405 Thia

Not to be confused with 453 Tea, Theia (planet), or Thiazzi (moon).

405 Thia

Discovery
Discovered by	Auguste Charlois
Discovery date	23 July 1895
Designations
MPC designation	(405) Thia
Pronunciation	/ˈθaɪə/[1]
Named after	Theia
Alternative designations	1895 BZ
Minor planet category	Main belt
Orbital characteristics[2]
Epoch 2023-Feb-25 (JD 2460000.5)
Uncertainty parameter 0
Observation arc	123.54 years
Aphelion	3.2145 AU (480.88 Gm)
Perihelion	1.9592 AU (293.09 Gm)
Semi-major axis	2.5861 AU (386.88 Gm)
Eccentricity	0.24341
Orbital period (sidereal)	4.16 yr (1518.3 d)
Mean anomaly	336.81°
Mean motion	0° 14^m 13.164^s / day
Inclination	11.937°
Longitude of ascending node	255.19°
Time of perihelion	2 June 2023[2]
Argument of perihelion	308.65°
Earth MOID	0.975 AU (145.9 million km; 379 LD)
Physical characteristics
Dimensions	108.894±0.312 km[2] 122.14 ± 7.69 km[3]
Mass	(1.38 ± 0.14) × 10^18 kg[3]
Mean density	1.44 ± 0.30 g/cm^3[3]
Synodic rotation period	10.08 h (0.420 d)
Geometric albedo	0.0468±0.002
Spectral type	C[2]
Absolute magnitude (H)	8.65

405 Thia is a very large main-belt asteroid. It is classified as a C-type asteroid and is probably composed of carbonaceous material. This object was discovered by Auguste Charlois on July 23, 1895, in Nice, and was named after Theia (sometimes written Thea or Thia), a Titaness in Greek mythology.[4]

In 2002, the asteroid was detected by radar from the Arecibo Observatory at a distance of 1.31 AU. The resulting data yielded an effective diameter of 125 ± 16 km.[5] NEOWISE data suggests the asteroid is 110 km in diameter.[2]

On 4 May 1990 Thia passed 0.969 AU (145.0 million km; 377 LD) from Earth[6] and will pass that close again on 29 April 2073.

405 Thia currently has a Minimum orbit intersection distance with Earth of 0.976 AU (146.0 million km; 380 LD)[2]. On 2 June 2023 the asteroid reached perihelion (closest approach to the Sun).[2]

Thia Earth approach on 2023-Mar-20

Date & time of closest approach	Earth distance (AU)	Sun distance (AU)	Velocity wrt Earth (km/s)	Velocity wrt Sun (km/s)	Uncertainty region (3-sigma)	Reference
2023-03-20 19:40	1.057 AU (158.1 million km; 411 LD)	2.006 AU (300.1 million km; 781 LD)	6.8	23.3	± 16 km	Horizons

References

1. Noah Webster (1884) A Practical Dictionary of the English Language
2. "JPL SBDB: 405 Thia (1895 BZ)". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Archived from the original on 21 February 2023. Retrieved 16 December 2024.
3. Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
4. Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names. Berlin, Heidelberg, New York: Springer. p. 48. ISBN 3-540-00238-3. Archived from the original on 14 March 2014.
5. Magri, Christopher; et al. (January 2007), "A radar survey of main-belt asteroids: Arecibo observations of 55 objects during 1999 2003" (PDF), Icarus, 186 (1): 126–151, Bibcode:2007Icar..186..126M, doi:10.1016/j.icarus.2006.08.018, archived (PDF) from the original on 3 December 2016, retrieved 14 April 2015.
6. "Horizons Batch for Thia in May 1990". JPL Horizons. Archived from the original on 20 February 2023. Retrieved 20 February 2023.

External links

• 405 Thia at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 405 Thia at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters