The cool white dwarf WDJ1330+6435 has accreted sodium-rich rocky material from its planetary system into its atmosphere. The immense atmospheric density causes the sodium to absorb light over broad range of yellow, orange, and red wavelengths, giving the WDJ1330+6435 a ghostly green appearance.

Mark A. Garlick / University of Warwick

The stars in our galaxy come in a beautiful assortment of colors. We see supergiants such as Betelgeuse that have a warm red glow, and others like Rigel that shine a brilliant blue-white. However, one colour has always been missing from the stellar rainbow: green.

Now, astronomers have identified a star that breaks this rule. A new study reveals that a white dwarf named WD J1330+6435, around 280 light-years from Earth, would appear green if we could view it up close.

Remarkably, this star isn’t alone in being an unusual colour.…