Earth Archives

August 14, 2020August 14, 2020 by Evan Gough

Did Snowball Earth Happen Because of a Sudden Drop in Sunlight?

This artist's illustration shows what an icy exo-Earth might look like. A new study says liquid water could persist under ice sheets on planets outside of their habitable zones. Image Credit: NASA

Hundreds of millions of years ago, Earth went through two episodes of severe glaciation. These two episodes—the Sturtian and the Marinoan glaciations—occured during the Earth’s Cryogenian Period. The Cryogenian lasted from about 720 million to 635 million years ago.

The phenomenon is called “Snowball Earth” and both instances of it happened in pretty quick succession. And while a planet encased in ice and snow sounds devastating, these episodes may have paved the way for the development of complex life.

The question is, what caused the Earth to freeze over like that?

August 4, 2020August 4, 2020 by Evan Gough

Microbes Were Dormant for Over 100 Million Years, But They Were Able to Spring Back to Life

Magnified image showing microbes revived from 101.5-million-year-old sediment. Image Credit:Japan Agency for Marine-Earth Science and Technology

At the bottom of the ocean in the South Pacific Gyre, there’s a sediment layer that is among the most nutrient-starved environments on Earth. Because of conditions in that area, there’s almost no “marine snow”—the shower of organic debris common in the ocean—that falls to the ocean floor. Without all that organic debris falling to the floor, there’s a severe lack of nutrients there, and that makes this one of the least hospitable places on Earth.

A team of researchers took sediment samples from that area, and extracted 101.5 million year old microbes. When they “fed” those microbes, they sprang back to life.

The results are expanding our knowledge of microbial life and how long it can be dormant when conditions force it to be.

July 24, 2020July 24, 2020 by Evan Gough

What Cracked the Earth’s Outer Shell and Started its Plate Tectonics?

A snapshot of a model from the new work, showing the late stages of growth and coalescence of a new global fracture network. Fractures are in black / shadow, and colors show stresses (pink color denotes tensile stress, blue color denotes compressive stress). Image Credit: Tang et al, 2020.

Earth’s lithosphere is made up of seven large tectonic plates and a number of smaller ones. The theory of plate tectonics that describes how these plates move is about 50 years old. But there’s never really been an understanding of how this system developed, and how the Earth’s shell split into separate plates and started moving.

Now a group of researchers have a possible explanation.

July 24, 2020July 24, 2020 by Evan Gough

800 Million Years Ago, it Was Raining Asteroids on the Earth and Moon

An artist's illustration of an asteroid shower on the Earth-Moon system. Image Credit: Murayama/Osaka Univ.

Natural processes here on Earth continually re-shape the planet’s surface. Craters from ancient asteroid strikes are erased in a short period of time, in geological terms. So how can researchers understand Earth’s history, and how thoroughly it may have been pummeled by asteroid strikes?

Scientists can turn their attention to our ancient companion, the Moon.

July 22, 2020July 22, 2020 by Evan Gough

Organic Matter Could Have Delivered Earth’s Water

This view of Earth’s horizon was taken by an Expedition 7 crewmember onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean. A new study suggests that Earth's water didn't all come from comets, but likely also came from water-rich planetesimals. Credit: NASA

The origin of Earth’s water is a big piece of the puzzle in Earth’s history. Did it come from comets and asteroids? From water-bearing space dust? The scientific debate is not settled.

Now a new study shows that water could have been delivered to Earth by organic matter.

July 13, 2020July 13, 2020 by Evan Gough

This Giant Iceberg Has Been Sailing the Southern Seas for Three Years Now

The iceberg A-68A floating in open waters about 1050 km from its birthplace. It's been floating for three years. Image Credit: contains modified Copernicus Sentinel data (2020), processed by ESA, CC BY-SA 3.0 IGO

An iceberg that calved off of from a larger ice formation has spent three years floating on the ocean near Antarctica. The iceberg broke off of the Larsen Ice Shelf in mid-July 2017. It’s been battered and split up into three pieces, but it’s still going.

July 10, 2020July 10, 2020 by Evan Gough

Even If We Cut Greenhouse Gas Emissions Tomorrow, it Would Take Decades for the Earth to Start Cooling Again

Our beautiful, precious, life-supporting Earth as seen on July 6, 2015 from a distance of one million miles by a NASA scientific camera aboard the Deep Space Climate Observatory spacecraft. Credits: NASA

If—or hopefully when—we cut our Greenhouse Gas (GHG) emissions, we won’t notice much difference in the climate. The Earth’s natural systems take time to absorb carbon from the atmosphere. We may have to wait decades for the temperatures to drop.

Of course, that doesn’t mean we shouldn’t do it. It’s just that we have to temper our expectations a little.

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 25, 2020June 25, 2020 by Evan Gough

Last Year’s Total Solar Eclipse on Earth, Seen From the Moon

The Moon casting its shadow on the Earth during an eclipse in 2018. Image Credit: MingChuan Wei (Harbin Institute of Technology, BG2BHC/BY2HIT), CAMRAS Dwingeloo Radio Telescope, Reinhard Kühn DK5LA. Image edit by Jason Major.

On July 2, 2019, the Moon cast its shadow on the surface of the Earth. This time, the shadow’s path travelled across the South Pacific Ocean. It also passed over some of Argentina and Chile. For surface dwellers in the path, the Moon briefly blocked the Sun, turning night into day.

But for one “eye” in orbit around the Moon, the view was different. A camera on a tiny satellite watched as the circular shadow of the Moon moved over the Earth’s surface.

June 11, 2020June 11, 2020 by Evan Gough

It Should Be Easiest to Search for Young Earth-like Planets When They’re Completely Covered in Magma

Artist's impression of magma ocean planet. Credit: Mark Garlick

How did Earth evolve from an ocean of magma to the vibrant, life-supporting, blue jewel it is now? In its early years, the Earth was a blistering hot ball of magma. Now, 4.5 billion years later, it’s barely recognizable.

Is it possible to find exoplanets out there in the vast expanse, which are young molten globes much like young Earth was? How many of them can we expect to find? Where will we find them?