Maat Mons, Venus
Our nearest planetary neighbour, Venus
Venus is the second-closest planet to the Sun, orbiting every 225 Earth days. The planet is named after Venus, the Roman goddess of beauty, and is sometimes called Earth’s ‘sister planet’ because they are similar in size and composition.
ESA’s Venus Express mission, launched to Venus in 2005, took this false-colour ultraviolet image with its Venus Monitoring Camera (VMC) in July 2007 from a distance of 35 000 km from the surface of the planet.
It shows the full view of the southern hemisphere from equator (right) to the pole. The south pole is surrounded by a dark oval feature. Moving to the right, away from the pole and towards the equator, we see streaky clouds, a bright mid-latitude band and mottled clouds in the convective sub-solar region.
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The long-sought double hurricane at Venus’s south pole has disappeared. New images from ESA’s Venus Express spacecraft shows that the so-called polar vortex, which was thought to swirl steadily around the planet’s poles at all times, is actually a chaotic maelstrom.
A gigantic hurricane with two calm, dark eyes was discovered at Venus’s north pole by the Pioneer Venus spacecraft in 1979. This double-eyed feature, dubbed the “dipole of Venus,” was thought to form when warm air from the planet’s equator rose and traveled toward the pole, where it cooled and sank to form a deep, swirling atmospheric pit.
For decades, astronomers expected to find a similar vortex at Venus’s south pole. While Venus itself rotates slowly, just once every 117 Earth days, its atmosphere whips around the planet once every 4 Earth days. This “super-rotating” atmosphere ought to form massive storms at both poles, astronomers reasoned.
So when Venus Express saw what looked like a double vortex at the south pole shortly after arriving at Venus in April 2006, scientists took it as confirmation that these whorls were stable and permanent. But as they watched, the vortices shifted and morphed.
“We had ironically observed it in a dipole configuration right at the beginning of the mission,” said astronomer Giuseppe Piccioni of the Italian National Institute for Astrophysics in Rome. “But we soon discovered that this was just a coincidence, since the dipole in reality is not a stable feature on Venus but just one shape among others.” Piccioni presented his results at the European Planetary Science Congress in Rome on September 23.
Data from the VIRTIS (Visible and InfraRed Thermal Imaging Spectrometer) instrument on Venus Express also showed that the dynamics at Venus’s poles are quite different from the rest of the planet. Near the equator, the wind speeds vary greatly with altitude, with wind speeds doubling from the lower clouds to the cloud tops, Piccioni said. By contrast, the 1800-mile-wide polar vortex rotates almost like a solid body. These two zones of rotation are separated by a ring of cold air called a “cold collar” surrounding the polar region.
Story from: Wired Science
Written by: Lisa Grossman
Beneath its dreary shroud of clouds, Venus could be positively hopping: Planetary geologists have spotted a lava flow they say is just decades old. If confirmed, it would be the youngest evidence for volcanism on Venus.
“The flow we studied seems to be very young — it is still warm inside,” says Nataliya Bondarenko, a planetary scientist at the University of California, Santa Cruz. She and her colleagues describe their findings in an upcoming issue of Geophysical Research Letters.
Researchers have long thought that Venus must be geologically active, since more than 1,000 volcanoes dot its surface. But scientists have struggled to gather definitive evidence that the planet is active today, like Earth, and not long dead, like Mars.
Bondarenko’s team analyzed microwave data collected by NASA’s Magellan mission, which orbited Venus in the early 1990s. Microwave radiation indicates heat coming from the planet, such as a lava flow in the process of cooling.
In the Bereghinia Planitia region in Venus’ northern hemisphere, the team found a flow that appeared up to 85 degrees Celsius hotter than expected. Had the flow been more than a century old, Bondarenko says, it would have cooled down enough that Magellan wouldn’t have spotted any excess heat.
The flow must have been at least 15 years old when detected by Magellan, she says, because the Pioneer Venus orbiter photographed it in 1978.
But there’s little other evidence supporting Bereghinia Planitia as recently volcanically active, says Suzanne Smrekar, a planetary geologist at the Jet Propulsion Laboratory in Pasadena, California.
In April, Smrekar and colleagues published a paper in Science describing lava flows from three regions in Venus’ southern hemisphere. All three were places known to be hot spots of geological activity, similar to Hawaii. Using data from the European Space Agency’s Venus Express mission, currently orbiting the second planet, Smrekar’s team found several flows that looked fresh. The flows’ unweathered appearance, compared with the surrounding landscape, suggests that they formed no more than 2.5 million years ago and probably in the past 250,000 years, the team concluded.
Because the Venus Express data come only from the southern hemisphere, they can’t say anything about whether Bereghinia Planitia is also active, Smrekar says. But any claim of a decades-old flow in the north “sort of falls into the ‘extraordinary claims require extraordinary proof’ category,” she says.
Taken from: Wired Science
Written by: Alexandra Witz
Venus has a Moon?
It has the rather unfortunate name of 2002 VE68, and it’s an earth orbit-crossing asteroid that has been designated a Potential Hazardous Asteroid by the Minor Planet Center.
2002 VE68 used to be a run of the mill, potential impact threat, Near Earth Object. But approximately 7,000 years ago it had a close encounter with Earth that kicked it into a new orbit. It now occupies a place in orbit around the Sun where at its closest it wanders inside the orbit of Mercury and at its furthest it reaches just outside the orbit of the Earth.
2002 VE68 is now in a 1:1 orbital resonance with Venus, which means they both take the same time to orbit the Sun once. So by definition, 2002 VE68 is considered a quasi-satellite of Venus.
Often these resonances result in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. In this case, scientists believe 2002 VE68 will only remain a Venusian quasi-satellite for another 500 years or so.
2002 VE68 is an X type asteroid, with an approximate size of 200 meters in diameter —based on its absolute magnitude— and with a spin rate of 13.5 hours. The amplitude of the fluctuation on the light curve of 2002 VE68 could imply hat it is actually a contact binary: two clumps of asteroidal material orbiting a center of mass in contact with each other.
• Source: Universe Today
I have been loving the conjunction between Venus and Jupiter in the Western sky these last few nights. Tonight, they are the closest - just separated by 3 degrees. Venus is just above, and to the right of Jupiter - it also is the brightest.
Venus will appear almost 8 times as bright!
So as always, keep your head up, and more specifically tonight - admire two of our celestial neighbors in all of their glory.
Who is going to see the Venus transit tonight? You don’t want to miss the last Venus transit of this century!
Check your local astronomy clubs and universities to see if they area having viewings.