You can participate in the following five categories:
People in Science
Scientists in their natural habitat.
Optical, electron, and scanning probe microscopy images all fall under this category.
Audio and video files, computer-generated imagery, etc.
Thematically linked images, that can be viewed as one set. Image set could be made up from up to 10 separate images.
Everything else goes into this category, from archaeology to zoology and from vulcanology to astronomy.