Sunday, August 20, 2017


The anticipation of the eclipse on August 21, 2017 made me reflect upon the intersection of objects orbiting in our solar system.  The nearest star to our Sun is about 18 trillion miles away.  Beyond that, and in all directions, are trillions of other stars.  A lot has happened in our 13.7 billion year old universe.  But I want to consider asteroids found in our solar system.


1.  Stirring the pot for chemical evolution.

Whether they formed from condensation in the gaseous cloud giving rise to the sun and its protoplantary disk, or via collision(s) of orbiting planets, moons, and satellites, they exist in abundance, orbiting in a belt extending from the orbit of Mars to the orbit of Jupiter.  Smaller numbers have orbits intersecting earth's orbit; many have probably already been cleared by the earth and the moon from our orbit.  Some evidence of a peak in asteroid strikes a few hundred million years before the Cambrian has been claimed.

The early strikes may have contributed two things.  Elements and some simple organic compounds, the latter formed in the protoplanetary cloud before liquids and solids condensed, added to the chemicals available for early chemical evolution leading to living systems.  Larger asterioids may have made depression of various sizes in locations, some of which were favorable to the process described in earlier posts.  In addition to the delivery or useful chemicals, the mixing affect of material ejected around the impact area may have enabled useful different products to be combined.

2.  The origin of sex.   is a post including a view of how asteroid extincton events may have spurred the origin of sex.
"The starvation of protists during the early life extinction events meant degrowth to eventual fatal levels if they could not eat another protist or, better yet, fuse with another to make a viable mass.  Perhaps the reductions during degrowth resulted in a reduced genome lacking essential genes.  Or continued reduction after fusion made the survival of only the normal genome [haploid set of chromosomes] an outcome that over time developed the needed stable genetic controls." (my 2010 Evolution Insights ms. p. 89)

3.  Making room for new species.

Reduction or extinction of dominant species may have enabled diversity to develop with less threat to survival in early poorly adapted stages of evolutionary lines.

The Pre-Cambrian/Cambrian unconformity may have been due to an intense period of asteroid bombardment opening up reduced predation which allowed pogonophorans to adapt to shallow seas as they gave rise to the hemichordates.

The end of the Paleozoic ended the dominance of trilobites and some other very successful groups.

The end of the Mesozoic Era with the demise of the dinosaurs simplified the success and rise of birds and mammals.

4.  Asteroid collisions were a probable cause of the abyssal region of the ocean serving as a refugium, or shelter, for some ancient animals, most importantly, the pogonophorans.  Pogonophoran adaptation to the deep sea allowed them to survive extinction events and repopulate, not only shallow water but portions of the ocean abyss that became anoxic, after oxygenated water currents from polar seas to abyssal regions was reestablished.


The space between the orbits of Mars and Jupiter is about 205,000,000 miles.  That is more than two time the 93,000,000 miles distance of the earth from the sun.  The dwarf planet, Ceres, wanders around the sun in a path using up about one-tenth the space between Mars and Jupiter orbits.  Craters exist on all the planets as well as many moons and larger asteroids.

Daytime surface temperatures on planets beyond earth are below freezing.  But Venus and Mercury are closer to the Sun and have temperatures much higher than boiling.  The extreme cold of outer reaches of the solar system means that many of the orbiting objects may be ice or other frozen gases.  The density of meteorites and/or asteroids may be high enough to suggest that their origin was closer to Earth and Mars.  Along with the gap in presence of planets in the asteroid belt, it suggests to me that collision of planet(s) and other large objects were the origin of much of the debris in the asteroid belt.

The reduced spacing and high orbital speed of the planets closer to the Sun would seem to be conducive to more asteroid inducing collisions.The orbital speed in miles per second for Earth is 18.5.  Speed decreases to 3.37 miles per second for Neptune which is about 30 times further from the Sun than Earth.  While we take a year to go around the Sun, it takes 165 of years for Neptune do so.

The rocky composition of planets nearer the sun is more like rocky asteroids than the gaseous planets beyond the asteroid belt.

The above factors would seem to indicate one or more collisions, involving one or more planets shattering, was a major source of asteroids.

Joe Engemann      Kalamzoo, Michigan    August 20, 2017

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