10.) Are We Alone? - radio telescopes have been scanning the space for life since 1977. There are 60 million potentially habitable planets in our Milky Way alone.
9.) Cosmic Rays - High-Energy particles hit the earth from outer space. Some can be traced to Super Novas & the sun , however , it is unknown where the higher strength rays originate.
8.) Dark Matter - Believe to exist due to discrepancy between the gravitational effect of large object in space & their mass. As it absorb lights , Dark Matter can't be seen.
7.) Reionization of the Universe - When the Universe formed by Big Bang , it was dense & opaque. An unexplained age of reionization then happened , making the Universe transparent.
6.) Dark Energy - The hypothetical energy that makes up 68% of the Universe. Researcher believe it has a low density , as there are only 6 tons in the solar system , within pluto's orbit.
5.) Sun's Corona - The sun's outer atmosphere is made from plasma , reaching temperatures of 27 million Fahrenheit. Researchers are unsure how such heat is generated , as the surface temp. is 5,000 Fahrenheit.
4.) Exploding Stars - When the stars runs out of fuel , it explodes into super nova , expelling debris up to a velocity of 30,000 km/s. The mechanics of how this happens & what occur in the star's core are unknown.
3.) Earth - Thought that have been formed by collisions of asteroids 4.6 billion years ago. Scientists are studying meteorites & the oldest rocks on earth to understand the exact formation process.
2.) Black Holes - Formed when a large star explodes and collapse on it self. With gravitational force so strong that is ****s light & matter , researchers are unable to see inside black hole.
1.) The Fate of Universe - The fate of Universe is dependent on the unknown density of matter & energy in cosmos. Possible outcome are that Universe will collapse in on itself or rip itself apart.