The Solar System

Ever wondered if there is life on Mars? Or if Jupiter has five moons? Look no further; here is the category concerning all questions about our solar system and the known planets!

17,323 Questions
Planet Mercury
The Solar System
The Sun

How far is Mercury from the Sun?


Planetary Science
The Solar System

What are the names of the planets in our solar system?

Names of the Planets

  1. Mercury - named after the Roman mythological counterpart of Hermes, the Greek god of messengers, commerce, thieves, and sports. Named as such because of the speed at which it revolves around the Sun.
  2. Venus - named after the Roman mythological counterpart of Aphrodite, the Greek goddess of love and beauty.
  3. Earth (also known by its Latin name, "Terra") - named after the titan of the Earth from Greek mythology.
  4. Mars - named after the Roman mythological counterpart of Ares, the Greek god of war.
  5. Jupiter - named after the Roman mythological counterpart of Zeus, the Greek king of the gods.
  6. Saturn - named after the Roman god of agriculture and harvest, Saturn. He is the Roman mythological counterpart of Cronus (Kronos), the Greek titan who fathered Zeus.
  7. Uranus - named after the Greek mythological Father of the Sky, Ouranos. "Uranus" is the Latin translation of "Ouranos".
  8. Neptune - named after the Roman mythological counterpart of Poseidon, the Greek god of the seas.

Jupiter, Saturn, Uranus, and Neptune are all made primarily of gas and are very large. Mercury, Venus, Earth and Mars are small and made of rock.

My Very eager Mother Just Served Us Noodles

Pluto was considered a planet from 1930 to 2006, but was reclassified as a "dwarf planet", because many Pluto-like bodies were discovered in orbits past Neptune.

The dwarf planets are Ceres, Pluto, Haumea, Eris, and Makemake.

The names of our planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Pluto isn't really classified as a planet anymore, (which I hate) but it is now a Dwarf Planet.

Another way to remember the planets names is to make a cool rhyme or little

poem. Like this one:

My Very Eager Mother Just Sold Us Notebooks
According to the 2006 definition by the IAU, there are 8 "planets" in our solar system:

  1. Mercury
  2. Venus
  3. Earth
  4. Mars
  5. Jupiter
  6. Saturn
  7. Uranus
  8. Neptune

Furthermore, there are a number of large moons orbiting the gas giant planets, and there are several dwarf planets including the former "planet" Pluto (reclassified in 2006). Many new candidates for the dwarf category have been found past the orbit of Neptune.
venus, mercury, saturn, earth, mars,jupiter,uranus,neptune and the sun
The planets in our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. In 2006 the IAU redefined planets and reclassified Pluto, demoting it from planet to minor or dwarf planet - so now we are considered to have only eight. If there is a ninth, it would have to 1) be in hydrostatic equilibrium, 2) be in orbit around the sun, and 3) to have cleared its orbit.
With the reclassification of the term "planet" in 2006, there are only eight planets in the solar system, and Pluto is considered a "dwarf planet".

The remaining 8 planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

(see the related question)

1. Mercury

2. Venus

3. Earth

4. Mars


5. Jupiter

6. Saturn

7. Uranus (pronounced "you're-on-us")

8. Neptune

*Dwarf Planet: Pluto
In order from the sun









mars, venus, earth, mercury, jupiter, saturn, uranus, neptune
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Mercury, Venus, Mars, Earth, Jupiter, Saturn, Uranus, Neptune. Pluto used to be listed as the ninth planet, but has since been demoted to a Dwarf Planet [See Link].

  1. Mercury
  2. Venus
  3. Earth
  4. Mars
  5. Jupiter
  6. Saturn
  7. Uranus
  8. Neptune
  9. Pluto (no longer considered a planet)

Also a way to remember that is: MVEMJSUNP = My Very Elegant Mom Just Served Us Nine Pizzas = Mercury, (and all the other planets)

Planetary Science
The Solar System

How many planets are there in our solar system?

There are a total of 13 known planets in our solar system:

There are 8 major planets in our solar system. Since the recent re-definition of 'planet', Pluto is a dwarf planet (along with 4 others in that classification).

