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Ceres (dwarf planet)

Ceres

Ceres
Discovery
Discovered by Giuseppe Piazzi
Discovery time January 1, 1801
Names
Name 1 Ceres
Other names A899 OF; 1943 XB
Group dwarf planet
main belt
Orbit
Reference date November 26, 2005
(JD 2453700.5)[1]
Longest distance from the Sun 447,838,164 km
2.987 AU
Shortest distance from the Sun 381,419,582 km
2.544 AU
Longest distance from the center of its orbital path
("semi-major axis")
414,703,838 km
2.765 956 424 AU[2]
How egg-shaped its orbit is
("eccentricity")
0.07976017[2]
How long it takes to complete an orbit 1679.819 days
4.599 years
Average speed 17.882 km/s
Mean anomaly 108.509°
Angle above the reference plane
("inclination")
10.586712°[2]
Longitude of where it comes up through the reference plane 80.40696°[2]
Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
73.15073°[2]
Size and Other Qualities
Distance from its center to its surface at its equator 487.3 ± 1.8 km[3]
Distance from its center to its surface at the poles 454.7 ± 1.6 km[3]
Flatness at the poles 0.067 ± 0.005
Mass 9.46 ± 0.04×1020 kg[4][5]
Average density 2.08 g/cm³[3]
Gravity at its surface 0.27 m/s²
0.028 g
Slowest speed able to escape into space
("escape velocity")
0.51 km/s
How long it takes to turn around one time
(in relation to the stars)
0.3781 d
9.074 h[6]
How much light it reflects 0.113 (geometric)[7]
Surface temp. Min. Avg. Max.
Kelvin ~167 K[10] 239 K[10]
Light-band group
("spectral type")
G[8]
Seeming brightness
("apparent magnitude")
6.7 to 9.32
True brightness
("absolute magnitude")
3.34[7]
Seeming size
("angular diameter")
0.84"[9] to 0.33"

Ceres (how to say: /ˈsɪəriz/, Latin: Cerēs), also known as 1 Ceres, is the smallest dwarf planet in the Solar System and the only one in the main asteroid belt. It was discovered on January 1, 1801, by Giuseppe Piazzi,[11] and is named after the Roman goddess Ceres—the goddess of growing plants, the harvest, and of motherly love. In Greek, it is known as Demeter, after the Greek goddess Demeter. After about 200 years from its discovery, the International Astronomical Union decided to upgrade Ceres from an asteroid (or minor planet) to dwarf planetary status in 2006.

With a diameter of about 950 km, Ceres is by far the largest and most massive object in the asteroid belt, and has about a third of the belt's total mass. It was once thought to be smaller than Vesta, which is brighter. Recent observations have discovered that the asteroid is spherical, unlike the irregular shapes of smaller bodies with lower gravity.[12]

On September 27, 2007, NASA launched the Dawn space probe to explore Ceres and Vesta.

References

1. Ted Bowell, Bruce v (January 2, 2003). "Asteroid Observing Services". Lowell Observatory. Retrieved 2007-01-17.
2. Yeomans, Donald K. (July 5, 2007). "1 Ceres". JPL Small-Body Database Browser. Retrieved 2007-07-05.—The listed values were rounded at the magnitude of uncertainty (1-sigma).
3. Thomas, P.C; Parker J.Wm.; McFadden, L.A.; et al. (2005). "Differentiation of the asteroid Ceres as revealed by its shape". Nature 437: 224-226. .
4. Pitjeva, E.V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research 39 (3): 176. .
5. D. T. Britt et al. Asteroid density, porosity, and structure, pp. 488 in Asteroids III, University of Arizona Press (2002).
6. Harris, A. W.; Warner, B.D.; Pravec, P.; Eds. (2006). "Asteroid Lightcurve Derived Data. EAR-A-5-DDR-DERIVED-LIGHTCURVE-V8.0.". NASA Planetary Data System. Retrieved 2007-03-15.
7. Tedesco, E.F.; Noah, P.V.; Noah, M.; Price, S.D. (2004). "IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0.". NASA Planetary Data System. Retrieved 2007-03-15.
8. Neese, C.; Ed. (2005). "Asteroid Taxonomy.EAR-A-5-DDR-TAXONOMY-V5.0.". NASA Planetary Data System. Retrieved 2007-03-15.
9. Ceres Angular Size @ Feb 2009 Opposition: 974km dia / (1.58319AU * 149 597 870km) * 206265 = 0.84"
10. Saint-Pé, O.; Combes, N.; Rigaut F. (1993). "Ceres surface properties by high-resolution imaging from Earth". Icarus 105: 271-281. .
11. Piazzi, Giuseppe (1801) (in Italian). Risultati delle osservazioni della nuova Stella scoperta il dì 1 gennajo all'Osservatorio Reale di Palermo. Palermo.
12. Ceres at Solarviews.com