It was the members of a Facebook group who noted that the auroras they'd seen didn't look like any that had been previously catalogued. So physicists asked them to take a few carefully timed photos.
Researchers invited the public to help them study the geographic spread of ticks that carry pathogens that can sicken humans. People were eager to oblige by sending in the pesky bugs that bit them.
Scientists and activists in India are training citizens to collect information on water issues like contamination — and upload it so it can be used to push for change.
The annual event invites bird-watchers of all levels to count the birds in their backyards, and submit the data to researchers at the Cornell Lab of Ornithology and the National Audubon Society.