The Cosmic Delivery: Did Icy Invaders Build Our Oceans?

Introduction

​For decades, scientists have looked at the vast, blue expanse of our oceans and asked one simple, profound question: Where did all this water come from? While some believe water was "baked" into the rocks of Earth during its formation, a competing theory suggests a much more violent and spectacular origin. The Comet Impact Hypothesis proposes that Earth was once a dry, rocky wasteland until it was bombarded by a relentless "cosmic delivery service"—trillions of tons of pure water-ice arriving via meteors and comet nuclei.

​But does the math actually hold up? If Earth were struck by icy bodies of varying sizes—from small 2 km "scouts" to massive 200 km "titans"—how long would it take to fill the basins of our world? In this post, we use Python to simulate the deposition rates of three distinct types of comet nuclei to see if 400 million years of bombardment is enough to create the world as we know it.

​The Hypothesis: Three Tiers of Impact

​To test this, we categorize our icy visitors into three types based on their diameter and arrival frequency:

Body Type Diameter Arrival Frequency

Type I 2 km Twice per year

Type II 20 km Once every 600 years

Type III 200 km Once every 1,000,000 years

Why 400 Million Years?

​Geologically speaking, the "Late Heavy Bombardment" is a period where impact rates were significantly higher. By calculating the Total Ice Deposition Rate, we can determine if the current volume of the oceans fits within this window of planetary development.

"""
BLOG POST HYPOTHESIS: HOW METEOR IMPACTS CREATED EARTH'S WATER
------------------------------------------------------------
Problem Statement & Parameters:
We explore the hypothesis that Earth’s oceans were filled by icy bodies (comets/meteors).
We assume these bodies consisted of three major spherical types made of pure water-ice:

1. **Type I**:   2 km diameter, arriving once every 6 months.
2. **Type II**: 20 km diameter, arriving once every 600 years.
3. **Type III**: 200 km diameter, arriving every one million years.

Goal: Calculate the volumes and deposition rates of these bodies to determine how long it
would take to create Earth’s current oceans.
"""

import math

# --- 1. Define Core Calculation Function ---
def vol_sphere(radius):
    """
    Calculates the volume of a sphere.
    Formula: (4/3) * pi * r^3
    """
    return (4/3) * math.pi * (radius**3)

# --- 2. Initialize Data and Constants ---

# Dictionary storing raw data for each comet type:
# Structure: "type-key": (diameter_in_km, arrival_interval_in_years)
comet_nuclei_data = {
    "type-I":   (2,   0.5),    # Arrives every 0.5 years (6 months)
    "type-II":  (20,  600),    # Arrives every 600 years
    "type-III": (200, 1e06)    # Arrives every 1,000,000 years
}

# Real-world scientific estimates used as a benchmark:
TOTAL_EARTH_WATER_LIQUID_KM3 = 1.33e09  # Total liquid water volume on Earth in km^3
ICE_TO_WATER_VOL_RATIO = 6              # Assuming 6 units of ice required for 1 unit of liquid water

# --- 3. Run Calculations & Process Data ---

# Create a new dictionary to store expanded results for each type.
# We iterate through the raw data and perform calculations on the fly.
processed_comet_results = {}

for k, (dia, interval) in comet_nuclei_data.items():
    # Calculate radius (needed for volume)
    radius = dia / 2
    
    # PROBLEM 1: What are the volumes of the three types of comet nuclei?
    volume_km3 = vol_sphere(radius)
    
    # Calculate arrival frequency per year
    frequency_per_yr = 1 / interval
    
    # Calculate ice deposition rate per year (Volume * Frequency)
    deposit_rate_km3_yr = volume_km3 * frequency_per_yr
    
    # Store calculated values in the new dictionary
    # Structure: "type-key": (dia, frequency, volume, deposit_rate)
    processed_comet_results[k] = (dia, frequency_per_yr, volume_km3, deposit_rate_km3_yr)


# --- 4. Generate Blog-Worthy Output Report ---

print("\n" + "="*80)
print("             METEOR IMPACT HYPOTHESIS REPORT: EARTH'S WATER ORIGIN")
print("="*80)

print(f"\n[BENCHMARK DATA]")
print(f"Current Estimated Total Liquid Water on Earth: {TOTAL_EARTH_WATER_LIQUID_KM3:,.2f} km³")
print(f"Assumed Ice-to-Liquid Water Expansion Ratio:  {ICE_TO_WATER_VOL_RATIO}:1\n")


print("-" * 73)
print(f"{'Comet Type':<12} | {'Dia (km)':>12} | {'Freq (/yr)':>12} | {'Volume (km³)':>16} | {'Dep. Rate (km³/yr)':>20}")
print("-" * 73)

# Print the processed table rows
for k, (dia, freq, vol, rate) in processed_comet_results.items():
    print(f"{k:<12} | {dia:>12.1f} | {freq:>12.6f} | {vol:>16,.0f} | {rate:>20,.2f}")

print("-" * 73)

# --- 5. Summary and Final Analysis ---

# Calculate Total Ice Deposition Rate by summing the individual rates
total_ice_deposition_rate = sum(item[3] for item in processed_comet_results.values())

# Calculate total ice required to fill current oceans
total_ice_required_for_water_km3 = ICE_TO_WATER_VOL_RATIO * TOTAL_EARTH_WATER_LIQUID_KM3

# Calculate time required (Ice Required / Deposition Rate)
time_required_years = total_ice_required_for_water_km3 / total_ice_deposition_rate

print(f"\n[FINAL ANALYSIS SUMMARY]")
print(f"1. Total Average Ice Deposition Rate:  {total_ice_deposition_rate:,.2f} km³ / year")
print(f"2. Total Ice Required for Current Water: {total_ice_required_for_water_km3:,.2e} km³")
print("-" * 80)
print(f"CONCLUSION: Time required to fill present oceans: {time_required_years/1e06:,.2f} million years")
print("="*80 + "\n")