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View Full Version : Hubble Finds Xena's Only a Little Bigger Than Pluto



Fraser
2006-Apr-12, 05:11 PM
SUMMARY: The powerful Hubble Space Telescope has finally been brought to bear on the newly discovered 10th planet (aka Xena), to help answer the question: is it really bigger than Pluto? Hubble is the only instrument that can make an actual visible light observation of Xena's diameter. Hubble found that Xena is is about 2400 km (1,490 miles) across, which makes it only 113 km (70 miles) larger than Pluto. This makes the 10th planet unusually bright, probably covered in brilliant white methane snow.

View full article (http://www.universetoday.com/am/publish/2003_ub313_large.html)
What do you think about this story? post your comments below.

hiro
2006-Apr-12, 05:47 PM
If the object itself is bigger than Mercury, then I think it should be accepted as a planet

antoniseb
2006-Apr-12, 05:56 PM
If the object itself is bigger than Mercury, then I think it should be accepted as a planet

Hi Hiro, welcome to the BAUT forum.

I think that the planet rules might not be as simple just diameter, however Xena is not bigger than Mercury. It is not even close.

raghunaram@yahoo.com
2006-Apr-13, 12:22 PM
If i am not wrong the Sub Committe Setup by IAU is yet to conclude definition of planet. Hence let us not jump to our conclusion based on newly discovered fact.

N.Sri Raghunandan Kumar,
Secretary General,
Planetary Society, India

baric
2006-Apr-13, 07:00 PM
If i am not wrong the Sub Committe Setup by IAU is yet to conclude definition of planet. Hence let us not jump to our conclusion based on newly discovered fact.

N.Sri Raghunandan Kumar,
Secretary General,
Planetary Society, India

Well, this is a public discussion forum, so I think it's OK for people to jump to conclusions as long as we remember that none of the opinions expressed carry the force of the IAU.

Ymir
2006-Apr-13, 09:19 PM
If it has an orbit around our sun, then it could be considered as a planet.
I don´t know what planet rules exist, but I believe size is not the issue... ;)

Tim Thompson
2006-Apr-14, 12:43 AM
The following is the text of an E-mail message I sent to our club's E-mail list a few days ago. It seems relevant here too.

Last year, as some of you might recall, it was determined by a Caltech team that 2003-UB313 was bigger than Pluto, as big as 1.5 times the size of Pluto. Obviously, it was quickly identified as a candidate 10th planet. The full report on it's discovery as a candidate 10th planet appeard in December ("Dicovery of a Planetary sized object in the scattered Kuiper Belt"; M.E. Brown, et al., Astrophysical Journal Letters 635: L97-L100, 2005 Dec 10).
You can access a text abstract & PDF copy here:
http://cul.arxiv.org/abs/astro-ph/0508633

Today, a preprint was released reporting precision observations of 2003-UB313 using the Hubble Space Telescope ("Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope"; M.E. Brown, et al., 11 April 2006 [submitted to ApJ letters]). It is still most likely bigger than Pluto, but now by only about 5%. It is estimated to be 1.05 times the size of Pluto, still big enough to be a planet, as long as Pluto is big enough. The reason for the dramatic shrinking is that earlier size estimates were based on the assumption of a surface much darker than it really is, much less reflective.
You can access a text abstract & PDF copy here:
http://cul.arxiv.org/abs/astro-ph/0604245

On the question of planethood, that will eventually be settled by the International Astronomical Union. This comes from Mike Brown's webpage ( http://www.gps.caltech.edu/~mbrown/planetlila/ ):


A special committee of the International Astronomical Union (IAU) was charged with determining "what is a planet."
Sometime around the end of 2005, this committee voted by a narrow margin for the "Pluto and everything bigger" definition, or something close to it.
The executive committee of the IAU then decided to ask the Division of Planetary Sciences (DPS) of the American Astronomical Society to make a reccomendation.
The DPS asked their committee to look in to it.
The DPS committee decided to form a special committee.
Rumor has emerged that when the IAU general assembly meets in August in Prauge they will make a decision on how to make a final decision!

