SN Online

LIFE
Plant species grafted together can swap DNA via energy-catching organelles. See “Plants swap chloroplasts via grafts.”

HUMANS
Social networks can spread users’ emotions. Learn more in “Catching a mood on Facebook.”

ATOM & COSMOS
A solar flare set off auroras around the Arctic Circle. See “Solar storm.”

BODY & BRAIN
Protein-based disease agents can jump species. Read “Prions more mobile than thought.”