IF Pluto is a comet or drwarf-planet, IS there another planet after pluto?

Question

I am not sure. Cause I just answered a question and I said 8. (PLUTO"S GONE!!! :( )

Answer 1

We know of 1000 objects as far out as Pluto or further out than Pluto. Whether they are planets is a matter of definition but space beyond Neptune is not as empty as was once thought.

What happened last week:

Pluto got reclassified as a dwarf planet (a new category of objects in our Solar System), along with Ceres Charon, Xena and a dozen others, mostly Trans-Neptunian Objects like Charon and Xena, but three of them are, like Ceres, asteroids lying between Mars and Jupiter.

Why did it happen?

There is understandable dismay at Pluto being demoted in status but people need to understand the reasons the IAU had to grapple with definitions and categories at this time:

(1) in 1930 we knew of just one body lying beyond the orbit of Neptune. Now we know of more than 1000

(2) we are discovering asteroids at a rate of 5000 a month

(3) we now know of 200+ extra-solar planets orbiting 170+ other stars, some of which we now know to have asteroid belts

Could they change the categories again?

It is conceivable the IAU may create more categories in the future in the light of more discoveries, The moment we find an extra-Solar System planet with extra-terrestrial life on it, for example, I would expect Habitable Zone Planet to be a new category and only Earth and Mars of our local 8 planets to be in it.

We already have the distinction between terrestrial planet (the inner 4 planets) and gas giant (the outer 4 planets) and are assessing new extra-Solar-System planets in the light of that distinction and a new category name for the informally-named "hot Jupiters" (i.e. large planets orbiting near to their star at less than 1 AU distance) of which we know several, may not be far away,

As science expands its knowledge, it needs more concepts and categories with which to describe that knowledge, That is perfectly normal and should neither surprise nor alarm us,

Has it happened before?

Creating new categories and reclassifying known objects in the light of them has happened before: in the 19th Century when the number of planets was pruned from 11 to 7 out of concern that being consistent and admitting other, newly discovered bodies to the planetary club that were similar to the ones they chose to kick out instead would have meant the number of planets could rapidly start to escalate and mushroom out of control,

Learning from history

To understand what is going on now, it helps to understand what went on then,

The number of bodies in the Solar System known to astronomers has been burgeoning for a long time now, but the general public seems unaware of this, given the way people blithely talk of Ceres (discovered 1801) Charon (discovered 1978) and Xena (discovered 2003) having "just been discovered",

There was a similar definitions crisis in the early 19th century and again in the mid-19th Century as the number of known objects in the Solar System started to grow and grow,

By 1807 the 8 Solar System bodies known to classical astronomy (the Sun, the Earth, our Moon and the 5 classical planets known from antiquity, Mercury, Venus, Mars, Jupiter, and Saturn) (1 star, 6 planets, 1 moon) had grown to 26. Uranus was found in 1781 making 7 planets. There were 4 Jovian moons, 7 Saturnine moons and 2 Uranian moons, 14 in all

And then there was the discovery of the first four asteroids. These were 1 Ceres on January 1, 1801, 2 Pallas on March 28, 1802, 3 Juno on September 1, 1804, and 4 Vesta on March 29, 1807,

What were astronomers to call these new objects? They weren't moons as they rotated around the Sun, so they had to be planets, didn't they? As there was, initially, no other category but moons or planets to put them in.

After 2 Pallas was discovered though, Sir William Herschel (the discoverer of Uranus) coined the term "asteroid" meaning "star-like"), in 1802.

But Ceres was meantime assigned a planetary symbol, and remained listed as a planet in astronomy books and tables (along with 2 Pallas, 3 Juno and 4 Vesta) for about half a century until further asteroids were discovered.

So we now had 1 star, 11 planets and 14 Moons, the beginnings of a distinction between major and minor planets and a sense of unease as to what we would do if more asteroids were discovered as the first four were all disappointingly small in size, so did they really belong in the planetary club? (Similar doubts were expressed about Pluto, right from the outset in 1930,)

38 years pass and then in 1845 the asteroid 5 Astraea is discovered and on September 23, 1846 the planet Neptune and a mere 17 days later on October 10, 1846, Neptune's moon, Triton. (We now have 1 star, 12 Planets 15 Moons and 1 non-planetary Asteroid.)

The pace of discovery then starts to really hot up. Four more asteroids in nine months: 6 Hebe on July 1, 1847, 7 Iris on August 13, 1847, 8 Flora on October 18, 1847, and 9 Metis April 25, 1848

Then on September 16, 1848 an 8th moon of Saturn called Hyperion is discovered,

Plus a further 6 asteroids are found in just over two years: 10 Hygiea on April 12, 1849, 11 Parthenope on May 11, 1850, 12 Victoria on September 13, 1850, 13 Egeria on November 2, 1850, 14 Irene on May 19, 1851 and 15 Eunomia on July 29, 1851.

And on October 24, 1851 a 3rd and a 4th moon of Uranus: called Ariel and Umbriel were discovered.

