Solar System


Our solar system is in the Milky Way galaxy and located in an outer spiral arm. This is where we call “home.” The solar system is made up of some major and minor players, all of which interact with each other.

The solar system consists of our sun, which is a star, and all that its gravity affects. The planets in our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

There are also dwarf planets such as Pluto, dozens of moons and millions of asteroids, comets and meteoroids of all shapes and sizes.

The solar system also includes an area that is past the outermost planet, Neptune, called the Kuiper Belt, which is home to a ring of icy bodies, including the dwarf planet Pluto.

Solar System with sizes

Just outside of the Kuiper Belt is the Oort Cloud, which is a huge spherical shell that envelopes our solar system 1.6 light years away.

While we have never been able to directly see the Oort Cloud, it’s believed to be made up of icy chunks of space debris that range from mountain size to larger. The Oort Cloud is the sun’s gravitational influence boundary.

Our system is “elliptical” in shape, which means that it’s shaped like an egg. The sun is the center of the solar system and all of the planets, moons, and other objects orbit around it due to the sun’s gravitational pull.

Solar systems contain quite a few different types of objects. Our Sun is also a star and is at the center of our solar system surrounded by planets, dwarf planets, moons, asteroids, gas, comets, and dust. To date, our Solar System contains:

  • 1 star
  • 8 planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune)
  • 5 dwarf planets (Pluto, Ceres, Haumea, Makemake, and Eris)
  • 181 moons
  • 566,000 asteroids
  • 3,100 comets

History of the Name:

We refer to the “solar system” as it has been named after our sun, called “sol” which is Latin for “sun.” The words “Solar System” relate to two things: Any celestial body that is “of the Sun,” and a collection of objects that work together to form the entire whole.


Scientists believe that our solar system was formed around 4.5 billion years ago. We have observed how systems are created and they begin with a dense cloud of interstellar dust and gas that experiences a collapse.

may be due as a result of the shockwave of the explosion of another star, called a supernova. When the collapse occurs it creates a “solar nebula,” which is a mass of swirling, spinning material.

As it spins, gravity occurs and pulls more and more material in until the pressure in the center becomes so great that hydrogen atoms combine with helium to release a huge amount of energy.


That energy results in the birth of a star such as our own sun, and in our case, our sun amassed over 99% of the available matter.

Further out of the disk mass, other items were also starting to merge together and they began to smash into each other creating bigger and bigger objects.

Some of these grew large enough so that their gravity assisted in shaping them into spheres, and these became planets, large moons, and dwarf planets.

If their own gravity wasn’t strong enough some of the clumps didn’t create planets but remained oddly shaped and remained in bits and pieces that were affected by the sun’s gravity.

Many of these ended up in the asteroid belt while other smaller pieces that were left over turned into comets, asteroids, meteoroids, and small misshapen moons.


Scientists believe that the early solar system looked completely different than the one that we see today. It’s thought that the planets that we have now were probably in totally different locations, with the gas giants formed and orbiting closer to the sun.

There is also a good possibility that we had many more objects rotating and some may have been kicked out of the solar system while others simply crashed into existing objects to be engulfed by them.


The arrangement of the planets and bodies in our solar system today is due to billions of years of changes. It’s believed that 4.5 billion years ago all of the planets settled into the current configuration.

When our solar system first formed, the intense heat of the sun could only allow the survival of rocky materials. This is why those planets closest to the sun are the smaller terrestrial planets with rocky, solid surfaces: Mercury, Venice, Earth, and Mars.

Gravity does have an influence on ice, liquid or gas, that was in the outer regions and the sun’s gravity held the gas giants of Jupiter and Saturn, and the ice giants of Uranus and Neptune.


We are sending more missions and probes out in space and with each one we learn more about our solar system. We have discovered that there are over 150 known moons in our solar system and it’s believed that there are more that are waiting for confirmation.

Only two planets don’t have any moons: Mercury and Venus. It seems that of all of the planets, the big giants have grabbed the most. Jupiter and Saturn have the most moons, so many that they have been compared to miniature versions of our own solar system.

Even the dwarf planet of Pluto way out in the Kuiper Belt has five moons of its own. Its moon Charon is responsible for giving Pluto its wobble.

As we continue to develop more powerful telescopes and send additional spacecraft missions out, we are finding that even some of the small asteroids have moons. A group of scientists in 2017 found that Florence, also known as “asteroid 3122,” had two little moons.

The Existence of Life

So far, our solar system is the only location that we know of that harbors life, and our planet Earth has an abundance of life in all shapes and sizes. However, as we explore some of the planets we are discovering that some of the moons may have liquid water, which is one of the requirements of life.

Jupiter’s moon, Europa, and Saturn’s moon, Enceladus have global saltwater oceans that exist under icy, thick shells.

Previous definitions of what we considered to be “habitable” environments have changed over the years. We maintain that to allow the growth and adaptation of life there needs to be liquid water, an energy source, and a source of food.

However, scientists have discovered life on Earth in areas that were previously thought to be uninhabitable. These life forms are called “extremophiles” and have altered opinions about how life might thrive on other worlds.

Space Visits:

As humans, we have been viewing, watching, and studying our solar system over the millennia. However, it wasn’t until the last number of centuries that our technology and science has been evolved enough to figure how things actually worked.

As we have expanded into the era of robotic spacecraft, we are learning so much more about our solar system and farther out into the universe.

