How Long is a Day on Venus? Astronomers Make Their Best Measurement Yet

A radar image of the surface of Venus showing one of the surface features used to measure a revised value for the length of the Venusian day. Image Credit: Campbell et al., 2019

There’s a problem with Venus. We don’t know how fast it rotates. For a space-faring civilization like ours, that’s a problem.

Measuring the length of day, or rotation rate, of most bodies is pretty straightforward. Mark a prominent surface feature and time how long it takes to rotate 360 degrees. But Venus is blanketed in thick clouds. Those clouds give it its reflectivity, and make it bright and noticeable in the sky, but they make it hard to measure Venus’ day length.

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This Dried Up Riverbed Shows that Water Once Flowed on the Surface of Mars

This image from ESA’s Mars Express shows a dried-up river valley on Mars named Nirgal Vallis. Copyright ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

From some viewpoints, Mars is kind of like a skeleton of Earth. We can see that it had volcanoes, oceans, and rivers, but the volcanoes no longer fume and the water is all gone. A new image from the ESA’s Mars Express drives the point home.

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Io’s Largest Volcano, Loki, Erupts Every 500 Days. Any Day Now, It’ll Erupt Again.

This picture from Voyager 1 shows the volcano Loki on Jupiter’s moon Io. When this picture was taken, the main eruptive activity came from the lower left of the dark linear feature (perhaps a rift) in the center. Below is the "lava lake," a U-shaped dark area about 200 kilometers across. Credit: NASA/JPL

Jupiter’s moon Io is in stark contrast to the other three Galilean moons. While Callisto, Ganymede, and Europa all appear to have subsurface oceans, Io is a volcanic world, covered with more than 400 active volcanoes. In fact, Io is the most volcanically active body in the Solar System.

Io’s largest volcano is named Loki, after a God in Norse mythology. It’s the most active and most powerful volcano in the Solar System. Since 1979, we’ve known that it’s active and that it’s both continuous and variable. And since 2002, thanks to a research paper in the Geophysical Research Letters, we’ve known that it erupts regularly.

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Whoa. Lakes on Titan Might be the Craters from Massive Underground Explosions

This artist's concept of a lake at the north pole of Saturn's moon Titan illustrates raised rims and rampartlike features such as those seen by NASA's Cassini spacecraft around the moon's Winnipeg Lacus. Credit: NASA/JPL-Caltech

The Cassini spacecraft ended its mission to Saturn and its moons two years ago when it was sent plunging into Saturn to be destroyed. But after two years, scientists are still studying the data from the Cassini mission. A new paper based on Cassini data proposes a new explanation for how some lakes on Titan may have formed.

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Mercury has Magnetic Poles that Drift Like Earth’s

The different colors in this MESSENGER image of Mercury indicate the chemical, mineralogical, and physical differences between the rocks that make up the planet’s surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

Earth’s magnetic poles drift over time. This is something that every airplane pilot or navigator knows. They have to account for it when they plan their flights.

They drift so much, in fact, that the magnetic poles are in different locations than the geographic poles, or the axis of Earth’s rotation. Today, Earth’s magnetic north pole is 965 kilometres (600 mi) away from its geographic pole. Now a new study says the same pole drifting is occurring on Mercury too.

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A Bunch of New Names for Pluto’s Surface Features Were Just Approved

14 of Pluto's surface features have new official names now. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Ross Beyer

Pluto is getting some new names. In the past, prior to the New Horizons mission, there wasn’t much to name. But now that that spacecraft has flew past Pluto and observed it up close, there’s some features that need naming.

Now the IAU (International Astronomical Union) has approved a new set of names for 14 of the dwarf planet’s surface features.

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There are Ring-Like Formations Around the Lakes on Titan

Map of Titan’s northern region of hydrocarbon ‘seas’ of methane and ethane, created from Cassini radar imaging. Credit: NASA/JPL/USGS.
Map of Titan’s northern region of hydrocarbon ‘seas’ of methane and ethane, created from Cassini radar imaging. Credit: NASA/JPL/USGS.

Some lakes on Titan have ring-like shapes around them, and scientists are trying to find out how they formed. Understanding how they formed may tell us something about how the entire region they’re in, including the lakes, formed. The ring-shaped features are found around pools and lakes at Titan’s polar regions.

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Martian Clouds Might Start with Meteor Trails Through the Atmosphere

Mars, as it was observed shortly before opposition in 2016 by the NASA/ESA Hubble Space Telescope. Credit: NASA/ESA/HST

On Earth, clouds form when enough droplets of water condense out of the air. And those droplets require a tiny speck of dust or sea salt, called a condensation nuclei, to form. In Earth’s atmosphere, those tiny specks of dust are lofted high into the atmosphere where they trigger cloud formation. But on Mars?

Mars has something else going on.

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Earth has a Water Cycle. Mars has a Dust Cycle

Comparison images of Mars taken by Hubble (left) and showing a global dust storm that engulfed it (right). Astronomers studying dust storms in the Aonia-Solis-Valles Marineris region over eight years have found a distinct periodicity in their occurrence. Image Credit: NASA

To say there are some myths circulating about Martian dust storms would be an understatement. Mars is known for its globe-encircling dust storms, the likes of which are seen nowhere else. Science fiction writers and Hollywood movies often make the dust storms out to be more dangerous than they really are. In “The Martian,” a powerful dust storm destroys equipment, strands Matt Damon on Mars, and forces him into a brutal struggle for survival.

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