The solar system
facts about the solar system
He Solar system It formed approximately 4.6 billion years ago and consists of the Sun, planets, dwarf planets, and other astronomical objects tied up in its orbit.
The formation was caused by the collapse of a giant molecular cloud, the mass at the center accumulating to form the Sun and a flat disk of dust around which planets and other bodies would eventually form.
99.86% of the system’s mass is found in the Sun and most of the remaining 0.14% is contained in the eight planets of the solar system.
4 planets
The four smaller inner planets, also known as the «terrestrial planets» (Mercury, Venus, Earth, and Mars), are composed primarily of rock and metal.
The four outer planets, also known as the «gas giants» (Jupiter, Saturn, Uranus, and Neptune), are substantially larger and more massive than the inner planets.
The two innermost gas giants, Jupiter and Saturn, are the largest of the four and are made mostly of hydrogen and helium.
The two outermost gas giants, Uranus and Neptune, are composed largely of ice (water, ammonia, and methane) and are also sometimes referred to as «ice giants.»
Other objects of interest in the Solar System are the dwarf planets (Ceres, Pluto, Haumea, Makemake, and Eris), moons, asteroids, the asteroid belt, comets, and the Kuiper belt.
What is the solar system?
To know exactly what we mean when we say «solar system» it is important to break it down into the two words that make up the expression.
First of all, the term «solar» is simply a word meaning «from the Sun.»
Second, a system is just a collection of objects that interact to form a whole. Therefore, putting the two words together yields the following definition:
The solar system is a set of objects that interact with each other, the fundamental interaction of each object being the one it has with the Sun.
Solar System Profile
01.-Age: 4.6 billion years02.-Number of planets: 803.-Number of dwarf planets: 504.-Number of moons: 18105.-Number of asteroids: 552,89406.-Number of comets: 3,08307.-Diameter: 18.75 billion kilometers (11.65 trillion miles)
Objects in our Solar System
There are many different types of objects found in the solar system: a star, planets, moons, dwarf planets, comets, asteroids, gas, and dust.
In terms of the numbers of each of these objects, our current knowledge is as follows:
1 star (The Sun)8 planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune)5 dwarf planets (Pluto, Ceres, Haumea, Makemake and Eris)181 moons566,000 asteroids3,100 kites
In terms of mass, the Sun comprises more than 99.8% of the Solar System, with the planet Jupiter accounting for most of the remaining mass.
How objects in the Solar System interact
All objects in the Solar System orbit the Sun; that is, they move around the Sun in elliptical paths.
Also, the orbits of these objects lie in approximately the same plane, called the ecliptic plane.
The mechanism that causes the orbit of objects in the Solar System is one of the fundamental forces of nature: gravity. While the natural tendency of objects in the Solar System is to continue in a straight line of motion, the Sun exerts a force (gravity) on each object and therefore «bends» the straight path into a curved one.
Additionally, other objects in the Solar System are massive enough to exert gravitational forces significant enough to disrupt the orbits of smaller objects.
For example, Earth’s gravity is strong enough to keep the Moon in orbit around Earth.
The size of the Solar System
Although it is common for most people to believe that the edge of the Solar System is that of Pluto’s orbit, this is far from the truth.
Throughout the 20th century, scientists not only hypothesized that the size of the Solar System extends to almost 2 light-years—that is, 125,000 times the distance between the Sun and Earth—but also that there are many objects beyond Pluto.
Scientists now believe that there are two main regions beyond Pluto. The first is the Kuiper Belt, a region of asteroids similar to the asteroid belt between Mars and Jupiter, and the Oort Cloud, a spherical region that contains numerous comets.
Visit the planets or dwarf planets pages for more information or browse through the various objects in the solar system by clicking on the images below.
The formation of the solar system
Although there is some debate about the formation of the Solar System, the following outline is currently the best-known explanation of how the Solar System developed.
Approximately 4.6 billion years ago, a large cloud of gas and dust was disturbed by some force. (Scientists have theorized that this force was a nearby supernova.)
As a result of this disturbance and the energy introduced into the cloud, the cloud began to move.
Once the movement started, the cloud began to collapse in on itself due to its own gravity.
During the collapse process, the cloud began to rotate and heat up.
As the cloud continued to collapse, the cloud’s temperature continued to rise and its rotation became faster and faster.
As a result, the cloud eventually began to flatten into a disk with most of the mass located at its center.
At some point the pressure and temperature became so great in the center of the cloud that nuclear fusion began to occur. It was then that the Sun was born.
After the Sun was born, gases and dust farther from the center of the disk began to cool and condense into tiny particles.
As more and more particles formed, they began to collide with each other and stick together, thus creating particles as large as rocks and boulders.
planetisimals
Like the smaller colliding particles, the rock-sized particles began to impact and stick together. These larger bodies are known as planetisimals.
Eventually enough planetisimals came together to form planetary embryos. Unlike small particles, boulders, and planetisimals, however, planetary embryos were massive enough to exert significant gravitational force on surrounding objects.
Therefore, instead of random collisions between objects, the planetary embryos dragged objects in the surrounding area towards themselves.
Once all the material in the area of each planetary embryo was attracted, the planets were born.
All other significant material in the solar system that did not coalesce to form the Sun or the planets condensed to form the moons, asteroids, or comets.
Over time, the orbits of the planets and other bodies stabilized in the solar system we know today.
How is the Solar system formed?
The Sun is the richest source of electromagnetic energy (mainly in the form of heat and light) in the solar system.
The Sun’s closest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light-years.
The entire solar system, along with local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars that we call the Milky Way.
The Milky Way has two small galaxies orbiting close to it, both of which are visible from the southern hemisphere.
magellanic cloud
They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The closest large galaxy is the Andromeda Galaxy.
It is a spiral galaxy like the Milky Way but is 4 times more massive and is 2 million light years away.
Our galaxy, one of billions of known galaxies, is traveling through intergalactic space.
The planets, most of the planets’ satellites, and asteroids revolve around the Sun in the same direction, in nearly circular orbits.
When viewed from above the Sun’s north pole, the planets orbit in a counterclockwise direction.
The planets orbit the Sun in or near the same plane, called the ecliptic. Pluto is a special case because its orbit is the most inclined (18 degrees) and the most elliptical of all the planets. Because of this, for part of its orbit, Pluto is closer to the Sun than Neptune.
The axis of rotation of most of the planets is almost perpendicular to the ecliptic. The exceptions are Uranus and Pluto, which are tilted to the sides.
Composition of the Solar System
The Sun contains 99.85% of all matter in the Solar System. The planets, which condensed from the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system.
Jupiter contains more than twice as much matter as all the other planets combined. The satellites of the planets, comets, asteroids, meteoroids and the interplanetary medium make up the remaining 0.015%.
The following table is a list of the distribution of masses within our Solar System.
Sun: 99.85%.Planets: 0.135%Comets: 0.01% ?Satellites: 0.00005%.Minor Planets: 0.0088cc2% ?Meteoroids: 0.0088cc1% ?Interplanetary Medium: 0.0088cc1%?
interplanetary space
Almost the entire solar system by volume appears to be a vacuum. Far from being nothing, this void of «space» comprises the interplanetary medium.
It includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas.
Interplanetary dust consists of microscopic solid particles. Interplanetary gas is a tenuous stream of gas and charged particles, primarily protons and electrons – plasma – streaming from the Sun, called the solar wind.
The solar wind can be measured by spacecraft, and it has a large effect on the tails of comets. It also has a measurable effect on the movement of spacecraft.
solar wind
The speed of the solar wind is about 400 kilometers (250 miles) per second in the vicinity of Earth’s orbit.
The point at which the solar wind meets the interstellar medium, which is the «solar» wind from other stars, is called the heliopause.
It is a boundary theorized to be roughly circular or teardrop-shaped, marking the edge of the Sun’s influence, perhaps 100 AU from the Sun. The space within the heliopause boundary, containing the Sun and the solar system, is called heliosphere.
The solar magnetic field extends out into interplanetary space; it can be measured on Earth and by spacecraft.
The solar magnetic field is the dominant magnetic field in all interplanetary regions of the solar system, except in the immediate surroundings of the planets which have their own magnetic fields.
Milky Way
The Solar System is part of a larger group of stars called…