(62412) 2000 SY178

Active main belt asteroid October 2025 yes (62412) 2000 SY 178 #D6D6D6 2000 SY178 DECam 2014-03-28.png 2000 SY 178 imaged by the Dark Energy Camera on 28 March 2014. The asteroid's faint tail is marked with green arrows. LINEAR Socorro, United States 28 September 2000 (62412) 2000 SY 178 Main belt 21 November 2025 (JD 2461000.5) 0 0.0758 3.1542 AU 2.9152 AU 3.3932 AU 4.7063° 328.814° 169.867° 86.746° 5.602 yr (2046.111 d) 0.1759° / day 1.9279 AU 1.6295 AU 3.197 13.86 (JPL) 3.33 0.01 h5 10.374 0.342 km3 ~6.4 x 4.2 km6 C-typeg–r = 0.43 0.02r–i = 0.14 0.02i–z = -0.01 0.024 0.0653 0.00973 1.5 g/cm3 (assumed)6 (62412) 2000 SY 178 is an unnamed active asteroid located in the outer main asteroid belt. It was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) project at Socorro, New Mexico on 28 September 2000. It is a member of the extensive Hygiea family, which originated from the large asteroid 10 Hygiea around 3 billion years ago. It is around 10 km mi on in size and rotates rapidly, revolving once every 3.33 hours. 2000 SY 178's activity was first observed in 2014, when it briefly hosted a faint comet-like tail. Orbit thumb|left|A diagram of 2000 SY 178's orbit, with the orbits of the inner planets and Jupiter shown. 2000 SY 178 orbits with an average orbital distance of 3.15 astronomical units (AU), placing it in the outer main asteroid belt.2 Along its orbit, its distance from the Sun varies from 2.92 AU at perihelion to 3.39 AU at aphelion due to its orbital eccentricity of 0.08. It has a moderate orbital inclination of 4.7° with respect to the ecliptic plane and takes 5.6 years to complete one orbit. It has a Jovian Tisserand's parameter (TJ) of 3.2, typical for main belt asteroids and outside the typical TJ value of 2–3 for Jupiter family comets.2 Its orbit is stable over the age of the Solar System;2 it has a Lyapunov time of 1.53 billion years (Gyr).10316 2000 SY 178's orbital characteristics place it within the Hygiea family, an extensive asteroid family associated with 10 Hygiea.2 The Hygiea family is likely very old,3 with an estimated age of 3.2 0.12 0.38 Gyr.10326 Within this family, 2000 SY 178 is associated with a candidate group of eight asteroids, of which the largest member is 4848 Tutenchamun. This group resides close to the 2:1 mean-motion resonance with Jupiter at 3.148 AU.10325 Physical characteristics 2000 SY 178's effective radius, when calculated from its absolute magnitude and geometric albedo, is 5.187 ± 0.171 km mi on.3 Analysis of its lightcurve, or variations in observed brightness over time, shows that it has a rapid rotation of 3.33 0.01 hours. The amplitude of 2000 SY 178's lightcurve suggests that it is elongated, with an a/b ≥ 1.51. Based on its rotation period and elongated shape, 2000 SY 178's inferred density is about 1.5 g/cm3Assuming it is a strengthless rubble pile.6—typical for C-type asteroids but denser than comets. 2000 SY 178 is small enough that its current rotation period is unlikely to be primordial, suggesting that some mechanism has modified its spin. However, it is large and distant enough that it lies near the threshold where the YORP effect can significantly modify its spin. If YORP spinup is not responsible for its current rotation period, then an impact event or the sublimation of ice on its surface could explain its rapid rotation.5–6 2000 SY 178 is a dark asteroid, with a geometric albedo of about 0.0653. Spectroscopic observations reveal that it has a flat spectral slope that, in combination with its low albedo, is consistent with a C-type classification. Its color closely correlates with those of other Hygiea family members, which is primarily composed of C-type asteroids.3–4 Activity On 28 March 2014, 2000 SY 178 was coincidentally imaged by the Cerro Tololo Inter-American Observatory's Dark Energy Camera (DECam) during a survey searching for extreme trans-Neptunian objects. Three DECam images discovered a faint tail extending about one arcminute away from the asteroid, making 2000 SY 178 the thirteenth identified active asteroid in the main asteroid belt. Followup observations did not detect a coma, and by 29 August the tail had disappeared.2,8 2000 SY 178 passed perihelion on 21 March 2013, about one year before its tail was first detected. The delay is consistent with ice sublimation with thermal lag, but the asteroid's low eccentricity and high perihelion suggest that near-perihelion activity may be coincidental.3 2000 SY 178's fast rotation, close to the point of breakup, likely plays a role in its activity. The alignment of its tail suggests that it is composed of relatively large particles, which could be the remnants of a prior outburst or material ejected by rapid rotation. The rapid rotation also likely shifts material on its surface, which could expose fresh ice that could then sublimate away.6–7 See also Active Asteroids – a citizen science project dedicated to finding active asteroids in Dark Energy Camera images Notes References (62412) = 2000 SY178 https://www.minorplanetcenter.net/db_search/show_object?object_id=62412 Minor Planet Center 15 October 2025 live 30 November 2024 https://web.archive.org/web/20241130123605/https://minorplanetcenter.net/db_search/show_object?object_id=62412 (2393 obs) 2025-06-21 last obs. JPL Small-Body Database Lookup: 62412 (2000 SY178) https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2000%20SY178 Jet Propulsion Laboratory 15 October 2025 live 9 May 2026 https://web.archive.org/web/20260509025055/https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2000%20SY178 The Damocloids August 2013 UCLA – Department of Earth and Space Sciences Jewitt, David C. http://www2.ess.ucla.edu/~jewitt/damocloid.html 15 October 2025 David C. Jewitt 28 August 2009 https://web.archive.org/web/20090828075257/http://www2.ess.ucla.edu/~jewitt/damocloid.html live Sheppard Scott S. Trujillo Chadwick Discovery and Characteristics of the Rapidly Rotating Active Asteroid (62412) 2000 SY178 in the Main Belt February 2015 The Astronomical Journal 149 2 44 44 10.1088/0004-6256/149/2/44 free 1410.1528 2015AJ....149...44S Xin Yingqi Shi Jianchun Ma Yuehua Research of the family associations of active asteroids in the main belt February 2024 Monthly Notices of the Royal Astronomical Society 527 4 10309–10334 10.1093/mnras/stad3883 free 2024MNRAS.52710309X External links 62412 62412 (62411) 2000 SX178 62412 (62413) 2000 SE179 Category:Active asteroids Category:C-type asteroids (Tholen) 62412 # 20000928