Moons of Pluto. Charon and the planet's small satellites


Satellite system Pluto is very compact, the three satellites occupy only 3% of the stability region where satellites with direct motion can exist and which is 2.2 million km. It can be assumed that the satellites were formed as a result of the collision of Pluto with a body on early stage formation of the solar system.

Discovery of Charon. Pluto's moon Charon was discovered in 1978 by Christie and Harrington in an image taken at the Naval Observatory, with the moon barely visible as a hump in the image of the planet. Maximum angular distance between the planet and the satellite is 0.9, so observing the system from Earth is very difficult. The main parameters of the Pluto-Charon system were obtained during mutual eclipses and occultations of the planet and satellite, which are observed when the plane of Charon’s orbit passes near the line connecting the Sun and Pluto. Such events repeat once every 124 years, which is equal to half the period of Pluto's revolution around the Sun. We witnessed these rare events that began in 1985 and continued until 1990. Photometric observations of the mutual passages of objects and their shadows across the planet's disk and satellite allowed us to most accurately determine the parameters of the system.
It turned out that it makes sense to consider the Pluto-Charon system as a binary system. Pluto and Charon are spherical bodies with diameters of 2245.4 and 1200 km. The ratio of the mass of the satellite to the mass of the planet is 0.15, which is the largest in the solar system, so both bodies revolve in circular orbits around general center mass per distance 19130 km apart from each other with a period of 6.38 days. Each body rotates around own axis with the same period. The rotation axes are perpendicular to the plane of Charon's orbit. Pluto and Charon are constantly oriented towards each other with the same sides. Thus, the system is considered to have completely completed its evolution - it is doubly synchronized - synchronization of the rotation of the planet and satellite with orbital motion.
Mass of the Pluto-Charon system is 1.47 x 10 25 g, which is about 0.00247 Earth mass. Charon is almost twice as dark as Pluto. Albedo of Pluto 60 %, albedo of Charon - 37%. Average Charon density 1.2-1.3 g/cm3, while Pluto 1.8-2.1 g/cm3. From this we can conclude that if the composition of Pluto is rocks and water ice, then Charon is an analogue of the icy satellites of Saturn. This difference indicates the independent origin of these celestial bodies. Thus, the question of the origin of Pluto and the Pluto-Charon pair remains open.

Discovery of the small satellites Nix and Hydra. On October 31, 2005, the International Astronomical Union Circular (IAUC 8625) announced the discovery of two new moons of Pluto. The objects, tentatively named S /2005 P 1 and S /2005 P 2, were observed using space Hubble telescope and on May 15 and 18 this year at a distance of 2? until 3? from the center of Pluto and had apparent magnitudes 22 and 23. Provided that the orbits are circular and located in the plane of Charon's orbit, their sizes and periods of revolution of the satellites around Pluto were calculated. For the first satellite S/2005 P1, which was named Hydra, the semimajor axis of the circular orbit is approximately 64,700 km, the period P = 38.2 days. For the second satellite S/2005 P 2 Nyx (Nikta), the semimajor axis of the circular orbit is 49400 km, and the orbital period is 25.5 days. A study of archival data obtained by the Hubble telescope showed the presence of these satellites near the predicted positions in images taken three years ago on June 14, 2002. Perhaps this best confirmation that the bodies are satellites of Pluto, and not objects of the Kuiper belt. Assuming that the moons have a reflectivity of 4%, like the darkest cometary nuclei, then the diameter of the largest of Hydra's moons is 160 km. With an albedo characteristic of Centaurs, namely 15%, the size of the satellite is 80 km; if the albedo is the same as Charon’s 38%, then the diameter of the satellite is 52 km. Nikta satellite at 25% weaker than the first, and provided that their reflectivities are the same, the size of the second satellite is 10% or 15% smaller than the first. Search unknown satellites in the orbital stability zone of (±100?) around Pluto, did not show any potential satellites brighter than apparent value V =27.1.

Orbital elements of Pluto's satellites per epoch 2452600.5


















































Number Temporary
designation 		Latin
Name 		Russian
Name 		Period
(days) 		Semi-major axis (km) Eccentric
tricity 		Tilt to orbit
Pluto
(hail) 		Longitude
ascending node
(hail)
 Longitude
periapsis
(hail) 		Average anomaly
in the era
(hail)
I Charon Charon 6.3872304 19 571.4 0.000000 96.145

223.046

- 257.946
II S/2005 P2 Nix Nikta 24.8562 48 675 0.0023 96.18 223.14 216 123.14
III S/2005 P1 Hydra Hydra 38.2065 64 780 0.0052 96.36 223.173 200.1 322.71

Periods orbital movements are treated as integers 6:4:1 (P1:P2:Charon), i.e. there is commensurability of average movements.