Important Events:

  • 2003: Spitzer Space Telescope: Spitzer contains an ultra-sensitive infrared telescope that is used to study everything from asteroids and comets, including near-earth-objects (NEOs), planets, and even galaxies that are far far away.
  • 2009 Kepler Telescope: The sophisticated telescope discovered over 2,600 planets outside of our solar system.
  • 2009 Herschel Space Observatory: An incredible number of discoveries that added to our knowledge of planetary science and astronomy.
  • 1992 Geotail Satellite: Monitoring the area of Earth’s magnetosphere known as the “long tail region”
  • 2015 DSCOVR: The Deep Space Climate Observatory monitors alterations in the solar win and sends space weather alerts to planetary scientists for following and forecasting any geomagnetic storms that could affect the Earth and our technologies.
  • 1965 Surveyor Model SD-1: Designed as a rehearsal mission to gather information about the surface of the moon that would be required for the future Apollo moon landings.
  • 1966 Surveyor Model 2: Designed to test the launch simulated Surveyor lunar lander spacecraft into a barycentric orbit toward the moon in preparation for future space missions.
  • 1968 Pioneer 09: Fourth probe in a series that were to continue studying interplanetary space from a heliocentric orbit in preparation for continued space missions.
  • 1967 Pioneer 08: Third probe in a series sent to study interplanetary space in a heliocentric orbit with a main mission to collect data on plasma, magnetic fields, and cosmic rays for preparation of additional space missions.

Facts about The Solar System for Kids:

  • The answer to “what is a moon” is a bit fuzzy: The International Astronomical Union is the organization that helps to define what a planet is and what isn’t. However, when it comes to the topic of moons, there isn’t an easy definition. Moons are thought to be bodies that orbit planets, but that explanation doesn’t cover conditions where bodies are orbiting double planets or asteroids.
  • Asteroids and Comets are leftover pieces of our solar system: These smaller bodies never made it to become part of planets or moons, but scientists believe that these “leftovers” may have brought liquid water and organics to our Earth.
  • All of our planets are on the same “plane” and orbit in the same direction: When you see an image of all eight of the planets in our solar system you will notice that they have a tendency to follow the same “path” in the sky, also called the “ecliptic.” They also orbit our sun in the same direction. This is one of the reasons that scientists believe that the planets, the moons, and the sun were all formed from a spinning condensed gas and dust cloud.
  • Our solar system is WAY out there: When you think of the Milky Way galaxy you usually see a spinning galaxy with billions of stars. Our sun may be one of those stars but we are way out in an outer “arm” of the galaxy. NASA has indicated that we are around 165 quadrillion miles from the center, which just so happens to be home to a supermassive black hole.
  • Our solar system is really big: When Voyager 1 was launched in 1977, it took 35 years for Voyager 1 to pass through the area where the sun’s gas and magnetic environment has any effect. This was 11 billion mi/17 billion km away from our Earth. This means that our solar system is really large.
  • We have a huge sun: Our sun collected 99.86% of our solar system’s mass. This shows you just how big our sun is. The sun is made up of hydrogen and helium and that demonstrates how much of these gasses are in the universe as compared to the metals and rocks as we have on Earth.
  • Our solar system is a good example to understand exoplanets: Exoplanets are very far away and look tiny even using the most powerful telescopes. Examining planets in our solar system such as Jupiter, that have miniature solar systems, so we can watch how super-Earths outside of our solar system possibly work.

Beyond the solar system:

Our Milky Way galaxy is a spiral shape that is around 100,000 light-years across. Our sun is only one of about 100 billion stars within the Milky Way.

stars are in a pinwheel-shaped pattern and the Milky Way has four major “arms” that span out. Our solar system is in one of these arms.

The Milky Way galaxy is only one of billions and billions of galaxies in the universe. The size of the universe is unknown, however, scientists believe that it is still continuing to expand outward.

  • The Sun

    Our solar system is in the Milky Way galaxy and located in an outer spiral arm. This is where we call “home.” The solar system is made up of some major and minor players, all of which interact with each other.

    Read More

  • The Moon

    Thus far, our Moon is the only location outside of our planet that human beings have personally visited and set foot.

    Read More

  • Asteroid Belt

    The asteroid belt is in the far region of the solar system between Mars and Jupiter. This is where a majority of the asteroids in our solar system are found.

    Read More

  • Lunar Eclipse

    An eclipse happens when one celestial body, such as the moon or a planet, moves into the shadow of another celestial body. On Earth, we have two types of eclipses: the eclipse of the moon called a lunar eclipse and the eclipse of the sun called a solar eclipse.

    Read More

  • Sunspots and Solar Wind

    Our sun is incredibly active. It’s made up of the gases hydrogen and helium and the process that it uses to create energy is called nuclear fusion.

    Read More

  • Meteor Showers

    A meteor has a name change once it enters the atmosphere of Earth. It’s then known as a “meteoroid” or a “space rock.” When it flies through the atmosphere it meets the resistance and begins to heat up.

    Read More

  • Meteorites

    Humanity has been observing meteors for thousands of years.

    Read More

  • Asteroids

    Asteroids are objects made up of mostly metals and rocks.

    Read More

  • Comets

    All through history, many civilizations observed comets and were both in awe and frightened by them. They didn’t know what they were and some thought that they were stars with “long hair” that would appear, possibly bringing bad news.

    Read More

  • Solar Eclipses

    An eclipse occurs when one celestial body, such as the moon or a planet, moves into the shadow of another celestial body.

    Read More

  • Oort Cloud

    Much of the information about the Oort Cloud is theoretical…

    Read More

  • Kuiper Belt

    The Kuiper Belt is located in the outer areas of our solar system, just past Neptune’s orbit, and is believed to be materials that were left over from the formation of the planets.

    Read More