8 Flora (asteroid)

Physical characteristics

Flora is an irregular, broadly ellipsoidal body with an overall diameter on the order of one to two hundred kilometers, making it one of the larger inner-belt asteroids. Studies of its lightcurve (brightness variations as it rotates) have established a rotation period of about 12–13 hours and reveal a non-spherical shape with surface variations in reflectivity. Its stony composition is dominated by silicate minerals and metal, consistent with ordinary chondrite meteorite material.

Orbit and brightness

Orbiting the Sun on an inner main-belt path, Flora has a semimajor axis of roughly 2.2 astronomical units and completes one revolution in a little more than three Earth years. Because it lies closer to the Sun than most large asteroids, Flora can reach relatively bright apparent magnitudes at favorable oppositions: its mean opposition brightness places it among the top ten brightest asteroids, and under ideal geometry it can approach magnitude +8 or slightly brighter. For general information about main-belt dynamics see main belt resources.

Discovery and observational history

8 Flora was discovered in the mid-19th century and named after the Roman goddess of flowers. Since its discovery, astronomers have monitored Flora with photometry, astrometry, and occultation measurements to refine its size, shape, rotation and orbit. No spacecraft missions have visited Flora, but ground-based measurements and stellar occultations have provided much of the present knowledge about its dimensions and orientation.

Flora family and scientific importance

Flora anchors a large collisional family of S-type asteroids that share similar orbital elements. The family is of interest because fragments from such collisions are plausible sources of many stony meteorites that reach Earth, and because families preserve information about collisional evolution in the inner solar system. Researchers use Flora and its family to study fragmentation processes, space weathering on silicate surfaces, and transport of small bodies toward Earth-crossing orbits.

Observing Flora and notable facts

Amateur astronomers can observe Flora with modest telescopes when it is at opposition. Its brightness and relatively low orbital inclination make it an accessible target for photometric study and occultation campaigns. For more on asteroids in general and observing opportunities see introductory material on asteroid studies and opposition phenomena at opposition guides.