Viewing Alert: Jupiter Impacted by a Fireball
(George Hall, an amateur astronomer in Dallas Texas, captured the impact flash in his webcam on 10 September 2012. Credit)
“From astronomer Heidi Hammel of the Space Science Institute comes news about a potential new impact on Jupiter. She reports there has been a visual sighting of an apparent fireball on Jupiter earlier today (about 10 hours ago, as of this posting) so the impact site should be visible again over the next few hours. According to amateur astronomers discussing this on G+, the impact area on Jupiter won’t be visible again until about 05:00 UTC, (01:00 EDT). The amateur who observed the flash reported it to Richard Schmude of the Association of Lunar and Planetary Observers (ALPO). Hammel says the report sounds realistic, but obviously it needs confirmation if possible: a) by looking for any ‘impact scar’ tonight or over the next few days; b) by searching any webcam video that any observers might have been recording at the time. From the time and position given, the flash was on the North Equatorial Belt at approximately L1=335, L2=219, L3=257. ‘Let’s hope someone has a record of it!’ Hammel says.”
(UPDATE: Confirmation!)
This event is another example of something by now we’re familiar with: the impact of small comets and asteroids onto planets, happening right in front of us. The most famous example in modern times is the impact of Comet Shoemaker-Levy 9 onto Jupiter in 1994. As in that instance, we might expect evidence of the resulting fireball to persist for some number of rotations of Jupiter, perhaps visible as a dark splotch on its surface to keen observers. We’re reminded by this that even billions of years after it’s formation, the Solar System continues to be a violent place. -JCB
See The Moon And Two Planets Tonight (August 22)
“The moon has been awesome these past few nights in the western twilight sky! It’s been moving past the very noticeable triangle there, consisting of two planets – Mars and Saturn – and the star Spica in the constellation Virgo. But of course the moon never stops moving. As darkness falls this evening in North America, the rather wide waxing crescent moon appears to the south of the constellation Libra, and to the east of the planets Saturn and Mars. In the Eastern Hemisphere – Europe, Africa, Asia, Australia and New Zealand – tonight’s moon will be closer to Mars and Saturn than it is in the Western Hemisphere.”
Look to the southwest tonight at dusk and find the Moon, then use the chart above to lead you on to Saturn and Mars. And when you find Mars, think about the fact that right now, there’s a rover from Earth there with a laser beam strong enough to vaporize solid rock… -JCB
Quasicrystals From Outer Space
The beautiful and bizarre mosaic-like structures called quasicrystals are almost all made in laboratories. Just one natural sample has ever been found, in a millimetre-sized rock fragment at the Museum of Natural History in Florence, Italy. Until now.
(The Florence Museum’s meteorite fragment, which holds a grain of quasicrystal. Credit: Paul J Steinhardt)
“In January this year, theoretical physicist Paul Steinhardt, of Princeton University in New Jersey, reported how he had traced the Florence rock back to its source — the Listvenitovyi Stream in the Koryak mountains in Chukotka, a remote gold-mining region in northeastern Russia. It turned out that a man named Valery Kryachko had dug up the stuff in 1979 while searching for platinum, and it was eventually smuggled to Florence.”
“In a review published in the journal Reports on Progress in Physics, Steinhardt and Luca Bindi (a mineralogist at the Florence museum) say that their expedition did find new rock fragments containing grains of quasicrystals: solids with a mosaic-like atomic structure that appears to show long-range order but never quite repeats its arrangement. And the evidence further backs up their January report that these quasicrystals appear to come from a meteorite some 4.5 billion years old. Rocks found around the site suggest the meteorite, a carbonaceous chondrite, landed on Earth before or during the last ice age, 15,000 years ago.”
