Macro or Micro? Scientists’ pictures baffle our sense of scale. It began when Stephen Young, a geography professor at Salem State University in Massachusetts, tricked his biologist colleague Paul Kelly into thinking a satellite image was one of his electron microscope scans. Can you guess whether they are close-up or very far away? (Photo by Paul Kelly)

Kagome Co's employee Shigenori Suzuki tries to eat a tomato which is fed to him by the newly-developed “Wearable Tomato” device for runners, during its unveiling event ahead of the weekend's Tokyo Marathon in Tokyo February 19, 2015. The eight-kilo (17.6-pound) contraption fits on a runner like a rucksack. It can distribute a total of seven medium-sized tomatoes, one by one, at the click of a button and supplies the runner with much needed nutrients during a long jog or race. (Photo by Toru Hanai/Reuters)

Behaviour winner; Courting Royals: two royal terns in courtship display by Kristian Bell. Another beautiful morning on a beautiful beach on the Gulf Coast of Florida seemed to prompt these two royal terns to commence an intricate courtship dance. The photograph was taken with a Canon 300mm lens and 2x extender. (Photo by Kristian Bell/Deakin University/Royal Society Publishing Photography Competition 2018)

A radio-controlled flying witch makes a test flight past a moon setting into clouds along the pacific ocean in Carlsbad, California October 8, 2014. Reuters was invited to photograph the testing of the life sized device by inventor Otto Dieffenbach lll. (Photo by Mike Blake/Reuters)

A partially frozen Niagara Falls is seen on the American side lit by lights during sub freezing temperatures in Niagara Falls, Ontario March 3, 2014. (Photo by Mark Blinch/Reuters)

The world’s largest public sauna has opened on a small island in the Arctic Circle and there’s room for you and about 100 of your closest mates.