Physical parameters















































Number Russian
Name 		Radius
(km) 		Weight FM
km 3 /sec 2 		Density
G /cm 3 		average value in opposition V Geometric albedo
I Charon 593. ± 13 [ 6 ] 1.90? 10 21 108. ± 6. 1.853 ± 0.158 17.26±0.01 0.372±0.012
II Nikta 137 ± 11
( albedo 0.04)
46 ± 4
( albedo 0.35 ) 		23.38 ± 0.17
III Hydra 167 ± 10
( albedo 0.04)
61 ± 4
( albedo 0.35 ) 		22.93 ± 0.12

Literature


      H. A. Weaver, S. A. Stern, M. J. Mutchler, A. J. Steffl, M. W. Buie, W. J. Merline, J. R. Spencer, E. F. Young, & L. A. Young. The Discovery of Two New Satellites of Pluto.(arXiv:astro-ph/ 0601018 v1 2 Jan 2006). Nature, Volume 439, Issue 7079, pp. 943-945 (2006).

    • Sicardy, B. et al. The 11 July 2005 Charon stellar occultation. AAS/Division for Planetary Sciences Meeting Abstracts3 7, 733 (2005).
    • Marc W. Buie, William M. Grundy, Eliot F. Young, Leslie A. Young, and S. Alan Stern. Orbits and photometry of Pluto’s satellites: Charon, S/2005 P1 and S/2005 P2. The Astronomical Journal, 132, p. 290-298, 2006.
    • S.A. Stern, H.A. Weaver, A.J. Steffl, M.J. Mutchler, W.J. Merline, M.W. Buie, E.F. Young, L.A. Young, & J.R. Spencer. A giant impact origin for Pluto's small moons and satellite multiplicity in the Kuiper belt.Nature 439 , 946-948, 2006.
    • Null, G.W., and Owen, W.M. 1996. ``Charon/Pluto Mass Ratio Obtained with HST CCD Observations in 1991 and 1993"", Astronomical Journal 111 , 1368.
    • Tholen, D.J. and Buie, M.W. 1990. ``Further Analysis of Pluto-Charon Mutual Event Observations-1990''. Bulletin of the American Astronomical Society 22 , 1129.
    • Reinsch, K., Burwitz, V., Festou, M. C. 1994. ``Albedo Maps of Pluto and Improved Physical Parameters of the Pluto-Charon System''. Icarus 108 , 209-218.
    • S teffl, A. J.; Mutchler, M. J.; Weaver, H. A.; Stern, S. A.; Durda, D. D.; Terrell, D.; Merline, W. J.; Young, L. A.; Young, E. F.; Buie, M. W.; Spencer, J.R. New Constraints on Additional Satellites of the Pluto System. 2006. The Astron. J., V. 132, Issue 2, pp. 614-619
    • Stern, S. A.; Mutchler, M. J.; Weaver, H. A.; Steffl, A.J.The Positions, Colors, and Photometric Variability of Pluto's Small Satellites from HST Observations 2005-2006. 2006. (arXiv:astro-ph/0605014). Lunar and Planetary Science XXXVIII (2007). LPI Contribution No. 1338, p.1722

Nikta satellite cinema, Nikta satellite Uzbekistan
Image of Nikta transmitted by the New Horizons apparatus (from July 14, 2015 from a distance of 165,000 km, a combination of data from Ralph and LORRI cameras)

History of discovery opening date Orbital characteristics era Major axle shaft

48,694 ± 3 km

Eccentricity

0.00230 ± 0.00022

Circulation period

24.854943 ± 0.000072 days

Orbital inclination Longitude of the ascending node Periapsis argument Average anomaly physical characteristics Diameter

54 × 41 × 36 km

Period of rotation around an axis

chaotic

Albedo Surface temperature Atmosphere

absent

Nikta on Wikimedia Commons
Information on Wikidata

Nikta (134340 II Nix, previously S/2005 P 2) - natural satellite Pluto, one of two (with Hydra) discovered in June 2005 space telescope Hubble. The photographs on which the discovery was made were taken on May 15 and 18, 2005. Satellites on them were first discovered on June 15, 2005. After additional research and testing, the discovery was made public on October 31, 2005. In 2006, satellites received proper names. Named after the Greek goddess of eternal night Nikta (ancient Greek Νύξ, Νυκτός, “night”)

From the available images, it can be concluded that the satellite is in a circular orbit, in the same plane as Charon, at a distance of approximately 50,000 km from Pluto. Nikta is approximately 20% darker than her companion Hydra. Previously, sizes were assumed to range from 32 to 145 kilometers. In 2015, during the New Horizons mission, it was determined that its dimensions are 54 × 41 × 36 kilometers. Thus, Nikta is the largest of Pluto's small satellites.

