20. The Interstellar Visitor ‘Oumuamua
In 2017, the elongated, cigar-shaped object known as ‘Oumuamua zipped through our solar system, capturing global attention. Its odd acceleration and shape fueled speculation that it might be an artificial probe, rather than a mere space rock. While natural explanations prevail, ‘Oumuamua’s fleeting visit prompted a fresh wave of scientific inquiry into mysterious interstellar objects that could hint at alien technology. Read more at Nature.