Quasicrystals inhabit the Wild West frontier of material science, having only relatively recently become part of the accepted mainstream — in fact, they helped win the Nobel Prize in Chemistry just last year, almost 30 years after having been discovered. In short, quasicrystals are materials whose structures are ordered but not periodic, whereas crystals are both of those things. So quasicrystals can intricate, symmetric patterns to the arrangement of their atoms, but those patterns only repeat over fairly short distance in the material: think of the intricate pattens in Islamic tile art.
(Credit: Wikipedia)
However, until very recently, we have never seen these materials in nature. The most interesting aspect of this story is that when we did encounter quasicrystals in nature, we found them not on Earth but in space. One thing that the Earth is good at doing is altering materials, both in its interior and on its surface; the oldest rocks we have yet found in Earth’s crust are still younger than the planet itself, with the oldest rocks considered now destroyed by forces of erosion and metamorphism. Most solar system surfaces don’t experience this kind of weathering and reconstitution, particularly on smaller bodies like asteroids. So the discovery of quasicrystals in meteorites (and not in the Earth) seems to suggest that that the Earth isn’t a conducive place to forming this phase of solid matter.
The other thing the discovery tells us is that the mechanisms for making quasicrystals outside the laboratory — whatever exactly they are — were operating a very long time ago. That is, unless there’s some previously unknown geologic process which can transform material into a quasicrystal over various periods of time. But it’s just possible these processes were acting in the very earliest days of the solar system as the Sun and planets were condensing out of the solar nebula. The opposite of a crystal — a totally disordered structure — is called the amorphous phase; the most familiar amorphous solid is glass. We have seen both of those phases in silicate minerals condensing out of the dusty disks around forming, young stars. But we have yet to see the telltale signature of quasicrystals; they may instead form later, after the disks condense into planets and asteroids. Or they’re forming early but in quantities too small for us to detect. Either way, the discovery of quasicrystals in meteorites opens an entirely new window into a rare and exotic phase of matter about which we still know so little. -JCB
How To Observe The Perseid Meteor Shower
As a follow-up to my previous post about watching golfballs hit the moon at 100,000 miles an hour, here’s a guide to the Perseids and how to enjoy them.
- What are the Perseids? They are particles shed by Comet 109P/Swift-Tuttle, a periodic comet that last passed near Earth in 1992. Composed of mostly silicate minerals, the typical meteor particle, or meteoroid, is about the size of a grain of sand. The motion of the Earth through its orbit carries us toward “streams” of these particles left behind in the comet’s wake; our relative motion toward them makes the particles encounter the Earth at a relative velocity of tens to hundreds of thousands of miles per hour. They meet the upper atmosphere and vaporize as they reach temperatures of thousands of degrees for a few brief seconds; we see their remnants as bright streaks of light commonly known as “shooting stars”. The Perseid shower is one of the year’s more notable events, leading sometimes to hundreds of meteors per hour being seen.
- How often do they happen? The Perseids are an annual event each August, and has been happening at least since antiquity. Last seen exactly 150 years ago during the Civil War, Swift-Tuttle was somewhat considered “lost” because its observations in 1862 were not sufficiently precise to nail down its orbit. The comet “announced” its coming return to the inner solar system during the 1991 Perseid shower with a huge burst of activity during the early morning hours over East Asia. Speculation as to whether this feature represented material recently shed by the comet was well founded; the comet re-appeared in Earth’s skies about a year later. Each time the comet returns, a new stream of particles is shed and the shower is replenished.
- Why are meteors important? There’s a lot of science involved. So many comets have come and gone over the history of the solar system that the inner part is chock full of dust particles. These particles constantly rain down on the Earth and other terrestrial planets, bringing many tons of cosmic material per year; early in the solar system’s history, this may have included the essential components needed in the chemistry of life. The particles are thought to be relatively pristine, in the sense that they avoided the thermal shocks and chemical mixing that occurred in the solar nebula. So a meteor seen streaking across our skies is a glowing messenger from the earliest times of our planetary system, telling us what conditions were like then.
