2024 YR4

2024 YR₄
	2024 YR4 (centered) tracked by the Very Large Telescope in January 2025
Discovery
Discovered by	ATLAS–CHL (W68)
Discovery site	Río Hurtado, Chile
Discovery date	27 December 2024
Designations
MPC designation	2024 YR4
Minor planet category	NEO; Apollo; risk-listed;
Orbital characteristics (JPL)
	Epoch 5 May 2025 (JD 2460800.5)
	Uncertainty parameter 3
Observation arc	91 days
Earliest precovery date	25 December 2024
Aphelion	4.180 AU
Perihelion	0.8515 AU; 0.8532 AU (2028); 0.8692 AU (2032);
Semi-major axis	2.5159 AU
Eccentricity	0.6616
Orbital period (sidereal)	3.991 yr; (1457.57 days)
Mean anomaly	40.40°
Mean motion	0.2470° per day
Inclination	3.4082°
Longitude of ascending node	271.366°
Time of perihelion	22 November 2024; 19 November 2028; 21 November 2032; mid-2036?;
Argument of perihelion	134.361°
Earth MOID	0.00283 AU (423,000 km; 1.10 LD)
Jupiter MOID	1.2716 AU
Physical characteristics
Mean diameter	60±7 m
Synodic rotation period	0.32440 ± 0.00002 h (19.4640 ± 0.0012 min)
Pole ecliptic latitude	~ −25°
Pole ecliptic longitude	~ 42°
Spectral type	R-type or Sa-type; S-type (most likely); L-type; K-type;
Apparent magnitude	24 (13 February); 25 (26 February); 26 (14 March); 29.4 (2026 opposition);
Absolute magnitude (H)	24.05±0.15 (phase corrected); 23.96±0.28 (JPL);

2024 YR₄ is an asteroid with an estimated diameter of 53 to 67 metres (174 to 220 ft)^[7] 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 2024 YR₄ impacting Earth in 2032 and lowered its Torino rating to 0. As of April 2025^[update], it retains a roughly 4% chance of impacting the Moon on 22 December 2032 around 15:19 UTC.

The asteroid was discovered by the Chilean station of the Asteroid Terrestrial-impact Last Alert System (ATLAS) at Río Hurtado on 27 December 2024.^[1]^[2] 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 United Nations–endorsed space agencies to begin planning asteroid threat mitigation.^[14]^[15]^[16]

The asteroid made a close approach to Earth at a distance of 828,800 kilometres (515,000 miles; 2.156 lunar distances) 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.^[3] Analysis of spectral and photometric time series suggests that 2024 YR₄ is a stony S-type (most likely), L-type or K-type asteroid, with a rotation period of approximately 19.5 minutes.^[11] A number of known asteroids, including other virtual impactors,^[c] follow orbits somewhat consistent with that of 2024 YR₄.^[17]

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Discovery^[1]^[2]
2024 YR₄ (centered) tracked by the Very Large Telescope in January 2025
Discovered by	ATLAS–CHL (W68)
Discovery site	Río Hurtado, Chile
Discovery date	27 December 2024
Designations
MPC designation	2024 YR₄
Minor planet category	NEO Apollo risk-listed
Orbital characteristics^[3] (JPL)
Epoch 5 May 2025 (JD 2460800.5)
Uncertainty parameter 3
Observation arc	91 days
Earliest precovery date	25 December 2024
Aphelion	4.180 AU^[a]
Perihelion	0.8515 AU 0.8532 AU (2028)^[4] 0.8692 AU (2032)^[5]
Semi-major axis	2.5159 AU
Eccentricity	0.6616
Orbital period (sidereal)	3.991 yr (1457.57 days)
Mean anomaly	40.40°
Mean motion	0.2470° per day
Inclination	3.4082°
Longitude of ascending node	271.366°
Time of perihelion	22 November 2024 19 November 2028^[4] 21 November 2032^[5] mid-2036?^[6]^[b]
Argument of perihelion	134.361°
Earth MOID	0.00283 AU (423,000 km; 1.10 LD)
Jupiter MOID	1.2716 AU
Physical characteristics
Mean diameter	60±7 m^[7]
Synodic rotation period	0.32440 ± 0.00002 h (19.4640 ± 0.0012 min)^[8]
Pole ecliptic latitude	~ −25°^[9]
Pole ecliptic longitude	~ 42°^[9]
Spectral type	R-type or Sa-type^[9] S-type (most likely) L-type K-type^[10]^[11]
Apparent magnitude	24 (13 February) 25 (26 February) 26 (14 March)^[12] 29.4 (2026 opposition)^[13]
Absolute magnitude (H)	24.05±0.15 (phase corrected)^[11] 23.96±0.28 (JPL)^[3]