Discovery [1] | |
---|---|
Discovered by | A. de Gasparis |
Discovery site | Naples Obs. |
Discovery date | 19 September 1852 |
Designations | |
(20) Massalia | |
Pronunciation | /mæˈseɪliə/ [2] |
Named after | Marseille (French city) [3] |
Massilia /mæˈsɪliə/ [4] | |
main belt [1] [5] · Massalia [6] | |
Adjectives | Massalian /mæˈseɪliən/ [2] |
Orbital characteristics [5] | |
Epoch 23 March 2018 (JD 2458200.5) | |
Uncertainty parameter 0 | |
Observation arc | 164.08 yr (59,929 d) |
Aphelion | 2.7514 AU |
Perihelion | 2.0662 AU |
2.4088 AU | |
Eccentricity | 0.1422 |
3.74 yr (1,366 d) | |
12.443° | |
0° 15m 48.96s / day | |
Inclination | 0.7087° |
206.11° | |
2021-Nov-04 | |
256.58° | |
Physical characteristics | |
Dimensions | 160×145×132 km [7] 160×145×130 km [8] |
145.50±9.3 km [9] | |
Mass | 5.2×1018 kg [10] 5.67×1018 kg [7] |
Mean density | 3.54±0.85 g/cm3 [7] |
8.098 h [11] | |
0.210 [9] | |
Tholen = S [5] SMASS = S [5] | |
8.3 [12] to 12.0 | |
6.50 [5] [11] | |
0.186" to 0.058" | |
20 Massalia is a stony asteroid and the parent body of the Massalia family located in the inner region of the asteroid belt, approximately 145 kilometers (90 miles) in diameter. Discovered by Italian astronomer Annibale de Gasparis on 19 September 1852, it was named for the Latin name of the French city of Marseille, from which the independent discover Jean Chacornac sighted it the following night. [3] It was the first asteroid that was not assigned an iconic symbol by its discoverer. [13]
It came to opposition 179 degrees from the Sun on 16 June 2023, [14] and came to aphelion (farthest distance from the Sun) on 17 September 2023.[ needs update ]
Massalia is the namesake and the parent body of the Massalia family ( 404 ), a very large inner belt asteroid family consisting of stony asteroids with very low inclinations. [6] [15] : 23 It is by far the largest body in this family. The remaining family members are fragments ejected by a cratering event on Massalia. [16]
It orbits the Sun in the inner main-belt at a distance of 2.1–2.8 AU once every 3 years and 9 months (1,366 days; semi-major axis of 2.41 AU). Its orbit has an eccentricity of 0.14 and an inclination of 1° with respect to the ecliptic. [5]
Massalia has an above-average density for S-type asteroids, similar to the density of silicate rocks. As such, it appears to be a solid unfractured body, a rarity among asteroids of its size. Apart from the few largest bodies over 400 km in diameter, such as 1 Ceres and 4 Vesta, most asteroids appear to have been significantly fractured, or are even rubble piles. In 1998, Bange estimated Massalia to have a mass of 5.2×1018 kg assuming that 4 Vesta has 1.35×10−10 solar mass. [10] The calculation of the mass of Massalia is dependent on the mass of 4 Vesta and perturbation of 44 Nysa. [10]
Light curve analysis indicates that Massalia's pole points towards ecliptic coordinates either (β, λ) = (45°, 10°) or (β, λ) = (45°, 190°) with a 10° uncertainty. [8] This gives an axial tilt of 45° in both cases. The shape reconstruction from light curves has been described as quite spherical with large planar, nonconvex parts of the surface.
In 1988 there was a search for satellites or dust orbiting this asteroid using the UH88 telescope at the Mauna Kea Observatories, but none were found. [17]
In February 2024, water molecules were discovered on 20 Massalia, alongside 7 Iris, marking the first time water molecules were detected on asteroids. [18] [19]
Massalia was discovered on 19 September 1852, by Annibale de Gasparis at Naples Observatory in Italy, and also found independently the next night by Jean Chacornac at Marseilles Observatory, France. It was Chacornac's discovery that was announced first. In the nineteenth century the variant spelling Massilia was often used. Asteroids discovered prior to Massalia were assigned iconic symbols, like the ones traditionally used to designate the planets. However, astronomers had begun to phase out this practice with the discovery of 16 Psyche in March 1852, and 20 Massalia (being the first object in the Solar System with a non-mythological name) [3] was the first asteroid that was not assigned an iconic symbol.
16 Psyche 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. 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, but recent observations cast doubt on that hypothesis. 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, with an expected arrival in 2029.
Juno is a large asteroid in the asteroid belt. Juno was the third asteroid discovered, in 1804, by German astronomer Karl Harding. It is one of the twenty largest asteroids and one of the two largest stony (S-type) asteroids, along with 15 Eunomia. It is estimated to contain 1% of the total mass of the asteroid belt.
