| Minorplanet: | yes |
| Bgcolour: |
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| 43 Ariadne | |
| Discoverer: | N. R. Pogson |
| Discovered: | 15 April 1857 |
| Mpc Name: | (43) Ariadne |
| Pronounced: | [1] |
| Adjective: | Ariadnean, Ariadnian |
| Named After: | Ariadne |
| Mp Category: | Main belt (Flora family) |
| Epoch: | 26 November 2005 (JD 2453700.5) |
| Semimajor: | 329.646 Gm (2.204 AU) |
| Perihelion: | 274.339 Gm (1.834 AU) |
| Aphelion: | 384.954 Gm (2.573 AU) |
| Eccentricity: | 0.168 |
| Period: | 1194.766 d (3.27 a) |
| Inclination: | 3.464° |
| Asc Node: | 264.937° |
| Arg Peri: | 15.948° |
| Mean Anomaly: | 101.582° |
| Dimensions: | [2] |
| Mass: | (3.27 ± 1.35/0.59) kg |
| Density: | 3.042 ± 1.255/0.547 g/cm3 |
| Rotation: | 0.2401 d[3] |
| Spectral Type: | S |
| Magnitude: | 8.8 to 13.42 |
| Abs Magnitude: | 7.93 |
| Albedo: | 0.274 |
| Angular Size: | 0.11–0.025 |
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.
Ariadne is very elongate (almost twice as long as its smallest dimension) and probably bi-lobed[4] or at least very angular. It is a retrograde rotator, although its pole points almost parallel to the ecliptic towards ecliptic coordinates (β, λ) = (−15°, 253°) with a 10° uncertainty.[5] This gives an axial tilt of about 105°.
43 Ariadne was in a study of asteroids using the Hubble FGS. Asteroids studied include (63) Ausonia, (15) Eunomia, (43) Ariadne, (44) Nysa, and (624) Hektor.