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90482 Orcus

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90482 Orcus
NASA picture of 90482 Orcus
Discovered byM. Brown,
C. Trujillo,
D. Rabinowitz
Discovery timeFebruary 17, 2004
Other names2004 DW
Reference date November 30, 2008 (JD 2 454 800)
Longest distance from the Sun7 188.17 Gm (48.05 AU)
Shortest distance from the Sun4 535.80 Gm (30.32 AU)
Longest distance from the center of its orbital path
("semi-major axis")
5 862.44 Gm (39.188 AU)
How egg-shaped its orbit is
0.226 18
How long it takes to complete an orbit89 606 d (245.33 yr)
Average speed4.68 km/s
Mean anomaly164.68°
Angle above the reference plane
Longitude of where it comes up through the reference plane268.722°
Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
Natural things which orbit around it1 (92-432 km)
Size and Other Qualities
Measures946.3 +74.1−72.3 km (diameter)[2]
Mass~7.5×1020 kg
Average density~1.5 g/cm³ (assumed)
Gravity at its surface~0.2 m/s²
Slowest speed able to escape into space
("escape velocity")
~0.44 km/s
How long it takes to turn around one time13.19h[3]
How much light it reflects19.75 +3.40−2.76 %
Avg. surface temp.~45 K
Light-band group
("spectral type")
B-V=0.68; V-R=0.37 [4]
Seeming brightness
("apparent magnitude")
19.1 (opposition)[5]
True brightness
("absolute magnitude")

90482 Orcus, originally known by the provisional designation 2004 DW) is a Kuiper belt object (KBO) and could be a dwarf planet. It was found by Michael Brown, Chad Trujillo and David Rabinowitz on February 17, 2004. It was also seen in pictures from November 8, 1951.


A moon of Orcus was found on 22 February 2007.[7] The orbit of this moon has yet to be found out.

The satellite was found at 0.25 arcsec from Orcus with magnitude difference of 2.7.[8] Assuming an albedo similar to that of the primary, the magnitude suggests a diameter of about 220 km. It is thought to be a smaller KBO that was captured.

Other websites


  1. Buie, Marc W. (2007-12-22). "Orbit Fit and Astrometric record for 90482". SwRI (Space Science Department). Archived from the original on 2012-02-08. Retrieved 2008-09-19.
  2. Stansberry, J.; Grundy, W.; Brown, M.; et al. (2007). Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope.
  3. "Overlooked dwarf planet candidates". BBC. 2008-02-19. Retrieved 2008-07-25.
  4. Tegler, Stephen C. (2006-01-26). "Kuiper Belt Object Magnitudes and Surface Colors". Archived from the original on 2007-11-16. Retrieved 2006-11-05.
  5. "HORIZONS Web-Interface". JPL Solar System Dynamics. Archived from the original on 2012-02-08. Retrieved 2008-07-02.
  6. "JPL Small-Body Database Browser: 90482 Orcus (2004 DW)". 2008-02-10 last obs. Archived from the original on 2012-02-08. Retrieved 2008-07-02.
  7. (90482) Orcus and Vanth Archived 8 February 2012 at WebCite
  8. Distant EKO The Kuiper Belt Electronic newsletter, March 2007