Earth Archives

June 15, 2023June 15, 2023 by Evan Gough

Did Life Need Plate Tectonics to Emerge?

New research indicates that mobile plate tectonics—thought to be necessary for the creation of a habitable planet—was not occurring on Earth 3.9 billion years ago. Image Credit: University of Rochester illustration / Michael Osadciw

It’s widely accepted that Earth’s plate tectonics are a key factor in life’s emergence. Plate tectonics allows heat to move from the mantle to the crust and plays a critical role in cycling nutrients. They’re also a key part of the carbon cycle that moderates Earth’s temperature.

But new research suggests that there was no plate tectonic activity when life appeared sometime around 3.9 billion years ago. Does this have implications for our search for habitable worlds?

June 14, 2023June 14, 2023 by Matt Williams

A Day on Earth Used to Only Be 19 Hours

A full disk view of the Earth, courtesy of Meteosat-I 1. Credit: ESA/Meteosat

On Earth, a single solar day lasts 24 hours. That is the time it takes for the Sun to return to the same place in the sky as the day before. The Moon, Earth’s only natural satellite, takes about 27 days to complete a single circuit around our planet and orbits at an average distance of 384,399 km (~238,854.5 mi). Since time immemorial, humans have kept track of the Sun, the Moon, and their sidereal and synodic periods. To the best of our knowledge, the orbital mechanics governing the Earth-Moon system have been the same, and we’ve come to take them for granted.

But there was a time when the Moon orbited significantly closer to Earth, and the average day was much shorter than today. According to a recent study by a pair o researchers from China and Germany, an average day lasted about 19 hours for one billion years during the Proterozoic Epoch – a geological period during the Precambrian that lasted from 2.5 billion years to 541 million years ago. This demonstrates that rather than gradually increasing over time (as previously thought), the length of a day on Earth remained constant for an extended period.

June 9, 2023June 9, 2023 by Matt Williams

If We Can Master Artificial Photosynthesis, We Can Thrive in Space

Illustration of a photobioreactor as a means of growing building materials on Mars. Credit: Joris Wegner/ZARM/Universität Bremen

By 2030, multiple space agencies will have sent astronauts to the Moon for the first time since the Apollo Program ended over 50 years ago. These programs will create lasting infrastructure, like the Lunar Gateway, Artemis Base Camp, Moon Village, and the International Lunar Research Station (ILRS). In the ensuing decade, the first crewed missions to Mars are expected to occur, culminating with the creation of the first human outposts on another planet. Commercial ventures also want to establish habitats in Low Earth Orbit (LEO), enabling everything from asteroid mining to space tourism.

One of the biggest challenges for this renewed era of space exploration (Space Age 2.0) is ensuring that humans can remain healthy while spending extended periods in space. Foremost among them is ensuring that crews have functioning life support systems that can provide a steady supply of breathable air, which poses its own technical challenges. In a recent study, a team of researchers led by Katharina Brinkert of the University of Warwick described how artificial photosynthesis could lead to a new type of life support system that is smaller, lighter, easier, and more cost-effective to send to space.

June 8, 2023June 9, 2023 by Nancy Atkinson

Phew, California’s Largest Reservoir is Nearly Full

Shasta Lake, California’s largest reservoir, filled to nearly 100 percent capacity, seen on May 29, 2023 as seen by the Operational Land Imager (OLI) on the Landsat 9 satellite. Credit: US Geological Survey/NASA Earth Observatory/Lauren Dauphin.

California residents will be glad to know their reservoirs are nearly full again after years of drought. New satellite photos show the levels of Shasta Lake, California’s largest reservoir, going from 31% capacity last November to nearly 100% in May 2023. The reservoir was filled with heavy rains and a significant mountain snowpack that melted into the nearby rivers.

This is the highest levels this lake has seen in over four years, following years of persistent and extreme drought in the US southwest. Scientists are working on ways to recharge ground reservoirs with any excess water, to minimize the effect of the next inevitable drought.

June 7, 2023June 7, 2023 by Evan Gough

Is it Time for a New Definition of “Habitable?”

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Credit: ESO/M. Kornmesser

Things tend to move from the simple to the complex when you’re trying to understand something new. This is the situation exoplanet scientists find themselves in when it comes to the term ‘habitable.’ When they were discovering the first tranche of exoplanets, the term was useful. It basically meant that the planet could have liquid water on its surface.

But now that we know of over 5,000 confirmed exoplanets, the current definition of habitable is showing its age.

May 19, 2023May 19, 2023 by Matt Williams

New Climate Model Accurately Predicts Millions of Years of Ice Ages

Artist's impression of ice age Earth at glacial maximum. Credit: Wikipedia Commons/Ittiz

Earth experiences seasonal changes because of how its axis is tilted (23.43° relative to the Sun’s equator), causing one hemisphere to always be tilted towards the Sun (and the other away) for different parts of the year. However, because of gravitational interactions between the Earth, Sun, Moon, and other planets of the Solar System, Earth has experienced changes in its orientation (obliquity) over the course of eons. This has led to significant changes in Earth’s climate, particularly the recession and expansion of ice sheets due to significant variations in the distribution of sunlight and seasonal changes.

