Astronomy Archives

January 10, 2014December 23, 2015 by Tammy Plotner

One Percent Measure of the Universe

An artist's concept of the latest, highly accurate measurement of the Universe from BOSS. The spheres show the current size of the "baryon acoustic oscillations" (BAOs) from the early universe, which have helped to set the distribution of galaxies that we see in the universe today. Galaxies have a slight tendency to align along the edges of the spheres — the alignment has been greatly exaggerated in this illustration. BAOs can be used as a "standard ruler" (white line) to measure the distances to all the galaxies in the universe. Credit: Zosia Rostomian, Lawrence Berkeley National Laboratory

When it comes to accuracy, everyone strives for a hundred percent, but measuring cosmic distances leaves a bit more to chance. Just days ago, researchers from the Baryon Oscillation Spectroscopic Survey (BOSS) announced to the world that they have been able to measure the distance to galaxies located more than six billion light-years away to a confidence level of just one percent. If this announcement doesn’t seem exciting, then think on what it means to other studies. These new measurements give a parameter to the properties of the ubiquitous “dark energy” – the source of universal expansion.

“There are not many things in our daily lives that we know to one-percent accuracy,” said David Schlegel, a physicist at Lawrence Berkeley National Laboratory (LBNL) and the principal investigator of BOSS. “I now know the size of the universe better than I know the size of my house.”

The research team’s findings were presented at the meeting of the American Astronomical Society by Harvard University astronomer Daniel Eisenstein, the director of the Sloan Digital Sky Survey III (SDSS-III), the worldwide organization which includes BOSS. They are detailed in a series of articles submitted to journals by the BOSS collaboration last month, all of which are now available as online preprints.

“Determining distance is a fundamental challenge of astronomy,” said Eisenstein. “You see something in the sky — how far away is it? Once you know how far away it is, learning everything else about it is suddenly much easier.”

When it comes to measuring distances in space, astronomers have employed many methods. To measure distances to planets has been accomplished using radar, but it has its constraints and going further into space means a less direct method. Even though they have been proved to be amazingly accurate, there is still an uncertainty factor involved – one that is expressed as a percentage. For example, if you were to measure the distance from an object 200 miles away to within a true value of 2 miles, then you have measured with an accuracy of 1%. Cosmically speaking, just a few hundred stars and a handful of star clusters are actually close enough to have their distances so accurately predicted. They reside within the Milky Way and are just a few thousand light-years away. BOSS takes it to the extreme… its measurements go well beyond our galactic boundaries, more than a million times further, and maps the Universe with unparalleled accuracy.

Thanks to these new, highly-accurate distance measurements, BOSS astronomers are making headway in the field of dark energy. “We don’t yet understand what dark energy is,” explained Eisenstein, “but we can measure its properties. Then, we compare those values to what we expect them to be, given our current understanding of the universe. The better our measurements, the more we can learn.”

Just how is it done? To achieve a one-percent measurement at six billion light years isn’t as easy as measuring a solar system object, or even one contained within our galaxy. That’s where the BOSS comes into play. It’s the largest of the four projects that make up the Sloan Digital Sky Survey III (SDSS-III), and was built to take advantage of this technique: measuring the so-called “baryon acoustic oscillations” (BAOs), subtle periodic ripples in the distribution of galaxies in the cosmos. These ripples are the signature of pressure waves which once cruised the early Universe at a time when things were so hot and dense that photons marched along with baryons – the stuff which creates the nuclei of atoms. Since the size of the ripple is known, that size can now be measured by mapping galaxies.

“With these galaxy measurements, nature has given us a beautiful ruler,” said Ashley Ross, an astronomer from the University of Portsmouth. “The ruler happens to be half a billion light-years long, so we can use it to measure distances precisely, even from very far away.

Using its specialized instrumentation which can make detailed measurements of a thousand galaxies at a time, BOSS took on a huge challenge – mapping the location of more than a million galaxies. “On a clear night when everything goes perfectly, we can add more than 8000 galaxies and quasars to the map,” said Kaike Pan, who leads the team of observers at the SDSS-III’s Sloan Foundation 2.5-meter Telescope at Apache Point Observatory in New Mexico.

Although the BOSS research team presented its early galaxy maps and beginning BAO measurements a year ago, this new data covers twice as much territory and gives an even more accurate measurement – including those to nearby galaxies. “Making these measurements at two different distances allows us to see how the expansion of the universe has changed over time, which will help us understand why it is accelerating,” explained University of Portsmouth astronomer Rita Tojeiro, who co-chairs the BOSS galaxy clustering working group along with Jeremy Tinker of New York University.

Also doing a similar study is Mariana Vargas-Magana, a postdoctoral researcher at Carnegie Mellon University. To enable even more accuracy, she’s looking into any subtle effects which could influence the BOSS measurements. “When you’re trying to reach one percent, you have to be paranoid about everything that could go even slightly wrong,” said Vargas-Magana — for example, slight differences in how galaxies were identified could have thrown off the entire measurement of their distribution, so different parts of the sky had to be checked carefully. “Fortunately,” Vargas-Magana said, “there are plenty of careful people on our team to check our assumptions. By the time all of them are satisfied, we are sure we didn’t miss anything.”

As of the present, these new BOSS findings would seem to be consistent with what we consider to be form of dark energy – a constant found throughout the history of the Universe. According to the news release, this “cosmological constant” is one of just six numbers required to create a model which coincides with the scale and structure of the Universe. Schlegel compares this six-number model to a pane of glass, which is pinned in place by bolts that represent different measurements of the history of the Universe. “BOSS now has one of the tightest of those bolts, and we just gave it another half-turn,” said Schlegel. “Each time you ratchet up the tension and the glass doesn’t break, that’s a success of the model.”

Original Story Source: Sloan Digital Sky Survey III News Release. For further reading: Max Planck Institute News Release.

January 10, 2014December 23, 2015 by David Dickinson

New Findings from NuSTAR: A New X-Ray View of the “Hand of God” and More

The "Hand ( or Fist?) of God" nebula enshrouding pulsar PSR B1509-58. The upper red cloud structure is RCW 89. The image is a composite of Chandra observations (red & green), while NuSTAR observations are denoted in blue.

One star player in this week’s findings out of the 223^rd meeting of the American Astronomical Society has been the Nuclear Spectroscopic Telescope Array Mission, also known as NuSTAR. On Thursday, researchers revealed some exciting new results and images from the mission, as well as what we can expect from NuSTAR down the road.

