26 June 2013

Mapping Our Cosmic Main Street

Milky Way seen from Kitt Peak National Observatory
Despite the fact that we can peer outward with our telescopes into deep space for billions of light-years, our local celestial landscape is downright murky.  I write about this conundrum in my latest Natural History column, where I discuss how astronomers first tried to map the Milky Way's spiraling arms. Click here to check it out.

09 February 2013

The Solar System Police

Once a planet
Pluto was not the first planet to be demoted. Another solar system object was not only demoted from planetary status but got re-promoted later. Read about in my latest column in Natural History magazine. Click here.

Image Credit: Hubble Space Telescope

25 September 2012

Cosmic Cradles

In 1995 Robert Williams had a crazy idea.  Then director of the Space Telescope Science Institute, he decided to use his allocated time on the Hubble Space Telescope to train its mirror on one tiny spot of the skya dark, starless region near the handle of the Big Dipper.  Over ten consecutive days the telescope took a series of 342 time-exposure photographs, images that were combined and computer-enhanced to produce the most deeply penetrating astronomical picture of its time.  It was called the Hubble Deep Field.  

What this stunning picture revealed were some 2,000 galaxies in different stages of development.  Like a geological core sample, it displayed galaxies in the local, intermediate, and distant universe altogether, out to some 12 billion light-years. 

Now a team of astronomers has assembled the eXtreme Deep Field, or XDF for short.  They've combined ten years worth of data taken by Hubble (some 2,000 images in all) from a patch of sky in the constellation Fornax.  This one digs some 13.2 billion years back into time, to just half a billion years after the Big Bang. 

Hubble's eXtreme Deep Field
All I can say upon gazing at this image is, "Wow!"  How can anyone doubt the possibility of other life beyond the solar system when we have these myriad cosmic cradles sprinkled through space and time.

18 June 2012

Remarkable Odyssey

Jane Luu

My congratulations go out to Jane Luu (MIT Lincoln Laboratory), David Jewitt (UCLA), and Michael Brown (Caltech) for winning this year's prestigious Kavli Prize in astrophysics, which includes a cash award of $1 million.  In 1992 both Luu, then at Harvard, and Jewitt, who was based at the University of Hawaii at the time, discovered the first large object orbiting the Sun beyond Neptune and Pluto. They quickly found others as well.  Brown followed up in 2005 by finding Eris, an object about the same size as Pluto but with nearly a third more mass.  


All in all, these three astronomers proved the existence of the "Kuiper belt," a disk of icy planetesimals long proposed to lie beyond the outer planets of our solar system.  Their discoveries ultimately caused Pluto to be demoted to "dwarf planet," joining its more similar companions in the belt.  


I was particularly thrilled for Jane, who I profiled in 1996 for Astronomy magazine.  Click here to read how Jane's life journey took her from war-ravaged Vietnam to the outer reaches of our solar system.


Image Credit: MIT Lincoln Laboratory

15 May 2012

Chasing Galaxies

Beatrice Tinsley
In this era that offers us such wondrous pictures of galaxies, showing their vivid evolution over the eons, it's easy to forget that astronomers once thought galaxies evolved relatively little after their initial formation in the early universe.  And the woman primarily responsible for changing that view was Beatrice Tinsley. She is said to have "changed the course of cosmological studies." Click here to read about this story in my latest column in the April issue of Natural History. 

03 April 2012

Curiouser and Curiouser

The bright star Sirius
and its tiny white-dwarf
companion. (Credit: The
McDonald Observatory)
One hundred and fifty years ago, two astronomers in Cambridgeport, Massachusetts, were testing the lenses of a new telescope they were building and in the process discovered an entirely new cosmic creature (although it took a while to figure that out).  Click here to read more about it in my latest column for Natural History magazine. Happy Anniversary, white dwarf star!

26 January 2012

An Unfettered Mind

I have another book review out, published in the Washington Post on Sunday, January 22.  This time the book is Stephen Hawking: An Unfettered Mind, by science writer Kitty Ferguson.  It's a new edition of an earlier biography of Hawking that Ferguson published in 1991.

