5145 Pholus facts for kids
| Discovery | |
|---|---|
| Discovered by | Spacewatch (David L. Rabinowitz) |
| Discovery date | January 9, 1992 |
| Designations | |
| 1992 AD | |
| Centaur, Asteroid | |
| Orbital characteristics | |
| Epoch November 30, 2008 (JD 2454800.5) | |
| Aphelion | 4784.1 Gm (31.98 AU) |
| Perihelion | 1305.9 Gm (8.730 AU) |
| 3045.2 Gm (20.356 AU) |
|
| Eccentricity | 0.5711 |
| 33547.41 d (91.85 yr) |
|
|
Average orbital speed
|
6.01 km/s |
| 67.49° | |
| Inclination | 24.65° |
| 119.44° | |
| 354.92° | |
| Physical characteristics | |
| Dimensions | 185±16 km |
| Mass | ~6.6×1018 kg |
|
Mean density
|
2.0? g/cm³ (assumed) |
| ~0.052 m/s² | |
| ~0.098 km/s | |
| 9.98 hours | |
| Albedo | 0.046±0.02 |
| Temperature | ~62 K |
|
Spectral type
|
(red) B-V=1.19; V-R=0.78 |
| 7.0 | |
5145 Pholus is a small, icy space object. It is called a Centaur. Centaurs are like a mix between asteroids and comets. They orbit the Sun in a very stretched-out path.
Pholus's orbit is quite unusual. At its closest point to the Sun (called perihelion), it is nearer than Saturn. At its farthest point (called aphelion), it is even farther than Neptune. This means it travels a huge distance!
Discovery and Name
Pholus was found on January 9, 1992. It was discovered by David L. Rabinowitz. He was part of the University of Arizona's Spacewatch Project.
This space object is named after Pholus. In old Greek stories, Pholus was a Centaur. He was the brother of Chiron. Another Centaur object, 2060 Chiron, was named first. This started the tradition of naming these objects after Centaurs from myths.
What Makes Pholus Special?
Pholus was only the second Centaur-type object ever found. Scientists quickly noticed something cool about it: it is very red! Because of its color, some people call it "Big Red."
Scientists think this deep red color comes from special organic compounds on its surface. These are carbon-based chemicals. They might have changed over time due to sunlight.
Unlike the first Centaur found, 2060 Chiron, Pholus does not show any signs of cometary activity. This means it does not have a glowing tail or a cloud of gas around it, like many comets do.
Size and Orbit
Scientists believe Pholus is about 185 kilometers (about 115 miles) wide. That is roughly the distance from New York City to Philadelphia!
Pholus does not often come close to other planets. It has not been within one astronomical unit (about 150 million kilometers or 93 million miles) of a planet since 764 BC. It will not get that close again until the year 5290. This shows how vast and empty space truly is!
Scientists think Pholus might have started its journey in the Kuiper belt. The Kuiper belt is a far-off region of icy objects beyond Neptune.
