Understanding the Origin of our Solar System |
Simulations boost the significance of image and measurement data from space missions: based on the example of an asteroid, Bernese astrophysicist Martin Jutzi shows how collisions with other celestial bodies can be reconstructed and that even the internal structure of so- called protoplanets can be described. These models help to understand the development of our solar system. The study appears as today’s cover story in the journal Nature.
Four and a half billion years ago, dust particles in a giant, dusty gas cloud combined to form increas- ingly large clumps. These collided, aggregated and thus grew into planets. Between the planetary or- bits of Mars and Jupiter, however, hundreds of thousands of smaller fragments remained. They formed the so-called asteroid belt and hardly changed their composition since then. Asteroids thus contain an inestimable amount of information on the origin of our solar system. In research, particular attention is paid to an asteroid called Vesta: with a diameter of around 500 kilometres, it is one of the three largest asteroids and considered to be a protoplanet. Moreover, it is the only known asteroid to have an earth-like structure – with a core, mantle and crust.
The formation of the Solar System and the collision that created the Moon.
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Cluster Mission Indicates Turbulent Eddies May Warm the Solar Wind |
The sun ejects a continuous flow of electrically charged particles and magnetic fields in the form of the solar wind — and this wind is hotter than it should be. A new study of data obtained by European Space Agency’s Cluster spacecraft may help explain the mystery.
The solar wind is made of an electrically-charged gas called plasma. One theory about the wind’s puzzling high temperatures is that irregularities in the flow of charged particles and magnetic fields in the plasma create turbulence, which, in turn, dissipates and adds heat to its surroundings. Using two separate sets of data sent back by Cluster, an international team of scientists has probed the spatial characteristics of this turbulence in more detail and at smaller scales than ever before. They saw evidence that the turbulence evolved to form very small “current sheets” — thin sheets of electrical current that separate regions of rotated magnetic field.
“For the first time, we were able to obtain direct evidence for the existence of current sheets at these very small scales, where dissipation of magnetic energy into heat is thought to occur,” said Melvyn Goldstein, project scientist for Cluster at NASA’s Goddard Space Flight Center in Greenbelt, Md. Goldstein is a co-author of a paper on these results that appeared in the Nov. 9, 2012, issue of Physical Review Letters.
This solar wind is a non-stop gale of plasma, mainly protons and electrons, which originates in the sun’s searingly hot lower atmosphere. It blasts outward in all directions at an average speed of about 250 miles per second. The outflow is so energetic that it pulls along the sun’s magnetic field. The solar wind travels across the entire solar system, until it reaches the boundary with interstellar space. The plasma cools as it expands during its outward journey. However, the amount of cooling is much less than would be expected in a constant, smooth flow of solar particles since the density is so low that the particles cannot be receiving extra heat from the most common method on Earth: collisions. continue reading
the simple understanding we all must keep in mind is this: we are not fit to survive on this planet. we’ve been extremely fortunate throughout our short time on Earth to not be wiped out by an asteroid or an undetected comet…yet.
even if we were hit by another extinction event, most life on this planet (residing deep in the depths of our oceans, volcanic tubes & beneath the ice) would survive, maybe even flourish in the wake of what would be, to us, a cataclysmic disaster.
it’s a privilege for us to be here now. which is why scientific literacy amongst our growing (but relatively small) population is necessary. disregard what we are already doing to this planet for a moment…the big picture is that we must open the gateway for our species to become space-faring if we wish to survive at all. and the only way that’s going to happen is if we make it happen. if we make science & scientific literacy the #1 priority for our generation & future generations to come, so that we can all successfully contribute to tomorrow’s generations being able to effectively progress off of our accomplishments & those of centures & eons ago.
we are humans who are going to suffer for our hinderances & negligence toward scientific literacy & understanding due to so many years of oppression, war & persecution by religious extremists who feared an overall understanding of the world, let alone the universe as we know it today. my only hope for this planet is that we leave behind traces of the work/damage we’ve done so that interstellar/galactic “passersby” may see our missteps & realize that other species may in fact be suffering the same type of fates if not aided & corrected sooner.
Remarkable Symmetry in Black Hole Jets |
Black holes range from modest objects formed when individual stars end their lives to behemoths billions of times more massive that rule the centers of galaxies. A new study using data from NASA’s Swift satellite and Fermi Gamma-ray Space Telescope shows that high-speed jets launched from active black holes possess fundamental similarities regardless of mass, age or environment. The result provides a tantalizing hint that common physical processes are at work.