NuSTAR was launched on June 13^th, 2012 on a Pegasus XL rocket deployed from a Lockheed L-1011 “TriStar” aircraft flying near the Kwajalein Atoll in the middle of the Pacific Ocean.

Part of a new series of low-cost missions, NuSTAR is the first of its kind to employ a space telescope focusing on the high energy X-ray end of the spectrum centered around 5-80 KeV.

Daniel Stern, part of the NuSTAR team at JPL Caltech, revealed a new X-ray image of the now-famous supernova remnant dubbed “The Hand of God.” Discovered by the Einstein X-ray observatory in 1982, the Hand is home to pulsar PSR B1509-58 or B1509 for short, and sits about 18,000 light years away in the southern hemisphere constellation Circinus. B1509 spins about 7 times per second, and the supernova that formed the pulsar is estimated to have occurred 20,000 years ago and would’ve been visible form Earth about 2,000 years ago.

A diagram of the NuSTAR satellite. (NASA/JPL/Caltech)

While the Chandra X-ray observatory has scrutinized the region before, NuSTAR can peer into its very heart. In fact, Stern notes that views from NuSTAR take on less of an appearance of a “Hand” and more of a “Fist”. Of course, the appearance of any nebula is a matter of perspective. Pareidolia litter the deep sky, whether it’s the Pillars of Creation to the Owl Nebula. We can’t help but being reminded of the mysterious “cosmic hand” that the Guardians of Oa of Green Lantern fame saw when they peered back at the moment of creation. Apparently, the “Hand” is also rather Simpson-esque, sporting only three “fingers!”

An diagram of the Hand of God. Credit: NASA/JPL/Caltech/McGill).

NuSTAR is the first, and so far only, focusing hard X-ray observatory deployed in orbit. NuSTAR employs what’s known as grazing incidence optics in a Wolter telescope configuration, and the concentric shells of the detector look like layers on an onion. NuSTAR also requires a large focal length, and employs a long boom that was deployed shortly after launch.

The hard X-ray regime that NuSTAR monitors is similar to what you encounter in your dentist’s office or in a TSA body scanner. Unlike the JEM-X monitor aboard ESA’s INTERGRAL or the Swift observatory, which have a broad resolution of about half a degree to a degree, NuSTAR has an unprecedented resolution of about 18 arc seconds.

The first data release from NuSTAR was in late 2013. NuSTAR is just begging to show its stuff, however, in terms of what researchers anticipate that it’s capable of.

“NuSTAR is uniquely able to map the Titanium-44 emission, which is a radioactive tracer of (supernova) explosion physics,” Daniel Stern told Universe Today.

NuSTAR will also be able to pinpoint high energy sources at the center of our galaxy. “No previous high-energy mission has had the imaging resolution of NuSTAR,” Stern told Universe Today. ”Our order-of-magnitude increase in image sharpness means that we’re able to map out that very rich region of the sky, which is populated by supernovae remnants, X-ray binaries, as well as the big black hole at the center of our Galaxy, Sagittarius A* (pronounced “A-star).”

NuSTAR identifies new black hole canidates (in blue) in the COSMOS field. Overlayed on previous black holes spotted by Chandra in the same field denoted in red and green. (Credit-NASA/JPL-Caltech/Yale University). — NuSTAR identifies new black hole candidates (in blue) in the COSMOS field. The discoveries in the image above are overlayed on previous black holes spotted by Chandra in the same field, which are denoted in red and green. (Credit-NASA/JPL-Caltech/Yale University).

Yale University researcher Francesca Civano also presented a new image from NuSTAR depicting black holes that were previously obscured from view. NuSTAR is especially suited for this, gazing into the hearts of energetic galaxies that are invisible to observatories such Chandra or XMM-Newton. The image presented covers the area of Hubble’s Cosmic Evolution Survey, known as COSMOS in the constellation Sextans. In fact, Civano notes that NuSTAR has already seen the highest number of obscured black hole candidates to date.

“This is a hot topic in astronomy,” Civano said in a recent press release. “We want to understand how black holes grew and the degree to which they are obscured.”

To this end, NuSTAR researchers are taking a stacked “wedding cake” approach, looking at successively larger slices of the sky from previous surveys. These include looking at the quarter degree field of the Great Observatories Origins Deep Survey (GOOD-S) for 18 days, the two degree wide COSMOS field for 36 days, and the large four degree Swift-BAT fields for 40 day periods hunting for serendipitous sources.

Interestingly, NuSTAR has also opened the window on the hard X-ray background that permeates the universe as well. This peaks in the 20-30 KeV range, and is the combination of the X-ray emissions of millions of black holes.

“For several decades already, we’ve known what the sum total emission of the sky is across the X-ray regime,” Stern told Universe Today. “The shape of this cosmic X-ray background peaks strongly in the NuSTAR range. The most likely interpretation is that there are a large number of obscured black holes out there, objects that are hard to find in other energy bands. NuSTAR should find these sources.”

And NuSTAR may just represent the beginning of a new era in X-ray astronomy. ESA is moving ahead with its next generation flagship X-ray mission, known as Athena+, set to launch sometime next decade. Ideas abound for wide-field imagers and X-ray polarimeters, and one day, we may see a successor to NuSTAR dubbed the High-Energy X-ray Probe or (HEX-P) make it into space.

But for now, expect some great science out of NuSTAR, as it unlocks the secrets of the X-ray universe!

January 10, 2014December 23, 2015 by Jason Major

Selling Rocks from Outer Space: an Interview with ‘Meteorite Man’ Geoff Notkin

Geoff Notkin at Aerolite Meteorites in Tucson, AZ. (© Geoff Notkin. Used with permission.)

What’s the oldest thing you’ve ever held in your hand? A piece of petrified wood? A fossilized trilobite? A chunk of glacier-carved granite? Those are some pretty old things, sure, but there are even older objects to be found across the world… that came from out of this world. And thanks to “Meteorite Men” co-host, author, and educator Geoff Notkin and his company Aerolite Meteorites, you can own a truly ancient piece of the Solar System that can date back over 4.5 billion years.

