is an asteroid with an estimated diameter of that is classified as an Apollo-type (Earth-crossing) near-Earth object. From 27 January to 20 February 2025, it had an impact rating of 3 on the Torino scale, reflecting its size and an estimated probability greater than 1% that it would impact Earth on 22 December 2032. The estimated impact probability peaked at 3.1% on 18 February 2025. By 23 February, additional observations effectively ruled out impacting Earth in 2032 and lowered its Torino rating to 0. As of 11 May 2025, there was about a 4% chance of a Moon impact on 22 December 2032 around 15:19 UTC, but two additional observations by the James Webb Space Telescope in February 2026 reduced that chance to 0%. will safely pass km from the surface of the Moon. Pending precovery images from 2016 also support the close approach distance.
The asteroid was discovered by the Chilean station of the Asteroid Terrestrial-impact Last Alert System (ATLAS) at Río Hurtado on 27 December 2024. When additional observations increased its impact probability to greater than 1%, the first step in planetary defense responses was triggered, prompting additional data gathering using several major telescopes and leading space agencies to begin planning asteroid threat mitigation.
The asteroid made a close approach to Earth at a distance of on 25 December 2024, two days before its discovery, and it will be moving away from the Sun until November 2026. Its next close approach will take place on 17 December 2028. Analysis of spectral and photometric time series suggests that is a stony S-type (most likely), L-type or K-type asteroid, with a rotation period of approximately 19.5 minutes. A number of known asteroids, including other virtual impactors, follow orbits somewhat consistent with that of .
Provisional designation The asteroid's provisional designation as a minor planet, "", was assigned by the Minor Planet Center when its discovery was announced on 27 December 2024. "Y", the first letter after the discovery year, indicates that the asteroid was discovered in the second half-month of December (16 to 31 December), and "" indicates that it was the 117th provisional designation to be assigned in that half-month.
Physical characteristics Size and mass
Measurements of 's mid-infrared thermal emission by the James Webb Space Telescope (JWST) on 26 March 2025 indicate that it has a diameter of , with an uncertainty of . This makes around the same size as the asteroid that caused the 1908 Tunguska event or the iron–nickel asteroid that created the Meteor Crater in Arizona 50,000 years ago. is significantly smaller than Dimorphos, the impact target of NASA's Double Asteroid Redirection Test (DART) in 2022. The possible size range implies a geometric albedo between 0.08 and 0.18, relatively low for a stony asteroid.
Prior to the JWST measurement, more uncertain estimates for 's diameter were based on its brightness (absolute magnitude) and using a range of plausible values for its surface reflectivity (geometric albedo). If reflects between 5% and 25% of visible light, as do the vast majority of asteroids with a measured albedo, then its diameter had to be between . An estimate by NASA for instance placed its diameter at by assuming a geometric albedo of 0.154.
The mass and density of have not been measured, but the mass can be loosely estimated with an assumed density and the estimated diameter. Assuming a density of , which is within the density range for stony asteroids such as 243 Ida, and the then nominal diameter of , the Sentry risk table estimated a mass of . Rescaling the diameter to the now better measured value of increases the estimated mass to . Both the assumed density and the inferred diameter contribute large uncertainties to the mass estimated.
Composition, rotation, and shape Preliminary spectroscopic analysis from the Gran Telescopio Canarias and Lowell Discovery Telescope suggests that is either an S-type asteroid (17% of the asteroid population), an L-type asteroid, or a K-type asteroid, all of which point to a stony composition. Spectro-photometry by the Gemini South telescope in February 2025 suggest either an R or Sa spectral type for . JWST measurements of 's thermal emission suggest "a rockier surface than commonly inferred."
Photometric observations by the Very Large Telescope (VLT) and the La Silla Observatory's telescope indicate has a rotation period near 19.5 minutes. Observations by the Gemini South telescope from February 2025 found similar results for 's rotation period. This is a relatively fast rotation period for an asteroid, although it is not fast enough to rule out a rubble pile structure for . The VLT has also observed at multiple phase angles from 5° to 35°, which would allow for the construction of a phase curve which can constrain the asteroid's surface properties.
