Luis Hernan was always curious about how wireless technologies like radio are transmitted through the air. So after finishing up his studies in architecture, computer science, and design, Hernan decided to research these invisible signals through a PhD at Newcastle University. Hernan set up a system that turned the wireless signals around him into colourful, ghostlike images using long-exposure photography, allowing people to see the strength of the signals around them. (Photo by Luis Hernan)

Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

Green Bay Packers' Johnathan Calvin rides a bike to NFL football training camp on July 27, 2017, in Green Bay, Wis. (Photo by Morry Gash/AP Photo)

A woman hands flowers to a member of the Wisconsin National Guard standing by as people gather for a vigil, following the police shooting of Jacob Blake, a Black man, in Kenosha, Wisconsin, U.S., August 28, 2020. (Photo by Brendan McDermid/Reuters)

A supporter of U.S. President Donald Trump fights with counter protesters during a march in response to various pro-Trump rallies held throughout D.C., in Washington, U.S., December 12, 2020. (Photo by Leah Millis/Reuters)

In this September 17, 2010 file photo a little brown bat is photographed in La Crosse Wis. Researchers for the first time found that little brown bats appear to be showing resistance to white-nose syndrome, which has killed millions of bats across North America. (Photo by Peter Thomson/La Crosse Tribune via AP Photo)

Men walk towards law enforcement with their hands up on August 24, 2020 in Kenosha, Wisconsin. A second night of civil unrest occurred after the shooting of Jacob Blake, 29, on August 23. Blake was shot multiple times in the back by Wisconsin police officers after attempting to enter into the drivers side of a vehicle. (Photo by Brandon Bell/Getty Images)

Actress Millie Bobby Brown (with her dog) during an interview with host Jimmy Fallon on Thursday, February 29, 2024 in New York. (Photo by: Todd Owyoung/NBC via Getty Images)