What is Anti-Pluto?
Orcus, a dwarf planet located in the Kuiper Belt, is widely referred to as "anti-Pluto" due to its striking similarities and intriguing orbital opposition to Pluto. This nickname highlights its unique relationship within our solar system's distant icy regions.
Understanding the Anti-Pluto Concept
The designation "anti-Pluto" stems from Orcus sharing several fundamental characteristics with Pluto while simultaneously exhibiting a contrasting orbital behavior. Both are classified as dwarf planets and reside in the Kuiper Belt, a vast ring of icy bodies beyond Neptune's orbit. They both share a 3:2 orbital resonance with Neptune, meaning for every two orbits Neptune completes, Pluto and Orcus complete three.
However, despite these resemblances, Orcus is considered Pluto's "opposite" in a crucial way: their orbital positions relative to Neptune. When Pluto is at its perihelion (closest point to the Sun), Orcus is at its aphelion (furthest point from the Sun) at the same phase of Neptune's orbit, and vice versa. This "anti-phase" relationship means that when one is closest to the Sun, the other is furthest, making them orbital counterparts. This significant opposition greatly contributed to the selection of Orcus's name.
Key Characteristics of Orcus
Orcus, officially designated (90482) Orcus, is a significant object in the outer solar system. Here are some of its notable features:
- Classification: Dwarf Planet and Plutino (a trans-Neptunian object in a 2:3 orbital resonance with Neptune).
- Location: Resides in the Kuiper Belt, a region of icy bodies beyond Neptune.
- Size: Similar in size to Pluto, though slightly smaller. Its diameter is estimated to be around 900-1000 km.
- Moon: Orcus has one known moon, Vanth, which is quite large relative to Orcus, possibly making them a binary system, much like Pluto and Charon.
- Surface: Believed to have a surface composed of water ice and possibly other volatiles like methane and ammonia.
Comparative Overview: Pluto vs. Orcus
The following table highlights some of the key points of comparison, emphasizing why Orcus is considered Pluto's orbital twin but opposite.
| Feature | Pluto | Orcus |
|---|---|---|
| Classification | Dwarf Planet, Plutino | Dwarf Planet, Plutino |
| Location | Kuiper Belt | Kuiper Belt |
| Orbital Resonance | 2:3 with Neptune | 2:3 with Neptune |
| Orbital Phase | Reaches perihelion (closest to Sun) at a specific point in Neptune's orbit | Reaches aphelion (furthest from Sun) at the same point in Neptune's orbit |
| Moons | Charon (largest), Styx, Nix, Kerberos, Hydra | Vanth |
| Nickname | N/A (formerly 9th planet) | "Anti-Pluto" |
Orcus's unique orbital dance with Pluto makes it a fascinating object of study, providing insights into the dynamics and formation of the outer solar system.
