When travelling above the clouds, airplane passengers sometimes witness a glory: a light phenomenon similar to a ring-shaped rainbow. Droplets in the clouds back-scattering the sunlight are responsible for this appearance. A team of scientists led by the Max Planck Institute for Solar System Research (MPS) in Göttingen have now fully imaged a glory on Venus – and thus for the first time on a planet other than Earth. The data was obtained by ESA’s space probe Venus Express. The data imply that the sulfuric acid in Venus’ cloud tops could additionally contain pure sulfur or iron chloride – and may help solve one of the oldest mysteries of Venus research.
The veil of clouds surrounding Venus is as beautiful as it is hostile to life. Sulfuric acid constitutes their main component. Together with the planet’s dense atmosphere composed mainly of carbon dioxide, this cloud cover causes Venus’ extreme greenhouse effect. Temperatures of more than 400 degrees Celsius are common on the planet’s surface. The exact composition of the creamy-yellow clouds is still unclear. Almost 90 years ago, ground-based observations had shown that these clouds “swallow” ultraviolet light of certain wavelengths. Sulfuric acid alone cannot be responsible for this effect.
NASA has released a natural-color image of Saturn from space, the first in which Saturn, its moons and rings, and Earth, Venus and Mars, all are visible.
The new panoramic mosaic of the majestic Saturn system taken by NASA’s Cassini spacecraft, which shows the view as it would be seen by human eyes, was unveiled at the Newseum in Washington on Tuesday.
Cassini’s imaging team processed 141 wide-angle images to create the panorama. The image sweeps 404,880 miles (651,591 kilometers) across Saturn and its inner ring system, including all of Saturn’s rings out to the E ring, which is Saturn’s second outermost ring. For perspective, the distance between Earth and our moon would fit comfortably inside the span of the E ring.
“In this one magnificent view, Cassini has delivered to us a universe of marvels,” said Carolyn Porco, Cassini’s imaging team lead at the Space Science Institute in Boulder, Colo. “And it did so on a day people all over the world, in unison, smiled in celebration at the sheer joy of being alive on a pale blue dot.”
Soon after the Sun dips below the western horizon on Sunday, September 8th, anyone looking in that direction will see a dramatic sight: a pretty crescent Moon paired closely with the dazzling planet Venus, the “Evening Star.”
“This is one you won’t want to miss,” says Alan MacRobert of Sky & Telescope magazine. “These are the two brightest objects in the nighttime sky.”
Start looking for the pair about 30 minutes after sunset. The farther south and east you are in North America, the closer they’ll appear. From locations along the East Coast, the they’ll be only about 1½° apart — about the width of your index finger at arm’s length. By the time darkness falls on the West Coast, the Moon will have edged slightly farther away.
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As the closest planet to Earth, Venus is a relatively easy object to observe. However, many mysteries remain, not least the super-rotation of Venus’ atmosphere, which enables high altitude winds to circle the planet in only four days. Now images of cloud features sent back by ESA’s Venus Express orbiter have revealed that these remarkably rapid winds are becoming even faster.
Similar in size to Earth, Venus has an extremely dense, carbon-dioxide-rich atmosphere and the planet’s surface is completely hidden by a blanket of bland, yellowish cloud. Only at ultraviolet wavelengths (and to a lesser extent in the infrared) do striking cloud streaks and individual cells emerge, due to the presence of some unknown UV absorber in the cloud deck.
By tracking the movements of these distinct cloud features, observers have been able to measure the super-hurricane-force winds that sweep around the planet at the cloud tops, some 70 km above the scorching volcanic plains.
A detailed study of Venus’ South Polar Vortex shows a much more chaotic and unpredictable cyclone than previously thought. The analysis reveals that the center of rotation of the vortex wanders around the pole differently at different altitude levels in the clouds of Venus. In its stroll around the Pole, in layers separated by 20 km, the vortex experiences unpredictable changes in its morphology.
The results of this study are published online in Nature Geoscience today.
The study, entitled ‘A chaotic long-lived vortex at the southern pole of Venus’, used infrared images from VIRTIS instrument onboard the European Space Agency’s Venus Express spacecraft. VIRTIS provides spectral images at different levels of the atmosphere and allows the observation of the lower and upper clouds of Venus.
