Space — a huge mystery! The universe, estimated to be about 13.7 billion years old, is constantly expanding. The galaxies are racing away from one another due to some very strange forces that we do not understand. It turns out that space is not one dark empty vacuum. Some strange and powerful forces lurk within it. One mysterious force, “dark energy”, accounts for roughly 71 per cent of the mass of our universe while about 25 per cent of it is made up of another powerful invisible glue that we call “dark matter” that appears to be holding the galaxies together.
Indeed it is remarkable that only 4.6 per cent of the mass of the universe is accounted for by the “ordinary” visible matter made up of atoms — the rest is dark matter and dark energy!
Our galaxy, the Milky Way, contains over 100 billion stars. Twenty “super earths” have been discovered that are at the right distances from their respective suns to have suitable temperatures for life to exist. Besides the right temperature, water must also be present for life, as we know it, to evolve. Water has been found on Jupiter’s moon “Europa”, Saturn’s small (300-mile wide) icy satellite Enceladus, and on our own moon.
After a certain period of time our earth’s magnetic field undergoes a reversal so that north becomes south, and south becomes north. This last occurred 780,000 years ago. The magnetic field is responsible for the “magnetosphere” that protects the earth from the damaging effects of cosmic rays. Life would not have existed in its present form without this protective effect.
Finally, while many may think that we are stationary, we are all actually traveling across space at an amazing velocity, 120 miles per second, on the giant spacecraft called “earth” towards the enormous Virgo cluster of galaxies! Mysteries surround us everywhere!
Building blocks of life originated in space! It has been speculated that the building blocks of life originated in space and were seeded on earth in its early history. However, it is only recently that convincing evidence is becoming available. What is this evidence?
Many molecules exist as mirror images of each other. They are called “chiral” molecules, and they are either left handed or right handed. A simple analogy to illustrate the concept of “chirality” is our left and right hands. They are symmetrical mirror images of one another but they are not super imposable.
Similarly, certain biologically important molecules, such as amino acids and sugars, exist in only one form that is either left handed or right handed. It has been a major dilemma to explain why evolution on earth led to only one of the two possible mirror image forms and not to the other. For instance amino acids, that are present in natural proteins, occur only in the left-handed form. Sugars present in the DNA of living organisms occur only in the right-handed form. Scientists have therefore speculated that such molecules may have arisen in outer space under conditions in which the formation of one of these two mirror image forms was favoured over the other (for example under the influence of circularly polarised light in the stars).
Two exciting developments during the last one year have provided strong support to this hypothesis that the building blocks of life originated in space. A team of scientists led by Louis d’ Hendecourt at the Institut d’ astrophysique spatiale (Université Paris-Sud 11 / CNRS), recreating the conditions that may have existed in interstellar conditions in space, succeeded in producing one of the two forms of amino acids in excess of the other. This provides strong support to the idea that chiral molecules on earth originated from extraterrestrial organic material that may have come from outside our solar system, and that contained predominantly one of the two possible chiral forms of amino acids. Circularly polarised infra red light present in massive star formation could have led to this effect (The Astrophysical Journal, 2011; 727 (2): L27 DOI: 10.1088/2041-8205/727/2/L27).
A second piece of important evidence comes from the recent discovery by scientists at NASA that certain meteorites from outer space contained two of the four nucleobases that constitute our genetic code, and that the material was not a contaminant from earth (Science, 2011; 332 (6035): 1304-1307 DOI: 10.1126/science.1203290).
All the elements found on earth, including every atom of our body, have been born in the centres of hot stars through fusion reactions. Oxygen, nitrogen, phosphorus, calcium, nickel, silver, gold — every element found on earth — has arisen in this manner.
With this new evidence about the origin of chiral molecules in outer space, an important piece of the jigsaw puzzle seems to be finally in place.
Dear visitor, the comments section is undergoing an overhaul and will return soon.