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Solar System Overview. The solar system has one star, eight planets, five dwarf planets, at least 290 moons, more than 1.3 million asteroids, and about 3,900 comets. It is located in an outer spiral arm of the Milky Way galaxy called the Orion Arm, or Orion Spur.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It was formed 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
Our solar system is made up of a star, eight planets, and countless smaller bodies such as dwarf planets, asteroids, and comets. Our solar system orbits the center of the Milky Way galaxy at about 515,000 mph (828,000 kph). We’re in one of the galaxy’s four spiral arms.
Hace 1 día · Solar system, assemblage consisting of the Sun and those bodies orbiting it: 8 planets with about 210 known planetary satellites; many asteroids, some with their own satellites; comets and other icy bodies; and vast reaches of highly tenuous gas and dust known as the interplanetary medium.
- Overview
- Home sweet home
- Moons and other matter
- Atmospheric conditions
- Life beyond?
Our solar system is made up of the sun and all the amazing objects that travel around it.
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If you were to look at a giant picture of space, zoom in on the Milky Way galaxy, and then zoom in again on one of its outer spiral arms, you’d find the solar system. Astronomers believe it formed about 4.5 billion years ago, when a massive interstellar cloud of gas and dust collapsed on itself, giving rise to the star that anchors our solar system—that big ball of warmth known as the sun.
Along with the sun, our cosmic neighborhood includes the eight major planets. The closest to the sun is Mercury, followed by Venus, Earth, and Mars. These are known as terrestrial planets, because they’re solid and rocky. Beyond the orbit of Mars, you’ll find the main asteroid belt, a region of space rocks left over from the formation of the planets. Next come the much bigger gas giants Jupiter and Saturn, which is known for its large ring systems made of ice, rock, or both. Farther out are the ice giants Uranus and Neptune. Beyond that, a host of smaller icy worlds congregate in an enormous stretch of space called the Kuiper Belt. Perhaps the most famous resident there is Pluto. Once considered the ninth planet, Pluto is now officially classified as a dwarf planet, along with three other Kuiper Belt objects and Ceres in the asteroid belt.
More than 150 moons orbit worlds in our solar system. Known as natural satellites, they orbit planets, dwarf planets, asteroids, and other debris. Among the planets, moons are more common in the outer reaches of the solar system. Mercury and Venus are moon-free, Mars has two small moons, and Earth has just one. Meanwhile, Jupiter and Saturn have dozens, and Uranus and Neptune each have more than 10. Even though it’s relatively small, Pluto has five moons, one of which is so close to Pluto in size that some astronomers argue Pluto and this moon, Charon, are a binary system.
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This digital collage brings together our solar system and points beyond in one view.
This digital collage brings together our solar system and points beyond in one view.
Illustration by NASA/JPL
The solar system is enveloped by a huge bubble called the heliosphere. Made of charged particles generated by the sun, the heliosphere shields planets and other objects from high-speed interstellar particles known as cosmic rays. Within the heliosphere, some of the planets are wrapped in their own bubbles—called magnetospheres—that protect them from the most harmful forms of solar radiation. Earth has a very strong magnetosphere, while Mars and Venus have none at all.
Most of the major planets also have atmospheres. Earth’s is composed mainly of nitrogen and oxygen—key for sustaining life. The atmospheres on terrestrial Venus and Mars are mostly carbon dioxide, while the thick atmospheres of Jupiter, Saturn, Uranus, and Neptune are made primarily of hydrogen and helium. Mercury doesn’t have an atmosphere at all. Instead scientists refer to its extremely thin covering of oxygen, hydrogen, sodium, helium, and potassium as an exosphere.
For centuries astronomers believed that Earth was the center of the universe, with the sun and all the other stars revolving around it. But in the 16th century, German mathematician and astronomer Nicolaus Copernicus upended that theory by providing strong evidence that Earth and the other planets travel around the sun.
Today, astronomers are studying other stars in our galaxy that host planets, including some star systems like our own that have multiple planetary companions. Based on the thousands of known worlds spotted so far, scientists estimate that billions of planetary systems must exist in the Milky Way galaxy alone.
So does Earth have a twin somewhere in the universe? With ever-advancing telescopes, robots, and other tools, astronomers of the future are sure to find out.
SOURCES
NASA: Our Solar System
NASA Science: Magnetospheres
- 4 min
The solar system consists of the Sun; the eight official planets, at least three “dwarf planets”, more than 130 satellites of the planets, a large number of small bodies (the comets and asteroids), and the interplanetary medium. (There are probably also many more planetary satellites that have not yet been discovered.)
Por Redacción National Geographic. Publicado 18 oct 2022, 07:46 GMT-3, Actualizado 16 ene 2024, 14:44 GMT-3. El sistema solar es un sistema planetario constituido por una estrella que ejerce atracción gravitacional sobre los cuerpos celestes que giran a su alrededor.
