Difference between Planet and Satellite

Introduction to the Solar System

Almost 4.6 billion years ago, a massive stellar cloud comprising of molecular hydrogen contracted due to the action of its gravitational force. The existing materials are distributed to form multiple high-density units with condensed structures. These units developed subsequently to form galaxies one of which is our Solar System that is centered on the massive star or the ‘Sun’. 

After Sun, Jupiter constitutes most of the mass though it is entirely made up of gas. Jupiter is the largest planet in this galaxy. All the eight planets in the solar system differ in their characteristics as the first four – Mercury, Venus, Earth, and Mars have solid surfaces while Jupiter and Saturn are the two biggest gas balls. The other two planets – Uranus and Neptune are made up of volatile helium and hydrogen that melts at a higher temperature compared to water. These planets revolve around the Sun in elliptical paths or orbits. 

Stars are illuminated gas formations that guide explorers on the earth for thousands of years. The nuclear reactions inside these hydrogen and helium structures produce light and heat that look pretty when viewed from the earth. 

Natural satellites revolve around planets or sometimes other satellites. Altogether 207 natural satellites have been discovered across six celestial systems. Generally, the satellites are 10,000 times lesser in size than their parent planet. Though we witness an exception in the Moon’s size which is almost 1/80th time of the earth’s size.

Planet – Characteristics 

Gradual research through the last few centuries has redefined the planets elaborately. The debates arising from research are significant because they enable us to learn the origin and evolution of the solar system. Also, it is necessary to abolish myths that were thought to be true in ancient Greek history. The Greeks believed that all the other planets in the Solar System revolved around the Earth centering which our galaxy sustained. Nicolaus Copernicus introduced the modern layout of the Solar System and proved his observations. 

To be termed as a planet the celestial object must revolve around centering the Sun. They should achieve sufficient volume to generate enough gravitational force required to pull objects present in their orbit. Also, this helps to maintain the hydrostatic equilibrium. In the end, a planet must be spherical.

Dwarf planets like Pluto, Eris, and Ceres are deprived of the planethood because of two main reasons: 

• They are smaller in diameter.
• They do not possess a gravitational atmosphere with sufficient forces to attract objects within their orbital radius.

Satellite-Characteristics 

Satellites revolve around planets that are bigger compared to them. The origin of these celestial bodies is accidental. Satellites were formed from trapped fragments of dirt and rock that combine with gas clouds. All of these particles fell inside the elliptical orbits surrounding each planet. Though our Earth has only one natural satellite – the moon, the Jupiter planet has 79 moons. They differ from planets and asteroids as they do not revolve around the sun. The time taken to complete one revolution varies as the different planets change their angle of revolution. They have an average orbital speed that they maintain throughout their lifespan. The natural satellites reflect the sunlight to light up the primary celestial objects or planets in absence of a direct source of light. An eclipse is a phenomenon when the satellite comes between the planet and the sun. The satellites also slow down the axial rotation speed of their parent planet. This is a consequence of the moon’s gravitational attraction. At times this helps in eliminating the chances of asteroid collisions by adjusting the tilt. Geologists predict storms tracking the path of the moon. 

Different between planets and satellites

Planets are greater in size compared to satellites. This concludes that planets exert a superior gravitational force on celestial bodies residing within their orbits. 

The planets rotate on a fixed axis that is tilted to a definite angle. In addition to this, they complete a revolution around the sun. On the other hand, satellites revolve around planets and dwarf planets. 

A satellite doesn’t need to exhibit a spherical shape while planets must always be spherical.

Satellites reflect the sun’s light to illuminate the planets in absence of a direct light source, the planets do not serve this purpose.

Examples of some natural satellites are – the moon, Europa, Titan, Dactyl, etc. Ganymede is the largest satellite in the solar system that revolves around Jupiter.

There are eight planets in the Solar System the names of which have been discussed above.

Conclusion

Almost 99% of the total volume of the Solar System is occupied by the sun. The sun is entirely made up of hydrogen and helium, nuclear reactions in the core region generate massive heat production. Surrounding the sun are the eight planets that exert gravitational forces on each element within its orbit. Natural satellites revolve around these planets throughout their lifespan and some of them act as sources of light. In their orbital path chances of collision exist as the planets keep on changing their revolutionary angles.