Steve lights up Canadian sky
• For years, a wispy strand of purple light has been seen running across Canada from east to west, sometimes flanked by neon green fingers that appear to wave. Nicknamed Steve, it looks like a piece of the Northern Lights but is beyond the bounds of normal Aurora Borealis sightings. A paper in Science Advances declared that Steve is a strip of ionised gas as hot as the Earth's core and moving through the air at about four miles per second.
• The hairyflower wild petunia passes its genes to the next generation with a bang. The plant flings tiny seeds from a torpedo-shape fruit more than 20 feet through the air. A study published in the Journal of the Royal Society Interface calculated that some of the seeds spin at a rate of more than 1,600 revolutions a second. Seeds at the top of the fruit tend to fly the farthest, while those at the bottom land closer to where they started.
• The excavation for Rome's newest subway line keeps on throwing up surprises. Two years after a second-century military barracks was found at the site of the Amba Aradam station, archaeologists have found the remains of a house with frescoed walls and mosaic floors that they say belonged to the commander of the military post.