Why did Earth thrive and our sister planet, Venus, died? From the fires of a sun’s birth… twin planets emerged. Then their paths diverged. Nature draped one world in the greens and blues of life. While enveloping the other in acid clouds… high heat… and volcanic flows. Why did Venus take such a disastrous turn?
The point of no return has been discovered at last. Fifty million light-years from Earth, in the heart of the Messier 87 galaxy, a black hole that is six billion times more massive than the Sun has provided scientists with the first measurement of what is known as an “event horizon,” the point beyond which matter is forever lost to the black hole.
“Once objects fall through the event horizon, they’re lost forever,” says Shep Doeleman, a research associate at the Harvard-Smithsonian Center for Astrophysics and lead author on the paper published in Science Express.
Black holes are the densest objects in the universe. “There’s such intense gravity there that it’s not just matter that can cross the event horizon and get sucked into the black hole but even a photon of light,” says co-author Jonathan Weintroub, also at the Harvard-Smithsonian Center for Astrophysics. “There’s a bit of a paradox in claiming that we’ve measured a black hole, because black holes are black. We measure light, or in our case, radiowaves” from around the black hole, not the black hole itself.
The black hole in question is one of the two biggest in the sky, according to a September 2011 paper titled, “The size of the jet launching region in M87,” which outlined how measurements of the event horizon could be taken.
Plans to send an interplanetary pedalo to Saturn’s largest moon Titan have been unveiled by scientists.
The robot craft would land in one of the moon’s lakes and sail around propelled by paddles.
Other versions of the probe are fitted with screws or wheels.
Titan is the nearest thing the Solar System has to Pandora, the Earth-like moon featured in the film Avatar.
Like Earth it has a thick atmosphere and large bodies of liquid on its surface – only Titan’s chilly seas consist of lighter fluid chemicals instead of water.
The hydrocarbon lakes, seas and rivers cover much of the moon’s northern hemisphere.
Their existence was confirmed by the European Space Agency’s Huygens lander which visited Titan as part of the Cassini mission in 2005.
Huygens landed on solid ground but was designed to float for short periods.
The new plans, presented at the European Planetary Science Congress in Madrid, envisage dropping a boat-like probe in the middle of Ligeia Mare, the largest lake near Titan’s north pole.
The craft would then set sail for the coast, taking scientific measurements on the way.
Astrophysicist Adam Frank’s new book mixes cosmology with humanity. How does our understanding of the universe and cosmic time inform our daily lives? Especially if time is an illusion?
The “rebels” who fight the Big Bang theory are mostly attempting to grapple with the concept of time. They are philosophers as much as cosmologists, unsatisfied with the Big Bang, unimpressed with string theory and unconvinced of the multiverse. Julian Barbour, British physicist, author, and major proponent of the idea of timeless physics, is one of those rebels–so thoroughly a rebel that he has spurned the world of academics.
Julian Barbour’s solution to the problem of time in physics and cosmology is as simply stated as it is radical: there is no such thing as time.
“If you try to get your hands on time, it’s always slipping through your fingers,” says Barbour. “People are sure time is there, but they can’t get hold of it. My feeling is that they can’t get hold of it because it isn’t there at all.” Barbour speaks with a disarming English charm that belies an iron resolve and confidence in his science. His extreme perspective comes from years of looking into the heart of both classical and quantum physics. Isaac Newton thought of time as a river flowing at the same rate everywhere. Einstein changed this picture by unifying space and time into a single 4-D entity. But even Einstein failed to challenge the concept of time as a measure of change. In Barbour’s view, the question must be turned on its head. It is change that provides the illusion of time. Channeling the ghost of Parmenides, Barbour sees each individual moment as a whole, complete and existing in its own right. He calls these moments “Nows.”
“As we live, we seem to move through a succession of Nows,” says Barbour, “and the question is, what are they?” For Barbour each Now is an arrangement of everything in the universe. “We have the strong impression that things have definite positions relative to each other. I aim to abstract away everything we cannot see (directly or indirectly) and simply keep this idea of many different things coexisting at once. There are simply the Nows, nothing more, nothing less.”
The drive by NASA’s Mars rover Curiosity during the mission’s 43rd Martian day, or sol, (Sept. 19, 2012) ended with this rock about 8 feet (2.5 meters) in front of the rover. The rock is about 10 inches (25 centimeters) tall and 16 inches (40 centimeters) wide. The rover team has assessed it as a suitable target for the first use of Curiosity’s contact instruments on a rock. The image was taken by the left Navigation camera (Navcam) at the end of the drive.
The rock has been named “Jake Matijevic.” This commemorates Jacob Matijevic (1947-2012), who was the surface operations systems chief engineer for the Mars Science Laboratory Project and the project’s Curiosity rover. He was also a leading engineer for all of the previous NASA Mars rovers: Sojourner, Spirit and Opportunity.
Curiosity’s contact instruments are on a turret at the end of the rover’s arm. They are the Alpha Particle X-Ray Spectrometer for reading a target’s elemental composition and the Mars Hand Lens Imager for close-up imaging.
