![]() Dimorphos captured by the
DART spacecraft, seconds before impact in September 2022 | |
Discovery [1] | |
---|---|
Discovered by | Petr Pravec et al. [a] |
Discovery site | Ondřejov Observatory |
Discovery date | 20 November 2003 |
Designations | |
Designation | Didymos I |
Pronunciation | /daɪˈmɔːrfəs/ |
Named after | Greek word for "having two forms" [2] |
S/2003 (65803) 1 Didymos B Didymoon | |
Orbital characteristics [3]: 17 | |
Pre-impact: 1.187±0.017 km [4] Post-impact: 1.152±0.018 km [3]: 17 | |
Eccentricity | Pre-impact: <0.03 [3]: 17 Post-impact: 0.0274±0.0015 [4] |
Pre-impact: 11.921493±0.000030 hr (11h 55m 17.4s ± 0.1s) [5]: 28 Post-impact: 11.3675±0.0004 hr (11h 22m 3.0s ± 1.4s) [5] | |
Average
orbital speed | Pre-impact: 0.174 m/s [b] Post-impact: 0.177 m/s [b] |
Inclination | 170.7°±0.5° (to ecliptic) [c] |
Satellite of | 65803 Didymos |
Physical characteristics [7]: 12 | |
Dimensions | Pre-impact: 179 × 169 × 115 m (± 1 × 4 × 1 m) [d] Post-impact: 192 × 148 × 118 m (± 12 × 8 × 14 m) [4] |
150.0±2.5 m (volume equivalent) | |
7.47×104 m2 | |
Volume | 1.76×106 m3 |
Mass | ≈ 4.3×109 kg (if same density as Didymos) [8]: 9 |
Mean
density | <2.4±0.3 g/cm3 (assuming same as Didymos) [8]: 9 [9] |
Pre-impact: synchronous [3]: 17 Post-impact: chaotic [10] | |
Albedo | 0.15±0.02 [8]: 6 |
Spectral type | S [11] |
21.4±0.2 [1] [e] | |
Dimorphos (formal designation (65803) Didymos I; provisional designation S/2003 (65803) 1) is a small, 150-meter (490 ft) diameter moon of the near-Earth asteroid 65803 Didymos, with which it forms a binary system. Discovered on 20 November 2003 by Petr Pravec and collaborators, Dimorphos was the target of NASA's Double Asteroid Redirection Test (DART) mission, which deliberately collided a spacecraft with the moon on 26 September 2022 to alter its orbit around Didymos. Around the same time, the Italian Space Agency's LICIACube spacecraft flew by Dimorphos to image the DART impact. The impact reduced Dimorphos's orbital period by 33 minutes and ejected over 10 million kg (22 million lb) of dusty debris into space, which produced an expanding dust plume and a 70,000-kilometer (43,000 mi)-long tail of dust swept away by solar radiation pressure. [3]: 9–10
Before DART impacted Dimorphos, the moon had an oblate spheroid shape with a surface covered in boulders and few small craters. The surface features of Dimorphos suggest that the moon is a weakly-held rubble pile that formed less than 300,000 years ago, as a result of Didymos shedding its mass by its rapid rotation. Computer simulations and telescopic observations by researchers indicate that, as a result of Dimorphos's rubble pile structure, the DART impact globally resurfaced Dimorphos and deformed its shape into an elongated ellipsoid, rather than creating an impact crater. Simulations and observations also suggest that the DART impact caused Dimorphos's rotation to begin tumbling chaotically. The European Space Agency's Hera mission is planned to arrive at the Didymos system in 2026 to further study the effects of DART's impact on Dimorphos.
Eclipsing binary lightcurve, radar
Designation, name
DART mission was selected in 2015, planetary defense goals
Five boulders (saxa) and six craters have been given names of traditional drums from several cultures. They are approximately 10 meters across or smaller: [12]
Name | Pronunciation | Feature | Named after | Date approved [12] |
---|---|---|---|---|
Atabaque Saxum |
UK:
/ætəˈbæki/ US: /ɑːtəˈbɑːki/ |
boulder | atabaque (Brazil) | 25 Jan 2023 |
Bodhran Saxum | /ˈbɔːrɑːn/ | boulder | bodhrán (Ireland) | 25 Jan 2023 |
Caccavella Saxum | /kækəˈvɛlə/ | boulder |
caccavella a.k.a. putipù (Italy) |
25 Jan 2023 |
Dhol Saxum | /ˈdɔːl/ | boulder | dhol (India) | 25 Jan 2023 |
Pūniu Saxum | /ˈpuːni.uː/ | boulder | pūniu a.k.a kilu (Hawaii) | 25 Jan 2023 |
Bala Crater | /ˈbælə/ | crater | balafon (Guinea, Senegal, Mali) | 14 Nov 2023 |
Bongo Crater | /ˈbɒŋɡoʊ/ | crater | bongo (Cuba) | 14 Nov 2023 |
Marimba Crater | /məˈrɪmbə/ | crater | marimba (Central America) | 14 Nov 2023 |
Msondo Crater | /ɛmˈsɒndoʊ/ | crater | msondo (Tanzania) | 14 Nov 2023 |
Naqqara Crater | /næˈkɑːrə/ | crater | naqqara (naker) (Mid East and India) | 14 Nov 2023 |
Tamboril Crater | /tæmbəˈrɪl/ | crater | tamboril (Uruguay, Candombe) | 14 Nov 2023 |
johnston
was invoked but never defined (see the
help page).Naidu2024
was invoked but never defined (see the
help page).Agrusa2021
was invoked but never defined (see the
help page).Nakano2022
was invoked but never defined (see the
help page).
