Smile! 5 Most Incredible Discoveries of the Week

A secret about Earth's core and an interstellar emoticon make the list:

• The Hubble Spots 'Smiley Face' in Space: You've probably experienced the phenomenon of "face pareidolia"—seeing non-existent faces in things—before, but this one is out of this world. The Hubble Telescope has captured a "smiley face" in space, though it's actually a product of something called "gravitational lensing."
• 8 Signs That Mean Cancer Death Is Nigh: A study has determined a group of "tell-tale" indicators that a cancer patient will soon die. It's admittedly depressing research, but there's a comforting reason to want to recognize the signs.

• Earth's Core Has Its Own Core: Researchers have literally unearthed something new in the center of our planet: What was once thought to be a single core of solid iron actually contains an inner core of its own, with properties very different from what geologists are now calling the "outer inner core." A Cambridge expert says it seems "something very substantial" happened around half a billion years ago to make it so.
• Scientists Figure Out Why Popcorn Goes 'Pop': Armed with a knowledge of thermodynamics and fracture mechanics, French engineers set out to find the "elusive" answer to this age-old question. It all starts with the fact that popcorn kernels are 14% water.
• How Many Licks to the Center of a Tootsie Pop?: In the classic commercial asking how many licks it takes "to get to the Tootsie Roll center of a Tootsie Pop," the conclusion was: "The world may never know." Turns out that was wrong, and scientists have finally figured out it takes about 1,000 licks to do so. But they had one major challenge to overcome.

Click to read about more discoveries, including a potential remedy for bad singers. (More discoveries stories.)