The audio ‘Chorus’ in this video was recorded on Sept. 5, 2012, by RBSP’s Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS).
For more info about the auroral chorus phenomena visit: captaincynic.com
Audio Credit: University of Iowa
Visualisation Credit: NASA/Goddard Space Flight Center
Small spherical objects fill the field in this mosaic combining four images from the Microscopic Imager on NASA’s Mars Exploration Rover Opportunity. The view covers an area about 2.4 inches (6 centimeters) across, at an outcrop called “Kirkwood” in the Cape York segment of the western rim of Endeavour Crater. The individual spherules are up to about one-eighth inch (3 millimeters) in diameter.
The Microscopic Imager took the component images during the 3,064th Martian day, or sol, of Opportunity’s work on Mars (Sept. 6, 2012). For a color view of the Kirkwood outcrop as Opportunity was approaching it two weeks earlier, see PIA16128 .
Opportunity discovered spherules at its landing site more than eight-and-a-half years earlier. Those spherules were nicknamed “blueberries.” They provided important evidence about long-ago wet environmental conditions on Mars because researchers using Opportunity’s science instruments identified them as concretions rich in the mineral hematite deposited by water saturating the bedrock. A picture of the “blueberries” from the same Microscopic Imager is PIA05564 .
The spherules at Kirkwood do not have the iron-rich composition of the blueberries. They also differ in concentration, distribution and structure. Some of the spherules in this image have been partially eroded away, revealing concentric internal structure. Opportunity’s science team plans to use the rover for further investigation of these spherules to determine what evidence they can provide about ancient Martian environmental conditions.
After a two-year study led by Tommaso Giannantonio and Robert Crittenden, scientists conclude that the likelihood of its existence stands at 99.996 per cent. Their findings are published in the Monthly Notices of the Royal Astronomical Society.
Professor Bob Nichol, a member of the Portsmouth team, said: “Dark energy is one of the great scientific mysteries of our time, so it isn’t surprising that so many researchers question its existence.
“But with our new work we’re more confident than ever that this exotic component of the Universe is real — even if we still have no idea what it consists of.”
Over a decade ago, astronomers observing the brightness of distant supernovae realised that the expansion of the Universe appeared to be accelerating. The acceleration is attributed to the repulsive force associated with dark energy now thought to make up 73 per cent of the content of the cosmos. The researchers who made this discovery received the Nobel Prize for Physics in 2011, but the existence of dark energy remains a topic of hot debate.
Many other techniques have been used to confirm the reality of dark energy but they are either indirect probes of the accelerating Universe or susceptible to their own uncertainties. Clear evidence for dark energy comes from the Integrated Sachs Wolfe effect named after Rainer Sachs and Arthur Wolfe.
On August 31, 2012 a long filament of solar material that had been hovering in the sun’s atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The coronal mass ejection, or CME, traveled at over 900 miles per second. The CME did not travel directly toward Earth, but did connect with Earth’s magnetic environment, or magnetosphere, with a glancing blow. causing aurora to appear on the night of Monday, September 3.
Four images of a filament on the sun from August 31, 2012 are shown here in various wavelengths of light as captured by NASA’s Solar Dynamics Observatory (SDO). Starting from the upper left and going clockwise they represent light in the: 335, 171, 304 and 131 Angstrom wavelengths. Since each wavelength of light generally corresponds to solar material at a particular temperature, scientists can compare images like this to observe how the material moves during an eruption. Credit: NASA/SDO/AIA/GSFC
A long filament erupted on the sun on August 31, 2012, shown here in a movie captured by NASA’s Solar Dynamics Observatory (SDO) from noon EDT to 1:45 a.m. the next morning. The filament lies in the lower left corner of the sun. The movie shows light at 304 Angstroms and 171 Angstroms, both of which help scientists observe the sun’s atmosphere, or corona. Credit: NASA/SDO/AIA
Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, NASA’s Kepler mission has discovered multiple transiting planets orbiting two suns for the first time. This system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.
This discovery proves that more than one planet can form and persist in the stressful realm of a binary star and demonstrates the diversity of planetary systems in our galaxy.
Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.
“In contrast to a single planet orbiting a single star, the planet in a circumbinary system must transit a ‘moving target.’ As a consequence, time intervals between the transits and their durations can vary substantially, sometimes short, other times long,” said Jerome Orosz, associate professor of astronomy at San Diego State University and lead author of the paper. “The intervals were the telltale sign these planets are in circumbinary orbits.”
The inner planet, Kepler-47b, orbits the pair of stars in less than 50 days. While it cannot be directly viewed, it is thought to be a sweltering world, where the destruction of methane in its super-heated atmosphere might lead to a thick haze that could blanket the planet. At three times the radius of Earth, Kepler-47b is the smallest known transiting circumbinary planet.
