The Solar System. Characteristics and structure

15/04/2026

The online solar system simulations on this page will help us to discover the structure and some of the most interesting characteristics of the space of the universe where we are.

This Thematic Unit is part of our Earth Sciences collection

Asteroid Belt

Region between Mars and Jupiter containing most of the system’s asteroids.

Astronomical Unit

Unit of distance equivalent to the average separation between Earth and the Sun.

Dwarf Planet

Spherical body orbiting the Sun that has not cleared its orbit, such as Pluto.

Gravity

Mutual force of attraction between bodies with mass.

Inner Planet

Rocky planet located near the Sun: Mercury, Venus, Earth and or Mars.

Kuiper Belt

Ring of icy objects located beyond the orbit of Neptune.

Oort Cloud

Giant spherical region of icy objects surrounding the solar system.

Orbit

Curved path followed by a physical object around another under the influence of gravity.

Outer Planet

Giant planet located beyond the asteroids: Jupiter, Saturn, Uranus and Neptune.

Planet

Celestial body orbiting a star, spherical in shape, and having cleared its orbit.

Solar System

Set of planets and other celestial bodies orbiting around the Sun.

What is the Solar System

The solar system is a fascinating planetary system found in the Milky Way, our galaxy. It is composed of the Sun, a G-type star that radiates light and heat, and all the celestial bodies orbiting around it, including planets, dwarf planets, asteroids, comets and other smaller objects.

Characteristics of the Solar System

The solar system is distinguished by its organization and dynamics, being a harmonic set where various celestial bodies interact under the influence of the Sun’s gravity, which acts as its energetic and gravitational core. The orbits of the planets and other objects follow elliptical trajectories, showing the complexity of the forces that govern them. It is also remarkable for its enormous scale, with distances between planets spanning millions of kilometers, underscoring the vastness of space. The diversity of materials and phenomena present in the solar system, from the intense heat near the Sun to the icy regions beyond Neptune, reinforce its role as a microcosm of the universe, full of contrasts and wonders.

Structure of the Solar System

The solar system is composed of a diversity of elements orbiting the Sun. Among these, the eight main planets stand out, each with unique characteristics. In addition, we find dwarf planets, asteroids, comets and other formations that enrich the complexity of this vast system.

The Sun

The Sun, located at the center of the solar system, accounts for more than 99% of the total mass of the system. It is a hot plasma sphere composed mainly of hydrogen and helium, which generates energy through nuclear fusion in its core. This energy is radiated into space in the form of light and heat, and is essential for sustaining life on Earth.

Planets of the Solar System

There are eight recognized planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. These planets vary in size, composition, and characteristics. The four inner planets, known as terrestrial planets (Mercury, Venus, Earth, and Mars), are rocky and relatively small. The four outer planets, known as giant gas planets (Jupiter, Saturn, Uranus, and Neptune), are much larger and are composed primarily of gases and liquids.

Other Solar System objects

In addition to the planets, the solar system is home to numerous smaller objects. Dwarf planets, such as Pluto and Eris, are smaller, planet-like bodies. Asteroids are irregular rocks that orbit the Sun, mainly in the asteroid belt between Mars and Jupiter. Comets are icy bodies that follow elliptical orbits around the Sun and, as they approach, may develop a bright coma and tail due to solar heating.

Beyond Neptune’s orbit extends the region called the Kuiper belt, which is home to a large number of icy bodies, including Pluto. Even further out lies the Oort cloud, a spherical region of comets in very distant orbits.

The online solar system simulations on this page are a very useful tool to improve our knowledge of our corner of the universe, so be sure to try them out!

Asteroid Belt

Region between Mars and Jupiter containing most of the system’s asteroids.

Astronomical Unit

Unit of distance equivalent to the average separation between Earth and the Sun.

Dwarf Planet

Spherical body orbiting the Sun that has not cleared its orbit, such as Pluto.

Gravity

Mutual force of attraction between bodies with mass.

Inner Planet

Rocky planet located near the Sun: Mercury, Venus, Earth and or Mars.

Kuiper Belt

Ring of icy objects located beyond the orbit of Neptune.

Oort Cloud

Giant spherical region of icy objects surrounding the solar system.

Orbit

Curved path followed by a physical object around another under the influence of gravity.

Outer Planet

Giant planet located beyond the asteroids: Jupiter, Saturn, Uranus and Neptune.