Nikta is close to orbital resonance with Charon, making one revolution around the planet per four orbital revolutions of Charon, as well as with Hydra (period ratio 3:2).

The name of the satellite was announced on June 21, 2006 in Circular No. 8723 of the International Astronomical Union. It was originally planned to name the satellite Nyx in honor of the ancient Greek goddess of the night. However, to avoid confusion between the satellite and asteroid 3908 Nyx, the spelling of the name was changed to the form used in late antiquity (Nix). The initial letters of the names of the newly discovered satellites Nix and Hydra (N and H) coincide with initial letters New Horizons mission.

Gallery

    Discovery of Nyx and Hydra

    Pluto, Charon (two bright object in the center), Nikta and Hydra (two faint spots to the right)

Notes

  1. The Pluto system: Initial results from its exploration by New Horizons- sciencemag.org
  2. IAUC 8723: Sats OF PLUTO; 2006db, 2006dc, 2006dd; 2006ap, 2006cz, 2006da

Links

  • IAU Circular No. 8625 - description of the discovery (English)
  • Background Information Regarding Our Two Newly Discovered Satellites of Pluto - Discoverers' Website
  • NASA's Hubble Reveals Possible New Moons Around Pluto - Press Release (English)
  • Two More Moons Discovered Orbiting Pluto (SPACE.com)
  • Popular article about Pluto and its moons
Pluto
Geography Pluto's Heart · Satellite Planitia · Cthulhu's Domain · Hillary Mountains · Norgay Mountains · Brass Knuckles (Krune · Ala · Balrog · Vucub-Came · Hun-Came · Meng-Po) · Hills of Coleta de Dados
Satellites Charon · Nikta· Hydra · Kerberos · Styx
Classification Planet · Dwarf planet · Plutoid · Definition of the term planet (2006) · Kuiper Belt · Trans-Neptunian object
Study Pluto Fast Flyby Pluto Kuiper Express Pluto – Kuiper Belt New Horizons
Opening Planets Beyond Neptune · Percival Lowell · Burney's Venice · Roger Putnam · Clyde Tombaugh
Other Solar Eclipse on Pluto Pluto's Rings
  1. 1 2 3 - canceled missions

Nikta satellite Armenia, Nikta satellite cinema, Nikta satellite Uzbekistan, Nikta satellite Jupiter

Nikta (satellite) Information About

Styx

Snapshot automatic interplanetary station"New Horizons" taken on July 13, 2015 from a distance of 632,000 kilometers

Styx (Styx; formerly: S/2012 (134340) 1, according to the old system: S/2012 P 1, unofficially: P5) is the fifth, smallest, natural Pluto. It was discovered by Mark Showalter in 9 images taken by the Hubble telescope on June 26, 27 and 29 and July 7 and 9, 2012. The first images of Styx and Kerberos using New Horizons' most sensitive LORRI camera were taken between April 25 and May 1, 2015.

Early estimates of the size of Styx ranged from 10 to 25 kilometers. After the New Horizons flyby, the size was estimated at 7 x 5 kilometers.

Styx orbits Pluto between the orbits of Nix. The semimajor axis of its orbit is 42±2 thousand km. The period of revolution around Pluto is about 19 days, that is, it is in a 1:3 resonance with Charon.

After its discovery, the satellite was given the temporary designation S/2012 (134340) 1 in accordance with the nomenclature of astronomical objects. If Pluto had not been stripped of its status, the designation would have been S/2012 P 1.

In the voting, which was held on a specially created website by Mark Showalter, who heads the group of scientists who discovered the new satellite, the options “Vulcan” and “Kerberos” won. However, on July 2, 2013, the object was officially given the name Styx, since Vulcan was not directly related to the kingdom of the dead.

Nikta

Image of Nikta transmitted by the New Horizons apparatus (dated July 14, 2015, a combination of data from Ralph and LORRI cameras)

Nix (134340 II Nix, formerly S/2005 P 2) is a natural satellite of Pluto, one of two (with Hydra) discovered in June 2005 by the Hubble Space Telescope. The photographs on which the discovery was made were taken on May 15 and 18, 2005. Satellites on them were first discovered on June 15, 2005. After additional research and testing, the discovery was made public on October 31, 2005. In 2006, the satellites received their own names. Named after the Greek goddess of eternal night Nikta (ancient Greek Νύξ, Νυκτός, “night”)

From the available images, it can be concluded that the satellite is in a circular orbit, in the same plane as Charon, at a distance of approximately 50,000 km from Pluto. Nikta is approximately 20% darker than her companion Hydra. Previously, sizes were assumed to range from 32 to 145 kilometers. In 2015, during the New Horizons mission, it was determined that its dimensions are 54 × 41 × 36 kilometers. Thus, Nikta is the largest of Pluto's small satellites.

Nikta is close to orbital resonance with Charon, making one revolution around the planet per four orbital revolutions of Charon, as well as with Hydra (period ratio 3:2).

The name of the satellite was announced on June 21, 2006 in Circular No. 8723 of the International Astronomical Union. It was originally planned to name the satellite Nyx in honor of the ancient Greek goddess of the night. However, to avoid confusion between the satellite and asteroid 3908 Nyx, the spelling of the name was changed to the form used in late antiquity (Nix). The initial letters of the names of the newly discovered satellites Nix and Hydra (N and H) coincide with the initial letters of the New Horizons mission.

Kerber

An image of the automatic interplanetary station “New Horizons” taken on July 14, 2015 from a distance of 396,100 kilometers

Kerberos (Kerberos; formerly: S/2011 (134340) 1, according to the old system S/2011 P 1, unofficially: P4) is the fourth satellite of Pluto. Opened June 28, 2011. According to preliminary estimates its diameter varied from 13 to 34 km. After the New Horizons flyby, the dimensions were estimated at 12 x 4.5 km. At the time of its discovery, it was the smallest of all the moons of Pluto, until the discovery of the fifth moon, Styx, in 2012.

Kerberos consists of two massive parts: one 8 km wide, the other 5 km wide. It could have been formed after the collision of two small bodies. Researchers note the high reflectivity of the surface of Kerberos. Presumably, it is covered with relatively pure water ice.

The semimajor axis of the satellite's orbit is approximately 59,000 km.

Kerberos's orbit lies between the orbits of Pluto's two other small moons, Nix and Hydra. The orbital period of the satellite around Pluto is 31 days.

The satellite was discovered while surveying the sky with the Hubble Space Telescope on June 28, 2011. New photographs were received on July 3 and 18. The official discovery of the new satellite was confirmed on July 20.

The object was given the temporary designation P4. As it was announced, the satellite was discovered by accident, that is, its discovery was not the result of a planned search.

As stated by NASA, the study of the S/2011 P 1 satellite was included in the research program carried out in 2015 spacecraft"New Horizons". The first images of Kerberos and Styx using New Horizons' most sensitive LORRI camera were taken between April 25 and May 1, 2015.

After its discovery, this satellite received the temporary designation S/2011 (134340) 1 in accordance with the classification system for astronomical objects. Mark Showalter, who leads the team of scientists who discovered the new satellite, said that in accordance with the rules of the International Astronomical Union, the satellite will be given a name from Greek mythology, associated with the underground kingdom of the dead (continuing the series - Pluto (god of the underworld), Charon (carrier of souls across the River Styx), etc.). In the voting, which was held on a specially created website, the options Vulcan and Cerberus won. On July 2, 2013, the satellite received official name- Kerberos (Kerber): it was decided to give the satellite its original name Greek transcription the name of this mythological character (Κέρβερος), so as to avoid confusion with the Latinized form previously used to name the asteroid (1865) Cerberus.

Hydra (134340 III, formerly S/2005 P 1) is one of five known natural satellites of Pluto, one of two (with Nikta) discovered in June 2005 by the Hubble Space Telescope. The photographs on which the discovery was made were taken on May 15 and 18, 2005. Satellites on them were first discovered on June 15, 2005. After additional research and testing, the discovery was made public on October 31, 2005. In 2006, the satellites received their own names.

From the available images, it can be concluded that the satellite is in a circular orbit, in the same plane as Charon, at a distance of approximately 65,000 kilometers from Pluto. Hydra is about 20% brighter than its companion, Nikta. Previously, sizes were assumed to range from 52 to 160 kilometers. In 2015, during the New Horizons mission, it was determined that it has the shape of a potato with dimensions of 44 × 33 kilometers. Thus, among the small satellites of Pluto, Hydra is the second largest, second only to Nix.

Hydra is close to orbital resonance with Charon, making one revolution around the planet per six orbital revolutions of Charon, as well as with Nikto (period ratio 2:3) and Styx (2:1).

The name of the satellite was announced on June 21, 2006 in the circular of the International Astronomical Union No. 8723 after the name of the character of ancient Greek mythology - the Lernaean Hydra, a mythological hundred-headed monster, the daughter of Typhon and Echidna. Hydra lived in the Lerne swamp in the Peloponnese and devastated the surrounding area. Also, the initial letters of the names of the newly discovered satellites Nix and Hydra (N and H) coincide with the initials of the New Horizons mission.

