This article is about an asteroid. For other uses, see Ida (disambiguation).
Ida
Galileo image of 243 Ida. The dot to the right is its moon Dactyl.
Discovery[1]
Discovered by
Johann Palisa
Discovery site
Vienna Observatory
Discovery date
September 29, 1884
Designations
MPC designation
(243) Ida
Pronunciation
/ˈaɪdə/[2]
Named after
Ida (nurse of Zeus)
Minor planet category
Main belt (Koronis family)[3]
Adjectives
Idean (Idæan) /aɪˈdiːən/[4]
Orbital characteristics[5]
Epoch 31 July 2016 (JD 2457600.5)
Aphelion
2.979 AU (4.457×1011 m)
Perihelion
2.743 AU (4.103×1011 m)
Semi-major axis
2.861 AU (4.280×1011 m)
Eccentricity
0.0411
Orbital period (sidereal)
1,767.644 days (4.83955 a)
Average orbital speed
0.2036°/d
Mean anomaly
38.707°
Inclination
1.132°
Longitude of ascending node
324.016°
Argument of perihelion
110.961°
Known satellites
Dactyl
Physical characteristics
Dimensions
59.8 × 25.4 × 18.6 km[6]
Mean radius
15.7 km[7]
Mass
4.2 ± 0.6 ×1016 kg[7]
Mean density
2.6 ± 0.5 g/cm3[8]
Equatorial surface gravity
0.3–1.1 cm/s2[9]
Synodic rotation period
4.63 hours (0.193 d)[10]
North pole right ascension
168.76°[11]
North pole declination
−2.88°[11]
Geometric albedo
0.2383[5]
Temperature
200 K (−73 °C)[3]
Spectral type
S[12]
Absolute magnitude (H)
9.94[5]
Ida, minor planet designation 243 Ida, is an asteroid in the Koronis family of the asteroid belt. It was discovered on 29 September 1884 by Austrian astronomer Johann Palisa at Vienna Observatory and named after a nymph from Greek mythology. Later telescopic observations categorized Ida as an S-type asteroid, the most numerous type in the inner asteroid belt. On 28 August 1993, Ida was visited by the uncrewed Galileo spacecraft while en route to Jupiter. It was the second asteroid visited by a spacecraft and the first found to have a natural satellite.
Ida's orbit lies between the planets Mars and Jupiter, like all main-belt asteroids. Its orbital period is 4.84 years, and its rotation period is 4.63 hours. Ida has an average diameter of 31.4 km (19.5 mi). It is irregularly shaped and elongated, apparently composed of two large objects connected together. Its surface is one of the most heavily cratered in the Solar System, featuring a wide variety of crater sizes and ages.
Ida's moon Dactyl was discovered by mission member Ann Harch in images returned from Galileo. It was named after the Dactyls, creatures which inhabited Mount Ida in Greek mythology. Dactyl is only 1.4 kilometres (0.87 mi) in diameter, about 1/20 the size of Ida. Its orbit around Ida could not be determined with much accuracy, but the constraints of possible orbits allowed a rough determination of Ida's density and revealed that it is depleted of metallic minerals. Dactyl and Ida share many characteristics, suggesting a common origin.
The images returned from Galileo and the subsequent measurement of Ida's mass provided new insights into the geology of S-type asteroids. Before the Galileo flyby, many different theories had been proposed to explain their mineral composition. Determining their composition permits a correlation between meteorites falling to the Earth and their origin in the asteroid belt. Data returned from the flyby pointed to S-type asteroids as the source for the ordinary chondrite meteorites, the most common type found on the Earth's surface.
^Cite error: The named reference Raab2002 was invoked but never defined (see the help page).
^Noah Webster (1884) A Practical Dictionary of the English Language
^ abCite error: The named reference Holm1994 was invoked but never defined (see the help page).
^"Idæan". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^ abcJPL 2008
^Belton et al. 1996
^ abBritt et al. 2002, p. 486
^Cite error: The named reference Belton1995 was invoked but never defined (see the help page).
^Cite error: The named reference ThomasBeltonCarcichChapman1996 was invoked but never defined (see the help page).
^Cite error: The named reference VokrouhlickyNesvornyBottke2003p147 was invoked but never defined (see the help page).
^ abCite error: The named reference Seidelmann Archinal A'hearn et al. 2007 p. 171 was invoked but never defined (see the help page).
^Cite error: The named reference WilsonKeilLove1999p479 was invoked but never defined (see the help page).
Ida, minor planet designation 243Ida, is an asteroid in the Koronis family of the asteroid belt. It was discovered on 29 September 1884 by Austrian astronomer...
This is a list of named geological features on asteroid 243Ida and its moon, Dactyl. Idaean regiones (geologically distinct areas) are named after the...
of 951 Gaspra, and discovered the first asteroid moon, Dactyl, around 243Ida. In 1994, Galileo observed Comet Shoemaker–Levy 9's collision with Jupiter...
of two asteroids orbiting their common barycenter. The binary nature of 243Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993...
convention Craters Caverns and grottos of the world Dorsa Galileo project participants Regiones Discoverer of Ida and places associated with the discoverer...
up Ida, ida, idä, or -ida in Wiktionary, the free dictionary. Ida or IDA may refer to: Ida Facula, a mountain on Amalthea, a moon of Jupiter 243Ida, an...
with radius-size craters. Medium-sized asteroids such as Mathilde and 243Ida, that have been observed up close, also reveal a deep regolith covering...
"-dactyl", a suffix used in taxonomy Dactyl (moon), a moon of asteroid 243Ida Dactyl (math), a 300 BC unit of measure being 40 poppy seeds wide or about...
member of this family, 243Ida. A photo of Ida (and its tiny moon Dactyl) is part of the composite image at right (numbered 243). Nesvorný, D.; Broz, M...
period in orbit. The Galileo spacecraft imaged 951 Gaspra in 1991 and 243Ida in 1993, then NEAR imaged 253 Mathilde in 1997 and landed on near–Earth...
and following companions of the Saturnian moon Dione. The discovery of 243Ida's natural satellite Dactyl in the early 1990s confirmed that some asteroids...
materials, but is similar in composition as another Koronis family member, 243Ida. It was discovered by Johann Palisa on 3 November 1886 in Vienna. The asteroid's...
been recovered from the Upper Cave. The crater Choukoutien on asteroid 243Ida was named after the location. The caves are located in Zhoukoudian Town...
history. On the other hand, observations of 243Ida by the Galileo spacecraft found weathering of Ida's surface, and the reflection spectra of freshly...
December 1995. Gravity assists also allowed Galileo to flyby two asteroids, 243Ida and 951 Gaspra. Ulysses In 1990, NASA launched the ESA spacecraft Ulysses...
Thus, Dactyl, the moon of 243Ida, was at first designated "S/1993 (243) 1". Once confirmed and named, it became (243) Ida I Dactyl. Similarly, the fourth...
Thus, Dactyl, the moon of 243Ida, was at first designated "S/1993 (243) 1". Once confirmed and named, it became (243) Ida I Dactyl. Similarly, the fourth...
which was Galileo, which flew past two: 951 Gaspra in 1991, followed by 243Ida in 1993. Both of these lay near enough to Galileo's planned trajectory...
so no information on Gaspra's mass was obtained. (Galileo also visited 243Ida where it discovered a moon, allowing a mass estimate there.) Galileo flew...
Ceres List of geological features on Vesta List of geological features on 243Ida and Dactyl List of craters on 253 Mathilde List of geological features...
constructed from the lightcurve, the shape of Koronis resembles that of 243Ida, an asteroid in the same family, although it is a bit larger. [1] A collision...
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