Planet

Celestial body orbiting a star, spherical in shape, and having cleared its orbit.

Solar System

Set of planets and other celestial bodies orbiting around the Sun.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Solar System Simulations

Representation
Scale
System

Solar System representation

This simulation is a generic representation of the Solar System that serves as an introduction to get to know it better. Try zooming in or out.

Solar System Scale

This simulation represents to scale what are the distances in the Solar System.

Solar system simulation

This complete solar system simulation allows you to predict how the position, mass, velocity and distance between planetary bodies affect their motion and orbits. It also illustrates how the gravitational force controls the motions of the planets and facilitates the exploration of the different motions that a group of planetary bodies can have.

Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

1643

–

1727

Isaac Newton formulated the law of universal gravitation and the three laws of motion, founding classical mechanics.

“If I have seen further, it is by standing on the shoulders of giants”

Johannes Kepler

1571

–

1630

Kepler formulated the three laws of planetary motion, establishing elliptical orbits and the relationship between planetary period and distance from the Sun

“The heavens teach the geometry that nature follows”

Become a giant

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The Radio Sky II: Observational Radio Astronomy

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Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Tycho Brahe

1546

–

1601

Tycho Brahe carried out highly precise astronomical observations before the telescope, developing a hybrid model between geocentrism and heliocentrism. His work was essential for Kepler

“The stars may shape destiny, but man observes their course”

Pierre-Simon Laplace

1749

–

1827

Pierre-Simon Laplace developed probability theory and mathematical statistics, and made fundamental contributions to astronomy and celestial mechanics.

“Probability theory is the science of analyzing chance”

Become a giant

Your path to becoming a giant of knowledge begins with these top free courses

Free mode

The Radio Sky II: Observational Radio Astronomy

Free mode

The Radio Sky I: Science and Observations

Free mode

Our Place in the Universe

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Introduction to Deep Earth Science

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Our Global Ocean – An Introduction Course

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Sensing Planet Earth – From Core to Outer Space

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Assessment Design with AI

Test your knowledge

What characterizes the solar system as an astronomical structure, and why is it considered an organized system centered around the Sun?

The solar system is a collection of astronomical bodies that orbit the Sun due to the gravitational force it exerts. It includes eight planets, their moons, dwarf planets, asteroids, comets and smaller objects distributed in regions such as the asteroid belt and the Kuiper belt. It is considered an organized system because each body follows a defined and stable orbit determined by its mass and distance from the Sun. The inner planets are rocky and located close to the Sun, while the outer planets are gas or ice giants found in colder, more distant regions. This structured arrangement allows scientists to study how the solar system formed, how its components evolve and how they interact, making it a fundamental model for understanding planetary systems throughout the universe.

How do the inner planets differ from the outer planets, and what does this division reveal about the formation of the solar system?

The inner planets—Mercury, Venus, Earth and Mars—are small, rocky and dense, formed in the hotter region close to the Sun where light gases could not accumulate. In contrast, the outer planets—Jupiter, Saturn, Uranus and Neptune—are much larger and composed mainly of gases or ices, having formed in colder regions where these materials could condense and gather in great quantities. This division reveals that the solar system developed according to distance from the Sun and the physical conditions of each region of the protoplanetary disk. The contrast between rocky planets and gas or ice giants reflects different formation processes and explains why the bodies in the solar system vary so much in size and composition.

Why do all the planets orbit the Sun instead of moving on their own?

Because the Sun has far more mass than any planet, and its gravity keeps all the bodies in the solar system bound in stable orbits. Without that force, the planets would move in straight lines and drift away. They orbit because they move fast enough not to fall into the Sun, but not fast enough to escape its gravity. It’s a constant balance.

Why are some planets huge while others are so small?

It depends on where they formed. Near the Sun, temperatures were too high for gases to accumulate, so only small rocky planets could form. Farther away, the environment was cold enough for light materials to condense, allowing planets to grow enormously and become gas or ice giants. It’s not luck—it’s physics.

Why isn’t Pluto considered a planet anymore if it’s still there?

Pluto still exists, but it doesn’t meet all the current criteria for being a planet. Although it orbits the Sun and is spherical, it hasn’t “cleared” its orbit, meaning it shares its region with many other Kuiper belt objects. For that reason, it’s classified as a dwarf planet. It’s not a downgrade—just a more precise definition..