![]() Dimorphos captured by the
DART spacecraft, seconds before impact in September 2022 | |
Discovery [1] | |
---|---|
Discovered by | Petr Pravec et al. [a] |
Discovery site | Ondřejov Observatory |
Discovery date | 20 November 2003 |
Designations | |
Designation | Didymos I |
Pronunciation | /daɪˈmɔːrfəs/ |
Named after | Greek word for "having two forms" [2] |
S/2003 (65803) 1 Didymos B Didymoon | |
Orbital characteristics [3]: 17 | |
Pre-impact: 1.187±0.017 km [4] Post-impact: 1.152±0.018 km [3]: 17 | |
Eccentricity | Pre-impact: <0.03 [3]: 17 Post-impact: 0.0274±0.0015 [4] |
Pre-impact: 11.921493±0.000030 hr (11h 55m 17.4s ± 0.1s) [5]: 28 Post-impact: 11.3675±0.0004 hr (11h 22m 3.0s ± 1.4s) [5] | |
Average
orbital speed | Pre-impact: 0.174 m/s [b] Post-impact: 0.177 m/s [b] |
Inclination | 170.7°±0.5° (to ecliptic) [c] |
Satellite of | 65803 Didymos |
Physical characteristics [7]: 12 | |
Dimensions | Pre-impact: 179 × 169 × 115 m (± 1 × 4 × 1 m) [d] Post-impact: 192 × 148 × 118 m (± 12 × 8 × 14 m) [4] |
150.0±2.5 m (volume equivalent) | |
7.47×104 m2 | |
Volume | 1.76×106 m3 |
Mass | ≈ 4.3×109 kg (if same density as Didymos) [8]: 9 |
Mean
density | <2.4±0.3 g/cm3 (assuming same as Didymos) [8]: 9 [9] |
Pre-impact: synchronous [3]: 17 Post-impact: chaotic [10] | |
Albedo | 0.15±0.02 [8]: 6 |
Spectral type | S [11] |
21.4±0.2 [1] [e] | |
Dimorphos (formal designation (65803) Didymos I; provisional designation S/2003 (65803) 1) is a small, 150-meter (490 ft) diameter moon of the near-Earth asteroid 65803 Didymos, with which it forms a binary system. Discovered on 20 November 2003 by Petr Pravec and collaborators, Dimorphos was the target of NASA's Double Asteroid Redirection Test (DART) mission, which deliberately collided a spacecraft with the moon on 26 September 2022 to alter its orbit around Didymos. Around the same time, the Italian Space Agency's LICIACube spacecraft flew by Dimorphos to image the DART impact. The impact reduced Dimorphos's orbital period by 33 minutes and ejected over 10 million kg (22 million lb) of dusty debris into space, which produced an expanding dust plume and a 70,000-kilometer (43,000 mi)-long tail of dust swept away by solar radiation pressure. [3]: 9–10
Before DART impacted Dimorphos, the moon had an oblate spheroid shape with a surface covered in boulders and few small craters. The surface features of Dimorphos suggest that the moon is a weakly-held rubble pile that formed less than 300,000 years ago, as a result of Didymos shedding its mass by its rapid rotation. Computer simulations and telescopic observations by researchers indicate that, as a result of Dimorphos's rubble pile structure, the DART impact globally resurfaced Dimorphos and deformed its shape into an elongated ellipsoid, rather than creating an impact crater. Simulations and observations also suggest that the DART impact caused Dimorphos's rotation to begin tumbling chaotically. The European Space Agency's Hera mission is planned to arrive at the Didymos system in 2026 to further study the effects of DART's impact on Dimorphos.
Eclipsing binary lightcurve, radar
Designation, name
DART mission was selected in 2015, planetary defense goals
Five boulders (saxa) and six craters have been given names of traditional drums from several cultures. They are approximately 10 meters across or smaller: [12]
Name | Pronunciation | Feature | Named after | Date approved [12] |
---|---|---|---|---|
Atabaque Saxum |
UK:
/ætəˈbæki/ US: /ɑːtəˈbɑːki/ |
boulder | atabaque (Brazil) | 25 Jan 2023 |
Bodhran Saxum | /ˈbɔːrɑːn/ | boulder | bodhrán (Ireland) | 25 Jan 2023 |
Caccavella Saxum | /kækəˈvɛlə/ | boulder |
caccavella a.k.a. putipù (Italy) |
25 Jan 2023 |
Dhol Saxum | /ˈdɔːl/ | boulder | dhol (India) | 25 Jan 2023 |
Pūniu Saxum | /ˈpuːni.uː/ | boulder | pūniu a.k.a kilu (Hawaii) | 25 Jan 2023 |
Bala Crater | /ˈbælə/ | crater | balafon (Guinea, Senegal, Mali) | 14 Nov 2023 |
Bongo Crater | /ˈbɒŋɡoʊ/ | crater | bongo (Cuba) | 14 Nov 2023 |
Marimba Crater | /məˈrɪmbə/ | crater | marimba (Central America) | 14 Nov 2023 |
Msondo Crater | /ɛmˈsɒndoʊ/ | crater | msondo (Tanzania) | 14 Nov 2023 |
Naqqara Crater | /næˈkɑːrə/ | crater | naqqara (naker) (Mid East and India) | 14 Nov 2023 |
Tamboril Crater | /tæmbəˈrɪl/ | crater | tamboril (Uruguay, Candombe) | 14 Nov 2023 |
johnston
was invoked but never defined (see the
help page).Naidu2024
was invoked but never defined (see the
help page).Agrusa2021
was invoked but never defined (see the
help page).Nakano2022
was invoked but never defined (see the
help page).