NASA/JPL CNEOS · MPC · IAU · Vol. IV
PHA Catalogue VOL. IV
Potentially Hazardous Asteroids · Sun-grazers, twilight discoveries & micro-asteroids
Data: JPL Small-Body Database · MPC · Carnegie/DECam Survey · JAXA
Data: JPL Small-Body Database · MPC · Carnegie/DECam Survey · JAXA
~1.5 km2022 AP7 diameter
114 d2021 PH27 period
~30 m1998 KY26 diameter
1.6×GR effect vs Mercury
Twilight survey: Asteroids orbiting inside Earth's orbit can only be observed at low solar elongation — at dawn or dusk. Scott Sheppard's DECam twilight programme at Cerro Tololo (2020–) has revealed a previously hidden population of large inner-solar-system PHAs, including several >1 km objects unknown until recently.
Discovery surveys by era — inner-solar-system completeness
Pre-1990
~50% (2005)
~90% (2020)
Inner pop.
NEOS 2028
Class
Torino 0 — No hazard
Torino 1 — Very low
Torino 2–3 — Attention
Torino 4+ — Concern
Designation / Name
H mag
Diam.
MOID
Period
Torino
Twilight survey discoveries — Carnegie/DECam 2021–2022
2022 AP7
2022 AP7 2022 PLANET-KILLER
Apollo · X-type · 1:5 resonance with Earth
17.3
~1.5 km
0.0465 au
5.01 yr
0
Discovered
2022 Jan 13 (DECam/Cerro Tololo)
Discoverers
S. Sheppard et al. (Carnegie)
Diameter range
0.9–2.3 km (albedo 0.05–0.25)
Best diameter est.
~1.5 km (H=17.3, alb=0.14)
Semi-major axis
2.923 au
Eccentricity
0.715
Perihelion
0.832 au
Aphelion
5.01 au (Jupiter region)
Inclination
13.8°
1:5 resonance
Crosses Earth orbit — opposite side
Nearest Earth approach
~April 2332 (nominal)
Impact prob.
Not risk-listed (JPL Sentry)
Largest PHA discovered in ~8 years; described by lead author Sheppard as a "planet killer" — a global-catastrophe-scale object if it ever struck Earth. Its 1:5 near-resonance with Earth means it currently crosses Earth's orbit when Earth is on the opposite side of the Sun, making it safe for the foreseeable future. Nominally it will not approach within 1 au of Earth until April 2332. The resonance will eventually erode, potentially allowing close encounters over a timescale of centuries to millennia. Discovered in twilight using the DECam imager, demonstrating the hidden inner population that standard surveys miss. Source: Sheppard et al. (2022) AJ 164, 168 · Wikipedia/MPC · JPL SBDB · NOIRLab press release 2022-10-31
2021 PH27
2021 PH27 SHORTEST PERIOD
Atira (IEO) · X-type · Sun-grazer
17.7
~1.2 km
0.228 au
0.31 yr
0
Discovered
2021 Aug 13 (DECam/Cerro Tololo)
Discoverer
S. Sheppard (Carnegie Institution)
Diameter estimate
~1.2 km (H=17.7, alb~0.098)
Orbital period
114.7 days — shortest known asteroid
Semi-major axis
0.462 au (inside Venus)
Eccentricity
0.712
Perihelion
0.133 au (inside Mercury)
Aphelion
0.790 au (inside Earth)
Inclination
31.9°
Perihelion speed
106 km/s at perihelion
Surface temp. (perihelion)
>1,000 K — melts lead
GR precession
~69 arcsec/century — 1.6× Mercury
Rotation period
3.49 h (VLT/VISIR 2022)
Spectral type
X-type (Sheppard & Santana-Ros 2025)
Pair
2025 GN1 — likely asteroid pair
Venus MOID
0.01466 au — possible Venus meteor shower
Impact prob. (Earth)
None — orbit interior to Earth
Guinness World Record holder for shortest orbital period of any known asteroid (114.7 days), as of 2026. Its perihelion at 0.133 au is inside Mercury's orbit — surfaces reach 1,000 K. It has the largest known general-relativistic perihelion precession of any solar system object: ~69 arcsec/century, or 1.6× that of Mercury. Sheppard et al. (2025, arXiv:2504.16175) identified 2025 GN1 as a likely split fragment with identical X-type colours; the pair probably separated 10,500–21,000 years ago by YORP-driven rotational disintegration. Source: Sheppard et al. (2022) AJ 164, 168 · Sheppard & Santana-Ros (2025) arXiv:2504.16175 · Guinness World Records Jan 2022
2021 LJ4
2021 LJ4 DECam
Atira (IEO) · X-type · Venus-crosser
20.5
300–400 m
0.249 au
0.67 yr
0
Discovered
2021 (DECam/Cerro Tololo)
Discoverers
S. Sheppard et al. (Carnegie)
Diameter estimate
300–400 m (brightness-based)
Spectral type
X-type (similar to 2021 PH27)
Orbit class
Interior Earth Object (IEO/Atira)
Aphelion
< 0.983 au (inside Earth's perihelion)
Crosses
Venus and Mercury orbits
Impact prob. (Earth)
None — orbit interior to Earth
Third member of the Sheppard/DECam twilight trio announced alongside 2022 AP7 and 2021 PH27. An Atira-class object whose entire orbit lies within Earth's, also crossing the orbits of Venus and Mercury. Only ~50 Atiras are known as of 2026, primarily because they are only observable in twilight at low solar elongation. Its X-type colours are similar to 2021 PH27, though the two are not believed to be co-genetic. Demonstrates the significant undiscovered population of decametre-to-hectometre objects orbiting entirely interior to Earth. Source: Sheppard et al. (2022) AJ 164, 168 · CBS News / NSF press coverage (Nov 2022)
Micro-asteroid & future mission targets
1998 KY26
1998 KY26 Hayabusa2# MICRO
Apollo · Xe-type · Fast rotator · Dark comet?