The 8 major planets in the solar system:

1. Mercury

2. Venus

3. Earth

4. Mars

5. Jupiter

6. Saturn

7. Uranus

8. Neptune

The 5 dwarf planets:

1. Ceres (a large asteroid)

2. Pluto

3. Haumea (Kuiper Belt Object)

4. Makemake (Kuiper Belt Object)

5. Eris (Kuiper Belt Object)

Pluto was designated a dwarf planet when it became obvious that there were several other objects of its size within the outer regions of the solar system. Three of them are now also dwarf planets: Eris, Haumea, and Makemake, and others (Quaoar, Sedna) are candidates to be named dwarf planets.

There were 9 planets following the discovery of Pluto in 1930. But with the improvements in telescopes in the 21st century, a surprising number of sizable planetoids found past Neptune, and astronomers realized that there could be dozens of objects being called planets. So in 2006, Pluto was reclassified as a "dwarf planet" by the International Astronomical Union. The asteroid Ceres and 3 other trans-Neptunian objects (Haumea, Makemake and Eris) were also classified as dwarf planets and there are several other pending candidates.
There were nine planets in our solar system, but in 2005, the International Astronomical Union finally devised some criteria for determining what astronomical bodies can be called a "planet". (There had never been an official definition for "planet".

The planet Pluto was demoted from "planet" to "dwarf planet", because Pluto had not "cleared its orbit" of other objects, which left only eight official planets. Pluto became a "dwarf planet", as did the asteroid Ceres, and three trans-Plutonian objects Makemake, Haumea, and Eris.
There were eight... Mercury, Venus, Earth,Mars, Jupiter Saturn, Neptune, Uranus & Pluto. However - recently, Pluto has been 'downgraded' to a 'minor planet' - since it's distance from the sun places it closer to the Kuiper belt.

The Solar System
The Sun

What is the importance of the sun in the solar system?

Clearly, we (Earth) can't live without the Sun. It gives us energy/ electricity and warmth. Plants need the Sun for photosynthesis, we need it as light during the day. The Sun plays a major role in our lives.
The importance of sun in our solar system is that if we don't have the sun then there will be no life on Earth since it is too cold for life to grow, and the Earth will be a frozen chunk of ice.

Planet Earth
Speed of Light
The Solar System

How much time would taken by sun rays to get to the sun from the earth?

8.3 seconds

Planetary Science
The Solar System

How many Planets are there?

There are 8 major planets, and 5 dwarf planets, in our solar system. There are also about a half dozen bodies that may be dwarf planets, though this status has not yet been confirmed. and more than a hundred more that may be considered in the future.

Outside of our Solar System, there are billions. These are called exoplanets.
In addition to the eight planets in our solar system, due to new equipment and new techniques, new planets are being found in other solar systems every week.

Planetary Science
The Solar System

How many moons are there in the solar system?

There are 178 known moons in the Solar System. The planet which has the most natural satellites is Jupiter with 66. There are also 104 asteroid moons and as many as 58 satellites of potential dwarf planet candidates.

Major Planets (171)

  • Mercury does not have any natural satellites (moons)
  • Venus does not have any natural satellites (moons).
  • Earth has 1 natural satellite (moon) called 'The Moon' or Luna (asteroid Cruithne orbits the Sun in a 1:1 orbital resonance with Earth)
  • Mars has 2 natural satellites (moons)
  • Jupiter has 66 natural satellites (moons)
  • Saturn has 62 (+1 unconfirmed) natural satellites (moons) and over 150 moonlets
  • Uranus has 27 natural satellites (moons)
  • Neptune has 13 natural satellites (moons)

Dwarf Planets (7)

  • Pluto has 4
  • Eris has 1
  • Haumea has 2
  • Ceres has none
  • Makemake has none

*For a complete list, see the related link below. There is also a link to more information at the Nine Planets website.
Planet/# of moons







Uranus- 27


The Solar System

Why did Galileo go to jail for publishing evidence supporting the sun centered solar system?

He did not actually go to jail, but his activities were severely restricted by the Roman Church, which then had real power in government and law.

The Catholic Church didn't like his conclusions about the theories of Copernicus. This was mainly based on early texts quoted in the Bible that stated that the Earth was immovable. Galileo was convicted of heresy in 1633 and spent the rest of his life under house arrest.