So now we had 42 objects: 1 star 12 planets 18 moons and 11 asteroids. If the latest asteroids were all to be regarded as planets, making a total of 23 planets (and 10 Hygiea was bigger than 3 Juno, just like Xena is bigger than Pluto), it was likely to start getting silly (by 1868 the number of asteroids was to rise to 107 and Victorian schoolchildren would have needed a massive 115-word mnemonic to remember all the names).

The unease grew to a crisis, a redefinition was clearly necessary and an inevitable decision was taken to regard all 15 asteroids as a separate category from planets and Ceres, Pallas, Juno and Vesta were kicked out of the planetary club, just like Pluto has been kicked out now.

There are some clear parallels between the situation in the 1850s and the situation now, Four under-sized runts had obtained planetary status, with seemingly more to follow as they were discovered, creating an overwhelming feeling among astronomers that the currency would be devalued if all these further objects were to then be automatically awarded planetary status. So they cried Whoa! And called a halt. And created a new category, Just like the IAU has now done,

SO HOW MANY OBJECTS HAVE WE GOT IN THE SOLAR SYSTEM NOW?

Stars: 1

Planets: 8

Moons: over 80 known moons of the dwarf planets, asteroids and other small solar system bodies.

(The asteroid 87 Sylvia has 2 moons for example as does the Kuiper Belt Object KBO 2003 EL61.)

AND another 162 moons orbiting around planets: Mercury has none, Venus has none, Earth has 1, Mars has 2, Jupiter has 63, Saturn has 56, Uranus has 27, Neptune has 13.

Kuiper Belt Objects: over 800 (all discovered since 1992).

Trans-Neptunian Objects: over 1000 (includes the 800+ KBOs) i,e, there are 200+ in the Scattered Disk and the Oort Cloud.

Asteroids: Hundreds of thousands of asteroids have been discovered within the solar system and the present rate of discovery is about 5000 per month. As of July 23, 2006, from a total of 338,186 registered minor planets, 134,339 have orbits known well enough to be given permanent official numbers. Of these, 13,242 have official names.

Current estimates put the total number of asteroids above 1 km in diameter in the solar system to be between 1.1 and 1.9 million

So you can see

(a) why some definitions are needed and why reclassification is necessary

(b) how totally unaware of the state of scientific knowledge the general public is and how uninformed people are when they get excited at tales of "3 new planets being discovered" and wonder if there might perhaps be more where those came from,

Finally, these issues need to be seen in the context of the 205 extra-solar planets we now know to exist and the asteroid belts that have now been detected in some of those stellar systems,

Consistency being a desirable thing to achieve in science, whatever definitions and categories the IAU now adopt, they need to be applicable to every star with other objects in orbit around it, throughout the entire universe, That is the context in which Pluto's status is now being discussed,

Answer 2

Another planet beyond Pluto is highly remote. We can tell how much force is effecting Plutos and other planets orbits by studing thier orbits. We knowit of force that Pluto has quite a bit of force acting on it that is opposite the sun. This force turned out not be be another planet..but all the objects in the Kuiper blet. There is a lot of mass inthe Kuiper belt, and thi mass adds up and effects Plutos orbit. This mass is why Percival Lowell thought there was a planet "X", but instead of one large planet it turn out that it was millions of small objects nearby instead of one large one farther out.

As far as other Dwarf planets...there will be many of these found this has been known by astronomers almost since the discovery of Pluto.

The Planets as we know them today.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Neptune is the fartherst planet, and Pluto is beyond Neptune.

Answer 3

Oh yes, there will be more planets discovered.. My question about Pluto is.. however, if Pluto is not a planet what is it... One cannot just call it a dwarf planet because that would still make it a planet.. Is it a star?

Answer 4

Pluto is twinned with Charon and both take the same orbital path. Beyond those two are a number of 'dwarf' planets including 2003 UB313 also nicked named 'Xena'.

Answer 5

YES. We live on one planet in one solar system in one galaxy in the universe. I believe there are millions of other planets. I mean scientist know that other galaxies exist so are we so vain that we think this is the only galaxy with planets. The universe goes on forever. It seems like a waste to only have 8 planets in a huge universe all alone.

Answer 6

After Neptune is the dwarf planet Pluto, then the planetoids Charon, and Xena.

Answer 7

there is a large gravitational force after Pluto that disrupts its orbit this was thought to be a sun for awhile however it would have been discovered by now; it is largely considered to be a massive planet in very a wide orbit this is why it has eluded detection for so long of course this is still not confirmed

Answer 8

Under the new definition, we know of no planet orbiting the Sun that is outside the orbit of Neptune, only dwarf planets and other small planetary objects.

Answer 9

no one knows what happens in the sky. according to the latest information pluto is not a planet. i still don belive that mars is a planet. you may see in a magazine about mars material. did they really go to the mars and collect the sample? we cant decide its material by the comets

Answer 10

a few hundred

at least

i mean only jupiter and saturn got like 50 satelites that fit

then about in all the cuiper belt

Answer 11

UB 313 might be a planet.....