A black hole is a region of spacetime exhibiting gravitational acceleration so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
This gigantic "King of Planets" is considered by some astronomers to be a "failed star". It is about as large as a gas giant planet can be, and still be a planet. It is composed of approximately 90% hydrogen and 10% helium, with small amounts of water, methane, ammonia, and rocky grains mixed into the brew. If any more material were added on to this immense planet, gravity would hug it tightly--while its entire radius would barely increase. A baby star can grow to be much larger than Jupiter. However, a true star harbors its own sparkling internal source of heat--and Jupiter would have to grow at least 80 times more massive for its furnace to catch fire. Earth's Moon is the largest and brightest object suspended in the darkness of the starry night sky. It is both lovely and enchanting, and it has, since ancient times, inspired curiosity and wonder in human beings who gaze up at the mysterious sky after the Sun has set. As such, Earth's Moon has long served as the inspiration for imaginative, wild and marvelous tales--it is the stuff of mythology and folklore. The "Man in the Moon" refers to several fantastic images of a human face that certain traditions see outlined in the gleaming disk of the full Moon. In November 2013, astronomers using data from the lunar-orbiting twins composing NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, announced that they have been acquiring new and fascinating insight into how this bewitching "face," etched on our Moon's disk, received its captivating and enchanting good looks! We earthlings love to look up at the moon. So much does the moon enamor us; we write movies, songs and poems by the droves that contain the name of the earth's super satellite. A case in point is the fact that one of the biggest selling record albums of all time is Pink Floyd's "Dark Side of the Moon."