Category: saturn

Vortex at Saturn’s North Pole Credi…

Vortex at Saturn’s North Pole

Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s atmosphere exhibits a banded pa…

Saturn’s atmosphere exhibits a banded pattern similar to Jupiter’s, but Saturn’s bands are much fainter and are much wider near the equator. The nomenclature used to describe these bands is the same as on Jupiter. Saturn’s finer cloud patterns were not observed until the flybys of the Voyager spacecraft during the 1980s. Since then, Earth-based telescopy has improved to the point where regular observations can be made. The composition of the clouds varies with depth and increasing pressure.

The winds on Saturn are the second fastest among the Solar System’s planets, after Neptune’s. Voyager data indicate peak easterly winds of 500 m/s (1,800 km/h).

Thermography has shown that Saturn’s south pole has a warm polar vortex, the only known example of such a phenomenon in the Solar System. Whereas temperatures on Saturn are normally −185 °C, temperatures on the vortex often reach as high as −122 °C, suspected to be the warmest spot on Saturn.

Credit: NASA/JPL-Caltech/Space Science Institute and Kevin M. Gill

Saturn and Titan Credit: NASA/JPL-Caltech/Spa…

Saturn and Titan

Credit: NASA/JPL-Caltech/Space Science Institute

Christiaan Huygens Christiaan Huygens (14…

Christiaan Huygens

Christiaan Huygens (14 April 1629 – 8 July 1695) was a Dutch physicist, mathematician, astronomer and inventor, who is widely regarded as one of the greatest scientists of all time and a major figure in the scientific revolution. In physics, Huygens made groundbreaking contributions in optics and mechanics, while as an astronomer he is chiefly known for his studies of the rings of Saturn and the discovery of its moon Titan. As an inventor, he improved the design of the telescope with the invention of the Huygenian eyepiece. His most famous invention, however, was the invention of the pendulum clock in 1656, which was a breakthrough in timekeeping and became the most accurate timekeeper for almost 300 years. Because he was the first to use mathematical formulae to describe the laws of physics, Huygens has been called the first theoretical physicist and the founder of mathematical physics.

In 1659, Huygens was the first to derive the now standard formula for the centripetal force in his work De vi centrifuga. The formula played a central role in classical mechanics and became known as the second of Newton’s laws of motion. Huygens was also the first to formulate the correct laws of elastic collision in his work De motu corporum ex percussione, but his findings were not published until after his death in 1703. In the field of optics, he is best known for his wave theory of light, which he proposed in 1678 and described in 1690 in his Treatise on Light, which is regarded as the first mathematical theory of light. His theory was initially rejected in favor of Isaac Newton’s corpuscular theory of light, until Augustin-Jean Fresnel adopted Huygens’ principle in 1818 and showed that it could explain the rectilinear propagation and diffraction effects of light. Today this principle is known as the Huygens–Fresnel principle. read more

Image credit: NASA/JPL, Commons.wikimedia

Six Moons of Saturn (Titan, Mimas, Tethys, E…

Six Moons of Saturn (Titan, Mimas, Tethys, Enceladus, Dione & Rhea)

Image Credit: Rafael Defavari

Saturn: Bright Tethys and Ancient Rings Imag…

Saturn: Bright Tethys and Ancient Rings 

Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

In October 1980 the Voyager probe discovered t…

In October 1980 the Voyager probe discovered three small moons of Saturn, Pandora, Atlas and Prometheus. (source & images)

Enceladus and Saturn Image credit: Gordan …

Enceladus and Saturn

Image credit: Gordan Ugarkovic

Dust Storms on Titan Spotted for the First T…

Dust Storms on Titan Spotted for the First Time

Data from NASA’s Cassini spacecraft has revealed what appear to be giant dust storms in equatorial regions of Saturn’s moon Titan. The discovery, described in a paper published on Sept. 24 in Nature Geoscience, makes Titan the third Solar System body, in addition to Earth and Mars, where dust storms have been observed.

The observation is helping scientists to better understand the fascinating and dynamic environment of Saturn’s largest moon.

“Titan is a very active moon,” said Sebastien Rodriguez, an astronomer at the Université Paris Diderot, France, and the paper’s lead author. “We already know that about its geology and exotic hydrocarbon cycle. Now we can add another analogy with Earth and Mars: the active dust cycle, in which organic dust can be raised from large dune fields around Titan’s equator.”

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Titan is an intriguing world – in ways quite similar to Earth. In fact, it is the only moon in the Solar System with a substantial atmosphere and the only celestial body other than our planet where stable bodies of surface liquid are known to still exist.

There is one big difference, though: On Earth such rivers, lakes and seas are filled with water, while on Titan it is primarily methane and ethane that flows through these liquid reservoirs. In this unique cycle, the hydrocarbon molecules evaporate, condense into clouds and rain back onto the ground.

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The weather on Titan varies from season to season as well, just as it does on Earth. In particular, around the equinox – the time when the Sun crosses Titan’s equator – massive clouds can form in tropical regions and cause powerful methane storms. Cassini observed such storms during several of its Titan flybys.

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When Rodriguez and his team first spotted three unusual equatorial brightenings in infrared images taken by Cassini around the moon’s 2009 northern equinox, they thought they might be the same kind of methane clouds; however, an investigation revealed they were something completely different.

“From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of the year are not physically possible,” said Rodriguez. “The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude – much higher than the 6 miles (10 kilometers) that modeling tells us the new features are located.”

The researchers were also able to rule out that the features were actually on the surface of Titan in the form of frozen methane rain or icy lavas. Such surface spots would have a different chemical signature and would remain visible for much longer than the bright features in this study, which were visible for only 11 hours to five weeks.

In addition, modeling showed that the features must be atmospheric but still close to the surface – most likely forming a very thin layer of tiny solid organic particles. Since they were located right over the dune fields around Titan’s equator, the only remaining explanation was that the spots were actually clouds of dust raised from the dunes.

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Organic dust is formed when organic molecules, formed from the interaction of sunlight with methane, grow large enough to fall to the surface. Rodriguez said that while this is the first-ever observation of a dust storm on Titan, the finding is not surprising.

“We believe that the Huygens Probe, which landed on the surface of Titan in January 2005, raised a small amount of organic dust upon arrival due to its powerful aerodynamic wake,” said Rodriguez. “But what we spotted here with Cassini is at a much larger scale. The near-surface wind speeds required to raise such an amount of dust as we see in these dust storms would have to be very strong – about five times as strong as the average wind speeds estimated by the Huygens measurements near the surface and with climate models.”

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The existence of such strong winds generating massive dust storms implies that the underlying sand can be set in motion, too, and that the giant dunes covering Titan’s equatorial regions are still active and continually changing.

The winds could be transporting the dust raised from the dunes across large distances, contributing to the global cycle of organic dust on Titan and causing similar effects to those that can be observed on Earth and Mars. source

Saturn and its moons at opposition (The visi…

Saturn and its moons at opposition (The visible moons are (from left to right) Dione, Enceladus, Tethys, Janus, Epimetheus and Mimas

Credit:

NASA, ESA, A. Simon (GSFC) and the OPAL Team, and J. DePasquale (STScI)