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Thread: Venus Spinning Slower Than Thought—Scientists Stumped

  1. Default Venus Spinning Slower Than Thought—Scientists Stumped

    "Mysterious decrease could affect future exploration missions.

    Planet lovers take note: Venus is spinning even slower than astronomers thought, according to new data from a European space probe.

    In the early 1990s scientists with NASA's Magellan mission calculated that a single rotation of Venus takes 243.015 Earth days, based on the speed of surface features passing beneath the orbiting spacecraft.

    But scientists now mapping Venus's surface with the European Space Agency's Venus Express orbiter were surprised to find the same features up to 12.4 miles (20 kilometers) from where they were expected to be, based on the previous measurements.

    According to the new data, Venus is rotating 6.5 minutes slower than it was 16 years ago, a result that's been found to correlate with long-term radar observations taken from Earth.

    (Related: "Japan Earthquake Shortened Days, Increased Earth's Wobble.")

    "When the two maps did not align, I first thought there was a mistake in my calculations, as Magellan measured the value [of Venus's spin] very accurately," Nils Müller, a planetary scientist at the DLR German Aerospace Centre, said in a statement.

    "But we have checked every possible error we could think of."

    Planet Slowed by Dense Atmosphere?

    One possible cause for the slowed spin is friction caused by Venus' thick atmosphere and high-speed winds. The motion of the atmosphere on Earth, for example, has been observed to affect the planet's rotation rate, albeit to a much smaller degree.

    Thanks to a heavy blanket of carbon dioxide-laden air, the surface pressure on Venus is 90 times what we experience on Earth at sea level, and opaque clouds of caustic sulphuric acid constantly whip around the planet at hurricane speeds.

    (Also see "Early Venus Had Oceans, May Have Been Habitable.")

    Still, "it is difficult to find a mechanism that will cause the average rotation rate to change this much in only 16 years," Venus Express project scientist Håkan Svedhem told National Geographic News.

    "The origin of this could lay in the solar cycle or in long-term weather patterns that modify the atmospheric dynamics. But this puzzle is not yet solved."

    (Related: "Hyperactive Sun Helping to Clear Out Space Junk.")

    Some reports cite an exchange of angular momentum between Venus and Earth as a possible cause for the variation. A moon, for example, can cause a planet to rotate slower than expected, because both objects share angular momentum.

    But with 23.6 million miles (38 million kilometers) between the two planets at their closest approach, "there is no exchange of momentum between Venus and the Earth," Svedhem stated.

    Instead, he said, further study is needed to discern the cause—or causes—of Venus' slight reduction in speed.

    Ultimately, he added, it's important to know exactly how fast the planet is spinning, since any possible future missions to explore Venus will need precise information to chose their landing sites.

    More: "Japan Probe Missed Venus—Will Try Again in Six Years" "



  2. Default

    Looks like the Mayans were right. They just got the wrong planet
    1. The Scientific debate remains open. Voters believe that there is no consensus about global warming within the scientific community. Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly. Therefore, you need to continue to make the lack of scientific certainty a primary issue in the debate, and defer to scientists and other experts in the field.--Luntz Research

  3. Default

    it's a shame the japanese probe didnt make it.

    "One of the ordinary modes, by which tyrants accomplish their purposes without resistance, is, by disarming the people, and making it an offense to keep arms."
    -Joseph Story

    "He that would make his own liberty secure, must guard even his enemy from oppression; for if he violates this duty, he establishes a precedent that will reach to himself."
    -Thomas Paine

  4. Default

    Venu has been spinning for how many billions of years? And now it's slowing down! Wow, it might come to a full stop by the end of this century.

    The probablity is that the earlier group miscalculated or this group got Ds in math. How about a tie-breaker?

  5. Icon3

    Venus likely water-free...

    ‘Electric Wind’ May Have Stripped Venus of Water
    June 20, 2016 - It is believed the planet once was home to oceans of water
    Seen from Earth, Venus is a soft yellow-orange, a bright planet that is known as the morning star. But up close -- watch out! Its atmosphere is hellish with average temperatures hot enough to melt lead and rain showers of sulphuric acid. Now, a new paper reveals it’s even worse than that. Writing in the journal Geophysical Research Letters, researchers at NASA’s Goddard Space Flight Center say there is an “electric wind” on the second planet from the sun that may have stripped Venus of its oceans. “It’s amazing, shocking,” said NASA scientist Glyn Collinson. “We never dreamt an electric wind could be so powerful that it can suck oxygen right out of an atmosphere into space. This is something that has to be on the checklist when we go looking for habitable planets around other stars.”

    Sister planets, but not twins

    Venus’s size and gravity are similar to Earth’s, so it's often thought of as Earth's sister planet. It is believed that like Earth, Venus once had oceans, but those boiled away in temperatures that can reach 460 Celsius. But while the atmosphere is very thick - about 100 times the pressure of Earth - there is relatively little water vapor in the air. Now researchers think Venus’ electric wind may have blasted water particles into hydrogen and oxygen ions, which later escaped from the atmosphere altogether. “We found that the electric wind, which people thought was just one small cog in a big machine, is in fact this big monster that’s capable of sucking the water from Venus by itself,” Collinson said. Any water left by the electric wind would likely have been finished up by the solar wind, researchers said.

    This June 2004 photo shows the transit of Venus, which occurs when Venus passes between the Earth and the sun.

    Researchers believe any planet with an atmosphere is surrounded by a weak electrical field, but Venus’ is much stronger than, say, Earth’s. On Earth, the electric field is less than 2 volts, while on Venus, it’s 10 volts. “We don’t really know why it is so much stronger at Venus than Earth,” Collinson said, “but, we think it might have something to do with Venus being closer to the sun, and the ultraviolet sunlight being twice as bright. It’s a challenging thing to measure and even at Earth to date all we have are upper limits on how strong it might be.”

    The stronger field helps push hydrogen and oxygen molecules upward and eventually out of the atmosphere. “If you were unfortunate enough to be an oxygen ion in the upper atmosphere of Venus, then you have won a terrible, terrible lottery,” Collinson said. “You and all your ion friends will be dragged off kicking and screaming into space by an invisible hand, and nothing can save you.” The researchers add that electric wind may have also played a role on Mars, which is also believed to have once had much more water than today. “We are actively hunting for Mars’ electric wind with MAVEN’s full arsenal of scientific instruments,” Collinson said. “MAVEN is a robotic detective on this four-billion-year-old mystery of where the atmosphere and oceans went, and the electric wind has long been a prime suspect.”


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