June 2013 : Kepler Mission updated its estimates. Here are these latest numbers right from the horses-mouth (Professor Ravi Kopparapu). As at 20 June 2013, Dr. Kopparapu, expert with the Kepler Mission estimates :
- Stars in the Galaxy : 400 billion
- The number of habitable earth-like exoplanets in our Milky Way Galaxy : 144 billion (> 1011).
- The OORT Cloud around our Sun (it is also hypothesized by some astronomers that most suns have OORT clouds) is estimated :
- to contain : several trillion individual asteroids (objects) larger than 1 km (0.62 mi).
- to reach 1 ly towards the next closest star just 4 ly away – Proxima Centauri.
Comets have a wide range of orbital periods, ranging from a few years to hundreds of thousands of years. Short-period comets originate in the Kuiper belt (eg Halley’s Comet – orbit 75 years). Longer-period comets are thought to originate in the Oort cloud (Orbit – thousands of years). The latest theory is that they are mostly water, with a frozen, dust-encrusted shell. This would explain why objects like the Chelyabinsk, in February 2013, often leave few meteorites (rock fragments).
This year (In 2013), ALMA (Atacama Large Millimeter/submillimeter Array (ALMA)) – which CANADA is part of – managed from Herzberg Institute in Victoria, BC) has confirmed that researchers have discovered an important pair of prebiotic molecules in the icy particles in interstellar space (ISM). ISM is the empty part of the spiral arms.
The chemicals, found in a giant cloud of gas about 25,000 light-years (half way to centre of the galaxy) from Earth in ISM, may be a precursor to a key component of DNA and the other may have a role in the formation of an important amino acid.
Researchers found a molecule called cyanomethanimine, which produces adenine, one of the four nucleobases that form the “rungs” in the ladder-like structure of DNA. The other molecule, called ethanamine, is thought to play a role in forming alanine, one of the twenty amino acids in the genetic code.
Previously, scientists thought such processes took place in the very tenuous gas between the stars. The new discoveries, however, suggest that the chemical formation sequences for these molecules occurred not in gas, but on the surfaces of ice grains in interstellar space.
In February 2013, NASA ALMA spokesman announced : “Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can ‘seed’ newly-formed planets with the chemical precursors for life.”
See Video Interview and Animations with Dr. Anthony Remijan of the National Radio Astronomy Observatory.
“…..Microbiology may be said to have had its beginnings in the nineteen-forties. A new world of the most astonishing complexity began then to be revealed. In retrospect I find it remarkable that microbiologists did not at once recognise that the world into which they had penetrated had of necessity to be of cosmic order. I suspect that the cosmic quality of microbiology will seem as obvious to future generations as the Sun being the centre of the solar system seems obvious to the present generation…..”
Sir Fred Hoyle