Facts about Orcus
- 10
Rotational studies indicate Orcus spins significantly slower than it did in its early history, suggesting a dramatic deceleration over billions of years in the distant Kuiper Belt.
- 09
Orcus completes one full orbit around the Sun in exactly the same 247-year period as Pluto, though their synchronized 2:1 orbital resonance keeps them perpetually separated by millions of kilometers.
- 08
Discovery observations by astronomers using the Palomar Observatory in November 2004 initially classified Orcus as a scattered disk object before reclassification as a plutino.
- 07
Occultation observations in 2017 determined that Orcus has a diameter of 910 kilometers with an oblateness suggesting rapid historical rotation that has since slowed considerably.
- 06
Orcus takes its name from a Roman god of the underworld and oaths, chosen to reflect its position as Pluto's distant counterpart in the outer solar system.
- 05
Orcus and Pluto orbit the Sun in a peculiar resonance pattern where Orcus never approaches closer than 50 astronomical units while Pluto's orbit brings it within 30 astronomical units.
- 04
In 2017, spectroscopic observations revealed that Orcus has a surface composition rich in methane and nitrogen ices similar to Pluto's.
- 03
Orcus possesses a large moon named Vanth that orbits at a distance of approximately 9,000 kilometers, making it one of the most massive satellite systems relative to primary body size in the Kuiper Belt.
- 02
At approximately 910 kilometers in diameter, Orcus ranks as the second-largest known plutino in the Kuiper Belt after Pluto itself.
- 01
The dwarf planet Orcus, discovered in 2004, orbits the Sun every 247 years at a distance of 39.5 astronomical units.