What really has everyone on the planet confused -- including scientists -- is dark energy.
To continue with the pie analogy, dark energy is a Garfield-sized portion at 73 percent of the known universe. It seems to pervade all of space and push galaxies farther and farther away from one another at increasingly faster speeds.
Some cosmologists think this expansion will leave the Milky Way galaxy as an "island universe" in a few trillion years with no other galaxies visible.
It might sound strange because we live on one, but planets are some of the more mysterious members of the universe.
So far, no theory can fully explain how disks of gas and dust around stars form planets -- particularly rocky ones.
Not making matters easier is the fact that most of a planet is concealed beneath its surface. Advanced gadgetry can offer clues of what lies beneath, but we have heavily explored only a few planets in the solar system.
The force that helps stars ignite, planets stay together and objects orbit is one of the most pervasive yet weakest in the cosmos
Scientists have fine-tuned just about every equation and model to describe and predict gravity, yet its source within matter remains a complete and utter mystery.
Some think infinitesimal particles called gravitons exude the force in all matter, but whether or not they could ever be detected is questionable.
Matter and energy abound in the universe, but only in a few places is the roll of the cosmic dice perfect enough to result in life.
The basic ingredients and conditions necessary for this strange phenomenon are better understood than ever before, thanks to abundant access to life here on Earth.
But the exact recipe -- or recipes -- to go from the basic elements of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur to an organism is a prevailing mystery.
The source of energy, matter and the universe itself is the ultimate mystery of, well, the universe.
Based on a widespread afterglow called the cosmic microwave background (and other evidence), scientists think that the cosmos formed from a "Big Bang" -- an incomprehensible expansion of energy from an ultra-hot, ultra-dense state.
Describing time before the event, however, may be impossible. (Link)
