National Geographic is holding its annual competition to choose the best pictures from the past year. Last year, 16,000 readers from 130 countries submitted and this year's winner will be awarded $10,000 among other prizes.
The nominees include a cloud formation that looks more like a UFO:
Photo credit: Dmitry Gorilovskiy
Photo credit: Catalin Marin
Take a look at the full gallery of pictures here.