The Planets
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The Planets

The Planets of the Solar System

The sun is over 300,000 times more massive than the earth, and the pull of its gravity is very strong. It is this pull that keeps the Earth and eight other large bodies circling in space around the Sun. These bodies are planets. From Earth, we can see the naked eye five planets- Mercury, Venus, Mars, Jupiter, and Saturn. We need a telescope to see the other three planets- Uranus, Neptune, and Pluto. 

The Earth itself is a planet. But until about 450 years ago, most people believed it was the center of the Universe. They thought that all the heavenly bodies-Sun, Moon, planets and stars revolved around the Earth. But this could not easily explain how the planets move through heavens. At times, for example, they appear to loop backwards. 

In the 1500s, a Polish priest named Nicolaus Copernicus realized what was wrong. The Sun must be the center of everything, not the Earth. He put forward the idea of a Sun-centered system, or Solar System, in 1543, and in so doing gave birth to modern astronomy. 

The Earth differs from the other planets in one very important respect. It boats conditions to allow millions of different life-forms to flourish. On all other planets, conditions are deadly to life as we know it. The planets divide neatly into two groups. Mercury, Venus and Mars are small rocky planets like the Earth. They are close enough to be considered neighbors. Jupiter, Saturn, Uranus and Neptune on the other hand are giant balls of gas. Like icy Pluto, they are far-distant worlds. The diagram at the foot of these pages shows the different sizes of the planets and compares them with the sun.

All of the planets except Mercury and Venus are the center of miniature systems of their own. They have moons circling around them. The Earth has only one moon, but the giant planets have multitudes. The remaining members of the Sun's family are much smaller. They include the asteroids which are miniature planets that circle around the Sun between the orbits of Mars and Jupiter as well as meteoroids and comets. Meteoroids that enter the Earth's atmosphere and burn up flash across the night sky as meteors, or shooting stars. A very few reach the ground as meteorites. All of these smaller bodies make up what is called the debris of the Solar System.

Planetary Statistics

Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
Diameter at equator(km) 4,878 12,104 12,756 6,794 142,800 120,000 51,800 49,500 2,300
Mean Distance(million km) 59.9 108.2 149.6 227.9 778.3 1,427 2,869.6 4,496.7 5,900
Revolution(day,year) 87.97d 224.7d 365.2d 686.98d 11.86y 29.46y 84.01y 164.79y 247.7y
Number of moons 0 0 1 2 16+ 22+ 15+ 8 1

The sizes of the planets drawn to the same scale. 

Jupiter, Saturn, Uranus and Neptune dwarf the size of the other planets but they themselves are dwarfed by the sun.










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Comments (3)

Great article Jerome! Loved your pics, especially the last one showing the movement of Pluto on its way through the skies. I am interested in knowing if you intended having your pics all so big? - If you did not, and I have managed to "solve" the problem of bring them down to your "intended" size by publishing first, then editing, and deleting them, one-by-one, and then re-installing one-by-one at the correct size. There seems to be a "glitch" in the system which I have tried to correct but it does not work first time around.

Ranked #27 in Astronomy

Thanks. I am happy you appreciate it

Ranked #27 in Astronomy

I made the size of the photos uniform Mr. Colin. What shall I do to improve my artice? :) Thanks