2102 Tantalus (1975 YA) is an Apollo asteroid discovered on December 27, 1975, by C. Kowal at Palomar Observatory.
[1] 2102 Tantalus is a potentially hazardous asteroid (PHA) because its minimum orbit intersection distance (MOID) is less than 0.05 AU and its diameter is greater than 150 meters.
The Earth-MOID is 0.0439 AU (6,570,000 km; 4,080,000 mi).
[1] Its orbit is well-determined for the next several hundred years.
[2] The shape of 2102 Tantalus is estimated to be roughly spherical in outline and fairly symmetrical; the surface is thought to be covered in a fine-grained regolith.