The brightness of varies by 0.42 magnitudes as it rotates, indicating it has an elongated shape with its longest equatorial length being at least 1.4 times that of its shortest equatorial length. Gemini South telescope measurements of 's rotational light curve at various phase angles show that the asteroid has a retrograde rotation and a highly flattened shape with an equatorial diameter roughly 3 times as long as its polar diameter.
Orbit As an Apollo-type near-Earth object, orbits the Sun on an elliptical orbit that crosses Earth's orbit. Since its close approach in December 2024, the asteroid has an orbital period of about and an orbital inclination of 3.41 degrees with respect to Earth's orbit (the ecliptic). The period, considered as an osculating element, dips slightly at the approach in December 2028 and then slowly rises to around by 2031.See this JPL Horizons run. Its orbit will be strongly perturbed at the close encounter of 2032. Astronomers Carlos and Raúl de la Fuente Marcos have proposed that could be related to a group of near-Earth asteroids on similar orbits that also have virtual impactors: , , 2019 SC, and . The 2015 Porangaba meteorite orbit has a 5% probability of matching that of .
Due to the Yarkovsky effect, 's retrograde rotation causes its orbit to shrink over time. This indicates originated farther out in the Solar System, specifically the central main asteroid belt. 's stony composition supports the possibility of an origin from the central main belt, since S-type and C-type asteroids are the most abundant spectral types in that region. The inward migration of from the main belt to near-Earth space was likely chaotic since the asteroid would have to cross multiple orbital resonances, such as the 3:1 mean-motion resonance with Jupiter's orbital period at 2.5 AU and the ν6 secular resonance with Saturn's orbital precession at 2.2 AU.
The asteroid reached perihelion (its closest approach to the Sun) on 22 November 2024, and made a close approach to Earth on 25 December 2024, two days before its discovery. During this encounter, passed 828,800 km (; ) from Earth and then from the Moon. The asteroid will make its next close approach to Earth on 17 December 2028, when it will pass from Earth. The 2028 encounter will provide astronomers the opportunity to perform additional observations and extend the observation arc by two years.
Since the 2032 close approach is very close to the Moon, the resulting perturbation by the Earth–Moon system is highly uncertain, and all close approaches after 2032 are therefore not well constrained either. The 1 March 2025 position of the asteroid is (as of March 2026) now known with a 3-sigma uncertainty in the asteroid's position of By mid-2034, this increases to about , but since will pass very close to the Moon in 2032, the post-2032 uncertainty may be even greater due to its trajectory being affected by gravitational focusing. The possible trajectories become more divergent with time and the greatest risk of an Earth impact (using data only through 2025) was in December 2047. Without the February 2026 observations, the uncertainty in the asteroid's position along its orbit in December 2047 was at least and wrapped around the asteroid's orbit. Around January 2052 the asteroid could pass as close as 3 million km from Earth, but is expected to pass 25 million km from Earth. By the year 2123, the uncertainty in the asteroid's position is .
2032 close approach On 22 December 2032, will come closest to Earth at 08:22 ± 3 minutes UTC, at a distance of , with a 3-sigma uncertainty of . The nominal closest approach to the Moon occurs at 14:57 UTC, with a nominal distance of about from the center of the Moon.
Due to 's size and previously greater-than-1% impact probability, it reached a rating of 3 on the Torino scale on 27 January 2025, which prompted the International Asteroid Warning Network to issue a notice on 29 January 2025. This was the second-highest Torino rating ever reached by an asteroid, behind 99942 Apophis which in late 2004 briefly reached a similar impact probability, but a rating of 4 due to its larger size. NASA's Sentry gave a rating on the Palermo scale as high as on 18 February 2025, when it had a 55-day observation arc and a 3.1% chance of impacting the Earth in 2032. This gave a corresponding impact hazard of 66% of the background hazard level, given the asteroid's relatively small size of . The asteroid approached but never exceeded the background risk of a random asteroid of the same size impacting Earth by 2032, which by definition corresponds to a Palermo rating of 0. On 18 February 2025, the European Space Agency's Aegis listed a 2.8% chance of an Earth impact in 2032. On 23 February 2025 (with a 60-day observation arc), was reduced to a Torino rating of 0.
