Grand Tack
(published 2/05/2020)
In the beginning, God created the heavens and the earth. The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters.
And God said, “Let there be light,” and there was light. (Genesis 1:1-3)
Figure 1 Proto-Solar System (Image credit: mj.peinture)
Figure 1 is an artist’s rendition of how our solar system might have appeared at its beginning, 4.568 billion years ago.
Scientists and theologians have pondered those first three words in the Bible – “In the beginning” – for centuries. Was God referring to what scientists call the “Big Bang”, a cosmic event that initiated our universe some 13.7 billion years ago? Or, was God speaking of the beginning of our solar system some 4.568 billion years ago, when our sun began to shine, and the Earth was formed?
In Chapter 1 of Genesis God speaks of land and water, but what was the source of this land and water? Did you know that when the Earth was being formed, there was no available water around? As with every other solar system observed in the universe, planets nearest their star are “rocky” and dry; distant planets are gassy and icy. Yet our planet Earth, though it is in an orbit 93 million miles (= one AU [Astronomical Unit]) from our Sun, contains both continents and oceans. Of the thousands of planets (exoplanets) observed by astronomers, they have yet to find one even remotely like Earth that has a balance of rock and water inside the proper temperature zone; thus far, Earth is unique within the universe.
Scripture informs us that in the beginning of our solar system, the first thing God did was to form our giant nuclear furnace, the Sun; that became the only source of light – “Let there be light”; everything else in orbit around the Sun was formless and dark, not capable of shining light. At that time, the Earth was “formless and void”. In fact, Earth had not yet even begun to form. The first planets to form following the Sun were the giant gas planets Jupiter and Saturn. At that time the solar system was a dense mess of dust, gas, and small asteroids of varying compositions. It was this “chaos” that the Holy Spirit hovered over. God had some serious work to do if he were to form a planet Earth composed of rocky constituents (containing a perfect balance of the elements listed in the Periodic Table) and water. To complicate matters, the rocky materials and watery materials were completely separated; rocky asteroids were in orbit between the Sun and Jupiter; icy asteroids were in orbit between Jupiter and distant Pluto.
Figure 2 Model of the Grand Tack (Image credit: www-n.oca.eu)
God solved this problem by speaking the Grand Tack (theory) into motion. Most amazing was he accomplished the formation of the early Earth in a short 600,000 years! Let’s walk through the Grand Tack model (Figure 2). Year zero sets the stage; the new Sun is born and shortly thereafter the huge gas planets, Jupiter, Saturn, Uranus, and Neptune arrive. Jupiter is in orbit 3.5 AU (325 million miles) from the Sun and Saturn is 4.5 AU (420 million miles) distant; between Jupiter and the Sun is a sea of rocky asteroids (S-type). Beyond Jupiter is an ocean of icy asteroids (C-type).
It appears like God intervened (“spoke”) into this chaos and caused Jupiter to suddenly leave its orbit and move inward on a collision course with the Sun. By year 70,000 Jupiter has moved to within 130 million miles of the Sun, compressing some rocky asteroids into planets (like Earth and Venus), absorbing many asteroids by its strong gravitational field, and driving the rest into the Sun or into outer space.
Year 100,000 Saturn suddenly leaves its orbit, driving and dragging numerous icy asteroids past Jupiter toward the Sun; many of the icy asteroids were captured by the newly accreting Earth, adding all-important water to the planet. At 1.5 AU (140 million miles) Saturn and Jupiter are locked in 2:3 resonance for a season. This Jupiter-Saturn “Do-Si-Do” continues for 200,000 years. Then abruptly at the 300,000-year mark, the process is reversed and both Jupiter and Saturn migrate away from the Sun; by 600,000 years they are established in their permanent orbits as observed today, Jupiter at 5 AU and Saturn at 9 AU. As a sailboat would “tack” into the wind, so Jupiter and Saturn tacked into a strong solar wind; thus, the term ‘Grand Tack’. Figure 3 provides another visual for this event.
Figure 3 (Image credit: Back Alley Astronomy)
Think of it, 600,000 years is but a moment, one thousandth (.001) of the total 4,567,000,000 years between the early formation of the solar system and a planet ready for human occupancy. I often wondered what the Holy Spirit was doing while “hovering” over the chaos pictured in Figure 1. As God views time from his transcendent, eternal perspective, this would have been just a moment – but look how much he accomplished! Grand Tack is only one of many events, equally spectacular, to equip the Earth to bring forth and sustain life. Now look at the final product, our solar system as it stands today (Figure 4).
Figure 4 Solar System (Credit: astronomyisawesome.com)
