Theia Archives

April 19, 2024April 19, 2024 by Evan Gough

The Giant Planets Migrated Between 60-100 Million Years After the Solar System Formed

The migration of the giant planets had a hand in shaping our Solar System, including Earth. New research shows the migration happened much earlier than thought. Image Credit: NASA

Untangling what happened in our Solar System tens or hundreds of millions of years ago is challenging. Millions of objects of wildly different masses interacted for billions of years, seeking natural stability. But its history—including the migration of the giant planets—explains what we see today in our Solar System and maybe in other, distant solar systems.

New research shows that giant planet migration began shortly after the Solar System formed.

April 3, 2024April 3, 2024 by Scott Alan Johnston

What's the Earliest the Moon Could Have Formed?

Artist's impression of the giant impact that shaped the Earth and created the Moon. Credit: NASA/JPL-Caltech.

Astronomers are pretty sure they know where the Moon came from. In the early Solar System, a Mars-sized object dubbed Theia smashed into Earth. This cataclysmic collision knocked a huge mass of material into orbit, which coalesced and cooled into the Moon. But establishing exactly when this occurred is a difficult task. At the 55th annual Lunar and Planetary Science Conference (LPSC 55) last month in The Woodlands, Texas, researchers proposed a new timeline of events that moves the giant impact earlier than previous predictions, at just 50 million years after the formation of the Solar System.

November 3, 2023November 3, 2023 by Evan Gough

Earth is Hiding Another Planet Deep Inside

During an ancient collision, the protoplanet named Theia slammed into Earth, leading to the creation of the Moon. But it left some of its remains inside Earth. Image Credit: CalTech

Earth’s early history is marked by massive collisions with other objects, including planetesimals. One of the defining events in our planet’s history, the formation of the Moon, likely resulted from one of these catastrophic collisions when a Mars-sized protoplanet crashed into Earth. That’s the Giant Impact Hypothesis, and it explains how the collision produced a torus of debris rotating around the Earth that eventually coalesced into our only natural satellite.

New research strengthens the idea that Theia left some of its remains inside Earth.

August 15, 2022August 15, 2022 by Scott Alan Johnston

Lunar Rocks Have Earth's Noble Gases Trapped Inside. More Evidence That the Moon Came From the Earth

Piecing together the history of the Solar System from the traces left behind isn’t easy. Bit by bit, however, we’re working it out. This month, new research examining the composition of lunar meteorites offers compelling evidence that the Moon and the Earth were formed from the same material, perhaps in the aftermath of a cataclysmic collision some 4.5 billion years ago.

September 28, 2021September 28, 2021 by Evan Gough

The Early Solar System was Messier and More Violent Than Previously Believed

This artwork shows a rocky planet being bombarded by comets. Image credit: NASA/JPL-Caltech

Our conventional models of planet formation may have to be updated, according to a pair of new papers.

Accretion is the keyword in current planet formation theory. The idea is that the planets formed out of the solar nebula, the material left over after the Sun formed. They did this through accretion, where small particles accumulate into more massive objects. These massive boulder-sized objects, called planetesimals, continued to merge together into larger entities, sometimes through collisions. Eventually, through repeated mergers and collisions, the inner Solar System was populated by four rocky planets.

But the new research suggests that the collisions played out much differently than thought and that objects collided with each other several times, in a series of hit and runs, before merging. This research fills some stubborn holes in our current understanding.

July 18, 2020July 18, 2020 by Matt Williams

The Moon Might Have Formed a Little Later than Originally Believed

According to the Giant Impact Hypothesis, the Moon formed when a Mars-sized object (named Theia) collided with Earth billion years ago, at a time when the Earth was still a ball of magma. This event not only led to the Earth-Moon system we recognize today, it is also beleived to have led to the differentiation of the Earth’s core region into an molten Outer Core and a solid Inner Core.

However, there has been an ongoing debate as to the timing of this impact and how long the subsequent formation of the Moon took place. According to a new study by a team of German researchers, the Moon formed from a magma ocean that took up to 200 million years to solidify. This means that the Moon finished forming about 4.425 billion years ago, or 100 million years later than previously thought.

July 7, 2020July 7, 2020 by Evan Gough

The Moon Might Be More Metal-Rich Than We Thought

The Moon contains more metal than previously thought, according to a new study. Is it time to re-think the giant impact hypothesis? Image Credit: NASA / GSFC / Arizona State University

A new study shows that the Moon is more metal-rich than previously thought. That has some far-reaching implications for our understanding of the Moon’s formation. If their results are solid, it means that we may need to re-think the giant impact hypothesis for the formation of the Moon.

June 26, 2020June 26, 2020 by Evan Gough

Do We Now Understand Why the Moon’s Near and Far Sides Look So Dramatically Different?

The Full Moon. Our view of the Moon is dominated by the large volcanic mares, and the especially dramatic Tycho Crater. Image Credit: By Gregory H. Revera - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11901243

The Moon is easily the most well-studied object in the Solar System, (other than Earth, of course.) But it still holds some puzzles for scientists. Why, for instance, is one side of the Moon so different from the other?

March 16, 2020 by Matt Williams

New Study Shows the Earth and Moon are not so Similar After All

Artist's conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth's moon. Credit: NASA/JPL-Caltech

According to the most widely-accepted theory, the Moon formed roughly 4.5 billion years ago when a Mars-sized object named Theia collided with Earth (aka. the Giant Impact Hypothesis). This impact threw up considerable amounts of debris which gradually coalesced to form Earth’s only natural satellite. One of the most compelling proofs for this theory is the fact that the Earth and the Moon are remarkably similar in terms of composition.

However, previous studies involving computer simulations have shown that if the Moon were created by a giant impact, it should have retained more material from the impactor itself. But according to a new study conducted by a team from the University of New Mexico, it is possible that the Earth and the Moon are not as similar as previously thought.

July 31, 2019July 31, 2019 by Evan Gough

The Moon is Older Than Scientists Thought

It is believed that 4.4 billion years ago, a celestial body (Theia) slammed into Earth and produced the Moon. Image Credit: NASA/JPL-Caltech

The most comprehensive and widely-held theory of how the Moon formed is called the ‘giant impact hypothesis.’ That hypothesis shows that about 150 million years after the Solar System formed, a roughly Mars-sized planet named Theia collided with Earth. Though the timeline is hotly-debated in the scientific community, we know that this collision melted Theia and some of Earth, and that molten rock orbited around Earth until it coalesced into the Moon.

But now a new study, though not contradicting the giant impact hypothesis, is suggesting a different timeline, and an older Moon.