
The appendage, which measures a colossal 13 light years in length, was spotted by Nasa's Galaxy Evolution Explorer (Galex) space telescope.
The researchers said that nothing like it had ever been spotted around a star.
They believe the star, known as Mira, will help them to study what happens as stars meet their demise.
Mira (also called Mira A) has captivated astronomers for more than 400 years.
Billions of years ago, Mira would have been much like our Sun, but as it now enters its death-throes it has swollen into a type of star known as a red giant.
Yet despite centuries of study, its spectacular tail had remained undetected.