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Abstract on the topic:

Nikta (satellite)



Nikta (134340 II Nix, previously S/2005 P 2) is a natural satellite of Pluto, one of two discovered in June 2005 by the Hubble Space Telescope. The photographs on which the discovery was made were taken on May 15 and May 18, 2005. Satellites on them were first discovered on June 15, 2005. After additional research and testing, the discovery was made public on October 31, 2005. In 2006, the satellites received their own names.

From the available images, it can be concluded that the satellite is in a circular orbit, in the same plane as Charon, at a distance of approximately 50,000 kilometers from Pluto. There is no exact data on its size yet, but, presumably, the diameter of the satellite is from 32 to 145 kilometers. More accurate data can be obtained by further analysis of its reflectivity. Nikta is approximately 20% darker than her companion, Hydra, and therefore appears to be smaller.

Nikta is in orbital resonance with Charon, making three revolutions around the planet per one orbital revolution of Charon, as well as with Hydra (period ratio 3:2).

The satellite, along with Pluto, will be studied in more detail in 2015, as part of the flight of the New Horizons unmanned probe.

The name of the satellite was announced on June 21, 2006 in Circular No. 8723 of the International Astronomical Union. Initially it was planned to give the satellite the name Nyukta (Nyx) in honor of the ancient Greek goddess of the night. However, to avoid confusing the satellite with asteroid 3908 Nyx, the spelling of the name was changed to the form used in late antiquity. The initial letters of the names of the newly discovered satellites Nix and Hydra ( N And H) match the initial letters of the New Horizons mission.


 Notes
  1. IAUC 8723: Sats OF PLUTO; 2006db, 2006dc, 2006dd; 2006ap, 2006cz, 2006da - www.cfa.harvard.edu/iauc/08700/08723.html
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This abstract is based on an article from Russian Wikipedia. Synchronization completed 07/14/11 11:50:11
Similar abstracts:

> > > Nikta

Natural Nikta satellite dwarf planet Pluto reveals secrets of the surface to spacecraft that have taken surveys and photographs from space.

In 2005, together with Hydra, another satellite was found in the orbit of Pluto - Nikta. These discoveries have expanded our knowledge of the solar system and its extent.

Discovery and name of the Nikta satellite

Pluto's moon Nix was spotted in a photo in 2005 by scientists from the Hubble telescope team searching for objects in the Kuiper Belt.

Also, Nikta and Hydra were found independently and in the same year by Max Muhsler and Andrew Stefflom. At that time, Nikta was called S/2005 P 2. Modern name went to honor the mother of Charon and the goddess of darkness and night. Officially established in 2006.

Characteristics of the Nikta satellite

Based on photos from the Hubble telescope, as well as albedo and shape, Nix's diameter is estimated at 56.3 km. But the images from New Horizons were increased to 42 km x 36 km.

Nix moves in a circular orbit around Pluto, where the eccentricity is 0.0020 and the orbital inclination is 0.13°. By orbital speed converges with Charon and is with Hydra in resonance 3:2. It circles the planet in 24.9 days.

The rotation is chaotic, which is influenced by its elongated shape. That is, the tilt of the Nix axis and the length of the day differ over short periods of time.

Composition of the Nikta satellite

The first observations noted the reddish color of Pluto's moon Nix. But the latest survey from Hubble's camera showed a gray surface. It turned out that the satellite is represented by water ice and may contain methane. If so, then the contact of methane deposits with ultraviolet rays will create tholins and the surface layer will turn red.

During the New Horizons flyby, images showed slight local reddening, which may be crater formation.

Exploration of the Nikta satellite

Only the New Horizons spacecraft flew to Pluto in 2015. It was with his help that we managed to obtain amazing photos dwarf planet and its lunar family. On July 13, the instruments determined the parameters of Nikta.

Previously, it was believed that Pluto was a loner, but now we know that it has as many as five satellites. Perhaps we will still go to Pluto, because behind it lies a huge number of mysteries called the Kuiper belt.

Thus, you found out which planet Nikta is a satellite of.

Basic parameters of the Nikta satellite
Opening information
opening date 2005
Discoverers H. Weaver
Orbital characteristics
Major axle shaft 48,708 km
Eccentricity 0,0030
Circulation period 24.86 days
Mood 0.195°
Satellite Pluto
physical characteristics
Dimensions ?
Diameter 88.0±10.0 km
Weight ?
Density ?
Albedo ?


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