Researchers from Monash University in Australia have hypothesized that about 466 million years ago, a ring formed around the Earth from the debris of an asteroid attracted by the planet, which lasted for several tens of millions of years. Scientists made this assumption by studying the location of meteorite craters on the surface of the Earth that appeared during the Ordovician period.
An artistic representation of a ring around the Earth. Image source: Oliver Hull
Researchers say that during the Ordovician period, the Earth experienced an increase in the number of meteorite craters. They mapped the locations of 21 known craters of this age and used mathematical models of the movement of tectonic plates to “rewind time” and track them to where they were at the time of the impact.
According to scientists, all meteorites crashed into our planet within 30 degrees of the equator. Researchers saw this as a statistical anomaly and tried to find a scientific basis for such a non-random distribution of craters over the Earth’s surface. They tried to find out which part of the continents of that period could preserve traces of collisions with meteorites to this day. The researchers focused on stable, intact areas of the Earth’s crust that date back to the mid-Ordovician period, excluding regions that were buried, eroded or affected by tectonic activity. The best results were obtained in Western Australia, Africa and parts of North America and Europe.
As a result of the study, scientists have put forward a theory to explain the fall of meteorites in the equator region – if the Earth captured a passing asteroid about 466 million years ago, the impact of gravitational forces could “tear” it into pieces and form a ring. Then, over several tens of millions of years, fragments of the asteroid methodically fell on our planet in the equatorial region. The meteorite debris in the studied craters did not spend much time in space before falling to Earth, which is consistent with the assumption of the destruction of a large asteroid and the appearance of a ring around the Earth.
The theory of an asteroid ring around the Earth may also explain several other mysteries from that historical period. About 20 million years later, Earth entered the Hirnantian Ice Age, when temperatures dropped to their lowest levels in half a billion years. Due to the tilt of the Earth’s axis of rotation relative to the Sun, a ring around the equator obscured part of the Earth’s surface, which could potentially cause global cooling.
«The idea that the ring system could influence global temperatures adds a new level of complexity to our understanding of how extraterrestrial events could have shaped Earth’s climate,” said study leader Professor Andy Tomkins.
It is possible that the rings are a phase that the Earth and other planets go through several times in their lives. Saturn’s rings appeared only 10 million years ago and may disappear in another 100 million. Mars is currently tearing apart one of its moons, which could form a new ring in 20 to 40 million years.
The study was published in the journal Earth & Planetary Science Letters. In the future, the authors plan to simulate the process of destruction of an asteroid, the formation of a ring and its transformation into meteorites over time. Subsequent work will also attempt to model the influence of the rings on climate. It should be noted that, despite all the courage, promise and seeming logic of the proposed theory, it can be based on a banal sampling error, since the study of the location of 21 craters on the earth’s surface can only be considered a statistically significant result only with great stretch.