Earth Archives

November 29, 2023November 29, 2023 by Evan Gough

It Doesn’t Take Much to Get Tilted Planets

Earth's axial tilt (or obliquity) and its relation to the rotation axis and plane of orbit. Credit: Wikipedia Commons

Chinese and Indian astronomers were the first to measure Earth’s axial tilt accurately, and they did it about 3,000 years ago. Their measurements were remarkably accurate: in 1120 BC, Chinese astronomers pegged the Earth’s axial tilt at 24 degrees. Now we know that all of the planets in the Solar System, with the exception of Mercury, have some tilt.

While astronomers have puzzled over why our Solar System’s planets are tilted, it turns out it’s rather normal.

October 18, 2023October 18, 2023 by Matt Williams

The Combination of Oxygen and Methane Could Reveal the Presence of Life on Another World

This artist’s impression shows a Super-Earth orbiting a Sun-like star. HD 85512 in the southern constellation of Vela (The Sail). This planet is one of sixteen super-Earths discovered by the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory. This planet is about 3.6 times as massive as the Earth lis at the edge of the habitable zone around the star, where liquid water, and perhaps even life, could potentially exist. Credit: ESO

In searching for life in the Universe, a field known as astrobiology, scientists rely on Earth as a template for biological and evolutionary processes. This includes searching for Earth analogs, rocky planets that orbit within their parent star’s habitable zone (HZ) and have atmospheres composed of nitrogen, oxygen, and carbon dioxide. However, Earth’s atmosphere has evolved considerably over time from a toxic plume of nitrogen, carbon dioxide, and traces of volcanic gas. Over time, the emergence of photosynthetic organisms caused a transition, leading to the atmosphere we see today.

The last 500 million years, known as the Phanerozoic Eon, have been particularly significant for the evolution of Earth’s atmosphere and terrestrial species. This period saw a significant rise in oxygen content and the emergence of animals, dinosaurs, and embryophyta (land plants). Unfortunately, the resulting transmission spectra are missing in our search for signs of life in exoplanet atmospheres. To address this gap, a team of Cornell researchers created a simulation of the atmosphere during the Phanerozoic Eon, which could have significant implications in the search for life on extrasolar planets.

October 12, 2023October 12, 2023 by Evan Gough

OSIRIS-REx Returned Carbon and Water from Asteroid Bennu

This is the outside of the OSIRIS-REx sample collector. Sample material from asteroid Bennu is on the middle right. There's evidence of carbon and water in the initial analysis of Bennu's regolith. Most of the sample is sealed inside the capsule. Photo: NASA/Erika Blumenfeld & Joseph Aebersold

Carbon and water are so common on Earth that they’re barely worth mentioning. But not if you’re a scientist. They know that carbon and water are life-enabling chemicals and are also links to the larger cosmos.

Initial results from OSIRIS-REx’s Bennu samples show the presence of both in the asteroid’s regolith. Now, eager scientists will begin to piece together how Bennu’s carbon, water, and other molecules fit into the puzzle of the Earth, the Sun, and even the entire Solar System and beyond.

September 28, 2023September 28, 2023 by Matt Williams

If Earth is Average, We Should Find Extraterrestrial Life Within 60 Light-Years

Illustration: Assortment of exoplanets — Astronomers have detected thousands of planets, including dozens that are potentially habitable. (NASA Illustration)

In 1960, while preparing for the first meeting on the Search for Extraterrestrial Intelligence (SETI), legendary astronomer and SETI pioneer Dr. Frank Drake unveiled his probabilistic equation for estimating the number of possible civilizations in our galaxy – aka. The Drake Equation. A key parameter in this equation was n_e, the number of planets in our galaxy capable of supporting life – aka. “habitable.” At the time, astronomers were not yet certain other stars had systems of planets. But thanks to missions like Kepler, 5523 exoplanets have been confirmed, and another 9,867 await confirmation!

Based on this data, astronomers have produced various estimates for the number of habitable planets in our galaxy – at least 100 billion, according to one estimate! In a recent study, Professor Piero Madau introduced a mathematical framework for calculating the population of habitable planets within 100 parsecs (326 light-years) of our Sun. Assuming Earth and the Solar System are representative of the norm, Madau calculated that this volume of space could contain as much as 11,000 Earth-sized terrestrial (aka. rocky) exoplanets that orbit within their stars’ habitable zones (HZs).

September 15, 2023September 15, 2023 by Matt Williams

NASA Confirms That 2023 was the Hottest Summer on Record

This map depicts global temperature anomalies for meteorological summer in 2023 (June, July, and August). It shows how much warmer or cooler different regions of Earth were compared to the baseline average from 1951 to 1980. Credit: NASA's Earth Observatory/Lauren Dauphin

Yesterday, NASA’s Goddard Institute of Space Studies (GISS) announced that the summer of 2003 was the hottest on record. This year saw a massive heat wave that swept across much of the world and was felt in South America, Japan, Europe, and the U.S. This exacerbated deadly wildfires in Canada and Hawaii (predominantly on the island of Maui) and are likely to have contributed to severe rainfall in Italy, Greece, and Central Europe. This is the latest in a string of record-setting summers that are the direct result of anthropogenic climate change.

August 9, 2023August 9, 2023 by Laurence Tognetti

Interpreting Dune Patterns: Insights from Earth and Mars

Examples of active dune fields within Nili Patera on Mars. Dunes like these were examined for this study in hopes of giving scientists better insights into how their interactions are influenced by a planet’s climate. (Credit: NASA/JPL-Caltech/Univ. of Arizona)

A recent study published in the journal Geology attempts to interpret the patterns of dunes, which are sand mounds frequently formed by aeolian (wind) processes and range in size from small ripples observed on beaches to massive structures observed in the desert. Specifically, the researchers focused on patterns of dune crestlines, which are the top of the dunes. Different dune crestline patterns might appear as mundane features, but their formations are often the result of a myriad of influences, including climate change, surface processes, and atmospheric phenomena.

June 21, 2023June 21, 2023 by Nancy Atkinson

The Most Intense Lightning Ever Seen Came From Last Year's Tonga Volcano Eruption

The Tonga Hunga volcanic eruption sent a tsunami across the Pacific. Air pressure disturbances from the tsunami distorted GPS signals. GOES imagery courtesy NOAA,NESDIS. — The Tonga Hunga volcanic eruption as seen by a GOES satellite. Credit: NOAA,NESDIS.

The enormous undersea volcano that erupted in Tonga last year was record-breaking in many regards. It generated the highest-ever recorded volcanic plume, it triggered a sonic boom that circled the globe twice, and was the most powerful natural explosion in more than a century.

Now, scientists studying the eruption say the volcanic plume created record-breaking amounts of volcanic lightning, the most intense lightning rates ever documented in Earth’s atmosphere. While the ash obscured the view, satellites and ground-based radio antennas with specialized instrument could peer through the ash and see every stage of the unfolding eruption. Over 200,000 lightning flashes were detected in the volcanic plume, more than 2,600 flashes every minute.

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.