“What we’re seeing is that once any black hole produces a jet, the same fixed fraction of energy generates the gamma-ray light we observe with Fermi and Swift,” said lead researcher Rodrigo Nemmen, a NASA Postdoctoral Program (NPP) fellow at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Gas falling toward a black hole spirals inward and piles up into an accretion disk, where it becomes compressed and heated. Near the inner edge of the disk, on the threshold of the black hole’s event horizon — the point of no return — some of the material becomes accelerated and races outward as a pair of jets flowing in opposite directions along the black hole’s spin axis. These jets contain particles moving at nearly the speed of light, which produce gamma rays — the most extreme form of light — when they interact.
“We don’t fully understand how this acceleration process occurs, but in active galaxies we see jets that have operated so long that they’ve produced trails of gas extending millions of light-years,” said Sylvain Guiriec, an NPP fellow at Goddard and a co-author on the study, which was published in the Dec. 14 issue of Science. continue reading
Killer Dinosaur Asteroid Also Wiped Out ‘Obamadon’ |
The asteroid collision widely thought to have killed the dinosaurs also led to extreme devastation among snake and lizard species, according to new research — including the extinction of a newly identified lizard Yale and Harvard scientists have named Obamadon gracilis.
“The asteroid event is typically thought of as affecting the dinosaurs primarily,” said Nicholas R. Longrich, a postdoctoral associate with Yale’s Department of Geology and Geophysics and lead author of the study. “But it basically cut this broad swath across the entire ecosystem, taking out everything. Snakes and lizards were hit extremely hard.”
The study was scheduled for online publication the week of Dec. 10 in the Proceedings of the National Academy of Sciences.
Earlier studies have suggested that some snake and lizard species (as well as many mammals, birds, insects and plants) became extinct after the asteroid struck Earth 65.5 million years ago, on the edge of the Yucatan Peninsula. But the new research argues that the collision’s consequences were far more serious for snakes and lizards than previously understood. As many as 83 percent of all snake and lizard species died off, the researchers said — and the bigger the creature, the more likely it was to become extinct, with no species larger than one pound surviving.
The results are based on a detailed examination of previously collected snake and lizard fossils covering a territory in western North America stretching from New Mexico in the southwestern United States to Alberta, Canada. The authors examined 21 previously known species and also identified nine new lizards and snakes.
They found that a remarkable range of reptile species lived in the last days of the dinosaurs. Some were tiny lizards. One snake was the size of a boa constrictor, large enough to take the eggs and young of many dinosaur species. Iguana-like plant-eating lizards inhabited the southwest, while carnivorous lizards hunted through the swamps and flood plains of what is now Montana, some of them up to six feet long.
“Lizards and snakes rivaled the dinosaurs in terms of diversity, making it just as much an ‘Age of Lizards’ as an ‘Age of Dinosaurs,’” Longrich said. continue reading
Useful to see what part of the atmosphere stops the different wavelengths, but the large visible light spectrum is completely misleading. Visible light is actually light with a wavelength from 400 to 700 nanometers. What we call radio waves, for instance, span much more wavelengths (from 1 millimeter to 100 kilometers).
Once a person puts on a cloak made with retro-reflective material (high-tech fabric covered with thousands and thousands of small beads that bounce light back exactly in the same direction from which it came — and very brightly) here’s the sequence of events:
- A digital video camera captures the scene behind the person wearing the cloak.
- The computer processes the captured image and makes the calculations necessary to adjust the still image or video so it will look realistic when it is projected.
- The projector receives the enhanced image from the computer and shines the image through a pinhole-sized opening onto the combiner.
- The silvered half of the mirror, which is completely reflective, bounces the projected image toward the person wearing the cloak.
- The cloak acts like a movie screen, reflecting light directly back to the source, which in this case is the mirror.
- Light rays bouncing off the cloak pass through the transparent part of the mirror and fall on the user’s eyes. Remember that the light rays bouncing off the cloak contain the image of the scene that exists behind the person wearing the cloak.
The person wearing the cloak appears invisible because the background scene is being displayed onto the retro-reflective material. At the same time, light rays from the rest of the world are allowed to reach the user’s eye, making it seem as if an invisible person exists in an otherwise normal-looking world.
NASA scientists took time on Wednesday (Nov. 28) to soothe 2012 doomsday fears, warning against the dark side of Mayan apocalypse rumors — frightened children and suicidal teens who truly fear the world may come to an end Dec. 21.
