Our solar system consists of our star, the Sun, and everything bound to it by gravity . The planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids.
The Sun, Moon, and brightest planets were visible to the naked eyes of ancient astronomers . Their observations and calculations of the movements of these bodies gave rise to the science of astronomy. Today the amount of information on the motions, properties, compositions of the planets and smaller bodies has grown to immense proportions.
The range of observational instruments has extended far beyond the solar system to other galaxies. Yet the solar system and its immediate outer boundary still represent the limit of our physical reach. They remain the core of our theoretical understanding of the cosmos as well. Earth-launched space probes and landers have gathered data on planets, moons, asteroids, and other bodies.
This data has been added to the measurements collected with telescopes and other instruments from below and above Earth’s atmosphere and to the information extracted from meteorites and from Moon rocks returned by astronauts. All this information is scrutinized in attempts to understand in detail the origin and evolution of the solar system. A goal toward which space scientists continue to make great strides.
Get in touch for more information. Please Read brief description of the solar system by Pritish Kumar Halder
There are many planetary systems like ours in the universe, with planets orbiting a host star. Our planetary system is named the “solar system” because our Sun is named Sol, after the Latin word for Sun, “solis,” and anything related to the Sun we call “solar.”
Size and Distance
Our solar system extends much farther than the eight planets that orbit the Sun. The solar system also includes the Kuiper Belt that lies past Neptune’s orbit. This is a sparsely occupied ring of icy bodies, almost all smaller than the most popular Kuiper Belt Object – dwarf planet Pluto.
Beyond the fringes of the Kuiper Belt is the Oort Cloud. This giant spherical shell surrounds our solar system. It has never been directly observed, but its existence is predicted based on mathematical models and observations of comets that likely originate there.
The Oort Cloud is made of icy pieces of space debris. Some Oort Cloud bigger than mountains. The Oort Clouds orbiting our Sun as far as 1.6 light-years away. This shell of material is thick, extending from 5,000 astronomical units to 100,000 astronomical units. One astronomical unit (or AU) is the distance from the Sun to Earth, or about 93 million miles (150 million kilometers). The Oort Cloud is the boundary of the Sun’s gravitational influence, where orbiting objects can turn around and return closer to our Sun.
The Sun’s heliosphere doesn’t extend quite as far. The heliosphere is the bubble created by the solar wind – a stream of electrically charged gas blowing outward from the Sun in all directions. The boundary where the solar wind is abruptly slowed by pressure from interstellar gases is called the termination shock. This edge occurs between 80-100 astronomical units.
There are more than 200 known moons in our solar system and several more awaiting confirmation of discovery. Of the eight planets, Mercury and Venus are the only ones with no moons. The giant planets Jupiter and Saturn lead our solar system’s moon counts. In some ways, the swarms of moons around these worlds resemble mini versions of our solar system.
Pluto, smaller than our own moon, has five moons in its orbit, including the Charon, a moon so large it makes Pluto wobble. Even tiny asteroids can have moons. In 2017, scientists found asteroid 3122 Florence had two tiny moons.
The relatively small inner planets have solid surfaces, lack ring systems, and have few or no moons. The atmospheres of Venus, Earth, and Mars are composed of a significant percentage of oxidized compounds such as carbon dioxide. Among the inner planets, only Earth has a strong magnetic field, which shields it from the interplanetary medium. The magnetic field traps some of the electrically charged particles of the interplanetary medium inside a region around Earth known as the magnetosphere. Heavy concentrations of these high-energy particles occur in the Van Allen belts in the inner part of the magnetosphere.
Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed, possibly due to the shockwave of a nearby exploding star, called a supernova. When this dust cloud collapsed, it formed a solar nebula – a spinning, swirling disk of material.
At the center, gravity pulled more and more material in. Eventually, the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99% of the available matter.
Matter farther out in the disk was also clumping together. These clumps smashed into one another, forming larger and larger objects. Some of them grew big enough for their gravity to shape them into spheres, becoming planets, dwarf planets, and large moons. In other cases, planets did not form: the asteroid belt is made of bits and pieces of the early solar system that could never quite come together into a planet. Other smaller leftover pieces became asteroids, comets, meteoroids, and small, irregular moons.
The order and arrangement of the planets and other bodies in our solar system is due to the way the solar system formed. Nearest to the Sun, only rocky material could withstand the heat when the solar system was young. For this reason, the first four planets – Mercury, Venus, Earth, and Mars – are terrestrial planets. They are all small with solid, rocky surfaces.
Meanwhile, materials we are used to seeing as ice, liquid, or gas settled in the outer regions of the young solar system. Gravity pulled these materials together. That is where we find gas giants Jupiter and Saturn, and the ice giants Uranus and Neptune.
The eight planets can be divided into two distinct categories on the basis of their densities (mass per unit volume). The four inner or terrestrial planets are Mercury, Venus, Earth, and Mars. They have rocky compositions and densities greater than 3 grams per cubic cm. In contrast, the four outer planets, also called the Jovian, or giant, planets—Jupiter, Saturn, Uranus, and Neptune.
They are large objects with densities less than 2 grams per cubic cm. They are composed primarily of hydrogen and helium (Jupiter and Saturn) or of ice, rock, hydrogen, helium (Uranus and Neptune). The dwarf planet Pluto is unique—an icy, low-density body smaller than Earth’s Moon. This is more similar to comets or to the large icy moons of the outer planets than to any of the planets themselves. Its acceptance as a member of the Kuiper belt explains these anomalies.