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9 Metis facts for kids

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For the moon of Jupiter, see Metis (moon).
9 Metis Astronomical symbol for 9 Metis
Discovery
Discovered by A. Graham
Discovery date April 25, 1848
Designations
1974 QU2
Main belt
Orbital characteristics
Epoch July 14, 2004 (JD 2453200.5)
Aphelion 400.548 Gm (2.678 AU)
Perihelion 313.556 Gm (2.096 AU)
357.052 Gm (2.387 AU)
Eccentricity 0.122
1346.815 d (3.69 a)
19.21 km/s
274.183°
Inclination 5.576°
68.982°
5.489°
Physical characteristics
Dimensions 235×195×140 km
Mass ~9×1018 kg
Mean density
~2.7 g/cm³
~0.070 m/s²
~0.11 km/s
0.2116 d (5.078 h)
Albedo 0.243 (geometric)
Temperature ~173 K
max: 282 K (+9° C)
Spectral type
S-type
8.1 to 11.83
6.28
Angular diameter
0.23" to 0.071"

9 Metis is one of the biggest main belt asteroids. It is made of silicates and metallic nickel-iron, and may be the core remnant of a big asteroid that was destroyed by an ancient collision.

Discovery and naming

Moon and Asteroids 1 to 10
The first 10 asteroids profiled against Earth's Moon. 9 Metis is second from right.

Metis was found by Andrew Graham on April 25, 1848; it was his only asteroid discovery. It is also the only asteroid to have been found as a result of observations from Ireland. Its name comes from the mythological Metis, a Titaness and Oceanid, daughter of Tethys and Oceanus. The name Thetis was also considered and rejected (it would later devolve to 17 Thetis).

Characteristics

Metis' direction of rotation is unknown at present.

Hubble space telescope images and lightcurve analyses are in agreement that Metis has a non-spherical stretched shape with one pointed and one broad end. Radar observations suggest the presence of a significant flat area, in agreement with the shape model from lightcurves.

What the surface is made of has been estimated as 30-40% metal-bearing olivine and 60-70% Ni-Fe metal.

Light curve data on Metis led to an assumption that it could have a moon. However, subsequent observations failed to confirm this. Later searches with the Hubble Space Telescope in 1993 found no moons.

Occultations

Metis has been seen to occult stars no less than 5 times.

— Horizons can be used to obtain a current ephemeris.
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