An Astrobiologist's Brief View on Life

What are life-forms on Earth, made of? What about celestial objects, like other planets, comets, asteroids, and stars – what are they made of?

As can be shown, by an instrument known as a mass spectrometer, they all share the same, fundamental chemistry of Earth and its companion planets. All of these are made from the common chemicals, minerals, and metals that are found in and on the Earth.

MACSJ0717.5+3745 Galaxy Cluster Imaged by the Hubble Space Telescope.

Living organisms - animal, bacterial, fungal, and floral, are composed of various combinations of these elements, which express themselves in varying molecular arrangements and can be found in the Periodic Table of the Elements. The myriad of potential arrangements accounts for the diversity of life on this planet.

Beyond hydrogen, all of this chemistry - entry but if it - was forged in the interiors of stars, namely, a type of star called a supernova.

A supernova is a catastrophic, stellar event, in which, the progenitor star collapses under its own weight, then, rebounds, blowing itself to smithereens - much of it, reduced to atomic nuclei. Due to a process called stellar nucleosynthesis (fusion reactions that take place at a star’s core, at extreme temperatures), at a certain temperature all of those elements are converted, one from the other, from the available hydrogen fuel; hydrogen converted to helium; helium to lithium; lithium to beryllium, and on to the heavy metals.

The galaxies (galaxies are, simply, large collections of stars, bound by a common gravitational field) and all of the planets of our solar system, its comets, asteroids, and our star, the Sun, and the exoplanets orbiting other stars (more than 2,000 have been confirmed by NASA/JPL and more than 350 are Earth-like) - all of these - including our very selves - are composed of these various molecular arrangements of those elements. Living things are not made up of some unique, special or mysterious substance. Cornell professor of astronomy and exobiologist, Carl Sagan, once made this accurate statement: “We are all star-stuff.”

Every niche, on this planet, is aggressively occupied by some form of life; no territory is wasted. Earth and its supporting star, the Sun, are rather average places; there is nothing outstanding about our Solar system – the sun and its planets - and, possibly, even ourselves, and yet, life arose here just the same. So, what are the chances of life arising elsewhere, in our or other galaxies in the universe? It seems to me that life, will, ultimately prove to be the rule and not the exception.

Dale Alan Bryant
Senior Contributing Science Writer