Despite years of debate and follow-up studies, an odd streak of cosmic light still defies a final explanation. Is it a giant black hole screaming through intergalactic space?

Here’s a mystery: below 8,400 meters there are no fish. There are other creatures: sea cucumbers, anemones, tiny worms, but no one has ever seen a fish. At 8,370 meters? There are fish. But not below 8,400 meters. At its deepest the ocean reaches roughly 11,000 meters, so there is plenty of space. And right below 8,400

The Y chromosome doesn’t seem to do much except determine sex – but its loss in older men might be linked to heart disease, cancer and Alzheimer’s.