The Unsolved Mystery of Saturn's Hexagon -4 Times the Size of Earth "Cassini is indebted to Voyager for its many fascinating discoveries and for pavingthe way for Cassini," says Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage." But the Voyager Mission left a few mysteries that Cassini has not yet solved. One of the most perplexing mysteries is Saturn's hexagpn. 'Now that we can see undulations and circular features instead of blobs in the hexagon, we can start trying to solve some of the unanswered questions about one of the most bizarre things we've ever seen in the solar system, said Kevin Baines, Atmospheric scientist at NASA's Jet Propulsion Laboratory after viewing Cassini images in 2009. After the sunlight faded, darkness shrouded the north pole for 15 years. The hexagon was originally discovered in images taken by the Voyager spacecraft in the early 1980s.
Radiation Rings Hint Universe Was Recycled Over and Over | Wired Science Most cosmologists trace the birth of the universe to the Big Bang 13.7 billion years ago. But a new analysis of the relic radiation generated by that explosive event suggests the universe got its start eons earlier and has cycled through myriad episodes of birth and death, with the Big Bang merely the most recent in a series of starting guns. That startling notion, proposed by theoretical physicist Roger Penrose of the University of Oxford in England and Vahe Gurzadyan of the Yerevan Physics Institute and Yerevan State University in Armenia, goes against the standard theory of cosmology known as inflation. The researchers base their findings on circular patterns they discovered in the cosmic microwave background, the ubiquitous microwave glow left over from the Big Bang. The circular features are regions where tiny temperature variations in the otherwise uniform microwave background are smaller than average. See Also:
Enceladus Saturn II Enceladus ("en SEL a dus") is the eighth of Saturn's known satellites: orbit: 238,020 km from Saturn diameter: 498 km mass: 7.30e19 kg In Greek mythology Enceladus was a Titan who was defeated in battle and buried under Mount Etna by Athena. Discovered in 1789 by Herschel. Craters and smooth plains Enceladus has the highest albedo (>0.9) of any body in the solar system. At least five different types of terrain have been identified on Enceladus. This means that Enceladus must have been active until very recently (and perhaps is still active today). Enceladus is much too small to be heated solely by the decay of radioactive material in its interior at present. Cassini closeup view (looks like Europa?) Enceladus is locked in a 1:2 resonance with Dione (similar to the situation between Io and Europa). Enceladus is very likely the source of the material in Saturn's tenuous E ring. More about Enceladus Open Issues What is the resurfacing mechanism? Home ...
Sights and Sounds of Titan Sights and Sounds of Titan The European Space Agency's Huygens probe has landed on Saturn's giant moon Titan. Listen to this story via streaming audio, a downloadable file, or get help. January 16, 2005: Congratulations, ESA! The European Space Agency's (ESA's) Huygens probe, carried to Saturn by the Cassini spacecraft, parachuted to the surface of Saturn's giant moon Titan on Friday, Jan. 14th, revealing finally what lies beneath Titan's thick orange clouds. Right: From an altitude of 16 km, Huygens photographed these drainage channels leading to a shoreline. First images released by the ESA depict sinuous drainage channels leading to an apparent shoreline. It's all a bit familiar, yet at the same time utterly alien. Above: Small "rocks," possibly made of water ice, at the Huygens landing site. Because Titan has a thick atmosphere, able to carry sound waves, the moon is a noisy place. Huygens was designed to float in case it landed in a river or lake--but it didn't.
The Sounds of Pulsars A pulsar is a highly magnetised neutron star, with a radius of 10-15 km, having somewhat greater mass than the Sun which has a radius of approximately 1 million km. Radiation is beamed out along the magnetic poles and pulses of radiation are received as the beam crosses the Earth, in the same manner as the beam from a lighthouse causes flashes. Being enormous cosmic flywheels with a tick attached, they make some of the best clocks known to mankind. These sounds directly correspond to the radio-waves emitted by the brightest pulsars in the sky as received by some of the largest radio telescopes in the world. To listen to the pulses of a radio pulsar, click on its arrow icon.
