We live on Earth, which is a planet, as you are undoubtedly aware. However, do you know what constitutes a planet and how it differs from a star? Just as Earth, Venus, and Jupiter orbit an elliptical path around stars, planets are masses of gas, metal, and stones that revolve around stars (like a star that emits light on its own, like the sun). Put differently, a planet is any entity that is incapable of emitting light or creating energy through nuclear fusion reactions on its own. As opposed to that, planets, like the sun, reflect starlight. Thus, you cannot identify a bright object in the sky as a star or a planet just by looking at it.
As members of the solar system, the Earth and the other planets that orbit the Sun are our neighbors. Our own galaxy, the Milky Way, contains our solar system. The Moon is the solar star that is closest to Earth (details on the Moon will be provided later).
In addition to Earth, other stars that orbit the sun are Uranus, Neptune, Pluto, Jupiter, Venus, Mars, and Saturn.
Mercury, about 58 million kilometers from the sun, is the closest planet to the sun. The furthest planet in the solar system, Pluto, is situated 5.91 billion kilometers from the sun.
The unique charm of the planets has drawn the attention of skygazers. On Earth, certain planets appear to travel on peculiar trajectories above the sun, while others revolve around it. Because the planets were thought to possess special powers due to their bright, shining points in the sky, early sky observers named them after gods. For instance, Jupiter, the largest planet in the solar system, is referred to as the king of the gods, and Mercury, the planet with the fastest revolution period, is known as Mercury, the Roman god with winged shoes and hats. And the names remain exactly as we use them.
Around 500 B.C., the Greeks became skilled sky researchers. They discovered that the moon, sun, and other luminous objects in the sky were in motion. Thus, the Greeks began to believe—a mistake they would later discover to be untrue—that everything revolved around the Earth.
Ptolemy, a Greek scientist who lived around 200 A.D., published a book in which he quoted the findings of other scientists and asserted that the Earth was the center of the universe, around which the sun and other planets orbited. Ptolemy's universe view has thus been applied to a number of absurd ideas.
Not long after new information was unearthed by Middle Eastern scholars, Greek astronomers made their observations. They went from place to place, collecting data and combining it with what they learned to create new information.
However, Nicolaus Copernicus, a Polish astronomer, made a significant discovery that altered the course of astronomy history around 1500. The Earth and other planets, he declared, did, in fact, revolve around the sun. Copernicus argued that because the moon revolves around the sun and other planets revolve around their suns and alter their shapes as they pass by, the moon orbits the Earth precisely in a circle.
The notion that Earth was the center of the universe at the time underpinned both religion and scientific theories. Copernicus' novel theories were, therefore, largely ignored by society. However, it was discovered long after his passing that the Earth does indeed orbit the sun.