Mercury
The surface of Mercury consists of cratered terrain and smooth plains and many
deep craters similar to those on the moon. The craters formed when meteors or
small comets crashed into the planet. The largest known crater is Caloris Basin,
with a diameter of 1300 km (800 miles). Like
the other terrestrial planets (Venus, Earth and Mars) Mercury is made mostly of
rock and metal. Mercury's surface appears to be much like that of the moon. It
reflects approximately 6 percent of the sunlight it receives, about the same as
the moon's surface reflects. Like the moon, Mercury is covered by a thin layer
of minerals called silicates in the form of tiny particles._ Mercury is a planet of extreme temperature variations. It is hotter on Venus, but with less fluctuations. The temperature on the planet may reach 450 degrees C (840 degrees F) during the day. But at night, the temperature may drop as low as -170 degrees C (-275 degrees F). The sunlight on Mercury’s surface is 6.5 times as intense as it is on Earth due its closeness to the sun. Mercury is dry, and almost airless. Mercury is too small for its gravity to retain any significant atmosphere over long periods of time. The weak atmosphere contains hydrogen, helium, oxygen, sodium, calcium and potassium. Due to the heat of the planet, the very thin atmosphere is blasted off its surface by the solar wind and quickly escapes into space. Mercury's atmosphere is constantly being replenished. Mercury does not have enough atmosphere to slow down meteoroids and burn them up by friction. The sun's rays are seven times as strong on Mercury as they are on the Earth. The sun also appears about 2 and a 1/2 times as large in Mercury's sky as in the Earth's.
Venus
Venus is a dim world of intense heat and volcanic activity. Similar in
structure and size to Earth, Venus' thick, toxic atmosphere traps heat
in a runaway "greenhouse effect." The scorched world has temperatures
hot enough to melt lead. Glimpses below the clouds reveal volcanoes and
deformed mountains. Venus spins slowly in the opposite direction of most
planets.The atmosphere of Venus is very hot and thick. You would not survive a visit to the surface of the planet - you couldn't breathe the air, you would be crushed by the enormous weight of the atmosphere, and you would burn up in surface temperatures high enough to melt lead. The atmosphere of Venus is made up mainly of carbon dioxide, and thick clouds of sulfuric acid completely cover the planet. The atmosphere traps the small amount of energy from the sun that does reach the surface along with the heat the planet itself releases. This greenhouse effect has made the surface and lower atmosphere of Venus one of the hottest places in the solar system. _
Earth
Earth is the only know planet that can support life.Earth consist of a gaseous
atmosphere, the hydrosphere (all water on earth), the lithosphere, the mantle,
the outer core and the inner core. Water in the form of oceans covers around
70% of the Earth’s surface. The remaining 30% is the 5 continents of land. These
are Eurasia (Europe and Asia), America, Africa, Antarctica and Australia.
Mars
Mars is the fourth planet from the sun. It is the closet planet to Earth, only 59 million kilometers away and is most likely to be the first planet man travels to. A day on Mars is a bit over half an hour longer than a day on earth. It has an average surface temperature of -23 degrees Celsius and two moons, one of which will eventually hit mars. its atmosphere is made up of 95% carbon dioxide, 3% nitrogen and 1.6% argon.
Jupiter
Jupiter is a gas planet, meaning it is made out of gas. It is the biggest planet in our solar system with a diameter of 85,788 miles and 12 earths could line up against it. Jupiter is quite cold, being so far away from the Sun. Its temperatures range from -163° C to >-121° C
Saturn
Saturn is a gas planet with a windy surface. Wind speeds have reached 1800km an hour on its equator and has 5 rings. Scientists believe that life could exist on one of Saturn's 62 moons, Titan. it was named after the Roman god for agriculture. its average temperature is -178 degrees Celsius and is around 10 times the size of Earth.
Neptune
the planet Neptune was named after the Roman god of the sea. It has 13 moons which include Triton and Nereid. It has a day of around 16 Earth hours and is around four and a half million kilometres from the sun. its atmosphere contains mainly hydrogen with some helium and methane. It has six rings surrounding it and has an average temperature of -201 degrees Celsius.