174567 Varda
A large, hot classical Kuiper belt object with a massive moon.
174567 Varda is a sizable object beyond Neptune, found on June 21, 2003, by American astronomer Jeffrey A. Larsen. He used survey images from the 0.9-meter Spacewatch telescope at Kitt Peak National Observatory. It belongs to the dynamically hot classical Kuiper belt, meaning it orbits in the Kuiper belt but on a tilted path compared to the flatter, colder population. Stellar occultations in 2018 suggest Varda is likely an oblate spheroid with a flattening of 0.07 and an area-equivalent diameter of 740 ± 14 km. Other shape models, such as triaxial ellipsoids, remain mathematically unconstrained.
The total mass of the Varda–Ilmarë binary system is about 2.675 +0.048 −0.049 × 10²⁰ kg, with Varda making up roughly 86 to 90 percent of that. Its bulk density estimates are highly uncertain. Data from the James Webb Space Telescope show a surface temperature of 44 K, and frozen carbon dioxide dominates its surface. Because of its large size, some astronomers—including Michael E. Brown and Noemi Pinilla-Alonso—have considered it a possible dwarf planet. However, it is hypothesized that trans-Neptunian objects in the 400–1000 km size range, like Varda, may never have compressed into fully solid bodies or achieved hydrostatic equilibrium, making dwarf-planet status unlikely. The density calculations for Varda are too ambiguous to clarify whether its density is high enough for such compression.
Varda has one known moon, Ilmarë, with a diameter of about 403 ± 40 km. The two are likely mutually tidally locked. The binary system has a very large mass ratio, comparable to that of Pluto and Charon.
**Observation history**
**Discovery** Varda was discovered on June 21, 2003, by Jeffrey A. Larsen as part of a United States Naval Academy Trident Scholar project. The discovery used survey images from the 0.9-meter Spacewatch telescope at Kitt Peak. Larsen’s survey ran for 34 months, covering about 8,000 square degrees of sky to detect slow-moving trans-Neptunian objects. At the time of its announcement, Varda was the only large object found by this program and was thought to be the tenth-largest known classical Kuiper belt object. The Minor Planet Center officially announced the discovery on January 7, 2006. Astronomers later found the earliest known precovery images of Varda from photographs taken at Siding Spring Observatory on March 19, 1980.
Quick Facts
- Symbol
- (astrological)
- Discoverer
- J. A. Larsen
- Discovery Site
- Kitt Peak National Obs.
- Discovered
- 21 June 2003
- Earliest Precovery Date
- 19 March 1980
- Mpc Name
- (174567) Varda
- Pronounced
- ˈ · v · ɑːr · d · ə
- Named After
- Varda / (figure by J. R. R. Tolkien)
- Mp Category
- TNO / classical (hot) / detached / distant / 15:8 resonance with Neptune10
- Epoch
- 31 May 2020 (JD 2459000.5)
- Uncertainty
- 2
- Observation Arc
- 39.12 yr (14,290 d)
Facts from the source article.
Lore & Background
Varda was discovered on 21 June 2003 as part of a United States Naval Academy Trident Scholar project, using survey images from the 0.9-meter Spacewatch telescope. The Minor Planet Center announced the discovery on 7 January 2006, and precovery images from 19 March 1980 were later identified. Its permanent minor planet number 174567 was assigned on 22 January 2008, and the names Varda and Ilmarë were announced on 16 January 2014, drawn from J. R. R. Tolkien's Middle-earth writings.
Varda orbits the Sun once every 309.2 years at an average distance of 45.7 AU, with an eccentricity of 0.14 and an inclination of 21.5°. It is a dynamically hot classical Kuiper belt object, likely scattered by Neptune's gravitational influence. A 2025 study suggested it may be in a 15:8 resonance with Neptune. Its orbit is very stable, with an estimated stability time of 22.1 billion years.
Stellar occultations in 2018 revealed Varda is likely an oblate spheroid with a flattening of 0.07 and an area equivalent diameter of 740±14 km. A 2026 reanalysis suggested a triaxial ellipsoid shape with dimensions 778 × 706 × 496 km, but the data cannot fully constrain its shape. Its surface temperature is 44 K, and abundant frozen carbon dioxide dominates its surface. The binary system has a total mass of 2.675+0.048−0.049×10^20 kg, with Varda contributing 86–90%.
Reader's Guide
Varda is significant as one of the largest known trans-Neptunian objects, ranking among the top 34 largest TNOs. Its binary system, with the moon Ilmarë (diameter ~403 km), exhibits a very large mass ratio comparable to Pluto and Charon, and the pair are likely mutually tidally locked. The object's size and mass have led some astronomers, including Michael E. Brown and Noemi Pinilla-Alonso, to consider it a possible dwarf planet. However, William M. Grundy hypothesized that objects in the 400–1000 km size range, such as Varda, have probably never compressed into fully solid bodies or achieved hydrostatic equilibrium, making dwarf planet status unlikely. Density calculations remain highly ambiguous, and it is unclear if Varda's density is high enough for full compression. Its low albedo is consistent with a lack of geological activity typical of larger dwarf planets. The 2018 stellar occultation also tested for a thin nitrogen atmosphere like Pluto's, but results were inconclusive due to potential camera issues. Varda's legacy lies in its role in understanding the formation and composition of Kuiper belt objects, the transition between small bodies and dwarf planets, and the dynamics of binary systems in the outer Solar System.
Did You Know?
- Varda's moon Ilmarë has a diameter of approximately 403±40 km, making the binary system's mass ratio comparable to that of Pluto and Charon.
- The earliest known precovery images of Varda were taken at Siding Spring Observatory on 19 March 1980.
- Varda's surface temperature is 44 K, and its surface is dominated by abundant frozen carbon dioxide.
- A 2025 study found that Varda could be in a 15:8 orbital resonance with Neptune.
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