5 Astraea is an asteroid in the asteroid belt. This object is orbiting the Sun at a distance of 385 million kilometres (2.5735 AU) with a period of 4.13 yr and an orbital eccentricity of 0.19. The orbital plane is inclined at an angle of 5.37° to the plane of the ecliptic. It is spinning with a period of 16.8 h. The surface of Astraea is highly reflective and its composition is probably a mixture of nickel–iron with silicates of magnesium and iron. It is an S-type asteroid in the Tholen classification system.
45 Eugenia is a large asteroid of the asteroid belt. It is famed as one of the first asteroids to be found to have a moon orbiting it. It was also the second triple asteroid to be discovered, after 87 Sylvia.
7 Iris is a large main-belt asteroid and possible remnant planetesimal orbiting the Sun between Mars and Jupiter. It is the fourth-brightest object in the asteroid belt. 7 Iris is classified as an S-type asteroid, meaning that it has a stony composition.
8 Flora is a large, bright main-belt asteroid. It is the innermost large asteroid: no asteroid closer to the Sun has a diameter above 25 kilometres, and not until 20-km 149 Medusa was discovered was an asteroid known to orbit at a closer mean distance. It is the seventh-brightest asteroid with a mean opposition magnitude of +8.7. Flora can reach a magnitude of +8.1 at a favorable opposition near perihelion, such as occurred in November 2020 when it was 0.88 AU from Earth.
9 Metis is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a percent of the total mass of the asteroid belt.
10 Hygiea is a major asteroid located in the main asteroid belt. With a mean diameter of between 425 and 440 km and a mass estimated to be 3% of the total mass of the belt, it is the fourth-largest asteroid in the Solar System by both volume and mass, and is the largest of the C-type asteroids in classifications that use G type for 1 Ceres. It is very close to spherical, apparently because it had re-accreted after the disruptive impact that produced the large Hygiean family of asteroids.
17 Thetis is a stony asteroid from the inner regions of the asteroid belt, approximately 90 kilometers in diameter. It was discovered on 17 April 1852, by German astronomer Robert Luther at Bilk Observatory in Düsseldorf, Germany who deferred to Friedrich Wilhelm August Argelander the naming his first asteroid discovery after Thetis from Greek mythology. Its historical symbol was a dolphin and a star; it is in the pipeline for Unicode 17.0 as U+1CECA .
32 Pomona is a stony main-belt asteroid that is 81 kilometres (50 mi) in diameter. It was discovered by German-French astronomer Hermann Mayer Salomon Goldschmidt on October 26, 1854, and is named after Pōmōna, the Roman goddess of fruit trees.
43 Ariadne is a fairly large and bright main-belt asteroid. It is the second-largest member of the Flora asteroid family. It was discovered by N. R. Pogson on 15 April 1857 and named after the Greek heroine Ariadne.
22 Kalliope is a large M-type asteroid from the asteroid belt discovered by J. R. Hind on 16 November 1852. It is named after Calliope, the Greek Muse of epic poetry. It is orbited by a small moon named Linus.
159 Aemilia is a large main-belt asteroid. Aemilia was discovered by the French brothers Paul Henry and Prosper Henry on January 26, 1876. The credit for this discovery was given to Paul. It is probably named after the Via Aemilia, a Roman road in Italy that runs from Piacenza to Rimini.
341 California is an asteroid belonging to the Flora family in the Main Belt. It was discovered by Max Wolf on 25 September 1892 in Heidelberg, and is named for the U.S. state of California. This object is orbiting the Sun at a distance of 2.20 AU with a period of 3.26 yr and an eccentricity (ovalness) of 0.19. The orbital plane is inclined at an angle of 5.7° to the plane of the ecliptic.
354 Eleonora is a large, stony main-belt asteroid that was discovered by the French astronomer Auguste Charlois on January 17, 1893, in Nice.
538 Friederike is a minor planet orbiting in the asteroid belt. It is a member of the Hygiea family of asteroids.
809 Lundia is a small, binary, V-type asteroid orbiting within the Flora family in the main belt. It is named after Lund Observatory, Sweden.
956 Elisa is a Flora asteroid from the inner regions of the asteroid belt, approximately 10.5 kilometers in diameter. It was discovered on 8 August 1921, by German astronomer Karl Reinmuth at the Heidelberg Observatory. The V-type asteroid has a rotation period of 16.5 hours. It was named after Elisa Reinmuth, mother of the discoverer.
9951 Tyrannosaurus, provisional designation 1990 VK5, is a stony Vestian asteroid from the inner regions of the asteroid belt, approximately 17 kilometers in diameter. It was discovered on 15 November 1990, by Belgian astronomer Eric Elst at ESO's La Silla Observatory in northern Chile. It was named after Tyrannosaurus, a genus of dinosaurs.
1622 Chacornac is a stony Flora asteroid from the inner regions of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 15 March 1952, by French astronomer Alfred Schmitt at the Royal Observatory of Belgium in Uccle, and named after astronomer Jean Chacornac.