There has been a mysterious giant green blob that has been on scientists' radar for years. How many years? Well it was first noted in 2000. The blob itself is made of gas (hydrogen, mainly) and dust and grows a sickly, bright green. But why does it glow like that? Link
One of the biggest mysteries surrounding the blob is where exactly the glow came from. Many theories arose, such as the idea that it was polarized light emitted by the blob might be from hidden galaxies. And this idea just might have been right on the money.
What's in the blob's core? Well, two huge galaxies...oh, and they may or may not be surrounded by a swath of smaller galaxies. Further observation revealed this and is supported by both the Hubble Space Telescope and the Keck Observatory in Hawaii.
These blobs actually have a bit more of a scientific name than, well, just blob. In particular, they're called Lyman-alpha blobs...and they are some of the biggest things that exist in space. This particular blob is named SSA22-Lyman-alpha Blob 1 (LAB-1) [that's not a mouthful or anything, right?]. It is also one of the LARGEST Lyman-alpha blobs, it measures 300,000 light years across. For reference, if you're not used to measuring objects in light years, it is over two times the size of the Milky Way Galaxy.
Jim Geach, the study's lead author, has expressed the true wonder of this blob..."The simulations also track gas and dark matter in the blob as it evolves into a galaxy. "Lyman-alpha Blob-1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster,"
The above picture is a composite of two different images taken with the FORS instrument on the Very Large Telescope of the Lyman-alpha blob LAB-1 in the constellation of Aquarius. Credit ESO/M. Hayes. It is licensed under CC 3.