These warming and cooling periods are known as interglacial and glacial periods (“ice ages”). Another interesting change is how the glacial-interglacial cycle has become slower with time. While scientists have long suspected that astronomical forces are responsible, they have only recently been able to test this theory. In a recent study, a team of Japanese researchers reproduced the cycle of glacial periods during the early Pleistocene Epoch (1.6 to 1.2 million years ago) using an improved computer model that confirmed astronomical forces were responsible.

May 19, 2023May 21, 2023 by Matt Williams

An Astronomical First! A Radiation Belt Seen Outside the Solar System

Artist’s impression of an aurora and the surrounding radiation belt of the ultracool dwarf LSR J1835+3259. Credit: Chuck Carter/Melodie Kao/Heising-Simons Foundation)

In 1958, the first satellites launched by the United States (Explorer 1 and 3) detected a massive radiation belt around planet Earth. This confirmed something that many scientists suspected before the Space Age began: that energetic particles emanating from the Sun (solar wind) were captured and held around the planet by Earth’s magnetosphere. This region was named the Van Allen Belt in honor of University of Iowa professor James Van Allen who led the research effort. As robotic missions explored more of the Solar System, scientists discovered similar radiation belts around Jupiter, Saturn, Uranus, and Neptune.

Given the boom in extrasolar planet research, scientists have eagerly awaited the day when a Van Allen Belt would be discovered around an exoplanet. Thanks to a team of astronomers led by the University of California, Santa Cruz (UCSC) and the National Radio Astronomy Observatory (NRAO), that day may have arrived! Using the global High Sensitivity Array (HSA), the team obtained images of persistent, intense radio emissions from an ultracool dwarf star. These revealed the presence of a cloud of high-energy particles forming a massive radiation belt similar to what scientists have observed around Jupiter.

April 24, 2023April 24, 2023 by Nancy Atkinson

Hakuto-R Spacecraft Just Captured its Own Stunning Version of ‘Earthrise’

The Hakuto-r lunar lander took this 'Earthrise"-like image from its current location in lunar orbit. Credit: ispace.

The Hakuto-R lunar lander, currently in orbit around the Moon, just captured a beautiful “Earthrise”-like image, and one with an interesting side note. The Mission 1 lander, from the Tokyo-based commercial company ispace, took the image during the time of the April 20 solar eclipse, where totality was visible in Australia; and so the photo includes a perfect view of the shadow of the Moon passing above the Land Down Under.

The spacecraft was approximately 100 km (60 miles) above the lunar surface when it took the photo.

March 13, 2023March 13, 2023 by Matt Williams

A Human Migration to Space is NOT so Inevitable, says New Research

Artist's depiction of a pair of O'Neill cylinders. Credit: Rick Guidice/NASA Ames Research Center

“It is possible even with existing technology, if done in the most efficient ways. New methods are needed, but none goes beyond the range of present-day knowledge. The challenge is to bring the goal of space colonization into economic feasibility now, and the key is to treat the region beyond Earth not as a void but as a culture medium, rich in matter and energy. Then, in a time short enough to be useful, the exponential growth of colonies can reach the point at which the colonies can be of great benefit to the entire human race.”

-Gerard K. O’Neill, The Colonization of Space, 1974

During the 1960s and 70s, coinciding with the height of the Space Age, scientists pondered how human beings could one day live in space. Among the many benefits, the migration of humans and industry to other celestial bodies and orbiting habitats presented a possible solution to overpopulation and environmental degradation. As O’Neill suggested in his writings, the key was to make this migration an economically feasible venture. Given the renewed efforts to explore space that are now underway and the rise of commercial space (NewSpace), there is a growing sense that humanity’s migration to space is within reach – and even inevitable.

But to paraphrase famed British historian AJP Taylor, “nothing is inevitable until it happens.” In a new study, Cornell graduate researcher Morgan A. Irons and Norfolk Institute co-founder and executive director Lee G. Irons reviewed a century of scientific studies to develop the Pancosmorio (“World Limit”) theory. They concluded that specific life-sustaining conditions on Earth that are available nowhere else in the Solar System could be the very thing that inhibits our expansion into space. Without an Earth-like “self-restoring order, capacity, and organization,” they argue, space settlements would fail to be sustainable and collapse before long.

March 3, 2023March 3, 2023 by Nancy Atkinson

Why are Earth’s Hemispheres the Same Brightness? New Research Solves a 50-year-old Mystery.

The Blue Marble from Apollo 17 — The Blue Marble image of Earth from Apollo 17. Credit: NASA

NASA’s Apollo program most notably explored the Moon. But it also helped us study the Earth as well, as it provided some of the first high-resolution images of our whole planet, like the famous “Blue Marble” photo taken by the Apollo 17 astronauts.

However, these full-Earth photos revealed a mystery. Scientists expected that Earth’s two hemispheres, the north and south, would have different albedos, a difference in the amount of light they reflect. This is because Earth’s northern and southern hemispheres of Earth are quite different from each other. The southern hemisphere is mostly covered with dark oceans, while the northern hemisphere contains vast land areas that are much brighter than the oceans

Yet, when observing Earth from space, the two hemispheres appear equally bright.

This symmetry in brightness has been a puzzle for over 50 years. But now, a new study shows that the albedos are roughly the same because of the increased clouds and storms in the southern hemisphere.