The official word (so far) from the IAU is that they will publish their definition of a planet in September, 2006. As long as they continue to accept Pluto as a planet (and I think it's extremely likely that they will), then it's a cinch that 2003 UB313 will get a real name, and become the 10th planet, before the year 2006 is over.

t@nn
2006-Apr-16, 01:01 PM
Having a planet named "Xena" seems odd to me. Breaks the convention of naming the planets after Greek and Roman gods. Do you think it will be renamed if and when it is officially designated a planet?

Eroica
2006-Apr-16, 03:06 PM
Having a planet named "Xena" seems odd to me. Breaks the convention of naming the planets after Greek and Roman gods. Do you think it will be renamed if and when it is officially designated a planet?
Earth isn't named after a Greek or Roman god, and it's definitely a planet!

raghunaram@yahoo.com
2006-Aug-19, 06:29 PM
Freinds Here i am like to present my interpretation of the Draft Resolution 5 for easy understanding.

Words in Red Colour and Magenta are my additions trying to trace the origin of various reports which we are reading in various websites and newspapers.

My sole intention is to carry forward my previous article, with an effort to make people understand the thing which would revolutionise our world.

My Interpretation of Draft Resolution 5 for GA-XXVI: Definition of a Planet

Introduction :

Contemporary observations are changing our understanding of the Solar System, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation “planets”.

Origin of Word Planet is explained here:
The word “planet” originally described “wanderers” that were known only as moving lights in the sky.

Reason of Definition and Upper Limit can be understood from this part of definition:
Recent discoveries force us to create a new definition, which we can make using currently available scientific information. (Here we are not concerned with the upper boundary between “planet” and “star”.)

Here we can see the exact words used to define the word planet under this resolution

Definition:
The IAU therefore resolves that planets and other Solar System bodies be defined in the following way:

(1) A planet is a celestial body that
(a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(b) is in orbit around a star, and is neither a star nor a satellite of a planet.


Explanation : Shape : This generally applies to objects with mass above 5 x 1020 kg and diameter greater than 800 km. An IAU process will be established to evaluate planet candidates near this boundary.

Satellite of a Planet : For two or more objects comprising a multiple object system, the primary object is designated a planet if it independently satisfies the conditions in this draft. A secondary object satisfying these conditions is also designated a planet if the system barycentre resides outside the primary. Secondary objects not satisfying these criteria are “satellites”.

Under this definition, Pluto’s companion Charon is a planet, making Pluto-Charon a double planet.


Classical Planets and other sun orbiting planetary objects have been distinguished here – Recognition to ceres as planet had been made – Here

(2) We distinguish between the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane, and other planetary objects in orbit around the Sun.
All of these other objects are smaller than Mercury. We recognize that Ceres is a planet by the above scientific definition.
For historical reasons, one may choose to distinguish Ceres from the classical planets by referring to it as a “dwarf planet.”


Explanation : Dwarf Planet : If Pallas, Vesta, and/or Hygeia are found to be in hydrostatic equilibrium, they are also planets, and may be referred to as “dwarf planets”.


Recognition of Pluto – Orbital Period – Highly Inclined Orbits – Eccentricities along with new word "pluton" is talked herein

(3) We recognize Pluto to be a planet by the above scientific definition, as are one or more recently discovered large Trans-Neptunian Objects.

In contrast to the classical planets, these objects typically have highly inclined orbits with large eccentricities and orbital periods in excess of 200 years.

We designate this category of planetary objects, of which Pluto is the prototype, as a new class that we call “plutons”.

Reference to Minor Planets had been made here which now replaced by the word “Small Solar System Bodies” :

(4) All non-planet objects orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.

Explanation : Small Solar System Bodies: This class currently includes most of the Solar System asteroids, near-Earth objects (NEOs), Mars-, Jupiter- and Neptune-Trojan asteroids, most Centaurs, most Trans-Neptunian Objects (TNOs), and comets. In the new nomenclature the concept “minor planet” is not used.

Source:IAU, Kindly refer to IAU proceedings at Prague for more information and original copy of this draft resolution.

I do hereby urge the scientific community all over the world to execute a mass movement of education among student community and general public before some selfish people with vested interest take advantage of ignorance in general public.

thank you

N.Sri Raghunandan Kumar
Secretary General,
Planetary Society, India
9347511132

jkmccrann
2006-Aug-19, 09:25 PM
I think when you write in statements in reference to Pluto you should colour that script in dark blue - I hear its quite dark out there! ;)