Explanation: A fifth moon has been discovered orbiting Pluto. The moon was discovered earlier this month in images taken by the Hubble Space Telescope in preparation for the New Horizons mission's scheduled flyby of Pluto in 2015. Pictured above, the moon is currently seen as only a small blip that moves around the dwarf planet as the entire system slowly orbits the Sun. The moon, given a temporary designation of S/2012 (134340) 1 or just P5 (as labeled), is estimated to span about 15 kilometers and is likely composed mostly of water-ice. Pluto remains the only famous Solar System body never visited by a human-built probe and so its origins and detailed appearance remain mostly unknown.
I find the barycenter article interesting, and then to find another moon... What to call it now? A Binary Dwarf Planet System?
Evidently Pluto tried very hard to "clear its path" and become a bigger planet...it just had not accomplished that...
"You have my curiosity, Bond-San"....You Only Live Twice.
Very interesting Discovery article, and I think it makes sense that Pluto and Charon could be binary. But it also seems that Charon, despite its mass, should be a satellite of Pluto. I guess for now we'll just take Charon as a moon.
Boomer12k wrote:
Evidently Pluto tried very hard to "clear its path" and become a bigger planet...it just had not accomplished that...
:---[===] *
Maybe i'm just speculating; but none of the planets have cleared their orbits! Otherwise we wouldn't have to worry about meteors! And Neptune still has pluto crossing into it's orbit! Yaa Pluto; PeeWee Power! Go little planet!
Boomer12k wrote:
Evidently Pluto tried very hard to "clear its path" and become a bigger planet...it just had not accomplished that...
Maybe i'm just speculating; but none of the planets have cleared their orbits! Otherwise we wouldn't have to worry about meteors! And Neptune still has pluto crossing into it's orbit! Yaa Pluto; PeeWee Power! Go little planet!
In the end stages of planet formation, a planet will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence. A large body which meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which shares its orbital neighbourhood with Kuiper belt objects such as the plutinos. The IAU's definition does not attach specific numbers or equations to this term, but all the planets have cleared their neighbourhoods to a much greater extent than any dwarf planet, or any candidate for dwarf planet.
The phrase may be derived from a paper presented to the general assembly of the IAU in 2000 by Alan Stern and Harold F. Levison. Stern, currently leading the NASA New Horizons mission to Pluto, disagrees with the reclassification of Pluto on the basis that—like Pluto—Earth, Mars, Jupiter and Neptune have not cleared their orbital neighbourhoods either. Earth co-orbits with 10,000 near-Earth asteroids (NEAs), and Jupiter has 100,000 Trojan asteroids in its orbital path. "If Neptune had cleared its zone, Pluto wouldn't be there", he now says.
However, in 2000 Stern himself wrote, "we define an überplanet as a planetary body in orbit about a star that is dynamically important enough to have cleared its neighboring planetesimals ..." and a few paragraphs later, "From a dynamical standpoint, our solar system clearly contains 8 überplanets"—including Earth, Mars, Jupiter, and Neptune. Most planetary scientists understand "clearing the neighborhood" to refer to an object being the dominant mass in its vicinity, for instance Earth being many times more massive than all of the NEAs combined, and Neptune "dwarfing" Pluto and the rest of the KBOs.>>
Exciting discovery! i found it a little odd seeing a North/East legend on the photo. Is there a convention for north, south, east and west used in space? What kind of directional conventions are used for space or envisioned for space travel?
JuanAustin wrote:
i found it a little odd seeing a North/East legend on the photo. Is there a convention for north, south, east and west used in space? What kind of directional conventions are used for space or envisioned for space travel?
A sky map is a mirror image of an Earth map.
When you look up in the sky in the Northern Hemisphere
to observe the planets near zenith: North is up and East is to you left.
WallyBalls wrote:I'm pretty sure I saw this new moon the other night with my Edmund 3" reflector.
I'm surprised you even saw Pluto at all.
