This map puts Mars Valles Marineris into perspective in terms of its size.
Valles Marineris on Mars is the longest and deepest canyon in the Solar System. The deep gash in the side of Mars is a pretty good companion for the tallest mountain in the Solar System, Olympus Mons, which also on Mars. The pair demonstrate the world of extremes that is the Red Planet. Valles Marineris is 4,000 km long, 200 km wide at points, and up to 7 km deep. It runs along the Martian equator and covers nearly a quarter of the planet’s circumference and 59% of its diameter. The Valles Marineris system is a network of interconnected valleys that begin in the west. Noctis Labyrinthus is considered the starting point of the system, then it moves east to include the Tithonium chasmata and Ius chasmata. In the mid region are the Melas, Ophir, Coprates, Ganges, Capri, and Eos chasmata. The canyon moves through an area of chaotic terrain(ridges, cracks, and plains jumbled together)before it ends in the basin region of Chryse Planitia. One of the largest debates surrounding the area is about how it formed. In the 1970s, erosion by water and/or melting permafrost were popular theories. Liquid water can not exist in current Martian conditions, but has in the past, making the feature billions of years old. Another theory from the 1970s was that the feature formed when subsurface magma withdrew from the area. At the end of 1989, a theory emerged that it was formed by tensional fracturing. The theory most widely shared today is that it formed by rift faults and was made bigger by erosion and the collapsing of the rift walls. A rift valley is usually formed between two mountain ranges and is caused by the formation of the mountains. In this case, the formation is tied to the Tharsis Bulge. Valles Marineris is named after NASA’s Mariner 9 spacecraft, which first photographed it up close in 1971-1972. Mariner 9 was the first spacecraft to orbit another planet, just ahead of the Soviet space program’s twin missions Mars 2 and Mars 3. Valles Marineris on Mars is the focus of many astrogeologists because of its tantalizing view into the Martian geologic past. Evidence within the valley also points to a much wetter and warmer climate on Mars millenia ago. You can be sure that scientists will be looking for more clues in every set of data from the area.
An exotic pair of binary stars have proved that Albert Einstein’s theory of relativity is still right, even in the most extreme conditions tested yet. ”The unusual pair of stars is quite interesting in its own right but we’ve learned it is also a unique laboratory for testing the limits of one of our most fundamental physical theories, general relativity” says University of Toronto astronomy professor Marten van Kerkwijk, a member of the research team.What makes the pair of stars exceptional are the unique characteristics of each and their close proximity to each other. One is a tiny but unusually heavyneutron star– one of the most massive confirmed to date. NamedPSRJ0348+0432, it is the remnant of a supernova explosion, and is twice as heavy as the Sun yet is only 20 kilometres across. The neutron star is a pulsar that gives off radio waves that can be picked up on Earth by radio telescopes.
The gravity at its surface is more than 300 billion times stronger than that on Earth and at its centre every sugarcube-sized volume has more than one billion tonnes of matter squeezed into it, roughly the mass of every human past and present.
The massive star spins 25 times each second and is orbited by a rather lightweight dwarf star every two and a half hours, an unusually short period. Only slightly less exotic, the white dwarf is the glowing remains of a much lighter star that has lost its envelope and is slowly cooling. It can be observed in visible light, though only with large telescopes – it is about a million times too faint to be visible with the naked eye.
In the new work, led by Bonn PhD student John Antoniadis, very precise timing of the pulsar’s spin-modulated emission with radio telescopes was used to discover a tiny but significant change in the orbital period of the binary, of eight-millionths of a second per year. Given the masses of the pulsar and the white dwarf, inferred with the help of observations of the light emitted by the white dwarf – using techniques perfected by Antoniadis and van Kerkwijk – this turns out to match exactly what Einstein’s theory predicts.
Einstein’s general theory of relativityexplains gravity as a consequence of the curvature of spacetime created by the presence of mass and energy. As two stars orbit each other, gravitational waves are emitted – wrinkles moving out in spacetime. As a result, the binary slowly loses energy, the stars move closer, and the orbital period shortens.
The test posed by PSR J0348+0432 is particularly interesting because the massive star is a truly extreme object in terms of gravity, even compared to other pulsars that have been used to test general relativity. As a result, it causes exceptionally strong distortion of spacetime. In many alternatives to Einstein’s theory, this would cause the orbit to lose energy much faster than is observed.
“The observations disprove these alternatives,” says van Kerkwijk, “and thus give further confidence that Einstein’s theory is a good description of nature – even though we know it is not a complete one, given the unresolved inconsistencies with quantum mechanics.”
This intense false-color view highlights and enhances color variations across the intensely cratered and cracked surface of Rhea.
To create the false-color view, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. This “color map” was then superposed over a clear-filter image. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.
Wispy markings were seen on the trailing hemispheres of both Rhea and Dione in images taken by the Voyager spacecraft, and were hypothesized by some researchers to be the result of material extruded onto the surface by ice volcanism. Cassini’s earlier revelation of the braided fractures on Dione led to speculation that Rhea’s wisps might also be created by fractures.
Credit: NASA/JPL/Space Science Institute
The combination of Titan’s low gravity and thick atmosphere would allow a human to fly by strapping “fake wings” to their arms.
