[4] It was discovered by C. H. F. Peters on October 22, 1879, in Clinton, New York and was named after the mythical Carthaginian queen Dido.

This asteroid is orbiting the Sun at a distance of 3.15 AU with an eccentricity (ovalness) of 0.058 and a period of 5.59 yr.

[4] 209 Dido is classified as a C-type asteroid and is probably composed of carbonaceous materials.

Photometric observations at the Palmer Divide Observatory during 2005 showed a rotation period of 5.7366±0.0005 hours with a brightness variation of 0.17±0.02 in magnitude.

[6] The pole orientation in ecliptic coordinates, as determined from multiple light curve studies, is (βp, λp) = (120°±6°, 66°±7°).