30 November 2011

Radioactive

Check out my latest book review, published in the Washington Post on November 13.  The book is titled Radioactive. It's an intriguing, visual work about Madame Curie and her husband Pierre.  The author is Lauren Redniss, who is both a writer and artist. Each skill is on beautiful display in this unusual presentation. Below, a sample of two of its 210 pages. 


28 September 2011

Fried Egg Nebula

Does the universe want bacon with that?

Fried Egg Nebula
An international team of astronomers recently used the European Southern Observatory's Very Large Telescope in Chile to capture a unique picture of a hypergiant star situated about 13,000 light-years from Earth in the direction of the constellation Scorpius.  For obvious reasons, they've playfully named it the Fried Egg Nebula.  


This humongous yellow star shines half a million times more brightly than our Sun (is there a sunblock strong enough?) and is a thousand times bigger. If it replaced our Sun, this 20-solar-mass star would almost engulf Jupiter.  Earth would be toast.


This star is quite active, hence the two spherical shells of dust and gas that surround the central star, setting up the fried-egg appearance.  This material was jettisoned outward in a series of explosive bursts over the last few hundred years.  When this hypergiant finally dies as a brilliant supernova some day, watch out! 

Image Credit: ESO/E. Lagadec

15 August 2011

Who Gave the Black Hole Its Name?


John Wheeler in Black Hole, Nova Scotia, 1981
Book after book attributes the phrase "black hole" to the Princeton physicist John Archibald Wheeler, who in the 1960s re-energized the field of general relativity by helping prove that if certain dying stars were massive enough they would not settle down as neutron stars but continue to collapse to a point, digging a pit into space-time. 


Wheeler liked to tell the tale that he first used the term at a 1967 conference, quickly set up at the NASA Goddard Institute for Space Studies in New York City once pulsars were discovered. Were the pulsars' mysterious beeps coming from red giant stars, white dwarfs, neutron stars?  Wheeler told the assembled astronomers they might be the "gravitationally collapsed objects" that he studied.  “Well, after I used that phrase four or five times, somebody in the audience said, ‘Why don’t you call it a black hole.’ So I adopted that,” Wheeler told me.   He used the phrase again several weeks later during an after-dinner talk at the annual meeting of the American Association for the Advancement of Science (AAAS) in New York City on December 29, 1967.  It made it into print when an article based on that talk, titled “Our Universe: The Known and the Unknown,” was published in American Scientist in 1968. 

But it turns out the term was already in the air.  It had been circulating among conferees four years earlier at a symposium on relativistic astrophysics held in Texas at the end of 1963. The proof?  Life magazine science editor Albert Rosenfeld mentioned black holes in his report on the conference. And the term was used again a few weeks later at the 1964 American Association for the Advancement of Science meeting held in Cleveland.  Ann Ewing of Science News Letter reported that astronomers and physicists at the conference were suggesting that “space may be peppered with ‘black holes.’” 

But it's certainly true that the phrase didn’t catch fire until 1967.  It seemed to need the imprimatur of John Wheeler, the dean of American general relativity, to give it gravitas.  Once Wheeler gave his blessing, the phrase began popping up in the official scientific literature—although over the first year it was usually denoted as “the black hole,” an expression so exotic it needed to be constrained within quotation marks. 

06 July 2011

Only Your Astrophysicist Knows for Sure

Is the universe planning to turn blonde?


The Rho Ophiuchi star formation region
Using a telescope perched high in the Chilean Andes, an international team of astronomers discovered molecules of hydrogen peroxide, the chemical that bleaches hair, in a dense cloud of gas and dust near the star Rho Ophiuchi some 400 light-years distant.  


