What makes this strange space blob glow?

That green clump might not be much to look at, but it's one of the rarest sights in the cosmos: a Lyman-alpha blob. They're among the universe's biggest structures, and only now are we starting to understand how they work.

Lyman-alpha blobs are up to 400,000 light-years across, making them much larger than the diameter of our own galaxy - and remember, each blob is a single vast unit of hydrogen gas. These leviathan structures are very bright, but they're only found at the furthest, most ancient parts of the observable universe, which helps explain why this particular blob might not look quite as remarkable as it really is.

Just what makes these blobs so bright has long been an open question. Now, scientists at the European Southern Observatory say they've found the answer:




For more, check out the ESO website.