Mercury is the closest planet to the sun and its diameter is 4.878 kilometres, approximately the 40 percent of the diameter of the Earth, the distance from the sun is 57.090.175 km. It orbits around the sun at 48 km/s, the fastest planet.
It’s mass is 3,30 x 1023 kg, the smallest planet in the Solar System, its’ volume is 6,1 x 1010 km3 , approximately the 5 percent of Earth’s volume; and it’s density is 5,4g/cm3, it’s the second densest planet in our Solar system. The temperatures vary from -173ºC to 427ºC.
The length of the day is 59 terrestrial days, if we measure a day from a dawn to another dawn. Mercury completes three rotations by each two around the Sun. Not to sleep during a whole day means not to sleep during 176 terrestrial days. The length of a year is 88 days.
It’s atmosphere is dry, extremely hot and without air and it has a low atmospheric pressure and it’s composed of potassium, sodium, oxygen, argon, helium, nitrogen and hydrogen. Mercury’s surface is covered by a layer of silicates, and its mainly plains, craters and cliffs; it has 74.800.000 km2. It doesn’t have satellites.
Only one spaceship has visited mercury: the mariner 10 between 1974 and 1975. The NASA has sent a spaceship: The messenger to enter in the orbit of mercury at the end of the decade. There is not inclination of the axis. The gravity in the surface is of 3,7 m/s2, a 39 percent of Earth’s gravity.
The earth is the 3rd closest planet to the sun and its diameter is 12756 km. It’s distance from the sun 150.000.000 km. It orbits around the sun at the speed of 30 km/s.
It’s mass is 5,97 x 1024 kg, only bigger than Mars and Mercury. It’s volume is 1,1 x 1012 km3; it’s density is of 5,5 g/cm3, the densest planet in the Solar System. The temperatures vary from -89,6ºC to 59ºC.
The length of the day is 23 hours 56 minutes. A year is composed of 365,25 days. We have a leap-year because each day has 4 minutes less than 24 hours, so summing up this 4 minutes day by day and year by year we obtain one day more each four years.
It’s atmosphere is divided in different layers. The atmosphere varies depending how high is the place, for example in the equator there are 18 km of atmosphere and in the Himalayas there are 8 km. The atmosphere is composed of nitrogen, oxygen, carbon dioxide, argon and water vapour. It’s surface is 510.072.000 km2. The surface is composed by a 70 percent of water, air and ground. The atmospheric pressure is of 1,03 kg/cm2.
The earth has seasons and they are opposite in each one of the hemispheres. The inclination of the axis is of 23,5º. The gravity is of 9,8 m/s2. It’s the only planet with life, and with water. It has a satellite called Moon.
By Rubén Iglesias and Daniel Ribeiro 1ºBachillerato A