Founded in 2005, Aerolite (which is an archaic term for meteorite) offers many different varieties of meteorites for sale, from gorgeous specimens worthy of a world-class museum to smaller fragments that you could proudly — and economically — display on your desk. Recently I had the opportunity to talk in depth with Geoff about Aerolite and his life’s work as a meteorite collector and dealer. Here are some of the fascinating things he had to say…

Geoff holds one of his found meteorites (© Geoff Notkin) — “I promised myself as a kid that one day I would have an actual meteorite.” (© Geoffrey Notkin)

So Geoff, what initially got you interested in meteorites and finding them for yourself?

“It’s been a lifelong passion for me, but I’m lucky in that I can really put my finger on a specific event when I was a kid and that was my mother taking me to the Geological Museum in London when I was six or seven… I was already a rock hound, I loved collecting fossils, and my dad was a very keen amateur astronomer. And so I had this love of astronomy and this fascination with other worlds for as long as I can remember. I’m a very tactile person; I’m very hands-on. I like to know how things work… I want to know all the bits and pieces. I was frustrated a bit, because I wanted to know more about astronomy. I could see all these planets and places through the ‘scope, but I couldn’t touch them. But I could touch rocks and fossils.

“So I’m six or seven years old, and I’m on the second floor of the Museum in the Hall of Rocks and Minerals. And at the back was this small display area that’s very dark. And you walked through an arch, it’s almost like walking into a cave. And it was very low light back there, and that was the meteorite collection.

“There were a couple of large meteorites on stands, and in those days — it was the late 60s — security wasn’t the issue that it is today. So you could touch the big specimens, and so I put my hands on these giant meteorites and I was absolutely enthralled. And I had this sort of epiphany: meteorites were the locus between my two interests, astronomy and rock-hounding. Because they’re rocks… they’re rock samples from outer space. I promised myself as a kid that one day I would have an actual meteorite.

“By finding or owning meteorites, you are forging a solid and tangible connection with astronomy.”

“Of course at the time there was no meteorite business, no meteorite magazines, there was no network of collectors like there is today. Back in the late 60s when I gave myself this challenge it was like saying I was going to start my own space program! But not only did it come true, it’s become my career.”

One of the meteorites offered at Aerolite.org (© Geoff Notkin) — One of the meteorites offered at Aerolite.org (© Geoffrey Notkin)

What makes Aerolite such a great place to buy meteorites?

“I think the caring for the subject matter really shows on the website. We have the best photography in the entire meteorite industry. I think we have the largest selection… we certainly spend a great deal of time discussing the history and importance of pieces… every single meteorite on our website has a detailed description and in most cases multiple photographs. My view is if you’re going to do something, you should really do it to the best of your ability. We don’t cut any corners, we don’t sell anything unless we’re one hundred percent sure of what it is and where it came from.

“I want buyers and visitors to look at the website and share my sense of wonder about meteorites. I think meteorites are the most wonderful things in existence, they’re actual visitors from outer space — they’re inanimate aliens that have landed on our planet.”

“We do this because we want to share our passion. We stand by every piece that we sell.”

How can people be sure they are getting actual meteorites (and not just funny-looking rocks?)

“This is something that’s more important to pay attention to now than ever. Are there fakes, are there shady people? Yes and yes. If you go on eBay at any given time you will find numerous pieces that are being offered for sale that are either not meteorites at all or are one thing being passed off as another thing. Sometimes this is malicious, sometimes people just don’t know any better. So the best way to buy a meteorite and know that it’s real is to buy from a respected dealer who has a solid history in the field.

“I’m by no means the only person who does this. There are a number of very well-established dealers around the world, and a good place to start is the International Meteorite Collectors Association (of which Geoff is a member) which is an international group with hundreds of members — collectors and dealers… it’s sort of a watchdog group that tries to maintain high standards of integrity in the field.

“My company has a very strict policy of never offering anything that’s questionable.”

“I see fakes all the time,” Geoff added. “On eBay, on websites, in newspaper ads… you do have to be careful. My company has a very strict policy of never offering anything that’s questionable. And we do get offered questionable things. There are some countries that have strict policies about exporting meteorites — Australia and Canada being two of them — and we work very closely with academia in both countries, and we have legally exported meteorites from those countries. Not only do we abide by international regulations, we actively support them.”

Geoff and some of his 'alien'-hunting gadgets in the Chilean desert. (© Geoff Notkin) — Geoff and some of his ‘alien’-hunting gadgets in the Chilean desert. (© Geoffrey Notkin)

So you not only offer meteorites for sale to the general public, but you also donate to schools and museums.

“We work very closely with most of the world’s major meteorite institutions. I have provided specimens to the American Museum of Natural History in New York, the British Museum of Natural History in London, the Vienna Museum of Natural History, the Center for Meteorite Studies… we work with almost everyone. When we find something that is new or different or exciting, we always donate a piece or pieces to our colleagues in academia. It’s just the right thing, it’s the right thing to do if you discover something important to make it available to science.

A sample of a beautiful, partially-translucent pallasite meteorite (© Geoff Notkin) — A sample of a beautiful, partially-translucent pallasite meteorite (© Geoffrey Notkin)

“Most universities and museums don’t have acquisitions budgets and can’t afford to buy things that they might like to have. In return they classify the meteorites that we found, and they go into the permanent literature and become more valuable as a result. A meteorite with a history and a name and classification is worth more than a random meteorite that somebody just found in a desert. So everybody benefits, it’s a really good match.”

In other words, you really are making a contribution to science as opposed to just “looting.”

“Exactly. And I have, a very few times, gotten emails from disgruntled viewers who didn’t understand what we were doing, saying ‘what makes you think it’s okay to come to Australia and take our meteorites,’ for example. So I wrote a very courteous email back saying that we were in Australia with the express permission and cooperation of the Australian park services and one of the senior park rangers was there with us. And not only did we follow the proper procedure in having those specimens exported from Australia, I donated rare meteorites to collections just as a ‘thank you’ for working with us. It wasn’t a trade, it was a thank you. So everywhere we go, whatever we do, we try and leave a good impression.”

Geoff added, “I do this out of love… this isn’t the best way to make a living! Being a meteorite hunter is probably not the best capital return on your time but it’s a very exciting and rewarding life in every other way.”

Geoff Notkin is also the host of STEM Journals, an educational show on COX 7 soon entering its third season (© Geoff Notkin) — Geoff Notkin is also the host of STEM Journals, an educational show on COX 7 soon entering its third season (© Geoffrey Notkin)

And thus, by buying meteorites from Aerolite, customers aren’t just helping pay for your expeditions and your work but also supporting research and education too.

“People who purchase from us are really participating in the growth of this science. Also, something very near and dear to my heart is science education for kids. You know that I am the host of an educational series called STEM Journals, which is a very — I think — amusing, entertaining, funny, fast-paced look at science, technology, engineering, and math topics. But you can’t make a living doing television shows like that. This is a labor of love… we do it because we think it’s important. If I didn’t have a commercial meteorite company to help underwrite the costs of educational programming and educational books, we just couldn’t do it. It’s as simple as that.

“So we always try to give back. That’s why I speak at schools and universities and give away meteorites to deserving kids at gem shows… because it was done to me when I was seven years old. The look of wonder you see on a kid’s face when you connect with them and they start to grasp the wonder of science… that’s something they’ll never forget.”

That’s great. And it sounds like you haven’t forgotten it yet either!

“I must say after all these years, I’ve been doing this close to full time for nearly twenty years and you never lose the amazement and the wonder of when a meteorite’s found or uncovered. I never go ‘oh, jeez, it’s just another billion-year-old space rock that fell to Earth!’ So it is a privilege to be in a work field where almost daily something wondrous happens.”

As we here at Universe Today know, when it concerns space that’s a common occurrence!

“Exactly!”

One last thing Geoff… do you think we’ll ever run out of meteorites?

“The meteorite collecting field has grown tremendously in the past ten years, and Meteorite Men is part of that. There is a finite supply of meteorites. Of course there are more landing all the time, but not enough to replenish the demand. Periodically there is a new very large discovery made, such as the Gebil Kamil iron in Egypt a couple of years ago. But what is happening is a significant increase in price and a decrease in selection, so some of the real staples we used to see… you can’t get them anymore.

“Still, people who want a meteorite collection, now is a great time for them to be buying because there are more meteorites available than in the past — but it’s not going to stay that way for very long. It’s like any other collectible that has a finite supply.”

Makes sense… I’ll take that as ‘inside advice’ to place an order soon!

______________

My thanks to Geoff for the chance to talk with him a little bit about his fascinating past, his passion, and his company. And as an added bonus to Universe Today readers, Geoff is extending a special 15% off on orders from Aerolite Meteorites — simply mention the code UNIVERSETODAY when you place an order!* (Trust me — once you browse through the site you’ll find something you want.) Also, if you’re in the Tucson area, Geoff Notkin and Aerolite Meteorites will have a table at the Tucson Gem and Mineral Show starting Jan. 31.

One of several meteorite-hunting books by Geoff, featuring an introduction by Neil Gaiman.

Be sure to check out Geoff’s television show STEM Journals on COX7 — the full first two seasons can be found online here and here, and shooting for the third season will be underway soon.

Want to know how to find “inanimate aliens” for yourself? You can find Geoff’s books on meteorite hunting here, as well as some of the right equipment for the job.

And don’t forget to follow Aerolite Meteorites and Geoff Notkin on Twitter!

*Sorry, the code isn’t valid for items already on sale or for select consignment items.

January 9, 2014December 23, 2015 by Tammy Plotner

Millisecond Pulsar Discovered In Rare Triple Star System

An illustration of the triple millisecond pulsar with its two white dwarf companions. According to the new model, this remarkable system has survived three phases of mass transfer and a supernova explosion, and yet it remained dynamically stable. Credit: Thomas Tauris

If you’re looking for something truly unique, then check out the cosmic menage aux trois ferreted out by a team of international astronomers using the Green Bank Telescope (GBT). This unusual group located in the constellation of Taurus includes a pulsar which is orbited by a pair of white dwarf stars. It’s the first time researchers have identified a triple star system containing a pulsar and the team has already employed the clock-like precision of the pulsar’s beat to observe the effects of gravitational interactions.

“This is a truly remarkable system with three degenerate objects. It has survived three phases of mass transfer and a supernova explosion, and yet it remained dynamically stable”, says Thomas Tauris, first author of the present study. “Pulsars have previously been found with planets and in recent years a number of peculiar binary pulsars were discovered which seem to require a triple system origin. But this new millisecond pulsar is the first to be detected with two white dwarfs.”

This wasn’t just a chance discovery. The observations of 4,200 light year distant J0337+1715 came from an intensive study program involving several of the world’s largest radio telescopes including the GBT, the Arecibo radio telescope in Puerto Rico, and ASTRON’s Westerbork Synthesis Radio Telescope in the Netherlands. West Virginia University graduate student Jason Boyles was the first to detect the millisecond pulsar, spinning nearly 366 times per second, and captured in a system which isn’t any larger than Earth’s orbit around the Sun. This close knit association, coupled with the fact the trio of stars is far denser than the Sun create the perfect conditions to examine the true nature of gravity. Generations of scientists have waited for such an opportunity to study the ‘Strong Equivalence Principle’ postulated in Einstein’s theory of General Relativity. “This triple star system gives us the best-ever cosmic laboratory for learning how such three-body systems work, and potentially for detecting problems with General Relativity, which some physicists expect to see under such extreme conditions,” says first author Scott Ransom of the National Radio Astronomy Observatory (NRAO).

“It was a monumental observing campaign,” comments Jason Hessels, of ASTRON (the Netherlands Institute for Radio Astronomy) and the University of Amsterdam. “For a time we were observing this pulsar every single day, just so we could make sense of the complicated way in which it was moving around its two companion stars.” Hessels led the frequent monitoring of the system with the Westerbork Synthesis Radio Telescope.

Not only did the research team tackle a formidable amount of data, but they also took on the challenge of modeling the system. “Our observations of this system have made some of the most accurate measurements of masses in astrophysics,” says Anne Archibald, also from ASTRON. “Some of our measurements of the relative positions of the stars in the system are accurate to hundreds of meters, even though these stars are about 10,000 trillion kilometers from Earth” she adds.

Leading the study, Archibald created the system simulation which predicts its motions. Using the solid science methods once employed by Isaac Newton to study the Earth-Moon-Sun system, she then combined the data with the ‘new’ gravity of Albert Einstein, which was necessary to make sense of the information. “Moving forward, the system gives the scientists the best opportunity yet to discover a violation of a concept called the Strong Equivalence Principle. This principle is an important aspect of the theory of General Relativity, and states that the effect of gravity on a body does not depend on the nature or internal structure of that body.”