25.7
~11–30 m
0.0018 au
1.37 yr
0
Discovered
1998 May 28 (Spacewatch)
Radar discovery
1998 Jun 6–8 (Goldstone)
Diameter (original)
~30 m (Ostro et al. 1999)
Diameter (revised 2025)
~11–17 m (VLT VISIR non-detection)
Spectral type
Xe-type (Bolin et al. 2025)
Rotation period
5.35 min (revised 2025; faster than known)
Semi-major axis
1.233 au
Eccentricity
0.201
Inclination
1.48°
Non-grav. acceleration
Detected — possible dark comet
Hayabusa2# rendezvous
July 2031 (first decametre-scale visit)
Torifune flyby (en route)
2026 (98943 Torifune / 2001 CC21)
Impact prob.
None known
Target of JAXA's extended Hayabusa2# (SHARP) mission, due to rendezvous in July 2031 — it will be the first spacecraft visit to a decametre-scale asteroid. A 2024 photometric campaign revised the original 30 m radar-based size estimate downward to 11–17 m (Santana-Ros et al., 2025) and found a rotation period of 5.35 min — faster than previously known and above the spin barrier for rubble piles, suggesting a monolithic structure. Non-gravitational acceleration has been detected, raising the possibility it is a "dark comet" — an asteroid with comet-like outgassing invisible to ground-based telescopes. Source: Ostro et al. (1999) Science 285 · Santana-Ros et al. (2025, in review) · PMC 12446490 · JAXA Hayabusa2# mission status
Contact binaries & metallic PHAs
(153201) 2000 WO107
2000 WO107 BINARY
Aten · X/M-type · Contact binary · Mercury-crosser
19.3
~510 m
0.0020 au
0.87 yr
0
Discovered
2000 Nov 29 (LINEAR)
Diameter (NEOWISE)
~510 m
Spectral type
X/M-type — possible metallic
Rotation period
5.02 h
Shape (Goldstone 2020)
Contact binary — two merged lobes
Semi-major axis
0.804 au
Eccentricity
0.753
Perihelion
0.198 au (crosses Mercury orbit)
Inclination
5.0°
2020 flyby
2020 Nov 29 — ~4.3 million km (11.2 LD)
Future approaches
Slightly closer: Nov 2040, Nov 2093
Perihelion speed
88 km/s (2020 Oct 13 perihelion)
Impact prob.
None known
Goldstone radar observations during the Nov 2020 flyby revealed a contact binary structure — two merged lobes of roughly similar size, akin to Toutatis and Castalia. The X/M spectral classification suggests a metallic or enstatite-rich composition, making it potentially one of the few metal-rich PHAs with a precisely known orbit. Its orbit crosses every inner planet: Mercury, Venus, Earth, and Mars — an unusually wide-ranging trajectory. Each future Earth flyby is slightly closer than the last, with the Nov 2093 approach being closest in the near-term forecast. Source: EarthSky/NASA JPL Goldstone (Dec 2020) · Wikipedia/MPC · Space Reference SBDB
(388945) 2008 TZ3
2008 TZ3 RADAR
Apollo · S-type · Elongated
20.3
~490 m
0.0157 au
1.97 yr
0
Discovered
2008 Oct 6 (Mt Lemmon CSS)
Diameter (NEOWISE)
~490 m
Albedo
~0.14
Rotation period
8.67 h (lightcurve)
Eccentricity
0.392
Semi-major axis
1.546 au
Inclination
5.0°
2022 flyby
2022 May 10 — ~3.6 million km
2025 flyby
2025 May 9 — ~2.93 million km (7.6 LD)
Impact prob.