The second-largest moon in the solar system, Saturn’s Titan is the only moon with a substantial atmosphere, which is much deeper than Earth’s. It’s so thick and the gravity so weak, in fact, that you could strap wings on your arms and flap them like a bird to fly. The air is mostly nitrogen, but the rest is mostly hydrocarbons, giving Titan’s atmosphere a thick orange smoggy haze that is opaque to visible light. Cassini studies Titan in infrared light (which can penetrate the haze) and with radar — and in 2004, via the Huygens Probe, an atmosphere probe became the first spacecraft to transmit from the surface of a moon other than our own. Titan is remarkably earthlike, apart from being so cold that water is as hard as rock; in addition to the atmosphere, it is the only place other than Earth known to have bodies of liquid on the surface — lakes as large as the Great Lakes, except that it’s not water: it’s probably methane or ethane. The climate is probably similar to some of our deserts, with gigantic monsoons perhaps once a decade or more, and long droughts between. NASA scientists are working on a mission called Titan Mare Explorer (TiME) specifically to study the lakes of Titan.
Read the full text here: http://mentalfloss.com/ It’s Raining on Titan! Illustration Credit & Copyright: David A. Hardy (AstroArt)
Binary and multiple star systems are very common in our universe. About half of all stars are found in systems containing two or more stars. This page shows the typical orbits for stars in binary, triple and quadruple star systems. These simulations show perfect star systems with stars of equal masses. Real multiple star systems are usually messier with stars of different masses at very different distances.
Binary Star Systems
Shown on the left is a typical binary star system. The two stars follow elliptical orbits around a common center-of-mass. Shown on the right is a special example of a binary star system where the stars follow perfectly circular orbits.
Triple Star Systems
Shown on the left is a typical triple star system. There are two stars orbiting each other at close range, and a third, more distant, star orbiting around the first two. Shown on the right is a very unusual type of triple star system. The three stars travel in a figure-of-eight trajectory. Computer simulations have shown that this type of orbit can be stable for billions of years. Nobody has yet found a figure-of-eight triple star system (a few astronomers have tried to find one), but it is possible that somewhere in our Galaxy there are stars which follow this orbit.
Quadruple Star Systems
Shown on the left is one type of quadruple star system. It consists of two pairs of binary stars orbiting about a common center-of-mass. Shown on the right is another type of quadruple star system. There are two very close stars orbiting each other rapidly. They are orbited by a third star as in a triple star system. These three stars are orbited by a distant fourth star.
NASA’s Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn’s north pole.
In high-resolution pictures and video, scientists see the hurricane’s eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon.
“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn’s hydrogen atmosphere.”
Scientists will be studying the hurricane to gain insight into hurricanes on Earth, which feed off warm ocean water. Although there is no body of water close to these clouds high in Saturn’s atmosphere, learning how these Saturnian storms use water vapor could tell scientists more about how terrestrial hurricanes are generated and sustained.
Both a terrestrial hurricane and Saturn’s north polar vortex have a central eye with no clouds or very low clouds. Other similar features include high clouds forming an eye wall, other high clouds spiraling around the eye, and a counter-clockwise spin in the northern hemisphere.
A major difference between the hurricanes is that the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. At Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Unlike terrestrial hurricanes, which tend to move, the Saturnian hurricane is locked onto the planet’s north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the fast swirls of wind as the planet rotates. The one on Saturn does not drift and is already as far north as it can be.
“The polar hurricane has nowhere else to go, and that’s likely why it’s stuck at the pole,” said Kunio Sayanagi, a Cassini imaging team associate at Hampton University in Hampton, Va.
Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn’s north pole was dark because the planet was in the middle of its north polar winter. During that time, the Cassini spacecraft’s composite infrared spectrometer and visual and infrared mapping spectrometer detected a great vortex, but a visible-light view had to wait for the passing of the equinox in August 2009. Only then did sunlight begin flooding Saturn’s northern hemisphere. The view required a change in the angle of Cassini’s orbits around Saturn so the spacecraft could see the poles.
“Such a stunning and mesmerizing view of the hurricane-like storm at the north pole is only possible because Cassini is on a sportier course, with orbits tilted to loop the spacecraft above and below Saturn’s equatorial plane,” said Scott Edgington, Cassini deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “You cannot see the polar regions very well from an equatorial orbit. Observing the planet from different vantage points reveals more about the cloud layers that cover the entirety of the planet.”
Cassini changes its orbital inclination for such an observing campaign only once every few years. Because the spacecraft uses flybys of Saturn’s moon Titan to change the angle of its orbit, the inclined trajectories require attentive oversight from navigators. The path requires careful planning years in advance and sticking very precisely to the planned itinerary to ensure enough propellant is available for the spacecraft to reach future planned orbits and encounters.
Image credit: NASA/JPL-Caltech/SSI
Over a millenia ago Earth witnessed an explosion in the heavens, that explosion was later discovered to be a supernova. Now, new data from NASA’s Chandra X-ray observatory adds to the awesome factor of SN 1006 and supernovae like it, which provides new details about the remains of this exploded star. As noted in Chandra’s official site:
“The Chandra data provides the best map to date of the debris field including information on important elements expanding into space.”
A new image of SN 1006 from NASA’s Chandra X-ray Observatory reveals this supernova remnant in exquisite detail. By overlapping ten different pointings of Chandra’s field-of-view, astronomers have stitched together a cosmic tapestry of the debris field that was created when a white dwarf star exploded, sending its material hurtling into space. In this new Chandra image, low, medium, and higher-energy X-rays are colored red, green, and blue respectively.
The Chandra image provides new insight into the nature of SN1006, which is the remnant of a so-called Type Ia supernova . This class of supernova is caused when a white dwarf pulls too much mass from a companion star and explodes, or when two white dwarfs merge and explode. Understanding Type Ia supernovas is especially important because astronomers use observations of these explosions in distant galaxies as mileposts to mark the expansion of the Universe.
This image is a composite of 25 separate images spanning the period of April 16, 2012, to April 15, 2013.
It uses the SDO AIA wavelength of 171 angstroms and reveals the zones on the sun where active regions are most common during this part of the solar cycle.
Credit: NASA/GSFC/SDO/AIA/S. Wiessinger