Steve Perlman rappels down a cliff in the Wailau Valley on the Hawaiian island of Molokai. He is a botanist who has spent the last 45 years searching for, and protecting, rare plants

It’s dark during the Arctic winter. The sun doesn’t rise for days or even months. But scientists are learning that all is not quiet in the Arctic night (seen here in an illustration). There’s a months-long party happening under the sea.

One in five people who wear contact lenses flush their used eyewear down the sink or toilet. That plastic pollutes the environment and can harm wildlife.

The 2013 Rim Fire, the largest Sierra Nevada fire to date, burned 1,040 square kilometers (400 square miles). Smaller, more frequent fires might have limited this damage and preserved water for surviving trees.