Galileo promoted the Copernican system with the Sun at the centre. The Vatican said it was OK to promote it as a way of modelling the movements of the planets, but he could not say it was the absolute truth unless there was proof. He continued saying it was the absolute truth and depicted the Pope as an idiot in one of his books, so was put on trial, and when the crunch came he was asked for proof of what he was saying, but he had no proof and he recanted. Proof did not come for another 200 years when the concept of kinetic energy had been invented in the 1800s. The story of the Catholic Church suppressing truth was convenient at the time to Protestant propagandists.

Planetary Science
The Solar System

Solar system mobile is called?

An orrery.

Planetary Science
The Solar System

Which planet rotates in a counter clockwise direction?

All of them with the exception of Venus and Uranus.

Improvement : I don't want to seem pedantic, but that answer always

"bugs me". I know you see it in books, but it's incomplete.

You need to add that the planets are being "viewed" from a position above

the Earth's North Pole.

If you looked at Venus from high above our South Pole it would rotate in a

counterclockwise direction.

Space Travel and Exploration
The Solar System

Which planet is the closest to the sun?


The Solar System

What occurs when an object in the outer reaches of the solar system passes between Earth and a far distant star?

It may temporarily block the light of the distant star. Astronomers call this an


It may also change the direction of the light, and briefly make it appear brighter (gravitational lensing).

Comment: I doubt that gravitational lensing would occur in this type of case.

The Solar System
The Sun

Does the sun accounts for 75 percent or 99 percent of all the matter in the solar system?

In fact, the Sun accounts for over 99.8% . Most of the rest is contained in Jupiter.

Planetary Science
The Solar System

Who was the Greek astronomer that argued that the sun was much larger than the earth and that the planets revolve around the sun?

Aristarchus of Samos was the Greek astronomer who argued that the Sun was larger than Earth and that the planets revolve around it.

The Solar System

What are the six parts of the solar system?

  1. The Sun - the star at the centre of the Solar System, which contains 99.98% of its total mass. By far the biggest, hottest, brightest and most massive object in the Solar System.
  2. The inner Solar System, containing four terrestrial planets orbiting close to the Sun - Mercury, Venus, Earth and Mars. Terrestrial planets are small, made of rock and metal, have a solid surface, thin atmospheres, no rings and few moons (Earth has one large Moon, Mars has two little ones.) Some asteroids (small objects made of rock and metal) orbit the Sun in this zone too - Mars' two small moons could be captured ex-asteroids.
  3. The asteroid belt, between Mars and Jupiter. Most asteroids orbit here. The largest asteroid, Ceres, is about 13 times smaller than Earth, and big enough for its gravity to pull it into a rounded shape, so it counts as a dwarf planet.
  4. The outer Solar System, containing four spread out giant planets - Jupiter, Saturn, Uranus and Neptune. All four are enormous planets, made of gas and ice, have no solid surface, thick atmospheres, all have rings, and all have many moons. A few asteroids (known as Centaurs) orbit here, as well as icy objects called comets. Comets on highly elliptical orbits sometimes pass into the inner Solar System too, where the Sun's heat warms them and the melted/evaporated ice forms a tail.
  5. The Kuiper Belt, a swarm of icy and rocky material beyond Neptune that was too spread out and moving too slowly to collect together into a big planet. Most Kuiper Belt objects are small chunks of ice and rock - comets and asteroids - but some are big worlds big enough to pull themselves into spheres, and these are dwarf planets too. Pluto is the most famous because it was classified as a planet before we knew about the other KBOs, but Eris is slightly larger and a lot more massive. The outer part of the Kuiper Belt, where Eris orbits, contains many KBOs on highly tilted, eccentric orbits, and is sometimes called the Scattered Disc and made into its own section.
  6. The Oort Cloud. We don't know for sure that this exists, but it's thought to be a huge spherical swarm of comets very, very far from the Sun. Most of the comets in the inner sections come from here.
Planetary Science
Dwarf Planets
The Solar System

How many plutoids are there in your solar system?

FOUR are known at present.

"Plutoids" is another term for Dwarf Planets like Pluto. (The Dwarf Planet Ceres is not a Plutoid because it's in the asteroid belt.)

