Last week, scientists announced that they had discerned new historical details about one of the planet’s most famous waterways, the Strait of Gibraltar. After analyzing core samples from the Gulf of Cádiz, they confirmed that water began trickling out of the Mediterranean Sea and into the Atlantic Ocean around five-million years ago, that it had increased dramatically by three-million years ago, and that it had established its current intensity by roughly one-million years ago. Because of its greater salinity and density, the Mediterranean outflow rushes along the bottom of the strait while the less saline, less dense Atlantic inflow skims along the top. Meanwhile, as if on cue, astronauts living aboard the International Space Station have snapped some outstanding photographs of the Strait of Gibraltar over the past few days. German astronaut Alexander Gerst tweeted this photograph five days ago, and American astronaut Reid Wiseman tweeted this photograph just three days ago. And finally, while we’re on the topic of waterways and ocean currents, you should also check out NASA’s now-classic animation, “Perpetual Ocean (2012),” which documents our planet’s various ocean currents with eye-popping detail.