- Do I need a telescope to observe the Perseids? Nope! Meteor showers are a phenomenon requiring no special equipment at all; in fact, binoculars and telescopes allow views of such relatively small parts of the sky that they’re mostly ineffective for meteor observing. Rather, showers like the Perseids contain many larger particles, which make for brighter meteors, and the best instruments to observe them are unaided human eyeballs. Our eyes are pretty sensitive once dark adaptation has occurred, and we can see a very large area of sky at a time with them, increasing the chances of seeing meteors.
- When should I look for Perseid meteors? The shower peaks in intensity around August 11-13, so it’s going on right now — even during daylight hours. However, for nighttime observing, the hours between midnight and dawn are best, because of the relative speed difference between the meteors and the Earth. Before midnight, we’re facing away from the direction the Earth moves in its orbit around the Sun, so to be seen the meteors have to “catch up” to us. After midnight, we’re facing the direction of motion and the relative speeds are highest. Speed correlates with meteor brightness (for a given particle size), so you’re likely after midnight to see fainter meteors as a result.
- What part of the sky should I look toward? The Perseids can be seen in any part of the sky, but they appear to “radiate” from a point in the constellation Perseus. In August, that constellation is rising in the northeastern sky toward midnight in the Northern Hemisphere. So facing northeast aligns the observer with the direction from which the meteors appear to originate and increases the chances they’ll be seen before burning out. Also, choice of seating is important, and a reclining lawn or lounge chair is highly recommended. Staring upwards for hours at a time is otherwise rough on the neck muscles!
- What can I expect to see? In an average year, observers can typically expect about one meteor per minute during the shower’s peak. The rate is somewhat variable, and at times several will be seen per minute. The Perseid shower is known for lots of bright, slow-moving fireballs, some of which explode at the end of their travel in a “terminal burst”. At times these fireballs are bright enough to cast shadows on the ground. There is rarely obvious color in meteors, but the Perseids tend toward a pale yellow, possibly due to emission of light from ionized sodium atoms. The Perseids, one of the most reliable meteor showers of the year, rarely fail to impress!
- Will the Moon be a problem? Yes and no. This year’s shower peaks a few days after the Moon is at last quarter, meaning two things: (1) The early part of the night will be Moon-free, and (2) After the Moon rises, it will present some interference. Moonlight adds to the sky background, making the faintest Perseids difficult to see. But don’t worry — the brightest meteors will easily outshine this light. The main tip here is to not look in the direction of the Moon, to keep its light from ruining one’s dark adaptation. One of the best tricks is to keep the Moon behind some obstruction, like a building or a tree, while maintaining a clear view to the northeast. Remaining in shadow will minimize the interference.
- Are my observations useful? Yes! Meteor watching is a great citizen-science opportunity. Meteor science still relies on boots-on-the-ground observations from people, many of whom are amateur astronomers and other interested skywatchers. Ways to participate can be found here, here and here. Having multiple people at one observing site helps in collecting observations, since several individuals can cover more of the sky at once than one person. But one person can still see a lot of sky, and solo observations are quite useful.
- Finally, stay warm, as the predawn hours in August can be cold in many parts of the Northern Hemisphere. My meteor watching inevitably involves a thermos of hot coffee to help ward of the chill and drowsiness.
Additional resources:
- Sky and Telescope: “Here Come The Perseids!”