There are actually a few confirmed Plutoids in our solar system. Also there are some likely objects yet to be officially named as Plutoids. Most of them are only recently discovered due to new technology. Most of the new ones have a "codename" rather than an actual name.

The confirmed Plutoid Dwarf Planets are:

- Eris

- Pluto

- Makemake

- Haumea

Some Possible Plutoids:

- Sedna

- Orcus

- Quaoar

- 2002 TX300

- 2002 AW197

- 2003 AZ84

- 28978 Ixion

- 20000 Varuna

- 2004 GV9

- 38628 Huya

- 1996 TL66

- 2003 MW12

- 2005 RN43

- 2005 RN43

- 2003 OP32

- 2001 UR163

- 2004 SB60

- 2005 RM43

- 2004 UX10

- 1999 DE9

Then again, there is also a list of planet-like objects in space which could be Dwarf Planets. But they need to be assessed further with more research before they can be classed as a Dwarf Planet or an Asteroid.

We are constantly making new discoveries.

See the related links below for the full list of confirmed and possible Dwarf Planets.

Scattergories and Words Starting with Certain Letters
The Solar System

What are some things in the solar system that begin with the letter B?

black hole (Except there isn't one of these in our solar system.)

Bebhionn, Bergelmir, and Bestla - moons of Saturn

Bianca and Belinda - moons of Uranus

Biela, Brorsen, Brooks, Brorsen-Metcalf, Boethin, Bus, Bowell-Skiff, Brewington, Barnard, Bennett, Beljawski, Bradfield, and several others - comets

Anything on Earth that starts with B...

Birmingham, Bromley, Bermondsey, and Buckingham are all in the solar system, plus Belgium and Barbados.

Planetary Science
The Solar System

How old is the solar system?

The Sun is about 4.57 billion years old, so is the solar system.

The age of the Solar System is determined through the radiometric dating of heavy elements such as uranium. Measurement of radioactive decay rates allow us to determine when the elements in the Solar System were formed.

The most current data places the age of these elements at 4.567 billion years old. This gives us an upper limit for the age of the Solar System. However, these 4.567 billion-year-old elements were formed by a nearby supernova, and the time it took them to travel from the location of the supernova site to the hydrogen cloud whose gravitational collapse into the Solar System by these elements is at present uncertain. Also uncertain is the precise amount of time it took for the collapse to complete from beginning to end. However, our best estimates place the age of the Solar System at 4.5 to 4.55 billion years.

The Solar System

How does the suns gravity affect the solar system?

Answer 1

It keeps the planets in orbit. Without something to pull us in, because also each planet has it's own attraction and repel force so that's also the second reason why the planets are stable in there own orbit and they not go far away.


Answer 2

Our sun plays a very small but important part in helping to keep all other bodies in our Solar System in their proper orbits. I say small because our solar system is also affected by other systems beyond our own. Certainly our system would still be there if the sun were to disappear, but you would find that because of its lack of gravitational effect on our system our position in the solar system would change.


Answer 3

It keeps the planets in orbit. Our sun plays a vital part in helping to keep all other bodies in our Solar System in their proper orbits. The system would not be there if the sun were to disappear because the lack of gravitation would cause everything to fly off at a tangent.

Planet Jupiter
The Solar System

How far is Jupiter from the Sun?

Because the orbit of Jupiter around the sun is not a perfect circle, its distance from the sun depends on where it is in its orbit.

At Perihelion(closest point in the orbit to the Sun): 740,573,600 km / 4.95 AU / 460,171,100 miles

At aphelion (farthest point in the orbit to the Sun): 816,520,800 km / 5.458 AU / 507,304,400 miles

The semimajor axis of its orbit is: 778,547,200 km / 5.2 AU / 483,711,400 miles

Its average distance from the sun is 5.2 AU (5.2 times the average earth/sun distance) or about 43.3 light-minutes.

Planet Mars
The Solar System

What planet is called the Red Planet?

