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Tag: venus

  • Venusian Gravity Currents

    Venusian Gravity Currents

    Radar measurements of Venus‘s surface reveal the remains of many volcanic eruptions. One type of feature, known as a pancake dome, has a very flat top and steep sides; one dome, Narina Tholus, is over 140 kilometers wide. Since their discovery, scientists have been puzzling out how such domes could form. A recent study suggests that the Venusian surface’s elasticity plays a role.

    According to current models, the pancake domes are gravity currents (like a cold draft under your door, an avalanche, or the Boston Molasses Flood), albeit ones so viscous that they may require hundreds of thousands of Earth-years to settle. Researchers found that their simulated pancake domes best matched measurements from Venus when the lava was about 2.5 times denser than water and flowed over a flexible crust.

    We might have more data to support (or refute) the study’s conclusions soon, but only if NASA’s VERITAS mission to Venus is not cancelled. (Image credit: NASA; research credit: M. Borelli et al.; via Gizmodo)

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  • Venusian Lava Flows

    Venusian Lava Flows

    Venus is often known as Earth’s twin, given its similar size and proximity. But, thanks to its runaway greenhouse effect, Venus is a hellish landscape buried beneath a hot atmosphere of carbon dioxide and sulfuric acid. Unlike Earth, Venus is not tectonically active, though it does have active volcanoes. A recent study re-examined synthetic aperture radar data from the Magellan spacecraft mission in the early 1990s and found that the data contained evidence of fresh lava flows.

    The team found two areas near volcanoes where the surface backscatter changed significantly between orbital observations. After examining many possible explanations for the changes, the team concluded that the differences were most likely due to new lava. They even performed the same analysis for a volcanic field here on Earth between known lava flows and observed the same behavior. Combined with another recent study that found evidence of volcanic activity in Magellan data, signs are pointing toward Venus being about as volcanically active as our own planet, even if the mechanisms driving the volcanism differ. (Image credit: NASA/JPL-Caltech; research credit: D. Sulcanese et al.; via Gizmodo)

  • How Venus Is Losing Its Water

    How Venus Is Losing Its Water

    Since Venus formed at the same time as Earth and is similar in size, scientists believe it once had the same amount of water our planet does. Today, hellish Venus has hardly any water, a fact scientists have struggled to explain completely. Most of its water was lost long ago, as incoming particles from the solar wind stripped water from the upper atmosphere; unlike Earth, Venus doesn’t enjoy the protection of a magnetic field.

    But that mechanism doesn’t explain just how arid Venus is now. A new study instead suggests that Venus’s water loss is ongoing, driven by simple chemical reactions. The team found that molecules of HCO+ (an ion made from one hydrogen, one carbon, and one oxygen atom) could mix with any remaining water to form a positively-charged molecule. Due to that charge, the chemical easily attracts loose electrons. Once combined, however, the resulting molecule is too energetic and breaks apart; when it does so, it releases highly-energetic hydrogen, which escapes the atmosphere into space. Without that hydrogen, water molecules can’t reform. This process of dissociative recombination could explain why the rest of Venus’s water has disappeared.

    Science missions that have flown to Venus so far haven’t been equipped to measure HCO+, and the authors recommend this as a priority for future missions to our neighbor. With that data, we could confirm or disprove this mechanism for Venusian water loss. (Image credit: NASA; research credit: M. Chaffin et al.; via Gizmodo)

  • The Variable Venusian Day

    The Variable Venusian Day

    Venus is a thoroughly unpleasant place thanks to its hellish temperatures and acidic clouds, but a new study adds another wrinkle to our strange sister planet: Venus’s day varies by up to 21 minutes in length. This peculiar factoid is the result of 15 years spent monitoring Venus’s rotation via radar. Previous attempts to pin down the exact length of Venus’s day produced differing answers; those disagreements make more sense in light of the new study, where individuals measurements of Venus’s rotation rate could differ by 3 minutes just from one (Earth) day to the next!

    So why does Venus’s rotation rate change so dramatically? Venus’s atmosphere is massive — 100 times more massive than Earth’s — and it spins incredibly fast. The upper layers of Venus’s atmosphere can complete a rotation in 4 Earth days, while the solid ground requires 243 Earth days. As the atmosphere spins and sloshes, some of its angular momentum gets transferred to the ground, changing the planet’s rotation rate. (Image credit: NASA/JPL-Caltech; research credit: J. Margot et al.; via AGU Eos; submitted by Kam-Yung Soh)

  • Venusian Waves

    Venusian Waves

    Despite its proximity, Venus remains largely mysterious, thanks to its cloudy atmosphere and incredible harsh conditions. A recent study using data from the Japanese satellite Akatsuki revealed an enormous bow-shaped wave in the Venusian atmosphere. The wave appeared at an altitude of about 65 km and stretched more than 10,000 km long, across both the northern and southern hemispheres. Although surface winds on Venus are believed to be small due to its incredibly slow rotation, winds higher in the atmosphere are much faster – so it was strange to observe this wave sitting essentially stationary for five days of observation.

    When the scientists mapped the location of wave relative to the surface, they found it was sitting over the Aphrodite Terra highlands, suggesting that this structure is a gravity wave generated by winds interacting with the topography. Similar, albeit smaller, gravity waves are often observed on Earth near mountains. The finding raises questions about our understanding of Venusian atmospheric dynamics and exactly how disturbances from surface winds could create enormous structures so high in the atmosphere. (Image credit: T. Fukuhara et al.; h/t to SciShow Space)

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    Going Supercritical

    Supercritical fluids exist at temperatures and pressures above the critical point, in a region of the phase diagram where there is no clear boundary between the liquid and gaseous state. Supercritical fluids have some of the properties of each state: they can move as freely as a gas, but they are still capable of dissolving materials like a liquid does. They also have no surface tension because there is no interface between liquid and solid. These properties make supercritical fluids very useful in industrial applications, including decaffeination and chemical deposition. Interestingly, the temperatures and pressures on Venus are so high that scientists think the atmosphere at the surface is a supercritical fluid. (Video credit: SCFED Project)