We explain what the solar system is and what its characteristics are. Also, the planets that make it up and the history of their exploration.
The solar system is made up of eight planets that orbit the Sun.
What is the solar system?
The solar system is the set of celestial bodies that orbit the Sun, and is part of the Milky Way.. In our planetary system, there are eight planets in constant orbit: four inner ones (Mercury, Venus, Earth and Mars) and four outer ones (Jupiter, Saturn, Uranus and Neptune).
There are also other objects in the solar system, such as the asteroid belt between Mars and Jupiter, where the dwarf planet Ceres is located, or the so-called trans-Neptunian objects, which are celestial bodies that are located beyond Neptune, at the limits of the solar system.
The solar system formed 4.6 billion years ago from gases and other materials that were part of a large molecular cloud. That cloud collapsed under its own gravitational forces, producing a rotating disk around a central core that would later become the Sun. As the disk’s material accumulated, dust grains coalesced and grew, forming the celestial objects that began to orbit the Sun.
See also: Stars
Features of the solar system
The solar system has the following characteristics:
- It was formed 4.6 billion years ago.
- At its center is a star called the Sun.
- It is made up of four inner and four outer planets.
- It is part of the galaxy known as the Milky Way.
- The planets that make it up are gaseous, terrestrial and dwarf.
Origin and location of the solar system
It is estimated that The solar system originated 4.6 billion years agodue to the collapse of a molecular cloud in the Milky Way. As the nebula collapsed, the material began to spin faster and the nebula flattened into a protoplanetary disk around a young, forming star, which would later become the Sun.
In this disk, small dust particles clumped together and merged to form larger objects called planetesimals, which, in turn, combined to form planets. This process of accretion and fusion resulted in the formation of the celestial bodies that today make up our solar system, such as planets, moons, and other objects.
The solar system is located in the galaxy known as the Milky Way., a large spiral with several arms. In one of these arms, known as the Orion Arm or Local Orion Arm, the solar system is located. The approximate distance from there to the center of the Milky Way is around 27,000 light years.
A light-year is a unit of measurement used in astronomy. It represents the distance that light travels in one year in a vacuum at a speed of approximately 299,792 kilometers per second. It is equivalent to almost 9.5 trillion kilometers.
Sun
The Sun contains 99.86% of the total mass of the solar system.
At the center of the solar system is the only body that emits its own light: the Sun.It is a type-G2 star (a yellow dwarf), composed mostly of hydrogen and helium in a constant state of nuclear fusion. To a much lesser extent, the Sun is also composed of oxygen, carbon and nitrogen.
With a total diameter of 1,392,000 kilometres, it contains 99.86% of the total mass of the solar system, which is why the entire system orbits around it. The energy radiated by the sun in the form of light and heat is essential for life on planet Earth, and determines the atmospheric conditions of all the other planets in the solar system.
See also: Sun
The planets
Earth is the only known planet capable of supporting organic life.
Planets can be classified according to their composition and size:
- Gas giant planetsThey are composed mainly of gases. They are significantly larger and less dense than the terrestrial planets. Jupiter, Saturn, Uranus and Neptune are gas planets.
- terrestrial planetsThey are rocky planets and have solid surfaces. Their surfaces may have craters, mountains, volcanoes and plains. Mercury, Venus, Mars and Earth are terrestrial planets.
- Tiny planets. They are planets smaller than terrestrial ones. The best-known dwarf planets are Pluto, Ceres, Makemake, Eris and Haumea. This category was adopted in 2006.
The orbits of the planets
The greater the distance from the Sun, the longer the orbit of a planet.
The eight planets of the solar system orbit the Sun in elliptical, almost circular orbits of varying lengths and at different speeds, according to their respective proportions and natures. This phenomenon is known as planetary translational motion.
The Earth takes 365 days (one year) to complete one solar orbit. There are also planets that take less time, such as Mercury (88 days) or Venus (225 days), and others that take longer, such as Jupiter (12 years), Saturn (29 years and 6 months) and Neptune (164 years).
Satellites and asteroids
The Moon is the only natural satellite of the Earth.
There are also asteroids in the solar system, which are small rocky or metallic bodies found in space. They can be found both in the belt between Mars and Jupiter and in the one beyond Neptune, and also in the rings that surround the large outer planets.
On the other hand, large satellites, such as our Moon or Deimos and Phobos on Mars, are celestial bodies much larger than asteroids, which are trapped in the gravitational field of a larger planet.
The outer planets have numerous satellites, for example Jupiter, which has more than ninety. On the other hand, the inner planets have fewer: Earth only one, and Venus and Mercury none.
Transneptunian planets
Pluto is considered one of the largest objects in the Kuiper belt.
Trans-Neptunian planets are a category of celestial bodies found beyond the orbit of Neptune in our solar system. These objects are part of the Kuiper Belt, a region containing a large number of small icy, rocky bodies and planetesimals.
The known trans-Neptunian planets are:
- Pluto. It was previously considered the ninth planet in the solar system, but was reclassified in 2006 by the International Astronomical Union (IAU) as a dwarf planet. Pluto has an elliptical orbit and has several moons, among which Charon is the largest and best known.
- ErisIt is a dwarf planet located in the Kuiper Belt. It is slightly smaller than Pluto, but has a greater mass. The discovery of Eris in 2005 led to a re-evaluation of the definition of “planet,” which eventually led to Pluto’s reclassification.
- HaumeaIt is a dwarf planet with an elongated shape. It was discovered in 2004 and is known to have two moons, Hi’iaka and Namaka.
- Makemake. It is a dwarf planet discovered in 2005, which shows a slightly inclined orbit and has no known moons.
Observation and exploration of the solar system
In ancient times, various cultures carried out astronomical observations to understand celestial movements and establish calendars.
The introduction of the telescope in the 17th century allowed significant advances in the observation of the solar system. Galileo Galilei (1564-1642) made pioneering observations of the phases of Venus, the moons of Jupiter and sunspots, contradicting heliocentric conceptions that held that our planet was at the center of the universe.
For his part, the German astronomer Johannes Kepler (1571-1630) developed the laws of planetary motion and Isaac Newton, with his law of universal gravitation, provided a theoretical framework to explain celestial movements.
In the 19th century, the invention of photography allowed the capture of detailed astronomical images, and the development of spectroscopy in the 19th and early 20th centuries made it possible to analyze the chemical composition of the stars.
The 20th century marked the beginning of space exploration. The Space Age began with the launch of Sputnik 1 in 1957 by the Soviet Union, followed by numerous space missions that explored planets, moons, and other bodies in the solar system. Probes such as Voyager, Pioneer, and more recently New Horizons provided crucial data on the geology, atmosphere, and composition of various celestial objects.
In the 21st century, space technology allowed for more sophisticated missions, such as the exploration of Mars with Curiosity and the Juno mission, which studies Jupiter. In addition, the launch of space telescopes such as Hubble has provided high-resolution images for understanding the formation and evolution of the solar system.
Follow with: