About 4.6 billion years ago , a giant cloud of dust and gas known as the solar nebula collapsed in on itself and began to form what would eventually become the Sun and the planets of our solar system.
The Sun, our star, is the center of our solar system, whose gravitational pull is so powerful that it keeps numerous planets, dwarf planets (like Pluto), comets and meteorites orbiting around it.
Not surprisingly, it is the largest object in our solar system, representing 99.8% of the mass of the solar system. Our sun is a G2V-type dwarf that is in the main sequence phase, the main phase of its evolution. This giant and violent fireball powered by nuclear reactions provides the energy that sustains life on Earth. This life-giving yellow dwarf is made of gas – about 91% hydrogen and 8.9% helium, according to NASA. Compared to other stars, the size of the sun is relatively small and it is only one of hundreds of billions of stars that we can find in our galaxy, the Milky Way.
The sun is between 25,000 and 30,000 light years from the supermassive black hole that forms the center of our galaxy. The Milky Way is a spiral galaxy, with curved arms of stars emanating from its center and our solar system forms one of the smallest arms, called the Orion arm (or local arm).
A curiosity: if our solar system were the size of your hand, the Milky Way would cover North America, according to the Night Sky Network of NASA’s Jet Propulsion Laboratory. The limit of the gravitational influence of our little star extends around 122 astronomical units (AU), where one AU is the distance between the Earth and the sun, or approximately 150 million kilometers.
Behind all the planets that are orbiting our whole, beyond the ice giant Neptune, the solar system extends to the Kuiper Belt and the Oort Cloud.
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