercury, unlike the planet Earth, is a geologically dead planet. This means that the surface shows no sign of volcanic activity or any other form of geological activity. It is for this reason that astronomers believe Mercury's core to be extremely cold. Earth on the other hand is a geologically living planet. Its continents still move, and hot lava is churned out of its core through volcanic eruptions and of course there is life on Earth!

Some Mercury Quick Facts …

• Most astronomers believed that Mercury would have a smooth surface before the first space-crafts flew to the planet. When Mariner 10 took pictures of Mercury, scientists soon discovered that Mercury was not a smooth surfaced planet at all. Actually it turned out to be the most cratered planet in the Solar System!

• Mercury has no atmosphere at all which causes sunlight to reflect off its surface. This is very similar to how light reflects directly off our Moon's surface. Mercury's lack of atmosphere also means that sunlight isn't spread through the atmosphere, so the planet's sky is dark.

• Mercury is slightly bigger than Earth's Moon (3475.6 km wide). Its volume is 6.083×1010km3 and weighs 3.3022×1023kg

• Mercury can only be seen just after the Sun has risen and just before the sun sets, because it's so close to the sun.

• If you were to stand on Mercury, the Sun would appear two and a half times bigger than it appears on Earth.

• Mercury's fast speed is caused by the Sun's strong gravitational pull. Hold a short piece of string with something tied to the end of it and spin it around. Try it again with a longer piece of string. Notice how much longer it takes for the object tied to the end of it to spin round. Your finger acts like the Sun, and the object acts like a planet orbiting the Sun.

• Despite being the closest planet to the Sun, Mercury is not the warmest. Venus is warmer. In fact, Mercury can be one of the coldest planets in the Solar System, because it has no atmosphere to keep the sun's warmth in.

• Because of its small size, Mercury has no moons and has low gravity (3.7m/s2)

Venus Fact Sheet

The planet Venus is the second planet in our solar system. It's named after Venus, the Roman goddess of love and beauty. The planet is named this way because it is the brightest object in the sky, except for the Sun and the Moon, and has been known since prehistoric times.

Venus has sometimes been regarded as Earth's sister planet because it's only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass), both have very few craters indicating relatively young surfaces and their densities and chemical compositions are similar. In fact, it was once thought that there may be life below its dense clouds. But, unfortunately, after more detailed study of Venus it was discovered that in many important ways Venus is very different from Earth and may be the least hospitable planet for life in the solar system.

Venus' atmosphere has been found to be composed mostly of carbon dioxide (96.5%). There are also trace amounts of nitrogen, sulfur dioxide, argon, water vapour, carbon monoxide, helium, and neon. There are several layers of clouds many meters thick composed of sulfuric acid which completely obscure our view of the planet's surface. This dense atmosphere produces a greenhouse effect that raises Venus' surface temperature by about 400° to over 740 Kelvin - that's actually hot enough to melt lead! Venus' average temperature is 730 K. Crazy enough, Venus' surface is actually hotter than Mercury's despite the fact that it's nearly twice as far from the Sun. Doesn't sound very habitable.

The very first spacecraft to visit the planet Venus was the Mariner 2 in 1962. It was then visited by many others (more than 20 so far), including the Soviet Venera 7 - the first spacecraft to land on another planet and Venera 9 - which returned the first photographs of the surface. Most recently, the orbiting US spacecraft Magellan produced detailed maps of Venus' surface using radar.

This data shows that there are several large shield volcanoes similar to Hawaii or Olympus Mons. Recently announced findings indicate that Venus is still volcanically active, but only in a few hot spots; for the most part it has been geologically quiet for the past few hundred million years.

Some Venus Quick Facts

· Venus probably once had large amounts of water like Earth but it's all been boiled away, leaving the planet very dry. Scientists have recently discovered that Earth would've suffered the same fate had it been just a little closer to the Sun! Studying Venus has taught us a lot about Earth.

· Venus has no magnetic field, perhaps because of its slow rotation (243.02 Earth days).

· Venus mass is 4.89 X 1024 kg and has a volume of 9.38×1011km3

· On June 8 2004, Venus passed directly between the Earth and the Sun, appearing as a large black dot traveling across the Sun. This event is known as a "transit of Venus" and is very rare: the last one was in 1882, the next one is in 2012 but after than you'll have to wait until 2117.

· Venus can be seen with the naked eye and it's sometimes called the "morning star".

· The periods of Venus' rotation and of its orbit are synchronized so that it always has the same side facing Earth when the two planets are at their closest. (Rotation = 243 Earth days; Revolution = 225 Earth days)

· The oldest terrains on Venus seem only to be about 800 million years old, because extensive volcano activity at that time wiped out the earlier surface including any large craters from early in Venus' history.

· Venus currently has no observable moons.

· Venus' gravity is 8.87m/s2

Earth Fact Sheet

Earth is the third planet from the sun and is the only planet that was not named after Greek Mythology.

The Center of the Universe…

It wasn’t until the sixteenth century that we actually came to terms with the fact that Earth is not the center of the Universe. The Polish astronomer Nicolaus Copernicus (1473-1543) was well known for advancing this theory after it was savagely rejected when Aristarchos, a Greek astronomer and mathematician, first introduced the concept.

