5426 Sharp
Bright Hungaria asteroid with a suspected but unconfirmed moon.
5426 Sharp (provisional designation 1985 DD) is a bright asteroid belonging to the Hungaria group, located in the inner main belt. It is a suspected binary system, with an estimated diameter of 2 to 3 kilometers. American astronomer Carolyn Shoemaker discovered it on 16 February 1985 at Palomar Observatory in California. The asteroid was named after Robert P. Sharp, an American geologist.
Sharp is classified as an E-type asteroid and is a member of the Hungaria family, the densest concentration of asteroids closest to the Sun. Its orbit takes it between 1.7 and 2.2 AU from the Sun, completing one revolution every 998 days (about 2 years and 9 months). The orbit has an eccentricity of 0.12 and an inclination of 24° relative to the ecliptic. No precovery images or earlier identifications exist; the observation arc begins with its discovery at Palomar.
Data from NASA’s WISE and NEOWISE surveys give Sharp a diameter of 2.033 kilometers and an exceptionally high albedo of 1.000. In contrast, the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 (a compromise between 0.4 and 0.2, typical for Hungaria asteroids as both a family and orbital group) and calculates a diameter of 3.85 kilometers based on an absolute magnitude of 14.0. The high albedo from WISE suggests Sharp belongs to the collisional Hungaria subgroup, thought to originate from a single parent body shattered in an ancient impact. The high reflectivity comes from enstatite, a magnesium-rich mineral that gives E-type asteroids their spectral signature.
A first rotational lightcurve of Sharp was obtained in November 2011 by American astronomer Brian Warner at the Palmer Divide Observatory in Colorado. The analysis hinted that a minor-planet moon might orbit the asteroid roughly every 24 hours. In 2014 and 2015, Warner re-examined Sharp with Vladimir Benishek (Belgrade Astronomical Observatory, Serbia) and Andrea Ferrero (Bigmuskie Observatory, Italy). This international collaboration was necessary because the moon’s orbital period was expected to be nearly exactly one Earth day, making it synchronous with Earth’s rotation and impossible to cover the full lightcurve from a single location. The combined observations yielded a well-defined rotation period of 4.5609 hours, a brightness variation of 0.18 magnitude, and an orbital period of 24.22 hours for the suspected satellite.
Quick Facts
- Minorplanet
- yes
- Background
- #D6D6D6
- Discovered
- 16 February 1985
- Discoverer
- C. Shoemaker
- Discovery Site
- Palomar Obs.
- Mpc Name
- (5426) Sharp
- Named After
- Robert P. Sharp / (American geomorphologist)
- Mp Category
- main-belt(inner) / Hungaria
- Epoch
- 4 September 2017 (JD 2458000.5)
- Uncertainty
- 0
- Observation Arc
- 31.94 yr (11,667 days)
- Aphelion
- 2.1828 AU
Facts from the source article.
Lore & Background
5426 Sharp is a bright E-type asteroid and a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun in the inner main-belt at a distance of 1.7–2.2 AU once every 2 years and 9 months (998 days), with an eccentricity of 0.12 and an inclination of 24° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Palomar, as no precoveries were taken and no prior identifications were made.
According to surveys by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Sharp measures 2.033 kilometers in diameter and has an outstandingly high albedo of 1.000. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 and calculates a diameter of 3.85 kilometers with an absolute magnitude of 14.0. The high albedo derived from WISE observations indicates that Sharp belongs to the collisional Hungaria asteroids, thought to have originated from the same parent body that shattered into fragments in an ancient asteroid collision. The high albedo is due to the magnesium-rich mineral enstatite, which led to the E-type spectral classification.
A first rotational lightcurve obtained in November 2011 by Brian Warner indicated the possibility that Sharp could be orbited by a minor-planet moon nearly every 24 hours. In 2014/15, Sharp was re-examined by Warner in collaboration with Vladimir Benishek and Andrea Ferrero, because the satellite's orbital period was expected to be almost exactly an Earth day, making it impossible to obtain photometric data from a single location. The combined lightcurves gave a well-defined rotation period of 4.5609 hours, a brightness variation of 0.18 magnitude, and an orbital period of 24.22 hours for the asteroid's moon. However, as no mutual occultation/eclipsing events were observed, the binary nature remains unconfirmed.
Reader's Guide
5426 Sharp is notable as a bright Hungaria asteroid with an exceptionally high albedo of 1.000 measured by NEOWISE, indicating it is a collisional fragment rich in enstatite. Its suspected binary nature, with a moon having an orbital period of 24.22 hours, required a multi-site observation campaign due to near-synchrony with Earth's rotation. The asteroid was named after geologist Robert P. Sharp, for whom the Martian crater Robert Sharp and Mount Sharp (Aeolis Mons) are also named. The naming citation was published on 17 March 1995. The unconfirmed moon, with a semi-major axis estimated at 4.5 kilometers by Johnstonsarchive, adds to the intrigue, though no diameter ratio could be derived. Sharp's study contributes to understanding collisional families and binary asteroid formation in the inner main-belt.
Did You Know?
- 5426 Sharp has an albedo of 1.000, one of the highest measured by NEOWISE.
- Its suspected moon has an orbital period of 24.22 hours, nearly synchronous with Earth's rotation.
- The asteroid is named after geologist Robert P. Sharp, who also has a Martian crater and Mount Sharp named after him.
- No mutual occultation or eclipsing events have been observed, so the binary nature remains unconfirmed.
Frequently Asked Questions
Who discovered 5426 Sharp and where?
Carolyn Shoemaker spotted the asteroid on 16 February 1985 while observing from Palomar Observatory in California. It carried the provisional designation 1985 DD before receiving its permanent number.
Who is 5426 Sharp named after?
The asteroid honors Robert P. Sharp, an American geologist. Like many numbered asteroids, it carries the name of a scientist who contributed to the broader field of Earth and planetary science.
What type of asteroid is 5426 Sharp?
Sharp is classified as an E-type asteroid, meaning its surface is rich in enstatite and olivine minerals. It is also a member of the Hungaria group, the densest cluster of asteroids orbiting closest to the Sun within the main belt.
Does 5426 Sharp have a moon?
Sharp is suspected to be a binary system, but the existence of a companion body has not been definitively confirmed. Its estimated diameter sits around 2 to 3 kilometers, consistent with a small primary that could plausibly host a satellite.
Where does 5426 Sharp orbit and how bright is it?
Its path keeps it between roughly 1.7 and 2.2 AU from the Sun, placing it in the inner main belt among the Hungaria asteroids. NEOWISE data gives it an albedo near 1.0, making it one of the brightest and most reflective objects in that region.
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