Pluto Go to Calendar page

Sun Mercury Venus Earth Mars Saturn Uranus Neptune Pluto HELP Forum ,1 ,2 ,3 ,4 ,5 , 6 , 7, 8 , 9, 10 Go to HELP Page

Average Distance From Sun:	5,913,520,000 Km
Diameter:	2274 KM
Mass:	0.002125 Earth Standard
Gravity:	0.2 Earth Standard
Atmosphere:	Nitrogen, Methane
Surface Temperature	43 Kelvin
Moons:	3, Charon, Hydra, Nix
Pluto Year:	248.54 Earth Years
Pluto Day:	-6.3872 Earth Days
Orbital eccentricity:	0.2482
Axis tilt:	122.52 degrees

Pluto was regarded as the smallest and, usually, outermost planet of the solar system. However, after a landmark IAU meeting, astronomers approved a historic new planet definition guidelines on the 24th August, 2006, and downsizing Earth's neighbourhood from nine principal heavenly bodies to eight by demoting Pluto. Pluto is now considered a Dwarf planet.
The existence of Pluto	Pluto Charon system was predicted by calculations made by Percival Lowell and located by Clyde Tombaugh on 18th February 1930, after he examined a pair of photographic plates he had exposed on the nights of Jan. 23 and 29 using the Lowell observatory's 13-inch Abbott Lawrence Lowell Telescope. The official announcement was made on March 13 1930. Pluto is also the name of the Roman god of the underworld. It was suggested by many people, but credit was given to an 11-year-old girl , Venetia Burney, from England. Among the rejected names were Cronus, Odin, Persephone, Erebos, Atlas, Prometheus and Minerva, the goddess of knowledge, which was already being used for another celestial object; and Constance, proposed by Constance Lowell — the widow of Percival Lowell, who first hypothesized Planet X.
Pluto is near the perihelion point in its orbit,	Orbits i.e. closest to the sun. For Pluto, this occurs once every 248 years, and last occurred in September 1989. The dwarf planet’s current brightness of magnitude 13.9 makes it within range of an eight-inch (or preferably larger) telescope. Currently, Pluto is located within the constellation of Serpens Cauda. A finder chart is necessary to help in identifying the dwarf planet. Pluto rotates on its side, as does Charon in its orbit around Pluto. Charon is 19,636 kilometres away from Pluto. Pluto is about 900 times fainter than the faintest star visible to the unaided eye, the most difficult to observe. It's at opposition on June 16, 2006. to read more
Pluto's highly elliptical orbit	Pluto Surface Map occasionally takes it within the orbit of Neptune, such as 1979-99. It is of low density, composed of rock and ice, with frozen methane on its surface and a thin atmosphere. Charon, Pluto's moon, was discovered 1978. It is about 1,000 km in diameter and orbits the dwarf planet at a height of about 19,600 km every 6.387 days - the same time that Pluto takes to spin on its axis. Some astronomers have suggested that Pluto was a former moon of Neptune that escaped. Charon remains permanently above the same place on Pluto.
Pluto has recently	retaken its posision as furthest planet (now considered a dwarf planet) from the Sun,On 11 February 1999 at 11:22 UT (6:22 a.m. EST), Pluto passed Neptune as the furthest planet from the Sun once again and will remain so until 5 April 2231. . As an update to this the `planet` is now regarded as as part of the Kuiper-belt family; and now not looked upon as a true planet.
Charon Charon Mean distance from Pluto (km) 19,636 Sidereal orbit period (days) 6.38725 Sidereal rotation period (days) 6.38725 Orbital inclination to Pluto (deg) 0.0 Orbital eccentricity 0.0 Equatorial radius (km) 603.6, ± 5 km Mass 0.003188 Earth Standard Mass (1021 kg) 1.90 Mean density (kg/cm3 ) 1.73 ± 0.08 Atmosphere: None Surface temperature 53 Kelvin Surface gravity (m/s2 ) 0.21 Escape velocity (km/s) 0.61 Albedo 0.5 Apparent visual magnitude 16.8 I n Greek mythology, Charon is the ferryman for the dead. The souls of the deceased are brought to him by Hermes, and ferries them across the river Acheron. He only accepts the dead which are buried or burned with the proper rites, and if they pay him an obolus (coin) for their passage…
Charon Surface Map The discovery image of Charon was taken on July 2, 1978. By measuring the distance between Pluto and the moon and knowing the orbital period, it was possible to calculate their mass. During the 1980’s, Earth crossed the orbital plane of Charon and a series of `eclipses` of the Pluto-Charon system occurred which led to the first accurate determination of the diameters of Pluto and Charon. Charon’s surface composition is different from Pluto's. The moon appears to be covered with water-ice rather than nitrogen ice. This difference, as well as the difference in density shows that Pluto and Charon formed independently.
On July 11 2005	, Scientists from MIT (Cambridge, Mass.) and Williams College (Williamstown, Mass.) observed Pluto's moon, Charon, occult the star C313.2. The MIT-Williams consortium used various telescopes around Chile, included the 8-metre Gemini South on Cerro Pachon, the 2.5-metre DuPont Telescope at Las Campanas Observatory, and the 0.8-metre telescope at the Cerro Armazones Observatory to observe the rare alignment. The resulting measurements, to unprecedented accuracy, of Charon's size and possible atmosphere provide insight into the way that this distant world may have formed. to read more
The upcoming New Horizons Pluto-Kuiper Belt mission	is designed to help us understand worlds at the edge of our solar system by making the first reconnaissance of Pluto and Charon – a "double dwarf planet" system and the last in our solar system to be visited by spacecraft. The mission would then visit one or more Kuiper Belt Objects, in the region beyond Neptune. New Horizons was launched in January 2006, and will swing past Jupiter for a gravity boost and scientific studies in February 2007, and reach Pluto and its moon, Charon, in July 2015. Then the spacecraft would head deeper into the Kuiper Belt to study one or more of the icy mini-worlds in that vast region, at least a billion miles beyond Neptune's orbit. Sending a spacecraft on this long journey could help us answer basic questions about these bodies’ surface properties, geology, interior makeup, and atmospheres. to read more
After the discovery of Pluto	in 1930, the dwarf planet drew considerable scrutiny. Unfortunately, modern analysis shows that many Pluto observations from the 1930s and 40s were unreliable. Measurements of Pluto's brightness made from photographic plates were off by as much as 1 magnitude because of errors in the brightness of comparison stars. This true-colour map shows how Pluto's surface varies in reflectivity. This map was created from data obtained at the McDonald Observatory in Texas during periods when Pluto was being partially eclipsed by its moon Charon. Because the two worlds are tidally locked, the map only shows Pluto's Charon-facing hemisphere. To know Pluto's true brightness during those earlier times, Luke T. Smith and Bradley E. Schaefer re-measured photographic plates from 1933-34 using modern equipment and have produced an accurate light curve for the Kuiper Belt objects in the years shortly after its discovery.... The two astronomers then compared Pluto's brightness to models developed by Marc W. Buie (Lowell Observatory). The light curve shows Pluto’s changing brightness over its 6.39-day rotation period. The light curve was created from photographic plates taken in 1933-34, but, Pluto was 0.05 magnitudes fainter than expected in the early 1930s. "We thought Pluto would be brighter than it actually was"- Luke Smith. Pluto's highly eccentric orbit causes significant brightness changes as well as the Kuiper-belt object showing different surfaces towards the Earth. When Pluto comes close to the Sun, it also forms a thin atmosphere. The gases freeze back on the surface of Pluto and its moon Charon when Pluto is far from the Sun. After accounting for Pluto's greater distance from the Sun in the 1940s and Earth's viewing geometry, Pluto turns out to be 0.05 magnitudes (5 percent) dimmer than Buie's model predicts. The key to explaining Pluto's faintness during this period lies in the planet's unusual spin axis, which is tipped by 120 degrees relative to the plane of Pluto's orbit. In the 1930s, Pluto's southern hemisphere was pointed almost directly toward the Sun, whereas in more recent decades, Pluto's equator has been aimed toward the Sun. In 1933-34, Pluto was approaching the Sun on its highly eccentric orbit at a distance of 40 astronomical units. With the Kuiper-belt object's southern hemisphere basking in perpetual sunlight, frosts of volatile compounds such as methane probably vaporized to form a rarefied atmosphere, and then condensed on the darker and colder northern hemisphere, which was hidden from view. With less ice on its Sun-facing side, Pluto would have grown slightly darker. "This is the only way to study Pluto that far back. Pluto's surface would have been different, and now we're starting to get a handle on that" - Bradley E. Schaefer. "We have seen implications of atmospheric changes from frost formation and vaporization directly as changes in its light curve. We know Pluto has an atmosphere, but there's a lot of work to understand how Pluto's atmosphere changes." - Luke Smith.
Pluto Map	The latest global map was produced using data obtained by Hubble's Advanced Camera for Surveys (ACS) between July 2002 and June 2003. The detailed map shows areas likely to be methane frost and a bright spot perhaps made of frozen carbon monoxide. An unusual bright spot near the centre of the global map could indicate the presence of carbon monoxide to read more
Using NASA's Hubble Space Telescope	to view the dwarf planet in our solar system, astronomers discovered Pluto may have not one, but three moons. If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system; Kuiper Belt Objects with satellite systems; and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune's orbit. Expand (25kb, 1023 x 549) "If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite" - Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery. Pluto was discovered in 1930. Charon, Pluto's only confirmed moon, was discovered by ground-based observers in 1978. The Kuiper Belt objects resides about 3 billion miles from the sun in the heart of the Kuiper Belt. "Our result suggests other bodies in the Kuiper Belt may have more than one moon. It also means planetary scientists will have to take these new moons into account when modelling the formation of the Pluto system" - Alan Stern of the Southwest Research Institute, Boulder, Colorado. Stern was co-leader of the research team. The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed approximately 27,000 miles away from Pluto. The objects are roughly two to three times as far from Pluto as Charon. The team plans to make follow-up Hubble observations in February to confirm the newly discovered objects are truly Pluto's moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2. The Hubble's Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. The candidates are roughly 5,000 times fainter than Pluto. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto. The team looked long and hard for other potential moons around Pluto. "These Hubble images represent the most sensitive search yet for objects around Pluto. It is unlikely that there are any other moons larger than about 10 miles across in the Pluto system" - team member Andrew Steffl of the Southwest Research Institute. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.
The Pluto system	as we understand it today, with Charon orbiting in the innermost position, and the two new satellites orbiting somewhat farther out. Positions and orbits are shown as seen from Earth for 15 May 2005. Very little is known about these new bodies at this time. We know their brightness, but not their rotation periods, their colours, their surface reflectivity, or their surface compositions. Both satellites appear to stray no farther than 3 arcseconds from Pluto; for reference, Charon orbits no farther than 0.9 arcseconds from Pluto. By comparing the positions of the satellites in different images on different dates, we find that the positions are consistent with both S/2005 P 1 and S/2005 P 2 having orbits that are nearly circular and which lie in Pluto’s equatorial plane. This is a preliminary conclusion, but if it holds up, then the orbital semi-major axes of P1 and P2 are near 64,700 ±850 and 49,500 ±600 km, respectively. These semi-major axes in turn correspond to orbital periods of approximately 38.2 ±0.8 and 25.5 ±0.5 days, respectively. The brighter satellite, S/2005 P 1, has a V-band magnitude of about 23.0. Because we do not yet know its surface reflectivity, we cannot definitively calculate its exact size. But by estimating surface reflectivity and using its distances from the Earth and Sun at the time of the HST observations, we can determine the range of plausible sizes it might have. Assuming surface reflectivity ranging from 4% (like the darkest known KBOs), to 15% (like many KBOs), to 35% (like Charon), this is what we find: Assumed Reflectivity Approximate Diameter 04% 160 km 15% 80 km 35% 52 km S/2005 P 2 is about 25% fainter than S/2005 P 1, so could be a 10% to 15% smaller than S/2005 P 1, assuming they have the same surface reflectivity. Despite the various uncertainties in what we know about P1 and P2 so far, and regardless of their surface reflectivity, these bodies are clearly very small compared to both Pluto (2284 km diameter) and Charon (1192 km diameter). Indeed, it is unlikely that either object has a mass larger than 3/10,000th of Pluto’s or 3/1000th of Charon’s.
21st June 2006	Pluto II Nix = S/2005 P 2 Pluto III Hydra = S/2005 P 1
28th January 2005	Pluto and its moon Charon is unique in our solar system because Charon is nearly half the size of the dwarf planet it orbits, whereas the diameters of most moons are just a fraction of the size of their parent planet. New findings shed new light on how the pairing formed and support the hypothesis that a large cosmic collision could have generated the moon. The object that hit Pluto probably measured between 1600 and 2000 kilometres in diameter, and struck the dwarf planet at a speed of 1 kilometre per second, and may have come from the Kuiper Belt . This collision probably occurred between 4.4 - 4.5 billion years ago because at that time Kuiper Belt objects were circling the Sun at relatively slow speeds. However, some researchers contend that Pluto's gravity could have captured a stray object from the nearby Kuiper belt without a collision.
	Latest News on Pluto and its moons (Charon, Nix, Hydra) to read more

Return to Solar Database