Need a refresher on the equivalence principle? Then if you don’t remember Galileo’s dropping two different weighted balls from the Leaning Tower of Pisa, then perhaps you’ll recall Apollo 15 Commander Dave Scott’s dropping of a hammer and a falcon feather while standing on the airless surface of the Moon in 1971. Thanks to mirrors left on the lunar surface, laser ranging measurements have been studied for years and provide the strongest constraints on the validity of the equivalence principle. Here the experimental masses are the stars themselves, and their different masses and gravitational binding energies will serve to check whether they all fall towards each other according to the Strong Equivalence Principle, or not. “Using the pulsar’s clock-like signal we’ve started testing this,” Archibald explains. “We believe that our tests will be much more sensitive than any previous attempts to find a deviation from the Strong Equivalence Principle.” “We’re extremely happy to have such a powerful laboratory for studying gravity,” Hessels adds. “Similar star systems must be extremely rare in our galaxy, and we’ve luckily found one of the few!”

Original Story Source: Astronomie Netherlands News Release. Further reading: Max-Planck-Institut für Radioastronomie (MPIfR) and NRAO Press Release.

January 9, 2014December 23, 2015 by David Dickinson

Chandra’s Verdict on the Demise of a Star: “Death by Black Hole”

A composite x-ray and optical image of a dwarf galaxy showing the x-ray transcient in the inset. Credit-CFHT (Optical), NASA/CXC/University of Alabama/GSCF/UMD/W.P. Maksym, D.Donato et al.

This week, astronomers announced the detection of a rare event, a star being torn to shreds by a massive black hole in the heart of a distant dwarf galaxy. The evidence was presented Wednesday January 8^th at the ongoing 223^rd meeting of the American Astronomical Society being held this week in Washington D.C.

Although other instances of the death of stars at the hands of black holes have been witnessed before, Chandra may have been the first to document an intermediate black hole at the heart of a dwarf galaxy “in the act”.

The results span observations carried out by the space-based Chandra X-ray observatory over a period spanning 1999 to 2005. The search is part of an archival study of observations, and revealed no further outbursts after 2005.

“We can’t see the star being torn apart by the black hole, but we can track what happens to the star’s remains,” said University of Alabama’s Peter Maksym in a recent press release. A comparison of with similar events seen in larger galaxies backs up the ruling of “death by black hole.” A competing team led by Davide Donato also looked at archival data from Chandra and the Extreme Ultraviolet Explorer (EUVE), along with supplementary observations from the Canada-France-Hawaii Telescope to determine the brightness of the host galaxy, and gained similar results.

The dwarf galaxy in the Abell 1795 cluster that was observed has the name WINGS J134849.88+263557.5, or WINGS J1348 for short. The Abell 1795 cluster is about 800 million light years distant.

WINGS denotes the galaxy’s membership in the WIde-field Nearby Galaxy-cluster Survey, and the phone number-like designation is the galaxy’s position in the sky in right ascension and declination.

Like most galaxies associated with galaxy clusters, WINGS J1348 a dwarf galaxy probably smaller than our own satellite galaxy known as the Large Magellanic Cloud. The Abell 1795 cluster is located in the constellation Boötes, and WINGS J1348 has an extremely faint visual magnitude of +22.46.

Optical — An optical view of the Abell 1795 galaxy cluster. Credit- NASA/CFHT/D. Donato et al.

“Scientists have been searching for these intermediate mass black holes for decades,” NASA’s Davide Donato said in a recent press release “We have lots of evidence for small black holes and very big ones, but these medium-sized ones have been tough to pin down.”

Maksym notes in an interview with Universe Today that this isn’t the first detection of an intermediate-mass black hole, which are a class of black holes often dubbed the “mostly” missing link between stellar mass and super massive black holes.

The mass range for intermediate black holes is generally pegged at 100 to one million solar masses.

What makes the event witnessed by Chandra in WINGS J1348 special is that astronomers managed to capture a rare tidal flare, as opposed to a supermassive black hole in the core of an active galaxy.

A bright, long duration flare may be the first recorded event of a black hole destroying a star in a dwarf galaxy. The dwarf galaxy is located in the galaxy cluster Abell 1795, about 800 million light years from Earth. A composite image of the cluster shows Chandra data in blue and optical data from the Canada-France-Hawaii Telescope in red, green and blue. An inset centered on the dwarf galaxy shows Chandra data taken between before and after 2005. The X-ray flare provides evidence that a large black hole has pulled in debris from a star that was torn apart by tidal forces. — A closeup view of the bright, long duration flare witnessed by Chandra pre-2005. Credit- NASA/CXC/University of Alabama/W.P. Maksym et al.

“Most of the time, black holes eat very little, so they can hide very well,” Maksym said in the AAS meeting on Wednesday.

This discovery pushes the limits on what we know of intermediate black holes. By documenting an observed number of tidal flare events, it can be inferred that a number of inactive black holes must be lurking in galaxies as well. The predicted number of tidal events that occur also have implications for the eventual detection of gravity waves from said mergers.

And more examples of these types of X-ray flare events could be waiting to be uncovered in the Chandra data as well.

“Chandra has taken quite a few pictures over the past 13+ years, and collaborators and I have an ongoing program to look for more tidal flares,” Maksym told Universe Today. “We’ve found one other this way, from a larger galaxy, and hope to find more. Abell 1795 was a particularly good place to look because as a calibration source, there were tons of pictures.”

Use of Chandra data was also ideal for the study because its spatial resolution allowed researchers to pinpoint an individual galaxy in the cluster. Maksym also notes that while it’s hard to get follow-up observations of events based on archival data, future missions dedicated to X-ray astronomy with wider fields of view may be able to scour the skies looking for such tidal flaring events.

The NuSTAR satellite was the latest X-Ray observatory to launch in 2012. NASA’s Extreme Ultraviolet Explorer picked up a strong ultraviolet source in 1998 right around the time of the tidal flare event, and ESA’s XMM-Newton satellite may have detected the event in 2000 as well.

This was also one of the smallest galaxies ever observed to contain a black hole. Maksym noted in Wednesday’s press conference that an alternative explanation could be a super-massive black hole in a tiny galaxy that just “nibbled” on a passing star, but said that new data from the Gemini observatory does not support this.

“It would be like looking into a dog house and finding a large ogre crammed in there,” Maksym said at Wednesday’s press conference.

This discovery provides valuable insight into the nature of intermediate mass black holes and their formation and behavior. What other elusive cosmological beasties are lying in wait to be discovered in the archives?