When you hear someone say “Once in a Blue Moon” you know what they mean. They’re usually talking about something rare, silly, and even absurd. After all, when was the last time you saw the Moon turn blue? Well, rare or not, we’re having one this week, and according to astronomer David Reneke writer and publicist for Australasian Science magazine, a Blue Moon is slated for the last day of this month, Friday, August 31.
It’s not at all clear where the term ‘Blue Moon’ comes from. According to modern folklore it dates back at least 400 years. A Blue Moon is the second Full Moon in a calendar month. “Usually months have only one Full Moon, but occasionally a second one sneaks in, David said. “Ancient cultures around the world considered the second Full Moon to be spiritually significant.”
Full Moons are separated by 29 days, while most months are 30 or 31 days long, so it is possible to fit two Full Moons in a single month. This happens every two and a half years, on average. By the way, February is the only month that can never have a Blue Moon by this definition. We had one Full Moon on August 2 this year and the second will be Friday night.
Via: New Scientist
GILBERT LEVIN aims to appropriate the Mars Science Laboratory for his own ends. “Since NASA has disdained any interest in MSL looking for life, I’m taking over,” he says. “I claim it.”
He is only half joking. If MSL’s rover Curiosity finds carbon-based molecules in the Martian soil, Levin – who led the “labelled release” experiment on NASA’s 1976 Viking mission – will demand that his refuted discovery of life on Mars is reinstated.
Levin, a former sanitary engineer, will make this call next week at the annual SPIE convention on scientific applications of light sources in San Diego, California. He wants an independent reanalysis of the data.
The experiment mixed Martian soil with a nutrient containing radioactive carbon. The idea was simple: if bacteria were present in the soil, and metabolised the nutrient, they would emit some of the digested molecules as carbon dioxide. The experiment did indeed find that carbon dioxide was released from the soil, and that it contained radioactive carbon atoms.
Levin’s team went out and bought champagne. He even took a congratulatory phone call from Carl Sagan. However, the party was ruined by a sister experiment. Viking’s Gas Chromatograph Mass Spectrometer (GCMS) was looking for carbon-based molecules and found none. NASA chiefs said that life couldn’t exist without these organic molecules, and declared Levin’s result moot. “NASA powers that be concluded that the lack of organics trumped the positive labelled release experiment,” says Robert Hazen, a geophysical scientist at the Carnegie Institution for Science in Washington DC.
This color image from NASA’s Curiosity rover shows part of the wall of Gale Crater, the location on Mars where the rover landed on Aug. 5, 2012 PDT (Aug. 6, 2012 EDT). This is part of a larger, high-resolution color mosaic made from images obtained by Curiosity’s Mast Camera.
This image of the crater wall is north of the landing site, or behind the rover. Here, a network of valleys believed to have formed by water erosion enters Gale Crater from the outside. This is the first view scientists have had of a fluvial system – one relating to a river or stream — from the surface of Mars. Known and studied since the 1970s beginning with NASA’s Viking missions, such networks date from a period in Martian history when water flowed freely across the surface. The main channel deposit seen here resembles a dirt road ascending into the mountains, which are actually the north wall and rim of Gale Crater.
Although Curiosity is about 11 miles (18 kilometers) away from this area and the view is obscured somewhat by dust and haze, the image provides new insights into the style of sediment transport within this system. Curiosity has no current plans to visit this valley system, since the primary objective of the rover is south of the landing site. But images taken later and with the 100-millimeter Mastcam are likely to allow scientists to study the area in significantly more detail.
The images in this mosaic were acquired by the 34-millimeter MastCam over about an hour of time on Aug. 8, 2012 PDT (Aug. 9, 2012 EDT), each at 1,200 by 1,200 pixels in size.
This color image from NASA’s Curiosity rover shows an area excavated by the blast of the Mars Science Laboratory’s descent stage rocket engines. This is part of a larger, high-resolution color mosaic made from images obtained by Curiosity’s Mast Camera.
With the loose debris blasted away by the rockets, details of the underlying materials are clearly seen. Of particular note is a well-defined, topmost layer that contains fragments of rock embedded in a matix of finer material. Shown in the inset in the figure are pebbles up to 1.25 inches (about 3 centimeters) across (upper two arrows) and a larger clast 4 inches (11.5 centimeters) long protruding up by about 2 inches (10 centimeters) from the layer in which it is embedded. Clast-rich sedimentary layers can form in a number of ways. Their mechanisms of formation can be distinguished by the size, shape, surface textures and positioning with respect to each other of the fragments in the layers.
The images in this mosaic were acquired by the 34-millimeter Mastcam over about an hour of time on Aug. 8, 2012 PDT (Aug. 9, 2012 EDT), each at 1,200 by 1,200 pixels in size.
In the main version, the colors portrayed are unmodified from those returned by the camera. The view is what a cell phone or camcorder would record since the Mastcam takes color pictures in the exact same manner that consumer cameras acquire color images. The second version, linked to the main version, shows the colors modified as if the scene were transported to Earth and illuminated by terrestrial sunlight. This processing, called “white balancing,” is useful for scientists to be able to recognize and distinguish rocks by color in more familiar lighting.