Earth Archives

January 11, 2024January 11, 2024 by Nancy Atkinson

Satellite Data Shows US East Coast is Sinking

Map shows vertical land motion along the East Coast. The yellow, orange and red areas on these maps denote areas of sinking. Image courtesy of Leonard Ohenhen.Virginia Tech.

Based on satellite imagery, geologists have determined major cities on the U.S. Atlantic coast are sinking, some areas as much as 2 to 5 millimeters (.08-0.2 inches) per year. Called subsidence, this sinking of land is happening at a faster rate than was estimated just a year ago. In a new paper published in the Proceedings of the National Academies of Sciences, researchers say their analysis has far-reaching implications for community and infrastructure resilience planning, particularly for roadways, airport runways, building foundations, rail lines, and pipelines.

January 8, 2024January 8, 2024 by Evan Gough

Can Alien Civilizations Detect Humanity?

Is anyone out there? A new study examines how likely it is that an advanced ETI can "see" us. Image Credit: Jon Hrubesch

One of the fascinating things about being a human in this age is that we can do more than wonder about other life and other civilizations. We can actually look for them, although there are obvious limitations to our search. But what’s equally fascinating is that we can wonder if others can see us.

December 20, 2023December 21, 2023 by Matt Williams

It Doesn't Take Much to Get a Runaway Greenhouse Effect

During the 1960s, the first robotic explorers began making flybys of Venus, including the Soviet Venera 1 and the Mariner 2 probes. These missions dispelled the popular myth that Venus was shrouded by dense rain clouds and had a tropical environment. Instead, these and subsequent missions revealed an extremely dense atmosphere predominantly composed of carbon dioxide. The few Venera landers that made it to the surface also confirmed that Venus is the hottest planet in the Solar System, with average temperatures of 464 °C (867 °F).

These findings drew attention to anthropogenic climate change and the possibility that something similar could happen on Earth. In a recent study, a team of astronomers from the University of Geneva (UNIGE) created the world’s first simulation of the entire greenhouse process that can turn a temperate planet suitable for Life into a hellish, hostile one. Their findings revealed that on Earth, a global average temperature rise of just a few tens of degrees (coupled with a slight rise in the Sun’s luminosity) would be sufficient to initiate this phenomenon and render our planet uninhabitable.

December 1, 2023December 1, 2023 by Nancy Atkinson

After Stalling Out for 40 Years, the Largest Iceberg in the World is on the Move

An animation from Copernicus Sentinel-1 images shows iceberg A23a’s movements from 2 November 2023, 14 November 2023 and 26 November 2023. Credit: ESA.

In 1986, a gigantic iceberg separated from the Fichner-Ronne ice shelf in West Antarctica. It was so big that it became grounded, stuck to the seafloor, and remained in position for 40 years. Finally, it has now been pushed off the seafloor and has begun drifting in the Weddell Sea to a region in the South Atlantic called Iceberg Alley. Designated A23a, this monster berg measures 4000 sq km (1,500 square miles) and is about 400 meters (1,300 feet) thick – the world’s largest.

November 24, 2023November 24, 2023 by Evan Gough

What Would Happen to Earth if a Rogue Star Came Too Close?

The speeding rogue star Kappa Cassiopeiae sets up a glowing bow shock in this Spitzer image (NASA/JPL-Caltech)

Stars are gravitationally fastened to their galaxies and move in concert with their surroundings. But sometimes, something breaks the bond. If a star gets too close to a supermassive black hole, for example, the black hole can expel it out into space as a rogue star.

What would happen to Earth if one of these stellar interlopers got too close?

November 21, 2023November 21, 2023 by Evan Gough

If You’re Trying to Prevent an Asteroid Impact, the Technical and Political Challenges are Staggering

Asteroids are out there, and some pose a threat to Earth. How will we react when we determine that one's coming for us? Credit: N. Bartmann (ESA/Webb), ESO/M. Kornmesser and S. Brunier, N. Risinger (skysurvey.org)

While preparing for the threat of an asteroid strike might seem like a hypothetical exercise, it’s really not. The Solar System has calmed down a lot from earlier times when impacts were more frequent. But it is only a matter of time before an asteroid heads straight for Earth. The probability of an impact is not zero.

Equally as difficult as determining when one will come for us is the task of getting humanity to cooperate and prepare for it.

November 14, 2023November 14, 2023 by Evan Gough

Earth’s Past and Future Habitability Depends on Our Protection from Space Weather

Sun with a huge coronal mass ejection. Image credit: NASA

A bewildering number of factors and variables led up to the planet we occupy today, where life finds a way to survive and even thrive in the most marginal conditions. The Sun is the catalyst for it all, propelling life on its journey to greater complexity with its steady fusion.

But the Sun is only benign because of Earth’s built-in protection, the magnetosphere. Both the Sun and the magnetosphere have changed over time, with each one’s strength ebbing and flowing. The Sun drives powerful space weather our way, and the magnetosphere shields the Earth.

How have these two phenomena shaped Earth’s habitability?

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.

November 2, 2023November 2, 2023 by Nancy Atkinson

Devastating Clouds of Dust Helped End the Reign of the Dinosaurs

Paleoart reconstruction depicting North Dakota in the first months following the Chicxulub impact event 66 million years ago, showing a dark, dusty, and cold world in which the last non-avian dinosaurs, illustrated with a Dakotaraptor steini, were on the edge of extinction. Artwork by Mark A. Garlick.

When a giant meteor crashed into Earth 66 million years ago, the impact pulverized cubic kilometers of rock and blasted the dust and debris into the Earth’s atmosphere. It was previously believed that sulfur from the impact and soot from the global fires that followed drove a global “impact winter” that killed off 75% of species on Earth, including the dinosaurs.

A new geology paper says that the die-off was additionally fueled by ultrafine dust created by the impact which filled the atmosphere and blocked sunlight for as long as 15 years. Plants were unable to photosynthesize and global temperatures were lowered by 15 degrees C (59 F).

October 27, 2023October 27, 2023 by Nancy Atkinson

Venus Might Have Had Plate Tectonics Just Like Earth

Radar image of Venus created by the Solar System Visualization project and the Magellan science team at the JPL Multimission Image Processing Laboratory. Credit: NASA/JPL.

Even though Venus is very similar to Earth in many ways, it’s a hell-world with a runaway greenhouse effect. It was assumed this was because it lacked plate tectonics like Earth to sequester carbon inside the planet. A new study suggests that the high nitrogen and argon in its atmosphere are evidence from outgassing when it had plate tectonics billions of years ago. This could mean that Venus was habitable for a long time before something went horribly wrong.