SOLAR SYSTEM
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. The largest of these objects are the eight planets, which in order from the Sun are four terrestrial planets (Mercury, Venus, Earth and Mars); two gas giants (Jupiter and Saturn); and two ice giants (Uranus and Neptune). The Solar System developed 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
All four terrestrial planets belong to the inner Solar System and have solid surfaces. Inversely, all four giant planets belong to the outer Solar System and do not have a definite surface, as they are mainly composed of gases and liquids. 99.86% of the Solar System’s mass is in the Sun and nearly 90% of the remaining mass are in Jupiter and Saturn. There is a strong consensus among astronomers that the Solar System also has nine dwarf planets, which consist of one asteroid-belt object – Ceres; five Kuiper-belt objects – Pluto, Orcus, Haumea, Quaoar, and Makemake; and three scattered-disc objects – Gonggong, Eris, and Sedna.
Solar system, assemblage consisting of the Sun—an average star in the Milky Way Galaxy—and those bodies orbiting around it: 8 (formerly 9) planets with more than 210 known planetary satellites (moons); many asteroids, some with their own satellites; comets and other icy bodies; and vast reaches of highly tenuous gas and dust known as the interplanetary medium. The solar system is part of the “observable universe,” the region of space that humans can actually or theoretically observe with the aid of technology. Unlike the observable universe, the universe is possibly infinite.
The Sun, Moon, and brightest planets were visible to the naked eyes of ancient astronomers, and 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, and compositions of the planets and smaller bodies has grown to immense proportions, and the range of observational instruments has extended far beyond the solar system to other galaxies and the edge of the known universe. Yet the solar system and its immediate outer boundary still represent the limit of our physical reach, and 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, and 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 astronomers continue to make great strides.
Composition of the solar system
Located at the center of the solar system and influencing the motion of all the other bodies through its gravitational force is the Sun, which in itself contains more than 99 percent of the mass of the system. The planets, in order of their distance outward from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Four planets—Jupiter through Neptune—have ring systems, and all but Mercury and Venus have one or more moons. Pluto had been officially listed among the planets since it was discovered in 1930 orbiting beyond Neptune, but in 1992 an icy object was discovered still farther from the Sun than Pluto. Many other such discoveries followed, including an object named Eris that appears to be at least as large as Pluto. It became apparent that Pluto was simply one of the larger members of this new group of objects, collectively known as the Kuiper belt. Accordingly, in August 2006 the International Astronomical Union (IAU), the organization charged by the scientific community with classifying astronomical objects, voted to revoke Pluto’s planetary status and place it under a new classification called dwarf planet. For a discussion of that action and of the definition of planet approved by the IAU, see planet.
Top 10 Facts about The Solar System
The Solar System is an awe-inspiring cosmic masterpiece of planets, moons, asteroids, and comets that orbits the Sun. It is the collection of all celestial bodies that are held together by the Sun’s gravitational pull. From the innermost planet, Mercury, to the farthest-reaching planet, Neptune, the Solar System is filled with fascinating wonders and mysteries. Its composition of planets, moons, asteroids, and comets has been studied and explored for centuries, and continues to be a source of wonder and fascination.
Plus, you can learn more about what’s in our Solar System with our Top 10 Facts on the Sun and the Moon; the planets Earth, Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune and the dwarf planet Pluto.
1. The Solar System has Eight Planets
The Solar System is all the planets and other things in space that orbit (go around) our sun.
This includes the planets Earth, Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune as well as the dwarf planet Pluto, asteroids and comets.
The planets are in the order Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune followed by the dwarf planet Pluto. Here is how we remember to order, with this sentence that has the same letters as the order of planets plus Pluto.
2. Earth is only a very small part of The Solar System
Earth is a big place but within the solar system it is quite small. It would take 1.3 million planets the size of Earth to fill up the sun. Earth is a lot smaller than planets like Jupiter and Saturn.
3. The Solar System formed 4.6 Billion years ago
The Solar System was formed 4.6 billion years ago from a cloud of gas and dust called the solar nebula.
A shock wave from a nearby supernova (big star) explosion probably started it.
The Sun formed in the center, and the planets formed around it.
4. The Solar System is part of The Milky Way
The solar system is part of the Milky Way, there are at least between 250 to 500 billion stars in our Milky Way galaxy – there might even be more. That’s at least 30 times more stars in The Milky Way than there are people on Earth.
There are over 700 known systems of planets orbiting stars.
5. The Sun is 93 million miles from the Earth
That’s the same as taking 1000 trips to Australia! Even though it’s so far away the light from the Sun only takes 8 minutes to travel to the Earth.
6. All planets and the Sun in the Solar System are shaped like balls
Once upon a time people thought the Earth was flat. We now know, and can prove through satellite pictures, that it is a sphere. All planets, as well as the Sun, are balls too.
7. Planets in our Solar System are different temperatures
The hottest planet is Venus with an average temperature of 460°C and the coldest planet is Uranus with an average temperature -220°C. By comparison Earth’s average temperature is 15°C.
8. There are 181 moons in The Solar System
Scientists are always discovering more moons in The Solar System and arguing over whether Saturn or Jupiter have more moons. Currently Jupiter and Saturn both have 53 confirmed moons but they also both have more than 30 moons NASA haven’t confirmed.
There is also 552,894 asteroids and 3,083 comets in The Solar System!
9. Neptune was the last planet to be discovered in The Solar System
Neptune was the last planet to be discovered. On the night of 23rd September 1846 astronomers discovered Neptune through a telescope.
10. You can see Venus from Earth
You can see some of The Solar System from Earth. For example, we have all seen the sun and our moon. You can also sometimes see Venus, which is also known as the evening or morning star. Yellow clouds made of sulfur cover the entire planet causing light from the sun to reflect off the surface meaning we can often see it at night. It is usually the first ‘star’ you will spot.
This makes Venus the second brightest object in the night sky after the Moon
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