16 Psyche

16 Psyche
	16 Psyche imaged by the Very Large Telescope's adaptive optics system in August 2019
Discovery
Discovered by	Annibale de Gasparis
Discovery site	Naples Observatory
Discovery date	17 March 1852
Designations
Designation	(16) Psyche
Pronunciation	/ˈsaɪkiː/
Named after	Psyche (Ψυχή)
Minor planet category	Main belt
Adjectives	Psychean (/saɪˈkiːən/)
Symbol	(historical)
Orbital characteristics
	Epoch 13 September 2023; (JD 2460200.5)
Aphelion	3.32 AU (497 million km)
Perihelion	2.53 AU (378 million km)
Semi-major axis	2.92 AU (437 million km)
Eccentricity	0.1342
Orbital period (sidereal)	4.999 yr (1825.95 d)
Mean anomaly	243.16°
Inclination	3.096°
Longitude of ascending node	150.03°
Time of perihelion	27 April 2025
Argument of perihelion	229.41°
Earth MOID	1.53 AU (229 million km)
Physical characteristics
Dimensions	(278±5 × 232±6 × 164±4) km; 277 km × 238 km × 168 km; 279 × 232 × 189 km (± 10%); (278+4; −8 × 238+4; −6 × 171+1; −5) km
Mean diameter	223±3 km; 222±4 km; 222+1; −4 km
Flattening	0.41
Volume	5.75×106 km3 (best fit)
Mass	(2.29±0.14)×1019 kg
Mean density	3.977±0.253 g/cm3
Surface gravity	~0.144 m/s2
Escape velocity	~180 m/s (~600 ft/s)
Synodic rotation period	4.195948±0.000001 h
Albedo	0.15±0.03; 0.34±0.08 (radar)
Spectral type	Tholen = M; SMASS = X; Bus-DeMeo = Xk
Apparent magnitude	9.22 to 12.19
Absolute magnitude (H)	6.21

16 Psyche (/ˈsaɪkiː/ SY-kee) is a large M-type asteroid, which was discovered by the Italian astronomer Annibale de Gasparis, on 17 March 1852 and named after the Greek goddess Psyche.^[10] The prefix "16" signifies that it was the sixteenth minor planet in order of discovery. It is the largest and most massive of the M-type asteroids, and one of the dozen most massive asteroids. It has a mean diameter of approximately 220 kilometers (140 mi) and contains about one percent of the mass of the asteroid belt. It was thought to be the exposed core of a protoplanet,^[11] but recent observations cast doubt on that hypothesis.^[8]^[6] Psyche will be explored by NASA, with a spacecraft of the same name, marking the first time a manmade object will journey to a metallic asteroid, launched on 13 October 2023,^[12] with an expected arrival in 2029.^[13]

^ Cite error: The named reference Webster-1884 was invoked but never defined (see the help page).
^ Cite error: The named reference OED-Psychean was invoked but never defined (see the help page).
^ ^a ^b ^c ^d Cite error: The named reference JPL was invoked but never defined (see the help page).
^ ^a ^b ^c ^d Cite error: The named reference Ferrais-Vernazza-etal-2020 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d Cite error: The named reference Shepard-Richardson-etal-2017 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Shepard2021 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference Vernazza2021 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference Elkins-Tanton_2020 was invoked but never defined (see the help page).
^ Cite error: The named reference PDS-taxonomy was invoked but never defined (see the help page).
^ Cite error: The named reference Schmadel-2012-dict-mp was invoked but never defined (see the help page).
^ Cite error: The named reference Bell_AsteroidsII was invoked but never defined (see the help page).
^ Cite error: The named reference Lockhart-2023-09-28 was invoked but never defined (see the help page).
^ "NASA Continues Psyche Asteroid Mission". JPL. NASA. 28 October 2022. Archived from the original on 8 November 2022. Retrieved 28 October 2022.

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[Webster-1884-1] Cite error: The named reference Webster-1884 was invoked but never defined (see the help page).

[OED-Psychean-2] Cite error: The named reference OED-Psychean was invoked but never defined (see the help page).

[JPL-3] Cite error: The named reference JPL was invoked but never defined (see the help page).

[Ferrais-Vernazza-etal-2020-4] Cite error: The named reference Ferrais-Vernazza-etal-2020 was invoked but never defined (see the help page).

[Shepard-Richardson-etal-2017-6] Cite error: The named reference Shepard-Richardson-etal-2017 was invoked but never defined (see the help page).

[Shepard2021-7] ^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Shepard2021 was invoked but never defined (see the help page).

[Vernazza2021-8] Cite error: The named reference Vernazza2021 was invoked but never defined (see the help page).

[Elkins-Tanton_2020-10] Cite error: The named reference Elkins-Tanton_2020 was invoked but never defined (see the help page).

[PDS-taxonomy-11] Cite error: The named reference PDS-taxonomy was invoked but never defined (see the help page).

[Schmadel-2012-dict-mp-12] Cite error: The named reference Schmadel-2012-dict-mp was invoked but never defined (see the help page).

[Bell_AsteroidsII-13] Cite error: The named reference Bell_AsteroidsII was invoked but never defined (see the help page).

[Lockhart-2023-09-28-14] Cite error: The named reference Lockhart-2023-09-28 was invoked but never defined (see the help page).

[jpl-20221028-15] "NASA Continues Psyche Asteroid Mission". JPL. NASA. 28 October 2022. Archived from the original on 8 November 2022. Retrieved 28 October 2022.

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