Sciency Words: Voorwerp

May 11, 2018

Today’s post is part of a special series here on Planet Pailly called Sciency Words.  Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


In 2007, Dutch schoolteacher and citizen scientist Hanny van Arkel was participating in the Galaxy Zoo project.  She was sorting through photos of galaxies (there are so many galaxies out there, scientists need help sorting through them all) when she came upon the image of a weird, green, blob-like object.

This mysterious object came to be known as Hanny’s Voorwerp, because voorwerp is the Dutch word for object.

Image courtesy of Wikipedia.

It’s hypothesized that the spiral galaxy in the upper part of the image had a quasar flare up at some point.  The resulting super accelerated jets of radiation must have hit a giant dust cloud, which we now see glowing green.

The quasar has since stopped, or at least calmed down for now, but that distinctive green glow can persist for tens of thousands of years. The color is almost certainly caused by ionized oxygen atoms.

Hanny’s Voorwerp is enormous, roughly the same size as our own Milky Way Galaxy.  We now know of several other glowing green blobs hanging around other suspected former quasers.  This paper identifies nineteen of them, and this collage from Wikipedia shows eight.

Image courtesy of Wikipedia.

These are commonly known as voorwerpjes. I have to admit I don’t know anything about Dutch (my linguistic education focused on Latin and Greek), but according to the j-part creates a diminutive form.  So Hanny’s Voorwerp is the big “object” and the others are like cute, little “objectlings.”  Well, little on the astronomical scale, at least.

Future research on Hanny’s Voorwerp and those voorwerpjes may tell us more about how quasar activity fluctuates over time. Also, it seems that getting zapped by a quasar may have triggered star formation inside Hanny’s Voorwerp. So we may be witnessing the very, very earliest beginnings of a brand new galaxy.