This find is more than an amusing curiosity. Hydrogen peroxide is formed when two hydrogen atoms link up with two oxygen atoms (H2O2), a pair of elements critical for life. Moreover, take just one oxygen out of hydrogen peroxide and you get water (H2O). So, further study of this molecule's chemistry out in deep space may help astronomers better understand the formation of water in the universe.  
Image Credit: ESO/S. Guisard 

29 June 2011

The Ever-Changing Record

I smiled when I heard the news.  An international team of astronomers has just announced the discovery of the most distant quasar, the luminous core of a young and active galaxy situated a whopping 12.9 billion light-years away.  That means the light from this quasar, likely generated as matter falls into a supermassive black hole, started on its journey just 770 million years after the Big Bang. 

This image of the record-setting quasar, ULAS J1120+0641, was
created from images taken from surveys made by both the Sloan
 Digital Sky Survey and the United Kingdom Infrared Telescope Deep
Sky Survey. The quasar appears as a faint red dot close to the center.


I smiled because this headline has been regularly appearing in the news for nearly half a century, ever since Caltech astronomer Maarten Schmidt recognized the first quasar in 1963.  Known as 3C 273, from its listing in a catalog of radio sources, Schmidt's quasar was about 2 billion light-years distant: small potatoes now but a huge cosmic distance in its day.  


Over the years, the most-distant-quasar record has gotten replaced as often as a newborn's diapers.  But now the distances are so great that they present some problems: the light from this newfound quasar suggests that the quasar is being powered by a black hole about two billion times more massive than our Sun. How did such a gargantuan object grow so quickly in the early days of the universe? As team member Daniel Mortlock, of Imperial College London, notes, "It's like rolling a snowball down the hill, and suddenly you find that it's 20 feet across!" Theorists will surely be putting on their thinking caps to find a way.
  

15 June 2011

Chicken or the Egg Question Answered?

One of the most fascinating findings in astronomy over the last decade has been the unique relationship between galaxies and the supermassive black holes lurking in their centers.  Rather than being rare, a giant black hole appears to reside in each and every elliptical or spiral galaxy throughout the cosmos.


Illustration of an active, supermassive
black hole in a galaxy's center
But which came first? The giant black hole, drawing in material to help form the galaxy, or did the galaxy form first, generating the environment for a dense collection of matter to collapse into a black hole at its heart?  


Astronomers and theorists from Yale, Rutgers, and the Universities of Hawaii and Michigan have now gathered evidence suggesting that each galaxy and its black hole grow in tandem, starting less than a billion years after the Big Bang.  As reported in the journal Nature, the team revealed this by looking at some 250 distant galaxies earlier spotted by the Hubble Space Telescope and searching with the Chandra X-Ray Observatory for the x-ray signals being emitted from each galaxy's central black hole.  What they find is a distinct connection: the black holes growing and evolving over time along with their host galaxies. "This finding," says team member Kevin Schawinski of Yale University, "tells us there is a symbiotic relationship between black holes and their galaxies that has existed since the dawn of time."  
Image Credit: NASA Goddard Space Flight Center

05 April 2011

In a Grain of Sand

There is something new under the Sun.  And it took some 42 years to find it.

In 1969, members of the Japanese Antarctic Research Expedition found nine meteorites lying on an icy field in the continent's Yamato Mountains.  Ever since, these specimens (along with the 40,000 meteorites collected in Antarctica afterward) have been avidly studied. Yet, even after four decades of analysis, some surprises remained. 

U.S. field team in Antarctica searching for meteorites in 1988-89.

One of the 1969 meteorites, known as Yamato 691, was recently examined with a transmission electron microscope located at NASA's Johnson Space Center in Houston, Texas.  This 21st-century nanotechnology allowed researchers from the United States, South Korea, and Japan to zoom in on isolated grains in the meteorite that are less than a hundredth the width of a human hair.  And what they discovered was an entirely new type of mineral, different from the 4,500 minerals already recognized by the International Mineralogical Association.  The researchers dubbed it "Wassonite," in honor of UCLA professor John Wasson, an international meteorite expert. 

