(528219) 2008 KV42
First trans-Neptunian object discovered with a retrograde orbit.
(528219) 2008 KV42, known by the nickname Drac, is a trans-Neptunian object that made history as the first such body found to travel in a retrograde orbit. Its backward motion, combined with an orbital tilt of 103°, marks it as a probable missing link—a bridge between its origin in the Hills cloud and the population of Halley-type comets. This unusual path offers scientists a clearer window into how the outer Solar System has evolved. The object is roughly 101 kilometers across, orbits the Sun at an average distance of 42 AU, and takes about 269 years to complete one circuit.
Astronomers at the Mauna Kea Observatory first spotted 2008 KV42 on 31 May 2008. The discovery team gave it the nickname "Drac," a nod to Count Dracula, because its steeply inclined orbit—nearly perpendicular to the ecliptic—evoked the vampire's ability to walk on walls.
The discovery was announced on 16 July 2008 by the Canada–France Ecliptic Plane Survey team, led by Brett Gladman of the University of British Columbia. The announcement came during the "Asteroids, Comets, Meteors" meeting in Baltimore, Maryland, with a Minor Planet Electronic Circular issued the same day and an IAU Circular following on 18 July. The initial images were taken on 31 May using the 3.5-meter Canada–France–Hawaii Telescope, with follow-up observations through 8 July from the Whipple Observatory and Cerro Tololo.
With a semi-major axis of 41.7 AU, 2008 KV42 was discovered at a distance of 32 AU and has a perihelion near the orbit of Uranus. Its 103° inclination makes it almost perpendicular to the ecliptic. As of July 2017, it is one of only six known objects with both an inclination greater than 60° and a perihelion beyond 15 AU; the others are (127546) 2002 XU93, 2007 BP102, (762135) 2010 WG9, 471325 Taowu, and (523719) 2014 LM28.
The object's unusual orbit suggests it was pulled inward from the Hills cloud by some unknown gravitational disturbance. Its discovery may help reveal the source regions of Halley-type comets, which also have retrograde orbits but whose origins remain unclear. 2008 KV42 itself is thought to be in an intermediate stage on its way to becoming a comet, offering clues to the formation and evolution of the outer Solar System.
2008 KV42 might even provide evidence for the hypothetical Planet Nine.
Quick Facts
- Minorplanet
- yes
- Background
- #C2E0FF
- Discoverer
- Mauna Kea Obs.
- Discovered
- 31 May 2008
- Mpc Name
- (528219) 2008 KV · 42
- Mp Category
- TNOcentaur / damocloiddistant
- Epoch
- 1 July 2021 (JD 2459396.5)
- Uncertainty
- 31
- Observation Arc
- 12.20 yr (4,456 d)
- Aphelion
- 62.917 AU
- Perihelion
- 21.152 AU
- Semimajor
- 42.035 AU
Facts from the source article.
Lore & Background
2008 KV42 was discovered by astronomers at Mauna Kea Observatory on 31 May 2008. The discovery team nicknamed it Drac after Count Dracula because of its high inclination in reference to its orbital plane resembling Count Dracula's ability to walk on walls. The discovery was announced on 16 July 2008 by the Canada–France Ecliptic Plane Survey team led by Brett Gladman from the University of British Columbia, during the 'Asteroids, Comets, Meteors' meeting in Baltimore, Maryland, followed by a Minor Planet Electronic Circular and an IAU Circular on 18 July. Further observations were made until 8 July from the Whipple Observatory and Cerro Tololo.
With a semi-major axis of 41.7 AU, it was discovered while at a distance of 32 AU and has a perihelion at roughly the distance of Uranus. Its 103° inclination makes it almost perpendicular to the ecliptic, and as of July 2017, it is one of only six objects known to have inclination and perihelion larger than 60° and 15 AU, respectively. Its unusual orbit suggests it may have been perturbed inwards from the Hills cloud by an unknown gravitational disturbance, and it is believed to be in an intermediate stage towards becoming a comet.
Reader's Guide
2008 KV42 is significant as the first trans-Neptunian object discovered with a retrograde orbit, a finding that challenges previous models of outer Solar System dynamics. Its high inclination of 103° and perihelion near Uranus suggest it originated in the Hills cloud and was perturbed inward, possibly by an unknown gravitational disturbance. This object may serve as a missing link between its source region and Halley-type comets, which also have retrograde orbits but whose origins remain unknown. The discovery provides further insight into the evolution of the outer Solar System and may even offer evidence for the hypothetical Planet Nine, as the Kozai effect inside mean-motion resonances with Planet Nine could cause periodic exchanges between inclination and eccentricity, creating orbits like that of 2008 KV42. As of July 2017, it is one of only six known objects with inclination over 60° and perihelion over 15 AU, underscoring its rarity and importance for understanding the architecture of the distant Solar System.
Did You Know?
- Its orbital inclination of 103° makes it almost perpendicular to the ecliptic.
- The object measures approximately 101 kilometers (63 miles) in diameter.
- It was nicknamed Drac after Count Dracula due to its high orbital inclination.
More in Trans-Neptunian Objects, Part 3 1-24
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