Congrats to Maksym and teams on this exciting new discovery, and the witnessing of a rare celestial event!

January 8, 2014December 23, 2015 by Jason Major

Dark Sky Regulations Bring Zodiacal Light to Rhode Island Observatory

Zodiacal light over Charleston, RI (Scott MacNeill, Frosty Drew Observatory)

The result of sunlight reflected off fine particles of dust aligned along the plane of the Solar System, zodiacal light appears as a diffuse, hazy band of light stretching upwards from the horizon after sunset or before sunrise. Most people have never seen zodiacal light because it’s very dim, and thus an extremely dark sky is required. But thanks to recent dark sky regulations that were passed in the coastal Rhode Island town of Charlestown, this elusive astronomical phenomenon has become visible — to the particular delight of one local observatory.

Frosty Drew Observatory is a small, privately-run observatory featuring a Meade Schmidt Cassegrain LX200 16″ telescope mounted on an alt-azimuth pier inside a dome that stands among the sports fields, parking areas, and nature trails of Ninigret Park and Wildlife Refuge in southern Rhode Island. Being a good distance from urban centers and developed areas, the skies there are some of the darkest in the state. But situated along the eastern seaboard of the United States, even Charlestown’s coast lies beneath a perpetual haze of light pollution.

A new town ordinance, passed in 2012, helped to darken the skies a notch. And while watching comet ISON one evening, astronomer Scott MacNeill became aware of the results.

The following is an excerpt from a Jan. 7 article by Cynthia Drummond of The Westerly Sun, reprinted with permission:

Scott MacNeill was in Ninigret Park, his telescope trained on the comet “Ison,” when he saw something he had never seen before: a celestial phenomenon called “zodiacal light.” After several decades of being obscured by light pollution, the feature was visible again, thanks to the town’s “dark sky” ordinance.

At first, MacNeill, an astronomer and the assistant director of the Frosty Drew observatory, didn’t believe what he was seeing. The cone of light, which he initially thought was light pollution, turned out to be a faint, white glow that astronomers at the observatory hadn’t glimpsed in recent memory.

A line of visitors is cast in silhouette against the evening sky as they wait to go into the Frosty Drew Observatory. (Susannah Snowden / The Westerly Sun)

“To see it in New England, period, is amazing, Zodiacal light is a common marker for the quality of a dark sky location.”

– Scott MacNeill, Astronomer, Frosty Drew Observatory

“I was sitting back for a minute, just looking at the sky, and I said ‘wait a minute. This is the southeast, and to the southeast is the ocean. What is coming up in the southeast?’ And then I noticed the cone. And I’m like ‘no way. That can’t be zodiacal light.’ I’ve heard so many stories about the days of old at Frosty Drew when you used to see zodiacal light here,” he said.

MacNeill credits Charlestown’s dark sky ordinance with reducing light pollution to the point where zodiacal light can be seen again. The ordinance, adopted in October 2012, regulates commercial outdoor lighting in order to improve the town’s dark sky for star-gazers, and to protect residents, wildlife and light-sensitive plants from the effects of light pollution.

One of the provisions of the ordinance requires that new lighting fixtures be designed to focus downward so light does not radiate up into the sky. Lighting installed before the ordinance was passed is exempt from the new regulations.

Building and Zoning Official Joe Warner explained that after the ordinance passed, two major sources of light pollution near the observatory were modified so they would be less polluting.

“At Ninigret Wildlife Refuge, some of the pole lights were changed to dark sky compliant lighting. The Charlestown Ambulance barn also replaced their lights with dark sky compliant lights,” he said.

Charlestown has been recognized as one of the only dark spots on the New England coast — a rare treat for people who enjoy looking at the night sky.

(Read the full article on The Westerly Sun’s website here.)

_________________

It’s fantastic to see results like this both occurring and being publicized, as dark skies have become quite rare in many populated areas of the world. People who live in or near major metropolitan areas — even in the surrounding sprawling suburbs — often never truly get a dark sky, not such that the dimmer stars, the Milky Way, meteor showers — and yes, the zodiacal light — can be readily seen on an otherwise clear night. The view of a star-filled night sky that has been a part of the human existence for millennia has steadily been doused by the murky glow of artificial lighting. Luckily groups like the International Dark Sky Association are actively trying to change that, but change isn’t always welcome — or quick.

At least, in one Rhode Island town anyway, a small victory has been won for the night.

(HT to Brown University’s Ladd Observatory in Providence for the heads-up on this story.)

January 8, 2014December 23, 2015 by David Dickinson

Gravitational Lens Seen for the First Time in Gamma Rays

An exciting new discovery was unveiled early this week at the 223rd meeting of the American Astronomical Society being held in Washington D.C., when astronomers announced that a gravitational lens was detected for the first time at gamma-ray wavelengths.

The study was conducted using NASA’s Fermi Gamma Ray Space Telescope, and promises to open a new window on the universe, giving astrophysicists another tool to study the emission regions that exist near supermassive black holes.

But the hunt wasn’t easy. A gravitational lens occurs when a massive foreground object, such as a galaxy, bends the light from a distant background object. In the case of this study, researchers targeted a blazar known as B0218+357, a energetic source located 4.35 billion light years away in the direction of the constellation Triangulum.

Blazar and quasar sources are named using their respective coordinates in the sky. Think of “0218+357” as translating into “Right Ascension 2 Hours 18 Minutes, Declination +35.7 degrees north” in backyard astronomer-speak. A blazar is a compact form of quasar that results from a supermassive black hole at the heart of an active galaxy. The term blazar was first coined by Edward Spiegel in 1978. The first quasar discovered was 3C 273 in 1970, which was also later found to be a blazar. 3C 273 is visible in Virgo using a large backyard telescope.

A foreground spiral galaxy seen face on lies along our line of sight between our vantage point and B0218+357. At 4 billion light years distant, the two have the smallest angular separation of any gravitationally lensed system so far identified at less than a third of an arc second across.

“We began thinking about the possibility of making this observation a couple of years after Fermi launch, and all of the pieces finally came together in late 2012,” said Naval Research Laboratory astrophysicist and lead scientist on the study Teddy Cheung in a recent NASA Goddard Spaceflight Center press release.

