2017 SG33

 (also written 2017 SG33) is a near-Earth object, meaning that it has an orbit which brings it into proximity with Earth. It is an Amor asteroid, meaning that its orbit does not cross Earth's orbit, but its perihelion is close to, but greater than, the aphelion of Earth. It was first observed on 25 September 2017, when the asteroid was less than 1 AU from Earth and had a solar elongation of 169°.

This asteroid is a lost asteroid. It has a very short observation arc of 0.83 days and has not been seen since 2017, so it has an orbit that is only roughly calculated. Also, there are variations in the absolute magnitude cataloged by various organizations, leading to variations in the estimated size of the asteroid (Sentry list H 23.9 implies 55 m vs MPC H 23.3 implies 75 m ). These variations are in addition to the uncertainty in the size estimate caused by the uncertainty in the albedo.

This asteroid is in the Risk List and the Priority List of the European Space Agency (ESA) - Space Situational Awareness (SSA). The asteroid is also in the Sentry List of the Jet Propulsion Laboratory (JPL) - Center for Near Earth Object Studies (CNEOS). According to the Sentry List, of the possible close encounters with Earth in the foreseeable future, an encounter on September 8, 2051 has the highest Palermo Technical Impact Hazard Scale value.

According to the Near Earth Objects Dynamic Site (NEODyS), of the possible close encounters with Earth in the foreseeable future, an encounter on 1 August 2023 is the most likely. This encounter has a minimum possible distance of zero, meaning that an impact onto Earth was thought possible.