Archive · 15 Jun 2025
Scientists Discover Ancient Oceans: Pale Green Dots
Imagine Earth long ago, when it looked different!
There wasn't much air, and the oceans were green because of iron.
Tiny organisms used iron for food, which made oxygen and changed everything.
Scientists found green water near a volcano similar to the old oceans.
This helps them understand what the Earth was like billions of years ago, and how it changed.
Depending on what’s in the water, oceans could even turn different colors, like purple or red.
Scientists deduced ancient oceans were green due to lack of atmosphere and iron.
Single-celled organisms used iron, releasing oxygen, leading to oxidation event.
Banded iron formations record shifts in iron oxidation from the Archean eon.
Green waters near Iwo Jima show similarities to ancient oceans, supporting algae.
Future scenarios include sulfur-driven purple bacteria and potential red oceans.
- Who
- Japanese scientists and astronomer Carl Sagan.
- What
- Scientists studied how ancient oceans might have looked and what they were made of.
- When
- During the Archean eon (3.8-1.9 billion years ago) and in the future.
- Where
- Researchers studied the waters around the volcanic island of Iwo Jima.
- Why
- To understand the Earth's early environment and how it evolved.
- Image
- Pale Green Dot
- Time Period
- Archean eon (3.8-1.9 billion years ago)
- Cause of Ocean Color
- Oxidized iron
- Organisms
- Single-celled organisms, blue-green algae, and potentially purple bacteria
- Significant event
- The Great Oxidation Event