On 2 April 2025, with a 91-day observation arc, NASA removed the chance of a 2032 Earth impact. The European Space Agency removed the chance of a 2032 impact on 8 March 2025. NEODyS removed the chance of a 2032 impact on 1 March 2025.
+JPL #79 nominal distance at the 22 December 2032 14:02 UT Virtual Impactor Scenario (not closest approach) JPL Horizonsnominal geocentricdistance (AU) uncertaintyregion(3-sigma)
Solution Observationarc(in days) JPL Horizonsnominal geocentricdistance (AU) uncertaintyregion(3-sigma) Impactprobability Torinoscale Palermoscale(max)2024 Dec 30 2 (53 obs) 1:1040 (0.096%) 1 −1.732024 Dec 31 3 (71 obs) 1:920 (0.11%) 1 −1.662025 Jan 1 4 (87 obs) 1:870 (0.11%) 1 −1.642025 Jan 2 6 (109 obs) 1:842 (0.12%) 1 −1.632025 Jan 3 7 (120 obs) 1:760 (0.13%) 1 −1.61JPL #14 2025 Jan 6 8 (145 obs) 1:730 (0.14%) 1 JPL #15 2025 Jan 6 11 (158 obs) 1:710 (0.14%) 1 −1.532025 Jan 11 14 (170 obs) 1:630 (0.16%) 1 −1.53JPL #27 2025 Jan 20 26 (198 obs) 1:320 (0.31%) 1 JPL #30 2025 Jan 22 28 (213 obs) 1:190 (0.52%) 1 −0.93JPL #32 2025 Jan 23 29 (219 obs) 1:110 (0.91%) 1 −0.69JPL #34 2025 Jan 24 30 (227 obs) 1:110 (0.91%) 1 −0.69JPL #35 2025 Jan 2733 (238 obs) 0.00004564 AU (6,829 km; 0.01776 LD) ± 1.605 million km1:83 (1.2%)3 −0.57JPL #36 2025 Jan 2834 (245 obs) ± 1.55 million km1:83 (1.2%) −0.56JPL #37 2025 Jan 2935 (257 obs) ± 1.408 million km1:77 (1.3%)3 −0.53JPL #39 2025 Jan 3036 (261 obs) ± 1.408 million km1:77 (1.3%)3 −0.53JPL #40 2025 Jan 3137 (276 obs) ± 1.2 million km1:63 (1.6%)3 −0.47JPL #41 2025 Feb 138 (284 obs) ± 1.119 million km1:59 (1.7%)3 −0.43JPL #42 2025 Feb 239 (289 obs) ± 1.049 million km1:71 (1.4%)3 −0.52JPL #43 2025 Feb 340 (292 obs) ± 998,000 km1:67 (1.5%)3 −0.49JPL #44 2025 Feb 441 (294 obs) ± 981,000 km1:63 (1.6%)3 −0.46JPL #45 2025 Feb 542 (307 obs) ± 892,000 km1:53 (1.9%)3 −0.40JPL #46 2025 Feb 643 (315 obs) ± 819,000 km1:43 (2.3%)3 −0.31JPL #47 2025 Feb 743 (325 obs) ± 792,000 km1:45 (2.2%)3 −0.32JPL #48 2025 Feb 844 (336 obs) ± 764,000 km3 −0.29JPL #49 2025 Feb 945 (343 obs) ± 739,000 km1:45 (2.2%)3 −0.34JPL #50 2025 Feb 1045 (347 obs) ± 712,000 km 1:48 (2.1%)3 −0.34JPL #51 2025 Feb 1245 (348 obs) ± 712,000 km 1:48 (2.1%)3 −0.35JPL #53 2025 Feb 1345 (346 obs) ± 712,000 km 1:48 (2.1%)3 −0.34JPL #54