Directional conventions in celestial images
Posted: Mon Jul 16, 2012 10:04 pm
by Anthony Barreiro
neufer wrote:
JuanAustin wrote:
i found it a little odd seeing a North/East legend on the photo. Is there a convention for north, south, east and west used in space? What kind of directional conventions are used for space or envisioned for space travel?
A sky map is a mirror image of an Earth map.
When you look up in the sky in the Northern Hemisphere
to observe the planets near zenith: North is up and East is to you left.
Please allow me to elaborate slightly on Neufer's answer:
North / South directions in celestial images generally refer to Earth's equatorial plane and the celestial north and south poles. On the surface of the earth north and south are called latitude; in the sky north and south are called declination. The celestial equator, the sky directly overhead from Earth's equator, has a declination of 0 degrees. The north celestial pole is declination + (plus) 90 degrees. Conveniently Polaris, the North Star, is less than one degree from the north celestial pole. The south celestial pole, declination - (minus) 90 degrees, is in the constellation Octans.
East / West directions in celestial images generally refer to the point where the ecliptic, the plane of Earth's orbit around the Sun, crosses the celestial equator from south to north, i.e. the point where the Sun is in the sky at the moment of the Spring equinox. On the surface of the earth east and west are called longitude; in the sky east and west are called right ascension. (Just as the decision to make the Royal Observatory in Greenwich England the zero point for longitude was completely arbitrary, the decision for the zero point of right ascension was also completely arbitrary.) Right ascension is measured in hours. The full circle all the way around Earth's sky has 24 hours of right ascension. The point of the Spring equinox (also called the first point of Aries), in the constellation Pisces, is designated 0 hours right ascension. Summer solstice is 6 hours right ascension, Fall equinox is 12 hours right ascension, Winter solstice 18 hours right ascension.
As Neufer said, when we're looking up into the sky (or at a celestial image or map) East and West are reversed relative to directions when we're looking down at a map of the surface of the Earth.
To slightly complicate matters, sometimes astronomers use directions relative to Earth's ecliptic plane rather than the equatorial plane, or relative to the plane of the milky way galaxy. But this would always be mentioned. If you see simply "North" and "East" as in this image, you can safely assume that these directions are relative to Earth's equatorial plane.
a little confused, perhaps by my lack of stellar education (take it as a pun, if you like...) considering the relative small size of pluto, how does it manage to keep (now) five moons circling in orbit? i understand the moons are of small size and limited composition, but how did pluto manage to collect these objects with such little gravity/mass? by comparison, why does earth not contain dozens of moons, having a higher probability of collecting a "circle of friends" due to our larger size and mass?
bookittyrun wrote:
a little confused, perhaps by my lack of stellar education (take it as a pun, if you like...) considering the relative small size of pluto, how does it manage to keep (now) five moons circling in orbit? i understand the moons are of small size and limited composition, but how did pluto manage to collect these objects with such little gravity/mass? by comparison, why does earth not contain dozens of moons, having a higher probability of collecting a "circle of friends" due to our larger size and mass?
The Earth's Moon has "cleared the neighbourhood" of its own orbital zone.
More distant orbitals (near to 3 to 6 times the monthly lunar period) would have been strongly influenced by Solar tidal forces.
Objects within Earth's geostationary orbit were pulled into the Earth by ocean tides.
Consider this; Scientists are searching of planets around other stars! Are they going to classify them as planets and dwarf planets as they are found? When a theoretical alien is counting planets around Sol are they going to classify them as we do? What does Planet mean? Wiki
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AdsAnswer:."Planet" means "wanderer"--a reference that contrasts planets from stars. If you look at the sky, planets can change position relative to the other stars in the sky. Stars tend to be grouped in a fixed pattern.
Fifth Moon Discovered Orbiting Pluto
And Neptune still has pluto crossing into it's orbit! 
Yaa Pluto; PeeWee Power! Go little planet! 
What does Planet mean? Wiki 
