Seth Carlo Chandler, Jr. (September 16, 1846 – December 31, 1913) was an American astronomer, geodesist, and actuary.

[1] He was born in Boston, Massachusetts to Seth Carlo and Mary (née Cheever) Chandler.

[2] During his last year in high school he performed mathematical computations for Benjamin Peirce, of the Harvard College Observatory.

[3] Chandler also made contributions to other areas of astronomy, including variable stars.

He independently co-discovered the nova T Coronae Borealis, improved the estimate of the constant of aberration, and computed the orbital parameters of asteroids and comets.