Researchers in the US are getting excited about seven dust particles, each no wider than one-50th the diamater of a human hair. Why? Because they may originate from another solar system.

The samples were collected by the Stardust spacecraft (pictured as artist’s impression) from the dust left by the comet Wild 2. Although Stardust collected the dust in 2002 and brought it back to Earth in 2006, the analysis of the samples is still ongoing at the University of Berkeley California and the National Naval Research Laboratory.

The particles contain traces of olivine (a mineral made up of magnesium, iron, silicon and oxygen) and spinel (made of magnesium, aluminum and oxygen.) Both are formed at extremely high temperatures, leading researchers to ponder the possibility they are interstellar dust, but originally formed near a star.

One possible counter to that theory is that three of the particles contain compounds of sulfur, which isn’t what scientists would expect to find in interstellar dust.

The next step is oxygen isotope testing, which measures the ratio of two different variations of oxygen, with an atomic mass of 16 and 18 respectively. If the ratio in the dust particles is significantly different to that found in other material known to come from our solar system, it will be much clearer evidence that it is interstellar dust — in fact, Rhonda Stroud of the National Naval Research Laboratory says it would be conclusive.

[Via: Popular Mechanics]

(Image credit: NASA)