Wassonite is made out of only two elements, sulfur and titanium.  Yet these atoms join up to form a crystalline structure that has not been previously observed in nature.  The mineral formed some 4.5 billion years ago, likely as part of an asteroid orbiting between Mars and Jupiter.  Further study of the novel crystal promises to offer new insights on conditions in the early solar system. "In the words of the great English poet William Blake," says Simon Clemett, a space scientist at the Johnson Space Center and co-discoverer of the new mineral, "we are now able 'to see the world in a grain of sand.'"
Picture Credit: Department of Earth and Planetary Sciences, Washington University in St. Louis

09 March 2011

Astrobites

A common refrain from my science-writing students is, "Where do you get story ideas?"


A good place to start is hanging out with graduate students and post-docs, who are often thinking and working on problems at the cutting edge.  Many of my best magazine articles when I was starting out involved the work of these pioneering newcomers (many of whom are now the leading lights in their fields). 


If those interested in writing on astronomy can't make a personal university visit to find out what's on a graduate student's mind these days, there's a new website that offers the next best thing: Called "astrobites," it's a daily astrophysical literature journal written by graduate students for undergraduates.  It beautifully fulfills its named mission―providing up-to-date summaries of the latest research in easy-to-go-down write-ups.  The graduate students who post these reports―from Harvard, Michigan, UC Santa Cruz, Colorado, Arizona―aim to make active research areas enticing and accessible to undergraduates, but it serves just as well as a convenient overview for journalists seeking hot new topics popping up in the field of astronomy and astrophysics. 


Christmas Tree Nebula: Here just because it's pretty.


09 February 2011

Cosmic Target Practice

When new astronomical images come across my desk, most are often variations on a theme: something I've seen before, perhaps with better resolution or a few new features.  But today I was wowed. Astronomers using both the Chandra X-Ray Observatory and the Hubble Space Telescope created a composite image of a celestial object known as Arp 147, which appears like the mother of all bull's-eyes.  The universe has pretty good aim when shooting at a target. 

The Cosmic Bull's-Eye: Arp 147

On the left in the image above, you see an elliptical galaxy that millions of years ago passed right through what used to be a spiral galaxy on the right.  All that remains of that spiral, located some 440 million light-years distant, is a massive ring of stars.  The collision triggered a tsunami of star formation that raced around the ring.  The ring is so bright in X rays that astronomers conclude that many of those newly-formed stars were likely quite massive.  Consequently, they lived fast and died young, exploding as luminous supernovae and leaving behind both neutron stars and black holes.  What a sight.

27 January 2011

In Honor of John Huchra

John Huchra, a veteran astronomer based at the Harvard-Smithsonian Center for Astrophysics (CfA), unexpectedly died last fall at the age of 61.  To honor his legacy, his friends and colleagues have now set up on the interactive website WorldWide Telescope a special tour titled, appropriately enough, "John Huchra's Universe."  I highly recommend taking a look.  To get instructions on how to access the tour on the WorldWide Telescope (or where to go to view a non-interactive version on YouTube), click here.  

Watching the program brought back many memories for me, for John provided me with one of my first "scoops" in science journalism.  In 1985 he and his collaborator Margaret Geller allowed me to get an early peek at their latest finding: a map of galaxy redshifts, taken through a narrow slice of the sky, out to more than half a billion light-years.  It showed that galaxies are not smoothly distributed through the universe but instead congregate to form gigantic, nested bubblesa cosmic foam.  Inside the bubbles were equally huge voids.  This wasn't a celestial architecture that anyone was expecting.  It was big news. I wrote a story on it for Science Digest, a report timed to coordinate with John and Margaret's discovery announcement at the 1986 annual meeting of the American Astronomical Society. 

The original 1986 CfA map of galaxy distributions

Theorists now believe that the bubblelike structures were forged when pressure waves moved through the early universe's hot primordial plasma, creating regions of compressed and rarefied matter.  This led to galaxies forming predominantly in the areas of compression and the less dense voids enlarging over time and remaining relatively empty.  Geller likened the distribution to a "kitchen sink full of soapsuds." 

