Due to the infinity of the Universe, astronomers use the astronomical unit (U.A.) as a basic measure, which corresponds to about 150 million kilometers.
Well, our planet is located in a galaxy called Milky Way It houses millions of suns (stars), planets, dwarf planets, asteroids, comets ... It receives such a peculiar name because, when viewed from Earth, it looks like a white path in the night sky.
The Milky Way has a spiral shape formed by two arms. In one of them, called The Orion Arm it's found the solar system which is a planetary system composed of eight planets that revolve around the Sun, the only star of this system.
The Solar System is considered to be approx. 25,800 light years from the center of the galaxy that houses it, the Milky Way. The imaginary limit between the Solar System and the interstellar space is estimated to be 100 U.A., approximately 15,000 million kilometers from our Sun. This boundary or border is called heliopause and, as we say, it is imaginary because in the Universe there is more emptiness than matter.
In this vacuum (interplanetary space) there is material from different elements of the Galaxy, both from comets and asteroids and from the activity of the planets that expel particles that, not being retained by any atmosphere, escape into space. Therefore, it could be said that the dust of interplanetary space is a variety of interstellar dust.
In addition, the Sun expels a plasma formed by gases, solid dispersed material and charged particles in the so-called solar wind. When this plasma reaches the ionosphere of the Earth's atmosphere, a beautiful visible phenomenon called Northern Lights. The imaginary external limit of our System, heliopause, is located in an area where the solar wind interacts with the flows from other stars, in interstellar space.
The dimensions of our galaxy are gigantic since comets, which are the bodies of the Solar System farthest from the Sun, have such eccentric orbits that reach a distance of more than 50,000 U.A.
Within the Solar System, Earth is the third planet closest to the Sun, so the distance that separates it from the king star is "only" 150 million kilometers.
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