Launched as GRAIL A and GRAIL B in September 2011, the probes were renamed Ebb and Flow by schoolchildren in Montana. The probes operated in almost circular orbit near the lunar poles at an altitude of approximately 34 miles, until their mission came to an end in December 2012. The distance between the twin probes altered a bit as they soared over areas of lesser and greater gravity that were caused by visible topological features on the Moon's surface, such as impact craters and mountains--as well as by masses that were secreted beneath the lunar surface. When President John F. Kennedy stated in 1960's that the US will go to the moon in less than a decade, most people were extremely skeptical. The reason for this stemmed from the fact that USSR had shown more accomplishments in the space race after the launch of Sputnik, which was the world's first satellite. Naturally, the skepticism was unfounded, since the US put all of its efforts in to the Moon program as billions of dollars were put in to it. The development of the Saturn rocket as well as the development of the Apollo lunar module took less than a decade, since the whole heart and soul of the American public was put into the Lunar program. Even the various tragedies such as the loss of Astronauts in the Apollo fire tragedy didn't deter the public. As a result, 1969 was an important year in the human history as mankind stepped into Lunar soil for the first time. Sadly, the program was discontinued and since the 1970's, no man has even stepped into the Lunar soil ever again. The Solar System forms a tiny part of the Milky Way Galaxy, a vast conglomeration of stars and planets. What makes astronomy so thrilling is that despite its size, the Milky Way is not the only galaxy in the universe. There are hundreds of billions of galaxies out there, probably more. The closest galaxy to our own Milky Way is Andromeda. Now, brace yourself for the distance: it is 2.3 million light years away. One of the most exciting phenomena for astronomers is the black hole. It is an area of the universe where the concentration of mass is so massive (no pun intended) that the gravitational pull it generates sucks in everything around it. Everything includes light. Remember that the escape velocity for any object in the universe is the speed required to escape the objects gravitational pull. The escape velocity for the Earth is slightly over 11 kilometers per hour while for the Moon is 2.5 kilometers per second. Well for a black hole, the escape velocity exceeds the speed of light. That is how strong the pull is.