Over the succeeding decades, astronomers have enlarged this map extensively.  Here's a look at the Two-Degree Field Galaxy Redshift Survey carried out in the 1990s that extends out to two billion light-years:


Each point in the image represents a galaxy—tens of thousands overall in two slices of the sky

05 January 2011

Rings of Fire


Over Christmas, two space telescopes—the European Space Agency's Herschel and XMM-Newton observatories—took a look at our closest spiraling neighbor, the Andromeda galaxy situated more than 2 million light-years away. It puts Andromeda in a whole new light....literally. The Herschel, which gathers invisible infrared light, detected intriguing rings of dust encircling the galaxy's center. Some speculate that these dust rings, not fully seen in the optical, may have formed from a past collision with another galaxy. Within these dusty circles, multitudes of new stars are forming.

Andromeda galaxy in infrared; x-ray sources in blue

Meanwhile, the Newton x-ray telescope spotted hundreds of x-ray sources (the blue dots in the picture) smack dab in the center. Some are the debris from exploding stars; others are stars in close binaries getting their mass pulled off by the intense gravitational pull of their denser partners. The x rays are given off from the intensely heated matter. What a show! Stellar birth and death, captured in one intriguing image.
Picture Credit: European Space Agency

21 December 2010

Let the Sunshine In

Today is the Winter Solstice. You may be lamenting the official start of winter (coincidentally the Boston area is now getting its first snowfall of the season), but I'm rejoicing.  Starting today, and continuing over the next six months until the summer solstice, our daylight hours will be growing by roughly two minutes each day.  Alleluia—the sun is coming back to us here in the northern hemisphere. 

And to put the cherry on the sundae, we get a lunar eclipse on the same day.  That hasn't happened since December 21, 1638. Sir Isaac Newton wasn't even born yet. That came four years later.

09 December 2010

Evidence for Tiny Black Holes?

Last month some astronomical news came out that didn't get much play, but I was fascinated by it.  UCLA scientists are claiming they might have detected evidence for primordial black holes, tiny cosmic denizens first predicted by Stephen Hawking in the 1970s.  If that's true, it's pretty big news, as here would be a means to study what happens when general relativity meets quantum mechanics—the holy grail of physics these last few decades.

What Hawking did was ask how a black hole might affect its surroundings from the viewpoint of an atom.  He concluded that space-time gets so twisted near a black hole that it enables pairs of particles (a nuclear particle and its antimatter mate) to pop into existence just outside the black hole.  You could think of it as energy being extracted from the black hole's intense gravitational field and then converted into matter.  At times, one of the particles disappears into the black hole, never to return, while the remaining one flies off. As a result, the hole's total mass-energy is reduced a smidgen.  This means the black hole is actually evaporating!

Illustration of primordial black hole's final evaporation
For stellar-size holes, this bizarre quantum-mechanical process is just about meaningless.  It would take trillions upon trillions of years for a regular black hole to shrink away to nothingness.  But Hawking suggested that the early universe, in the first turbulent moments of the Big Bang, might have manufactured a multitude of tiny black holes.  The smallest would have vanished by now, but objects containing the mass of a mountain, yet compressed to the size of a proton, would be shedding the last of their mass at this very moment in a short and spectacular burst of gamma rays. 

That's what the team of UCLA scientists, led by David Cline, believe they are seeing.  Looking over data from a number of gamma-ray telescopes, they have detected gamma-ray bursts lasting less than 100 thousandths of a second.  That's the type of signal expected from the evaporation of primordial black holes.  Of course, such signals could be also be arriving from a more common stellar process not yet identified.  As Carl Sagan liked to say, "Extraordinary claims require extraordinary evidence."  Cline agrees.  He's urging others to start studying these events as well, to see if their claim holds up to scrutiny. 
Image Credit: Virginia Tech Department of Electrical and Computer Engineering