Observations of the blazar suggested that it would be flaring in September 2012, making it a prime target for the study. In fact, B0218+357 was the brightest extra-galactic gamma-ray source at the time. Cheung was granted time spanning late September into October 2012 to use Fermi’s Large Area Telescope (LAT) instrument to study the blazar in outburst.

Fermi‘s LAT instrument doesn’t have the resolution possessed by radio and optical instruments to catch the blazar in single images. Instead, the team exploited a phenomenon known as the “delayed playback effect” to catch the blazar in action.

“One light path is slightly longer than the other, so when we detect flares in one image we try and catch them days later when they replay in the other image,” Said team member Jeff Scargle, astrophysicist based at NASA’s Ames Research Center.

Cheung presented the findings of the study Monday at the American Astronomical Society meeting, which included three distinct flaring episodes from the background blazar that demonstrated the tell-tale delayed playback events with a period spanning 11.46 days.

A Hubble Space Telescope image of the gravitational lensing of B0218+357. Credit: NASA/ESA and the Hubble Legacy Archive.

Follow-up observations in radio and optical wavelengths supported the key observations, and demonstrate that Fermi’s LAT imager did indeed witness the event. Interestingly, the delay for the gamma-rays from the lensed blazar takes about a day longer than radio waves to reach the Earth. B0218+357 is also about four times brighter in gamma-rays than in radio wavelengths.

This occurs because the gamma-rays are emanating from a slightly different region than radio waves generated by the blazar, and are taking a different path though the gravitational field of the foreground galaxy. This demonstrates that assets like Fermi can be used to probe the heart of the distant energetic galactic nuclei which harbor supermassive black holes. This opens the hot topic of gravitationally lensed blazars and their role in extra-galactic astronomy up to the gamma-ray spectrum, and gives cosmologists another gadget for their tool box.

“Over the course of a day, one of these flares can brighten the blazar by 10 times in gamma-rays but only 10 percent in visible light and radio, which tells us that the region emitting gamma-rays is very small compared to those emitting at lower energies,” Said Stockholm University team member Stefan Larsson in the recent press release.

Using the analysis of lensing systems at gamma-ray wavelengths will not only help to probe these enigmatic cosmological beasts, but it may also assist with refining the all-important Hubble Constant, which measures the rate at which the universe is expanding.

But Fermi may just beginning to show its stuff when it comes to hunting for extra-galactic sources. The really exciting breakthrough, researchers say, would be the discovery of an energetic extra-galactic source being lensed by a foreground galaxy in gamma-rays that hasn’t been seen been seen at other wavelengths. This recent finding has certainly demonstrated how Fermi can “see” these tell-tale flashes via a clever method. Expect more news in the coming years!

Read the entire paper on the arViv server titled Fermi-LAT Detection of Gravitational Lens Delayed Gamma-ray Flares from Blazar B0218+357.

January 6, 2014December 23, 2015 by Jason Major

Kepler Finds an Earth-Sized “Gas Giant”

Artist's impression of KOI-xxx, fjkdshfkdsajhkfdkfd

Gas planets aren’t always bloated, monstrous worlds the size of Jupiter or Saturn (or larger) they can also apparently be just barely bigger than Earth. This was the discovery announced earlier today during the 223rd meeting of the American Astronomical Society in Washington, DC, when findings regarding the gassy (but surprisingly small) exoplanet KOI-314c were presented.

“This planet might have the same mass as Earth, but it is certainly not Earth-like,” said David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery. “It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants.”

Discovered by the Kepler space telescope — ironically, during a hunt for exomoons — KOI-314c was found transiting a red dwarf star only 200 light-years away — “a stone’s throw by Kepler’s standards,” according to Kipping. (Kepler’s observation depth is about 3000 light-years.)

Relative size comparison of KOI-314c and Earth; both have similar mass. (J. Major)

Kipping used a technique called transit timing variations (TTV) to study two of three exoplanets found orbiting KOI-314. Both are about 60% larger than Earth in diameter but their respective masses are very different. KOI-314b is a dense, rocky world four times the mass of Earth, while KOI-314c’s lighter, Earthlike mass indicates a planet with a thick “puffy” atmosphere… similar to what’s found on Neptune or Uranus.

Unlike those chilly worlds, though, this newfound exoplanet turns up the heat. Orbiting its star every 23 days, temperatures on KOI-314c reach 220ºF (104ºC)… too hot for water to exist in liquid form and thus too hot for life as we know it.

In fact Kipping’s team found KOI-314c to only be 30 percent denser than water, suggesting that it has a “significant atmosphere hundreds of miles thick,” likely composed of hydrogen and helium.

It’s thought that KOI-314c may have originally been a “mini-Neptune” gas planet and has since lost some of its atmosphere, boiled off by the star’s intense radiation.

Not only is KOI-314c the lightest exoplanet to have both its mass and diameter measured but it’s also a testament to the success and sensitivity of the relatively new TTV method, which is particularly useful in multiple-planet systems where the tiniest gravitational wobbles reveal the presence and details of neighboring bodies.

(Watch the latest Kepler Orrery video here)

“We are bringing transit timing variations to maturity,” Kipping said. He added during the closing remarks of his presentation at AAS223: “It’s actually recycling the way Neptune was discovered by watching Uranus’ wobbles 150 years ago. I think it’s a method you’ll be hearing more about. We may be able to detect even the first Earth 2.0 Earth-mass/Earth-radius using this technique in the future.”

Source: Harvard Smithsonian CfA press release

January 6, 2014December 23, 2015 by David Dickinson

Astro-Challenge: Nabbing Venus… at Inferior Conjunction

Venus as seen on the morning of inferior conjunction January 11th from Rekyavik, Iceland. Created by the author using Stellarium

Residents of high northern latitudes can take heart this frigid January: this coming weekend offers a chance to replicate a unique astronomical sighting.

Veteran sky watcher Bob King recently wrote a post for Universe Today describing what observers can expect from the planet Venus for the last few weeks of this current evening apparition leading up to Venus’s passage between the Earth and the Sun on January 11^th. Like so many other readers, we’ve been holding a nightly vigil to see when the last date will be that we can spot the fleeing world… and some great pics have been pouring in.

But did you know that when the conditions are just right, that you can actually spy Venus at the moment of inferior conjunction?

No, we’re not talking about a rare transit of Venus as last occurred on June 6^th, 2012, when Venus crossed the disk of the Sun as seen from our Earthly perspective… you’ll have to wait until 2117 to see that occur again. What we’re talking about is a passage of Venus high above or below the solar disk, when spying it while the Sun sits just below the horizon might just be possible.

