It is one of the biggest and brightest known Cepheids in the Milky Way galaxy and has one of the longest periods for this class of star at 41.5 days.

Because it is located in a large nebula, astronomers using the ESO's New Technology Telescope at La Silla Observatory, Chile have been able to measure its distance in 2008 by strictly geometric analysis of light echoes from particles in the nebula, determining it to be 1,992 ± 28 parsecs (6,497 ± 91 ly) from Earth, the most accurate measurement achieved for any Cepheid as of early 2008.

[11] The light echo technique was used again in 2014, this time with Hubble Space Telescope Advanced Camera for Surveys polarimetric images.

[8] In Gaia Data Release 2, a direct geometric parallax of 0.5844±0.0260 mas was derived, corresponding to a distance of 1,710 ± 80 parsecs (5,580 ± 260 ly).

[7] RS Puppis is a classical Cepheid variable and its brightness changes regularly due to pulsations during which its size and temperature both vary.