Up until Copernicus helped us to accept that the sun was the center of the Solar System, it was widely known and accepted for the last 1000 years that the heavenly bodies revolved around Earth. This theory was tied very tightly with the church and anyone who tried to say differently was persecuted.

The Earth unlike the rest of the planets can be studied easily without space shuttles and satellites. Even though we live on this planet - it wasn’t until the twentieth century that we had maps of its entire surface! These pictures from space not only help us to fully understand it’s terrain they’re also helping with predicting dangerous weather including hurricanes!

What Makes Earth…

The Earth has four main layers:

• The Crust

• The Mantle

• Outer Core

• Inner Core

The Crust is solid and it’s thickness varies. This means that the crust is thinner under the oceans and thicker under the continents. The Mantle layers are said to be semi-fluid or resembling a kind of plastic. The Inner Core is under so much pressure that it's said to be solid. The Core is probably made up entirely of iron, although many scientists believe that there are some lighter elements present. The heat from the Inner Core is so extreme that the Outer Core is not solid but molten and made up of 90% iron and 10% sulfur. We have to stop and take a moment to understand that our knowledge of the Earth’s interior is mostly theoretical. No one has actually been to the center of the Earth to confirm if it’s made up of iron.

The Forever Shifting Planet…

One thing that is unique to the planet Earth is the fact that our continents move and that we have tectonic plates. This basically means that the crust of the earth is separated into sections called tectonic plates. These continuously move and spread apart. When the tectonic plates spread apart they move away from each other and magma from under the crust comes up to create new crust. Sometimes when the plates move they are colliding together and one gets pushed under the other and is destroyed by the mantle layer of the planet. There are also many great earthquakes at the site of these colliding plates.

Our Atmosphere…

The Earth's atmosphere is mostly made up of is 77% nitrogen, 21% oxygen. The tiny amount of carbon dioxide that is in the atmosphere is extremely important to the Earth's surface temperature because of its role in the greenhouse effect. The greenhouse effect raises the average surface temperature about 35 °C and without it the oceans would freeze and life as we know it would be impossible.

Fun Earth Quick Facts:

• 71% of the Earth's surface is covered with water.

• Earth is the only planet on which water can exist in liquid form on the surface.

• Earth's temperature ranges from 184 K to 331 K

• The interaction of the Earth and the Moon slows the Earth's rotation by about 2 milliseconds per century. Current research indicates that about 900 million years ago there were 481 18-hour days in a year.

• The oldest fossils of living organisms are less than 3.9 billion years old.

• The Earth is 4.5 to 4.6 billion years old.

• The Earth is the densest major body in the solar system. It weighs 6 X 1024 kg and has a volume of 1.08321×1012km3

• The Earth's current population is 6,840,507,000!

• The world's termites outweigh the world's humans 10 to 1

• A one-day weather forecast requires about 10 billion math calculations

• You share your birthday with 9 million others in the world.

Mars Fact Sheet

Mars is the fourth planet from the Sun and is commonly known as the Red Planet, because the soil, rocks, and sky give the planet a red tint. This very distinctive red coloring has been observed by scientists all throughout history. Given the fact that Mars looks red in the night sky, it's easy to see why it was given its name by the Romans to honor their god of war.

Is there Life on Mars?!

Mars was once considered the best candidate for life outside of Earth. Astronomers saw straight lines crisscrossing it's surface and thought they could be irrigation canals constructed on the planet's surface by intelligent life. Enough people believed in the possibility of invading Martians that it caused a near panic when Orson Welles broadcasted a radio drama based on the science fiction classic War of the Worlds by H.G. Wells, in 1938.

Mars also appears to have a seasonal colouring change, which of course lead people to find yet another similarity to Earth and think of life on Mars. We finally had our first pictures of Mars in 1965 when the Mariner 4 gave us 22 pictures of its surface. Very disappointingly, all that was revealed was that the surface contains many craters and the canals that had brought so much hope turned out to be naturally occurring channels with no evidence of artificial canals or flowing water.

Viking Landers 1 and 2, touched down on the surface of Mars in 1976 and discovered very unique chemical activity in the planet's soil. Although there was no clear evidence of living microorganisms, after further study they found that Mars is "self-sterilizing". This means that the combination of solar ultraviolet radiation that saturates the surface, the extreme dryness of the soil and the oxidizing nature of the soil chemistry prevent the formation of living organisms in the Martian soil. Although there is still no evidence of life on Mars, the question if there was life there at some time in the distant past remains unknown. Large yet weak magnetic fields were discovered to exist in various parts of Mars. This unexpected finding made by Mars Global Surveyor was interpreted to be remnants of an earlier global field that has since disappeared. This may have important implications for the past history of Mars' atmosphere and the possibility of ancient Martian life.

Why We Haven't Found Life...

Mars was much more like Earth early in its history. As with Earth almost all of Mars' carbon dioxide was used up to form carbonate rocks. But because it lacks the Earth's plate tectonics, Mars is unable to recycle any of this carbon dioxide back into its atmosphere and so cannot sustain a significant warming greenhouse effect. Because of this the surface of Mars is much colder than Earth would be at that distance from the Sun.