In Flyby of Saturn's Moon Rhea, Cassini Probe Gets First Whiff of Non-Earthly Oxygen NASA's Cassini spacecraft has taken a breath of oxygen while passing over the icy surface of Saturn's second-largest moon, marking the first time a spacecraft has directly sampled oxygen in the atmosphere of another body. Cruising just 60 miles above Rhea, one of more than 60 moons orbiting Saturn, Cassini found an extremely thin atmosphere of oxygen and carbon dioxide likely sustained by high-energy particles slamming into the moon's frozen surface. Rhea's isn't the only other atmosphere in the universe, but it is so thin that Cassini had to fly through it just to confirm that it was there at all (other atmosphere's have been detected and studied from afar by tools like the Hubble Space Telescope). According to Cassini's onboard science instruments, Rhea's atmosphere contains something like 50 billion oxygen molecules per cubic meter, matched by 20 billion carbon dioxide molecules. [Guardian]
Enceladus Enceladus [en-SELL-ah-dus] is one of the brightest objects in our solar system. Covered in water ice that reflects sunlight like freshly fallen snow, Enceladus reflects almost 100 percent of the sunlight that strikes it. Because Enceladus reflects so much sunlight, the surface temperature is extremely cold, about -201° C (-330° F). About as wide as Arizona, Enceladus is quite similar in size to Mimas but has a smoother, brighter surface. Unlike Mimas, Enceladus displays at least five different types of terrain. Parts of the moon show craters no larger than 35 kilometers (about 22 miles) in diameter.
How Long Has Titan's Chemical Factory Been in Business? Saturn’s giant moon Titan hides behind a thick, smoggy atmosphere that’s well known to scientists as one of the most complex chemical environments in the Solar System. It’s a productive “factory” cranking out hydrocarbons that rain down on Titan’s icy surface and cloak it in soot. With a brutally cold surface temperature of around minus 270 degrees Fahrenheit (minus 170 degrees Celsius), the hydrocarbons form lakes of liquid methane and ethane. However, the most important raw ingredient in Titan’s chemical factory is methane gas. These papers used data collected by two instruments onboard NASA’s Cassini spacecraft in orbit around Saturn and one instrument on the European Space Agency’s Huygens probe that landed on Titan’s surface in January 2005. Isotopes are versions of an element with different weights, or masses. By modeling how the concentration of heavy methane changes over time, the scientists predicted how long Titan’s chemical factory has been running.
Scientists Now Know: We're From Sagittarius Dwarf Galaxy! Scientists Now Know: We're Not From Here! Summary & comments by Dan Eden for Viewzone "This first full-sky map of Sagittarius shows its extensive interaction with the Milky Way," Majewski said. "Both stars and star clusters now in the outer parts of the Milky Way have been 'stolen' from Sagittarius as the gravitational forces of the Milky Way nibbled away at its dwarf companion. The study's map of M giants depicts 2 billion years of Sagittarius stripping by the Milky Way, and suggests that Sagittarius has reached a critical phase in what had been a slow dance of death. "After slow, continuous gnawing by the Milky Way, Sagittarius has been whittled down to the point that it cannot hold itself together much longer," said 2MASS Science Team member and study co-author Martin Weinberg of the University of Massachusetts. Does this mean we are at a unique moment in the life of our galaxy? Implications in Global Warming? Other changes happening in our system * A growth of dark spots on Pluto. Dave
Super-Earth Atmosphere May Be Mostly Water | Wired Science The first direct measurement of a super-Earth exoplanet's atmosphere finds the world is either shrouded in steam or covered in clouds. "This is the first probe of an atmosphere of a super-Earth planet," said exoplanet observer Jacob Bean of the Harvard-Smithsonian Center for Astrophysics, lead author of a paper describing the cloudy world in the Dec. 2 Nature. "It's a real big step in the direction of doing this kind of work for a planet that's potentially habitable." The planet, called GJ 1214b, is the smallest planet yet to have its atmosphere examined -- but it's just the latest in nearly a decade of probing exoplanet atmospheres. When the first exoplanet atmosphere was measured in 2002, many astronomers dismissed it as a one-time success. Astronomers hope eventually to find true twins of Earth: small rocky planets with liquid water and atmospheres that could support life. "Ultimately the goal is to try to look for biosignatures," Bean said. Image: Paul A.
Seriously jaw-dropping picture of the Sun Need your slice of awesome today? Then check out this truly astonishing picture of a detached prominence off the limb of the Sun: Holy wow! Click to ensolarnate. And I mean it: you want to see the bigger version of this. This picture was taken by Alan Friedman, who is no stranger to this blog: his picture of the boiling Sun last year was hugely popular, and so amazing I featured it as one of my top pictures of 2010. And with this he’s done it again… and maybe even topped it. Alan used a filter that lets through only a very narrow wavelength of light emitted by hydrogen (called Hα for those of you keeping track at home), so this tracks the activity of gas on the solar surface. The scene-stealer is that detached prominence off to the left. The beauty of this picture belies its violence and sheer magnitude: the mass of material in a prominence can easily top 10 billion tons! Yegads. You really need to go and see the rest of Alan’s photography at his site, Averted Imagination. Related posts: