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12 strange reasons humans haven't found alien life yet
Scientists have been searching for evidence of extraterrestrial life for decades. So, where are all the aliens? Here are 12 intriguing theories ...
From 'Lucy' to the 'Hobbits': The most famous fossils of human relatives
Countdown Lucy may be the best-known prehuman fossil in the world. But other famous fossils have given us important insight into our evolutionary history.
7 centuries-old suits of battle armor from around the world
Countdown From Roman "fish scale" armor to Japanese samurai suits, these examples of battle armor were designed to protect and impress.
The 9 most massive numbers in existence
From the humble trillion to Graham's number, here are some of the most massive numbers ever conceived by humans.
32 physics experiments that changed the world
From the discovery of gravity to the first mission to defend Earth from an asteroid, here are the most important physics experiments that changed the world.
32 things on Mars that look like they shouldn't be there
The more scientists study the Red Planet, the more they find unusual objects and patterns scattered across Mars' surface. Here are some of the most baffling.
32 alien planets that really exist
Beyond our solar system, countless alien worlds of lava, ice, water and noxious gas swirl through the cosmos. Here are some of the strangest exoplanets that scientists have discovered so far.
32 weird ways to fight climate change that just might work
From "MooLoos" to painting mountains, these silly scientific suggestions could actually help with climate change.
