- Alinda family
The Alinda asteroids are a group of
asteroid s with asemi-major axis of about 2.5 AU and an orbital eccentricity approximately between 0.4 and 0.65. The namesake is887 Alinda , discovered byMax Wolf in 1918.These objects are held in this region by the 1:3
orbital resonance with Jupiter, which results in them being close to a 4:1 resonance withEarth . An object in this resonance has its orbital eccentricity steadily increased by gravitational interactions with Jupiter until it eventually has a close encounter with an inner planet that breaks the resonance.Some Alindas have perihelia very close to
Earth 's orbit, resulting in a series of close encounters at almost exactly four-year intervals, due to the 4:1 near resonance.One consequence of this is that if an Alinda asteroid happens to be in an unfavorable position for viewing at the time of its close approach to Earth (for instance, at a small elongation from the
Sun ), then this situation can persist for decades. Indeed, as of 2004, the Alinda asteroids3360 Syrinx and1915 Quetzálcoatl had not been observed since 1985, and2608 Seneca had not been observed since 1994.Another consequence is that some of these asteroids make repeated relatively close approaches to Earth, making them good subjects for study by Earth-based
radar . Examples are4179 Toutatis and6489 Golevka .Asteroids in this family
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