Image: Artist’s conception of the rogue planet Nibiru, or Planet X. Credit: gilderm | sxc.hu
These fears are based on misinterpretations of the Mayan calendar. On the 21st, the date of the winter solstice, a calendar cycle called the 13th b’ak’tun comes to an end. Although Maya scholars agree that the ancient Maya would not have seen this day as apocalyptic, rumors have spread that a cosmic event may end life on Earth on that day.
Thus NASA’s involvement. The space agency maintains a 2012 information page debunking popular Mayan apocalypse rumors, such as the idea that a rogue planet will hit Earth on Dec. 21, killing everyone. (In fact, astronomers are quite good at detecting near-Earth objects, and any wandering planet scheduled to collide with Earth in three weeks would be the brightest object in the sky behind the sun and moon by now.)
“There is no true issue here,” David Morrison, an astrobiologist at NASA Ames Research Center, said during a NASA Google+ Hangout event today (Nov. 28). “This is just a manufactured fantasy.”
Unfortunately, Morrison said, the fantasy has real-life consequences. As one of NASA’s prominent speakers on 2012 doomsday myths, Morrison said, he receives many emails and letters from worried citizens, particularly young people. Some say they can’t eat, or are too worried to sleep, Morrison said. Others say they’re suicidal.
“While this is a joke to some people and a mystery to others, there is a core of people who are truly concerned,” he said.
Not every 2012 apocalypse believer thinks the world will end on Dec. 21. Some, inspired by New Age philosophies, expect a day of universal peace and spiritual transformation. But it’s impressionable kids who have NASA officials worried.
“I think it’s evil for people to propagate rumors on the Internet to frighten children,” Morrison said.
Myths and misconceptions
NASA scientists took questions via social media in the hour-long video chat, debunking doomsday myths from the rogue planet Nibiru to the danger of killer solar flares.
In fact, said NASA heliophysicist Lika Guhathakurta, it’s true that the sun is currently in an active phase of its cycle, meaning electromagnetic energy has picked up. Large solar flares can impact electronics and navigation systems on Earth, but satellites monitoring the sun give plenty of warning and allow officials to compensate for the extra electromagnetic activity when it hits our atmosphere. What’s more, Guhathakurta said, this particular solar maximum is the “wimpiest” in some time — scientists have no reason to expect solar storms beyond what our planet has weathered in the past.
Nor are any near-Earth objects, planetary or otherwise, threatening to slam into our planet on Dec. 21, said Don Yeomans, a planetary scientist who tracks near-Earth objects at NASA’s Jet Propulsion Laboratory. The only close asteroid approach on the horizon is forecast to occur on Feb. 13, 2013, when an asteroid will pass within 4.5 Earth radii to our planet (for perspective, Earth’s radius is 3,963 miles, or 6,378 kilometers). The asteroid is not going to hit Earth, Yeomans said.
Other rumors — that the Earth’s magnetic field will suddenly reverse or that the planet will travel almost 30,000 light-years and fall into the black hole at the center of the Milky Way galaxy — were also dismissed. (A light-year is the distance light travels in one year, or about 6 trillion miles, or 10 trillion km.)
One popular rumor that the planet will undergo a complete blackout from Dec. 23 to 25 earned a “What?” and blank looks from the panel of scientists.
Ultimately, concerns about Earth’s fate would be better focused on slow-acting problems such as climate change rather than some sort of cosmic catastrophe, said Andrew Fraknoi, an astronomer at Foothill College in California.
Mitzi Adams, a heliophysicist at NASA’s Marshall Space Flight Center, agreed.
“The greatest threat to Earth in 2012, at the end of this year and in the future, is just from the human race itself,” Adams said.
Solar systems with life-bearing planets are, so far, unique. There is only one. But they would be rare anyway, if they are dependent on the presence of asteroid belts of just the right mass, according to two US astronomers. Rebecca Martin, a NASA Sagan Fellow from the University of Colorado and astronomer Mario Livio of the Space Telescope Science Institute in Baltimore suggest that the size and location of an asteroid belt, shaped by the evolution of the Sun’s protoplanetary disk and by the gravitational influence of a nearby giant Jupiter-like planet, may determine whether complex life could evolve on an Earth-like planet. So asteroids aren’t just a nuisance? They propose instead that asteroid collisions with planets may provide a boost to the birth and evolution of complex life, and might have here - by delivering water and organic compounds to the early Earth. According to the concept of punctuated equilibrium, occasional asteroid impacts might accelerate the rate of biological evolution by disrupting a planet’s environment to the point where species must try new adaptation strategies. (via Asteroid Belts: Why Complex Life Is Unique In The Universe (So Far))