Previous studies have also demonstrated potential links between space travel and an increase in oxidative stress, which experts have suggested contributes to aging and, in turn, graying hair. However, no study has directly linked spaceflight-related oxidative stress to hair color changes.

Needham, Massachusetts, native Suni Williams flexed for cameras Monday after addressing the media for the first time since her return to Earth after a longer-than-expected stint in space.

Astronauts Butch Wilmore and Suni Williams were scheduled to return home last year before issues with Boeing’s spacecraft extended their stay.