There Were Glaciers… on Mercury?

A view of Mercury’s north polar chaotic terrain (Borealis Chaos) and the Raditladi and Eminescu craters where evidence of possible glaciers has been identified. Red areas identified regions of potential salt glaciers
A view of Mercury’s north polar chaotic terrain (Borealis Chaos) and the Raditladi and Eminescu craters where evidence of possible glaciers has been identified (Credit: NASA)

I have lost count of how many times I have given public lectures and explained the temperature differences between Mercury and Venus. How Mercury, surprisingly isn’t the hottest planet in the Solar System and how that badge goes to Venus, thick atmosphere blah blah blah.  Mercury and its complex surface geology does of course get a good chunk of time but a recent paper has rather caught my attention and turned what I thought I knew about Mercury on its head! In short, a team of scientists have announced evidence for salt glaciers on Mercury!

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A Day on Earth Used to Only Be 19 Hours

Meteosat
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.

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Venus’ Outer Shell is Thinner and “Squishier” Than Previously Believed

Artist's illustration of Quetzalpetlatl Corona on Venus displaying both active volcanism and a subduction zone. (Credit: NASA/JPL-Caltech/Peter Rubin)

While Earth and Venus are approximately the same size and both lose heat at about the same rate, the internal mechanisms that drive Earth’s geologic processes differ from its neighbor. It is these Venusian geologic processes that a team of researchers led by NASA’s Jet Propulsion Laboratory (JPL) and the California Institute of Technology hope to learn more about as they discuss both the cooling mechanisms of Venus and the potential processes behind it.

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Meteorites are Contaminated Quickly When They Reach Earth

Image of an Earth-altered sample of the Winchcombe meteorite; scale bar in micrometers. (Credit: University of Glasgow)

On Earth, geologists study rocks to help better understand the history of our planet. In contrast, planetary geologists study meteorites to help better understand the history of our solar system. While these space rocks put on quite the spectacle when they enter our atmosphere at high speeds, they also offer insights into both the formation and evolution of the solar system and the planetary bodies that encompass it. But what happens as a meteorite traverses our thick atmosphere and lands on the Earth? Does it stay in its pristine condition for scientists to study? How quickly should we contain the meteorite before the many geological processes that make up our planet contaminate the specimen? How does this contamination affect how the meteorite is studied?

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Scientists Examine Geological Processes of Monad Regio on Neptune’s Largest Moon, Triton

Global color mosaic of Neptune's largest moon, Triton, taken by NASA's Voyager 2 in 1989. (Credit: NASA/JPL-Caltech/USGS)

In a recent study submitted to the journal Icarus, a team of researchers at the International Research School of Planetary Science (IRSPS) located at the D’Annunzio University of Chieti-Pescara in Italy conducted a geological analysis of a region on Neptune’s largest moon, Triton, known as Monad Regio to ascertain the geological processes responsible for shaping its surface during its history, and possibly today. These include what are known as endogenic and exogenic processes, which constitute geologic processes occurring internally (endo-) and externally (exo-) on a celestial body. So, what new insights into planetary geologic processes can we learn from this examination of Monad Regio?

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Perseverance is Putting its Samples Onto the Surface of Mars, So a Future Helicopter can Pick Them Up

This image shows the location where NASA's Perseverance will begin depositing its first cache of samples. NASA's Perseverance Mars rover captured it on Dec. 14, 2022, the 646th Martian day, or sol, of the mission. This enhanced color image was taken by the rover's Mastcam-Z camera and is not representative of the way the scene would look to the human eye. Image Credit: NASA/JPL-Caltech/ASU/MSSS

At this point in its mission, NASA’s Mars Perseverance Rover has collected almost 50% of its samples. The rover is now building its first sample ‘depot’ on the surface of Mars. The depot is a flat, obstacle-free area with 11 separate landing circles, one for each sample tube and one for the lander.

A future mission will retrieve these samples by helicopter.

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Scientists Piece Together the Shoreline of an Ancient Ocean on Mars

Stitched together from 28 images, this view from NASA's Curiosity Mars rover was captured after the rover ascended the steep slope of a geologic feature called "Greenheugh Pediment." In the distance at the top of the image is the floor of Gale Crater, which is near a region called Aeolis Dorsa that researchers believe was once a massive ocean. Credit: NASA/JPL-Caltech/MSSS.

Scientists have long suspected that Mars was once warm and wet in its ancient past. The Mars Ocean Hypothesis says that the planet was home to a large ocean around 4 billion years ago. The ocean filled the Vastitas Borealis basin in the planet’s northern hemisphere. The basin is 4–5 km (2.5–3 miles) below Mars’ mean elevation.

A new topographic map of Mars reinforces the hypothesis and adds more detail.

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Scientists Have Been Underestimating the Asteroid That Created the Biggest Known Crater on Earth

South Africa's Vredefort Crater is Earth's largest impact crater. New Research clarifies the power of the impact and its catastrophic effects. Image Credit: NASA Earth Observatory image by Lauren Dauphin / University of Rochester illustration by Julia Joshpe

Ancient impacts played a powerful role in Earth’s complex history. On other Solar System bodies like the Moon or Mercury, the impact history is preserved on their surfaces because there’s nothing to erase it. But Earth’s geologic activity has erased the evidence of impact craters over time, with some help from erosion.

Earth’s complex history has elevated its status among its Solar System siblings and created a world that’s rippling with life. Ancient giant impacts have played a role in that history, bringing catastrophe and disruption and irrevocably changing the course of events. Deciphering the role these giant impacts played is difficult since the evidence is missing or severely degraded. So how do scientists approach this problem?

One crater at a time.

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A Geologic map of the Entire Moon has Been Released at 1:2,500,000-Scale

Chinese scientists took 10 years to create the most detailed map yet of the Moon. Image Credit: Jinzhu Ji et al. 2022.

Chinese scientists have created the most detailed map of the Moon yet. It took them 10 years and involved hundreds of researchers. The new map will be a boon to lunar exploration and for anyone who just wants to study our natural satellite in more detail.

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