The disk of Venus at inferior conjunction. Simulation created by the author using Starry Night. — The disk of Venus at inferior conjunction. Simulation created by the author using Stellarium.

Not all inferior conjunctions of Venus are created equal. The planet’s orbit is tilted 3 degrees with respect to our own and can thus pass a maximum of eight degrees north or south of the Sun. Venus last did this on inferior conjunction in 2009 and will once again pass a maximum distance north of the Sun in 2017. For the southern hemisphere, the red letter years are 2007, and next year in 2015.

You’ll note that the above periods mark out an 8-year cycle, a period after which a roughly similar apparition of the planet Venus repeats. This is because Venus takes just over 224 days to complete one orbit, and 13 orbits of Venus very nearly equals 8 Earth years.

And while said northern maximum is still three years away, this week’s inferior conjunction is close at five degrees from the solar limb. The best prospects to see Venus at or near inferior conjunction occur for observers “North of the 60”. We accomplished this feat two Venusian 8-year cycles ago during the inferior conjunction of January 16^th, 1998 from latitude 65 degrees north just outside of Fairbanks, Alaska. We set up on the Chena Flood Channel, assuring as low and as flat a horizon as possible… and we kept the engine of our trusty Jeep Wrangler idling as a refuge from the -40 degrees Celsius temperatures!

A daytime Venus just over five days from inferior conjunction. Credit — A 1.3% illuminated daytime Venus just over five days from inferior conjunction. Credit Shahrin Ahmad www.shahgazer.net

It took us several frigid minutes of sweeping the horizon with binoculars before we could pick up the dusky dot of Venus through the low atmospheric murk and pervasive ice fog. We could just glimpse Venus unaided afterward, once we knew exactly where to look!

This works because the ecliptic is at a relatively shallow enough angle to the horizon as seen from the high Arctic that Venus gets its maximum ~five degree “boost” above the horizon.

A word of warning is also in order not to attempt this sighting while the dazzling (and potentially eye damaging) Sun is above the horizon. Start sweeping the horizon for Venus about 30 minutes before local sunrise, with the limb of the Sun safely below the horizon.

Venus presents a disk 1’ 02” across as seen from Earth during inferior conjunction, the largest of any planet and the only one that can appear larger than an arc minute in size. Ironically, both Venus and Earth reach perihelion this month. Said disk is, however, only 0.4% illuminated and very near the theoretical edge of visibility known as the Danjon Limit. And although the technical visual magnitude of Venus at inferior conjunction is listed as -3.1, expect that illumination scattered across that razor thin crescent to be more like magnitude -0.6 due to atmospheric extinction.

The mid-January passage of Venus through the field of view of SOHO's LASCO C3 imager. Field orientation is set for January 7th. Created using Starry Nite Software. — The mid-January passage of Venus through the field of view of SOHO’s LASCO C3 imager. Field orientation is set for January 7th. Created using Starry Nite Software.

Are you one of the +99% of the world’s citizens that doesn’t live in the high Arctic? You can still watch the passage of Venus from the relative warmth of your home online, via the Solar Heliospheric Observatory’s (SOHO) vantage point in space. SOHO sits at the sunward L1 point between the Earth and the Sun and has been monitoring Sol with a battery on instruments ever since its launch in 1995. A great side benefit of this is that SOHO also catches sight of planets and the occasional comet that strays near the Sun in its LASCO C2 and C3 cameras. Venus will begin entering the 15 degree wide field of view for SOHO’s LASCO C3 camera on January 7th, and you’ll be able to trace it all the way back out until January 14th.

Venus post solar transit as seen in SOHO's LASCO C3 imager. Credit-ESA/NASA — Venus post solar transit as seen in SOHO’s LASCO C3 imager. Credit-ESA/NASA

From there on out, Venus will enter the early morning sky. When is the first date that you can catch it from your latitude with binoculars and /or the naked eye? Venus spends most of the remainder of 2014 in the dawn, reaching greatest elongation 46.6 degrees west of the Sun on March 22^nd, 2014 and is headed back towards superior conjunction on the farside of the Sun on October 25^th, 2014. But there’s lots more Venusian action in 2014 in store…. more to come!

January 3, 2014December 23, 2015 by Susie Murph

This Town Celebrates Every New Year with a Falling Meteor

Wetumpka Impact Crater geology. Credit: Auburn Astronomical Society

Video from YouTube User Pam Bergmann

The popular jazz tune “Stars Fell on Alabama” was inspired in part by the Leonid meteor shower in November of 1833, sometimes referred to as “the night the stars fell.” But the central region of Alabama region has a history of meteorite impacts, including a massive impact over 84 million years ago. The town of Wetumpka, Alabama sits in the middle of an ancient 8-kilometer-wide impact crater that was blasted into the bedrock, creating the unique geology of what is now Elmore County.

To celebrate this “striking” heritage, Wetumpka celebrates every New Year’s Eve with a spectacular recreation of a falling, exploding meteor.

Geologists have pieced together the events from millions years ago, when an asteroid nearly the size of a football stadium crashed into what was at the time a coastal basin covered with a shallow sea. The jumbled and disturbed geology of the area hadn’t made sense to local geologists since they started studying it in the 1800’s, and they had no explanations until mapping in the early 1970’s showed that the rocky layers were pointing away from a central location, which led them to suspect some sort of large impact.

However, this location wasn’t verified as an impact crater until fairly recently, when core samples drilled in 1998 confirmed the impact by detecting the presence of shocked quartz. The Wetumpka Impact Crater was officially recognized in 2002, and is now considered to be the best preserved marine impact crater ever discovered.

Meteor Drop, Wetumpka, Alabama (TripAdvisor)Credit: Peggy Blackburn The Wetumpka Herald

And so, in honor of this history, the folks of Wetumpka have been ringing in the new year by having their own ‘meteor’ streak across the sky and drop to the ground, guided by a wire and followed by fireworks. This event has been recognized as one of the top 10 unique New Year’s Celebrations in the U.S. by TripAdvisor.

You can see the preparation for the event at WSFA 12’s story here.
For more information regarding the crater, visit these sites:
Wetumpka Impact Crater Commission
Wetumpka Meteor Crater Tour by the Auburn Astronomical Society
Wetumpka Impact Crater Page

Also, I was born in Wetumpka, so Happy New Year!