(875163) 1998 SH₂

(875163) 1998 SH₂
Discovery
Discovered by	Spacewatch
Discovery site	Kitt Peak Observatory
Discovery date	17 September 1998
Designations
Alternative designations	1998 SH2 · 2016 EC156
Minor planet category	NEO · Apollo · PHA
Orbital characteristics
	Epoch 9 June 2026 (JD 2461200.5)
	Uncertainty parameter 0
Observation arc	27.10 years
Aphelion	4.701 AU
Perihelion	0.785 AU
Semi-major axis	2.743 AU
Eccentricity	0.71379
Orbital period (sidereal)	4.543 years
Mean anomaly	70.005°
Mean motion	0° 13m 1.115s / day
Inclination	2.426°
Longitude of ascending node	6.074°
Argument of perihelion	268.72°
Earth MOID	0.019 AU
Jupiter MOID	0.499 AU
Physical characteristics
Mean diameter	0.383 ± 0.057 km (0.238 ± 0.035 mi)
Geometric albedo	0.058±0.024
Absolute magnitude (H)	20.88

(875163) 1998 SH₂ is an Apollo-type near-Earth asteroid with an estimated diameter of about 383 m (1,257 ft).^[5] It was discovered by the Spacewatch survey of the Kitt Peak National Observatory from Arizona, USA on 17 September 1998.^[1]

Physical characteristics

Infrared observations from the NEOWISE spacecraft revealed that asteroid 1998 SH₂ may have a diameter of about 383 m (1,257 ft) assuming a geometric albedo of about 0.058.^[5] Astrometric measurements up to 2025 revealed orbital perturbations consistent with weak outgassing,^[6] indicating that this object might be also a comet.^[7]

Orbit

As of June 2026^[update], 1998 SH₂ currently has a perihelion of about 0.785 AU (117.4 million km) and aphelion of about 4.701 AU (703.3 million km) from the Sun, completing one revolution once every 4.54 years.^[4]

It made a close encounter with Earth at a distance of 0.0208 AU (3.11 million km) on 30 August 2025.^[8] By 2037, it will approach Jupiter at a distance of 0.98 AU (147 million km), followed by another Earth flyby at 0.0695 AU (10.40 million km) away on 8 September 2052.^[8] It is considered a potentially hazardous asteroid, however there is no significant impact risk with Earth in the foreseeable future.^[9]

References

1 2 A. Sugie; G. J. Garradd; F. B. Zoltowski; et al. (19 September 1998). G. V. Williams (ed.). "1998 SH₂". Minor Planet Electronic Circular. 1998-S10. Bibcode:1998MPEC....S...10S.
↑ A. F. Tubbiolo; R. Matson (15 March 2016). G. V. Williams (ed.). "1998 SH₂ = 2016 EC₁₅₆". Minor Planet Electronic Circular. 2016-E174. Bibcode:2016MPEC....E..174T.
1 2 "(875163) 1998 SH₂ – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 18 July 2026.
1 2 "(875163) = 1998 SH₂ = 2016 EC₁₅₆". Minor Planet Center. Retrieved 19 July 2026.
1 2 3 J. R. Masiero; C. Nugent; A. K. Mainzer; et al. (2017). "NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos". The Astronomical Journal. 154 (4): 168–178. arXiv:1708.09504. Bibcode:2017AJ....154..168M. doi:10.3847/1538-3881/aa89ec.
↑ D. Farnocchia; O. R. Hainaut; D. Z. Seligment (2026). "Non-gravitational acceleration indicative of cometary activity of near-Earth object" (PDF). Nature Astronomy. Bibcode:2026NatAs.tmp..159F. doi:10.1038/s41550-026-02913-7.{{cite journal}}: CS1 maint: bibcode (link)
↑ I. J. O'Neill; K. Fox; M. Wasser (16 July 2026). "NASA Study Finds Near-Earth Asteroid Is Actually Comet". jpl.nasa.gov. NASA / Jet Propulsion Laboratory. Retrieved 18 July 2026.
1 2 R. Weryk; R. Wainscoat; L. Wells; et al. (15 July 2026). D. W. Green (ed.). "(875163) = Comet P/1998 SH₂ = P/2016 EC₁₅₆" (TXT). Central Bureau for Astronomical Telegrams. 5716: 1.
↑ K. Kasal (15 July 2026). "Asteroid with unexplained orbital shift turns out to be a 'dark comet'". Phys.org. Retrieved 19 July 2026.

External links

(875163) 1998 SH₂ at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters
(875163) 1998 SH₂ at the Minor Planet Center database
(875163) 1998 SH2 at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
(875163) 1998 SH₂ at Seiichi Yoshida's website

[MPEC_1998-S10-1] 1 2 A. Sugie; G. J. Garradd; F. B. Zoltowski; et al. (19 September 1998). G. V. Williams (ed.). "1998 SH₂". Minor Planet Electronic Circular. 1998-S10. Bibcode:1998MPEC....S...10S.

[MPEC_2016-E174-2] A. F. Tubbiolo; R. Matson (15 March 2016). G. V. Williams (ed.). "1998 SH₂ = 2016 EC₁₅₆". Minor Planet Electronic Circular. 2016-E174. Bibcode:2016MPEC....E..174T.

[jpldata-3] 1 2 "(875163) 1998 SH₂ – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 18 July 2026.

[MPC-4] 1 2 "(875163) = 1998 SH₂ = 2016 EC₁₅₆". Minor Planet Center. Retrieved 19 July 2026.

[Masiero_2017-5] 1 2 3 J. R. Masiero; C. Nugent; A. K. Mainzer; et al. (2017). "NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos". The Astronomical Journal. 154 (4): 168–178. arXiv:1708.09504. Bibcode:2017AJ....154..168M. doi:10.3847/1538-3881/aa89ec.

[Farnocchia_2026-6] D. Farnocchia; O. R. Hainaut; D. Z. Seligment (2026). "Non-gravitational acceleration indicative of cometary activity of near-Earth object" (PDF). Nature Astronomy. Bibcode:2026NatAs.tmp..159F. doi:10.1038/s41550-026-02913-7.{{cite journal}}: CS1 maint: bibcode (link)

[NASA-20260716-7] I. J. O'Neill; K. Fox; M. Wasser (16 July 2026). "NASA Study Finds Near-Earth Asteroid Is Actually Comet". jpl.nasa.gov. NASA / Jet Propulsion Laboratory. Retrieved 18 July 2026.

[CBET_5716-8] 1 2 R. Weryk; R. Wainscoat; L. Wells; et al. (15 July 2026). D. W. Green (ed.). "(875163) = Comet P/1998 SH₂ = P/2016 EC₁₅₆" (TXT). Central Bureau for Astronomical Telegrams. 5716: 1.

[PHYS-20260715-9] K. Kasal (15 July 2026). "Asteroid with unexplained orbital shift turns out to be a 'dark comet'". Phys.org. Retrieved 19 July 2026.

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(875163) 1998 SH₂

Physical characteristics

Orbit

See also

References

External links