- The International Meteor Organization (IMO) Perseid page
- The North American Meteor Network (NAMN) star charts for recording meteor observations
- MeteorObs: An internet forum for meteor observers of all levels
- StarDate: “Perseid Meteors Pierce The August Sky”
Pluto Now Has Five (Yes, Five) Moons
Observations made with the Hubble Space Telescope in just the past two weeks have revealed yet another moon in the Pluto system: S/2012 P 1, aka “P5” (circled, above). This wayward chunk of ice and rock may be no more than about 15 miles in diameter, the size of a small city, and irregularly shaped. Why should anyone care how many moons this “former” planet has? Because a spacecraft from Earth is on its way to give us our first close-up view of this distant moon — the New Horizons mission, arriving in 2015. We’ll be in largely uncharted waters, and the discovery of more Plutonian moons means that even smaller ones may exist that we can’t see from Earth. That makes for a potentially dangerous flyby, although we will be as prepared as we can to visit this totally unfamiliar place. There are new discoveries to be made right here, in our own Solar System, still. -JCB
(via discoverynews)
Venus 12 Days After Transit
ImageSouce CCD and 16 inch Ritchey–Chrétien telescope. 3 min video processed with Registax software.
(Credit & Copyright: Dean Salman / National Optical Astronomy Observatoroes (NOAO) / Association of Universities for Research in Astronomy, Inc.)
Get Ready, Because Voyager I Is **This Close** to Leaving Our Solar System
We’re on the cusp of one of the greatest scientific accomplishments of all time, but we may not know when the moment strikes. Or, rather, there may be no moment.
(An artist’s rendering of the two Voyager spacecraft at the outer edge of our solar system. Credit: NASA)
“Last week, in the corners of the Internet devoted to outer space, things started to get a little, well, hot. Voyager 1, the man-made object farthest away from Earth, was encountering a sharp uptick in the number of a certain kind of energetic particles around it. Had the spacecraft become the first human creation to “officially” leave the solar system?”
“It’s hard to overstate how wild an accomplishment this would be: A machine, built here on Earth by the brain- and handiwork of humans, has sailed from Florida, out of Earth’s orbit, beyond Mars, beyond the gas giants of Jupiter and Saturn, and may now have left the heliosphere — tiny dot in the universe beholden to our sun. Had it really happened? How would we know?”
Space Scientists Hold Bake Sales To Highlight NASA Cuts
Focusing on a $300 million NASA budget cut for planetary exploration, some American astro-brains will hold bake sales and car washes Saturday to raise a little political capital.
(Image Credit: AFP/File, Stan Honda)
“Organizers say about 20 fund- and attention-raising events are planned nationwide.”
“‘We’re not asking for more of the pie, we’re asking for less of a bite out of the pie,’ said Laura Seward, a graduate student at the University of Central Florida in Orlando and organizer of the Planetary Exploration Car Wash and Bake Sale. ‘A strong robotic planetary exploration program is essential for a strong human planetary exploration program.’”
“Among the cuts in his February budget, President Obama canceled joint U.S.-European robotic missions to Mars in 2016 and 2018, forcing NASA scientists to figure out how to still reach the Red Planet in 2018, when it makes its closest approach to Earth in 15 years.”
“‘It’s important these cuts be repaired to maintain U.S. leadership in this area of science, to prevent mission cuts, and to prevent student and research job losses,’ said Alan Stern of the Southwest Research Institute in Boulder, Colo., which is sponsoring the day’s events.
“Astronomer Jill Tarter of the Center for SETI Research said the the nation ‘risks the loss of a generation of upcoming, talented engineers and researchers whose careers are centered on the exploration of our solar system in the quest for life beyond Earth.’”
(Blogger’s editorial note: The level of tone deafness involved in this event is stunning. The planetary science community, like the astronomy community, is quickly going to have to learn how to do as much as it can with significantly less federal funding. While standing up publicly for their craft is admirable, it comes across as a stunt, one that seems designed to merely forestall the inevitable. In an era of dwindling budgets, branches of science without obvious angles for commercial exploitation are slow-moving targets for bureaucrats, and American planetary science swims against this rising tide at its own peril. -JCB)
Venus Transit in hydrogen alpha light, 5 June 2012
(Credit & copyright: Gilbert A. Esquerdo)
Astronomy news, recent research results, and pretty pictures from the media along with context, commentary, and explanations for folks who dig this sort of thing. Written by a quasi-professional astronomer affiliated with the University of Texas at Austin.
