In 1994, cosmologist Paul Francis, current professor at Australian National University and creator of a free online cosmology course, discovered something peculiar in the distant reaches of the universe.

He was looking at a giant cloud of hydrogen gas or Lyman Alpha Blobs—one of the largest known objects in the universe.

The blob was massive—much larger than a galaxy. And it glowed with an unusual intensity.

“The hydrogen gas must be really traumatized in some way to be glowing as intensely as we observe,” Francis describes in a Reddit Ask Me Anything session.

Since his original discovery, “dozens more have been found.”

What makes these clouds remarkable is that they are full of red compact galaxies, emitting infra-red radiation.

“They look blobby, hence the name ‘Blob,’ which was independently chosen by two of the early discoverers,” he explains.

Francis describes the find:

“One theory is that we are seeing the formation of massive galaxies ‘caught in the act.’ Primordial gas is raining down on these galaxies, causing them to grow, and in the process getting very hot and hence glowing. I call this the ‘outside-in’ theory. A second possibility is the reverse. A massive galaxy is forming lots of stars (hidden behind dust, which is why it appears red), and hence lots of supernovae are going off. These supernovae heat up the gas in the galaxy and blow it out, forming a ‘superwind’ which makes the giant gas cloud we see. A third possibility is that the red galaxy contains a hidden quasar, whose ultra-violet light is escaping in some directions (but not towards us) and zapping the gas, heating it up. Right now it looks like these things are complicated – all three of these processes can occur, often together in combination…”

Check out the entire AMA with cosmologists Brian Schmidt and Paul Francis here.