None known
Made a series of close Earth flybys in 2022 and 2025, allowing Goldstone and Arecibo follow-up observations that refined its shape model as elongated — aspect ratio estimated at roughly 2:1 based on lightcurve amplitude. The May 2025 flyby at 7.6 lunar distances drew attention as one of the larger PHAs making a close pass in 2025. Consistent radar detections across multiple apparitions have pinned its orbit to high precision. Source: CNEOS close approach table · Lightcurve Database (LCDB) B. Warner · JPL SBDB
Notable Amor-class & Mars-crossing PHAs
(1036) Ganymed
Ganymed
Amor · S-type · Largest known NEA
9.5
~37.7 km
0.0344 au
4.34 yr
0
Discovered
1924 Oct 23
Discoverer
W. Baade (Bergedorf, Hamburg)
Diameter (WISE)
37.7 ± 4.5 km
Albedo
0.29
Rotation period
10.31 h
Semi-major axis
2.665 au
Eccentricity
0.534
Perihelion
1.237 au
Inclination
26.7°
Orbit class
Amor — does not cross Earth orbit
Impact risk
Amor — perihelion > 1.017 au
Mass (est.)
~1.8 × 10¹⁹ kg (density ~2.5 g/cc)
At ~37.7 km diameter, the largest known near-Earth asteroid — larger than any PHA listed in this series. It is technically a PHA because its MOID of 0.034 au is inside the 0.05 au threshold and H = 9.5 is brighter than H = 22. However, as an Amor asteroid, its perihelion of 1.237 au means its orbit does not currently cross Earth's. Any impact would require orbital evolution over a very long timescale. Named after one of Jupiter's moons (and the Ganymede of Greek myth). Discovered by Walter Baade at Bergedorf. Source: JPL SBDB · Warner et al. (2009) LCDB · Tedesco et al. (2002) WISE/IRAS
(3552) Don Quixote
Don Quixote
Amor · D-type · Possible extinct comet
12.8
~18.7 km
0.0144 au
8.68 yr
0
Provisional desig.
1983 SA
Discovered
1983 Sep 26 (P. Wild, Zimmerwald)
Diameter (Spitzer)
18.7 ± 3.7 km
Albedo
0.03 (extremely dark)
Rotation period
3.70 h
Semi-major axis
4.237 au
Eccentricity
0.714
Perihelion
1.211 au
Aphelion
7.263 au (near Jupiter's aphelion)
Inclination
31.1°
Cometary activity
Coma + tail detected (Spitzer 2009)
Impact prob.
None known
Long classified purely as an asteroid, Don Quixote was found to display a coma and faint tail in Spitzer Space Telescope thermal infrared observations during its 2009 perihelion passage (Mommert et al. 2014, ApJ), confirming it as one of the first known active NEAs with cometary behaviour. Its D-type spectrum, very low albedo (0.03), and Jupiter-family-like orbit strongly support it being an extinct or dormant comet nucleus rather than a native asteroid. Second-largest known NEA after Ganymed. Named after Cervantes's literary knight errant. Source: Mommert et al. (2014) ApJ 781, 25 · JPL SBDB · Wikipedia
Active Sentry & recently elevated objects (2025–2026)
2024 PT5
2024 PT5 MINI-MOON 2024
Amor · Q/L-type · Temporary capture
27.4
~10–15 m
0.0034 au
~1.00 yr
0
Discovered
2024 Aug 7 (ATLAS)
Survey
ATLAS South Africa
Size estimate
~10–15 m (brightness-based)
Spectral type
Q/L-type — rare, near-lunar spectrum
Lunar spectrum match
Closest known lunar-like asteroid
Temporary capture
2024 Sep 29 – Nov 25 (~2 months)
Capture class
"Mini-moon" (temporarily captured flyby)
Orbital origin
Horseshoe orbit — Arjuna class
Semi-major axis
~1.00 au (co-orbital with Earth)
Impact prob.
None
Spectroscopic observations by de León et al. (GTC, 2024) revealed 2024 PT5 has a lunar-like near-infrared spectrum — the closest asteroid spectral match to the Moon ever found — strongly suggesting it originated from the Moon itself, likely ejected by a meteorite impact. It briefly became Earth's "mini-moon" (temporarily captured flyby object) for approximately 2 months from 29 Sep to 25 Nov 2024. Its horseshoe co-orbital trajectory with Earth places it in the Arjuna dynamical class — objects that perennially shadow Earth in its orbit and may be regularly captured and released. Source: de León et al. (2024) arXiv preprint · ATLAS discovery MPEC · Carlos de la Fuente Marcos et al. (2024) RNAAS