The ancient main-sequence solar proxy HIP 102152 unveils the activity and rotational fate of our Sun.

We present a detailed analysis of the possible future Sun's rotational evolution scenario based on the 8-Gyr-old solar twin HIP 102152. Using HARPS high-cadence observations (and TESS light curves), we analysed the modulation of a variety of activity proxies (Ca  ii  , H  i Balmer, and Na  i lines), finding a strong rotational signal of 35.7 ± 1.4 d (log  B factor ∼ 70, in the case of Ca  ii K line). This value matches with the theoretical expectations regarding the smooth rotational evolution of the Sun towards the end of the main sequence, validating the use of gyrochronology after solar age. [ABSTRACT FROM AUTHOR]