|  | 
                      |  | 
                      |  | 
                      |                                                       | NASA balloon tracks electric blue clouds |                              |  |                              | A balloon mission flying over the North Pole captured 6 million images of these bright blue noctilucent clouds as they wafted across the upper atmosphere. Read more and watch a video. 
 
  A NASA balloon observed these noctilucent - or night-shining - clouds over the Arctic in July 2018. Image via NASA/PMC Turbo/Joy Ng.
 |                              |  |  |