galactic habitable zone Archives - DOES GOD EXIST? TODAY

Since astronomers have discovered more than 5,000 exoplanets orbiting stars other than our Sun, many insist there must be life elsewhere in the cosmos. For those of us who believe in God, that isn’t really an issue. If there is life out there, God created it, but the Bible only speaks to our planet. However, the evidence is growing that our planet is more unique than most people realize. A “Goldilocks” planet is at the proper distance from its star so that the temperature is “just right” for liquid water to exist on the surface. Some exoplanets appear to be in the habitable zones of their stars, but many other factors must also be just right for life to exist there.

Most known exoplanets are like Jupiter, having no terrestrial surface. To support life, a planet must be the right size, have a stable orbit inside the habitable zone of a stable star, and have the right atmosphere. It must also have working plate tectonics and a large moon to maintain a stable axis tilt. To be just right for life to exist, a planet must also be in the habitable zone of its galaxy – not near the center, exposing it to lethal gamma-ray bursts.

Our Sun is a G spectral star, but only 9% of the stars in our galaxy are that type. M-class dwarf stars are the most common and long-lived stars, but they emit large amounts of radiation that would cook any life on their planets. Also, planets around such a star would become tidal-locked, with one side facing the star being excessively hot while the other remains cold.

Another star system requirement for life would be having outer planets large enough and in the correct position to sweep away asteroids and comets that would bombard an inner planet. To support life, a planet also needs a strong magnetic field to shield the surface from the star’s radiation and cosmic rays.

Our Earth is just right for life to exist. We are defining life as the biology books do: being able to move, breathe, respond to outside stimuli, and reproduce. Any conjecture about fire people or rock people is in science fiction – not scientific fact. The bottom line is that Earth is a special place created by God for a special purpose and is unique among all other objects in the cosmos.

Reference: “Is Earth the Only Goldilocks Panet?” in Discover magazine, July/August 2024, pages 54 -57.

Cosmology provides strong evidence for God’s existence. The basic cosmological argument for God involves three simple questions:

1) Was there a beginning to time, space, and matter/energy? The evidence says there was.

2) Was the beginning caused or uncaused? Taking the position it was uncaused violates scientific conservation laws.

3) If it was caused, what or who was the causer? The evidence is that the cause can not be blind, mechanistic chance. Logic suggests that the cause was an intelligence, in other words, God.

As more data becomes available to support intelligence as the cause of planet Earth, the cosmological argument for God becomes stronger. If we define life as that which can breathe, move, respond to outside stimuli, and reproduce, what is necessary for life to exist? Astronomers now talk about the habitable zone (HZ) of stars. This is the zone around stars where the temperature on a planet would allow water to exist in the liquid state on the surface.

Recent discoveries have shown that M-class dwarf stars are the most common and longest-lived stars. The problem with these stars is that their HZ is very close to the star, so tidal forces would lock the rotation of any planet so its same side would always face the parent star. One side of the planet would be constantly hot while the other would be cold. Also, M-class stars would bombard these planets with stellar flares causing massive radiation levels that would eliminate any possibility of life. Other star types create various problems for a life-supporting planet.

Astronomers have determined there is a galactic habitable zone (GHZ) in addition to the star’s habitable zone. A star must be far from the galactic center to have a planet with life on it. The high star density near the core of a galaxy exposes the star system to deadly supernovae and gamma-ray bursts. Mass distribution within a galaxy is also an issue because, near the galaxy’s core, mass concentrations cause gravitational instability.

The basic cosmological argument for God is now supported by a vast number of parameters that must be within precise limits to allow life to exist in a planetary system. Having a large moon is essential to the survival of life on a planet. Likewise, having a shield against incoming cosmic bodies is critical. A body the size of Comet Hale Bopp hitting planet Earth would have sterilized it, killing even microbes that might be present. The Earth’s shield is the arrangement of the Jovian planets. Jupiter, Saturn, Uranus, and Neptune preventing objects like Hale Bopp from reaching Earth.

The more we look at the cosmos, the unique qualities of our planet reinforce the cosmological argument for God. Proverbs 8 personifies Wisdom speaking of God’s creative power and design. As we learn more about the cosmos, the stronger the evidence becomes that “in the beginning God created the heavens and the earth” (Genesis 1:1).

Reference: “Is Earth the Only Goldilocks Planet?” by Klaus R. Brasch in Astronomy Magazine for July 2023, pages 18-23.

Tag: galactic habitable zone

Just Right for Life to Exist

The Cosmological Argument for God