ESA’s Venus Express has made unique observations of Venus during a period of reduced solar wind pressure, discovering that the planet’s ionosphere balloons out like a comet’s tail on its nightside. The ionosphere is a region of weakly electrically charged gas high above the main body of a planet’s atmosphere. Its shape and density are partly controlled by the internal magnetic field of the planet.
For Earth, which has a strong magnetic field, the ionosphere is relatively stable under a range of solar wind conditions. By comparison, Venus does not have its own internal magnetic field and relies instead on interactions with the solar wind to shape its ionosphere. The extent to which this shaping depends on the strength of the solar wind has been controversial, but new results from Venus Express reveal for the first time the effect of a very low solar wind pressure on the ionosphere of an unmagnetised planet.
As this significantly reduced solar wind hit Venus, Venus Express saw the planet’s ionosphere balloon outwards on the planet’s ‘downwind’ nightside, much like the shape of the ion tail seen streaming from a comet under similar conditions.
Six years of observations by ESA’s Venus Express have shown large changes in the sulphur dioxide content of the planet’s atmosphere, and one intriguing possible explanation is volcanic eruptions. The thick atmosphere of Venus contains over a million times as much sulphur dioxide as Earth’s, where almost all of the pungent, toxic gas is generated by volcanic activity.
Most of the sulphur dioxide on Venus is hidden below the planet’s dense upper cloud deck, because the gas is readily destroyed by sunlight. That means any sulphur dioxide detected in Venus’ upper atmosphere above the cloud deck must have been recently supplied from below.
A previous analysis of infrared radiation from the surface pointed to lava flows atop a volcano with a composition distinct from those of their surroundings, suggesting that the volcano had erupted in the planet’s recent past. Now, an analysis of sulphur dioxide concentration in the upper atmosphere over six years provides another clue.
Venus Express has spied a surprisingly cold region high in the planet’s atmosphere that may be frigid enough for carbon dioxide to freeze out as ice or snow.
The planet Venus is well known for its thick, carbon dioxide atmosphere and oven-hot surface, and as a result is often portrayed as Earth’s inhospitable evil twin.
But in a new analysis based on five years of observations using ESA’s Venus Express, scientists have uncovered a very chilly layer at temperatures of around –175ºC in the atmosphere 125 km above the planet’s surface.
The curious cold layer is far frostier than any part of Earth’s atmosphere, for example, despite Venus being much closer to the Sun.
Approximately 6,000 astronomy enthusiasts of all ages gathered at NASA’s Ames Research Center, Moffett Field, Calif. to view Venus cross in front of, or transit, the sun. People from all around the Bay Area — as well as one dedicated enthusiast who came from Seattle specifically for the transit — were drawn to Ames for its unique educational and viewing opportunities pertaining to the rare celestial event that took place on June 5, 2012, and will not occur again until December 2117.
At the beginning of the program, attendees perused exhibits set up within the visitor center, gleaning information about astronauts and life in space. The vast amount of people interested in learning about the solar event crowded the room to the extent that additional chairs were brought up from storage to accommodate them, and people needed to be counted at the door to prevent the center from exceeding maximum capacity. Once inside, children eagerly poked their heads through astronaut cutouts and walked through a model of the International Space Station interior as their parents snapped photos. Natalie Batalha, Kepler mission scientist at Ames, gave a talk about how astronomers are using transit events today to search for other worlds beyond our galaxy. After the talk, attention turned to the live NASA TV feed of the event from atop Mauna Kea in Hawaii. Videos on the history of Venus and its major contributors, including 17th century German astronomer and mathematician Johannes Kepler, were featured in the programming.
ESA’s Venus Express and Proba-2 space missions, along with the international SOHO, Hinode, and Hubble spacecraft, are preparing to monitor Venus and the Sun during the transit of Earth’s sister planet during 5-6 June. ESA’s Venus Express is the only spacecraft orbiting Venus at the moment and while the transit is being watched from Earth, it too will use light from the Sun to study the planet’s atmosphere.
As sunlight filters through the atmosphere it reveals the concentration of different gas molecules at different altitudes.
Meanwhile, NASA/ESA’s Hubble Space Telescope will use the Moon as a giant mirror to capture diffuse, reflected sunlight: a small fraction of that light will have passed through the atmosphere of Venus en-route to the Moon.
This will test techniques aimed at measuring the atmospheres of Earth-sized rocky exoplanets that could potentially reveal traces of life on planets outside our Solar System.