Mars is the "Red Planet".Mars is the red planet because it looks red with various oxides of iron (hematite mostly) in very, very fine particles, and trace amounts of other elements including titanium, chlorine and sulfur.
Mars is known as the Red Planet because of its rust color. Some time in the past Mars had an atmosphere with oxygen and something happened and the oxygen all went into the soil/rock which then became oxidized. This means it is theoretically possible for us to extract oxygen from the ground if a colony was ever sent to Mars.
The red planet is the nickname given to Mars because of its slight reddish appearance. You can see the reddish appearance with your own eyes, but the redness is due to a rusty layer and it is only a few millimeters thick.
Mars...Mars, the fourth planet in our solar system and the next planet out from us, is known as the "Red Planet" because of the high levels of iron oxide present on its surface which gives the planet a red hue.
Mars. It appears red, even from earth, due to the large amount of Iron Oxides on the surface.
Mars(a little on Jupiter) is the planet which is all red. It is red because it is rusty in colour and it is made out of iron.
Mars is known as the red planet. Mars appears red, even from earth, due to the large amount of Iron Oxides on the surface - a bit like rust.
The Solar System

List all object that are part of the solar system?

From the sun outwards...

Sol (sun)

Mercury (planet)

Venus (planet)

Earth (planet) + moon (Luna)

Mars (planet) + moons (Phobos, Deimos)

Asteroid Belt (asteroids)

Ceres (Dwarf planet)*

Vesta (Protoplanet)*

Pallas (Protoplanet)*

Jupiter (planet) + moons (Io, Europe, Ganymede, Callisto, and other smaller satellites)

Saturn (planet) + moons (Titan and other smaller satellites)

Uranus (planet) + moons (Titania, Oberon, Ariel, Umbriel, Miranda, and smaller satellites)

Neptune (planet) + moons (Triton, Nereid, Proteus, and other smaller satellites)

Orcus (Dwarf planet) + moon (Vanth)**

Pluto (Binary dwarf planet, paired with Charon) + moons (Nix, Hydra)**

Charon (Binary dwarf planet, paired with Pluto) + moons (Nix, Hydra)**

Kuiper Belt (asteroids, dwarf planets)

Haumea (Dwarf planet) + moons (Hi'iaka, Namaka)**

Quaoar (Dwarf planet) + moon (Weywot)***

Makemake (Dwarf planet)***

"Snow White"--2007 OR10 (Dwarf planet)

Eris (Dwarf planet) + moon (Dysnomia)

Sedna (Dwarf planet)

Oort Cloud (asteroids, comets)

*Orbits within the Asteroid Belt

**Orbits within the inner region of the Kuiper Belt

***Orbits within the outer region of the Kuiper Belt

Please note that there are quite a few candidates for dwarf planets in the Kuiper Belt, and we're always discovering new things, even within our own "Neighborhood."

Dwarf Planet Eris
The Solar System

Where is the asteroid belt located?

The asteroid belt is located between Mars and Jupiter.

The Solar System
Space Travel and Exploration

Why were early spaceflights unmanned?

You don't risk a human life on an as-yet untested technology. First, there were test flights of the rocket/capsule combination to be sure it worked. Then several flights with chimpanzees as the cargo (the Russians used dogs). Finally, manned flight.

Planetary Science
The Solar System
The Sun

How far are the planets from the Sun?

These are the *average* distances (for Mercury and Pluto, the variation in distance is substantial. Pluto's perihelion is closer than Neptune's aphelion.)

  • Mercury is 57.9 million km (36 million miles) from the Sun (0.38 AU)
  • Venus is 108.2 million km (67.2 million miles) from the Sun (0.72 AU )
  • Earth is 149.6 million km (93 million miles) from the Sun (1 AU)
  • Mars is 227.9 million km (141.6 million miles) from the Sun (1.52 AU)
  • Jupiter is 778.4 million km (483.6 million miles) from the Sun (5.2 AU)
  • Saturn is 1.4 billion km (870 million miles) from the Sun (9.5 AU)
  • Uranus is 2.87 billion km (1.78 billion miles) from the Sun (19.2 AU)
  • Neptune is 4.5 billion km (2.8 billion miles) from the Sun (30 AU)

3 of the 5 Dwarf Planets

  • Pluto is 5.9 billion km (3.6 billion miles) from the Sun (40 AU)
  • Ceres is 414 million km (257 million miles) from the Sun (2.77 AU)
  • Eris is 10.1 billion km (6.2 billion miles) from the Sun (67.67 AU)

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