Planets

Our galaxy – the Milky Way – is a spiral galaxy with arms extending from the center like a pinwheel. Our solar system is in the Orion arm of the Milky Way. Our Sun is one of about 100 billion stars in the Milky Way. And our galaxy is just one of roughly 100 billion in the visible universe.

The planet count in our solar system has gone as high as 15 before new discoveries prompted a fine tuning of the definition of a planet. The most recent change was in 2006 when scientists reclassified Pluto as a new kind of object – a dwarf planet. Today we currently have 8 planets namely, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

I have mentioned earlier that Pluto was reclassified as a dwarf planet last 2006. What was a dwarf planet anyway? Dwarf planets are also just like planets but they were just too small to be considered as a planet. This new class of worlds helps us categorize objects that orbit the Sun but aren’t quite the same as the rocky planets and gas giants in our solar system. There are 5 dwarf planets in the Milky Way but there could be hundreds more of these small worlds far out there waiting to be discovered.

Many disagreed in 1930 when Pluto was added as our solar system’s ninth planet. The debate flared again in 2005 when Eris — about the same size as Pluto — was found deep in a zone beyond Neptune called the Kuiper Belt. Was it the 10th planet? Or are Eris and Pluto examples of an intriguing, new kind of world?

The International Astronomical Union decided in 2006 that a new system of classification was needed to describe these new worlds, which are more developed than asteroids, but different than the known planets. Pluto, Eris and the asteroid Ceres became the first dwarf planets. Unlike planets, dwarf planets lack the gravitational muscle to sweep up or scatter objects near their orbits. They end up orbiting the sun in zones of similar objects such as the asteroid and Kuiper belts.

Our solar system’s planet count now stands at eight. But the lively debate continues as we continue to explore and make new discoveries.

In our solar system, eight planets circle around our Sun. The Sun sits in the middle while the planets travel in circular paths (called orbits) around it. These planets travel in the same direction (counter- clockwise looking down from the Sun’s north pole).

The solar system is made up of two parts: the inner and the outer solar systems.

The inner solar system is contains Mercury, Venus,Earth and Mars. These four planets are closest to the Sun. While on the other hand, the outer solar system contains Jupiter, Saturn, Uranus, Neptune and Pluto.

The planets are interesting to study since each of them have different characteristics to discover which varies from one another. Each of these characteristics provides the distinction between them. For me, the planets are just like brothers and sisters in a one big family- the Milky Way. Each of them surrounds their father, the sun. We are living in the earth, the third planet in the solar system, the only planet that is available for us to thrive on. The earth is the only planet that has the right temperature and oxygen that enables us to survive. The Mars is also studied because it is said to have the potential of a new world for humans to thrive on. Unfortunately, it has no oxygen in it.

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