Hubble can't look at the Sun directly, so it will observe the Venus transit with sunlight reflected off the Moon.

On June 5, 2012, the last Transit of Venus will happen in your lifetime. Unless, of course, you plan on living until December 2117 to catch the next one. Because it is the “last chance of a lifetime,” folks are clamoring about when and how to observe it. But I’ve found that many people have even more basic questions like “What exactly is happening?” “Why should I care?” and “Won’t Hubble get the pretty pictures for us?”

First off, the event is that the planet Venus will pass directly between Earth and the Sun. For several hours, Venus will appear as a dark dot moving across the Sun’s brilliant face. The precise alignment required for such a transit happens very rarely: pairs of Venus transits are separated by eight years, with 105.5- or 121.5-year separations between pairs. The first of this current pair occurred in 2004. The 2012 transit of Venus is only the eighth since the telescope was invented in 1609.

Historically, Venus transits were very important in measuring the precise distance to the Sun. A single measurement of a transit provides the relative sizes and distances to Venus and the Sun. Multiple measurements from multiple places on Earth enable astronomers to triangulate the true distance to the Sun. In the 1700s and 1800s, no other astronomical observation could provide this measurement, and grand expeditions were funded to observe Venus transits.

Today, we have radar measurements of the distance to Venus, so transits are not the unique opportunity they once were. For Hubble, however, the 2012 transit of Venus will be a unique opportunity of a totally different dimension.

Exciting discoveries can be made by studying an extrasolar planet that transits in front of its star. Some of the star’s light passes through the planet’s atmosphere, and we can determine the composition of that atmosphere. The same argument applies to the transit of Venus. However, since we know the composition of Venus’ atmosphere, observing its transit can provide an invaluable calibration and substantiation of the techniques used on extrasolar planets.

But, Hubble never looks at the Sun. Our star’s dazzling light would irreparably damage the telescope’s optics. Instead, Hubble will use the Moon as a giant mirror, studying its reflected sunlight to glean information about the Venus transit. It is a difficult observation, but one that mimics some of the complexity of observing extrasolar planets.

Who would have thought that the path to searching for habitable planets in the universe would involve examining Venus in a lunar mirror?

Data from ground-based and orbiting telescopes will be united in the National Virtual Observatory.

Being an astronomer in the year 2030 will be notably different than it is today. Yes, scientists will still be pondering, among other mysteries, the evolving universe, life on other worlds, and the nature of dark energy.

But how they explore the universe is already changing. This is partly driven by the fact that we are riding an exponential curve of increasing telescope size and detector sensitivity, but much more importantly, huge amounts of observational data are being harvested and archived faster than astronomers can analyze.

In addition, amateur astronomers are becoming more heavily involved in this analysis than in recent decades because of the “democratization” of space via huge, publicly accessible astronomical databases.

The consequences are that we are on the cusp of a knowledge explosion in astronomy, where discoveries expand at an unprecedented rate across the globe. Our knowledge of the universe is becoming, well, inflationary.

One prime example is the Barbara A. Mikulski Archive for Space Telescopes (MAST), housed at the Space Telescope Science Institute. This remarkably vast database contains astronomical observations from 15 NASA space astronomy missions, including the Hubble Space Telescope and the James Webb Space Telescope.

MAST presently contains approximately 200 terabytes of data that are used and reused many times by astronomers. New data are constantly flowing into the archive, but even more data is flowing out. Today, more than half of published scientific papers containing Hubble data used archival observations. This number has increased steadily over the past five years.

Facilities like MAST will lead to a new breed of “office-chair astronomer” who explores a “virtual universe” of vast, interconnected online databases. This is called the Virtual Observatory, and it is now in its developmental period.

What’s more, “citizen scientists” — those without formal degrees in astronomy — will have open and free access to the same data mines to make their own discoveries.

In 2030, a typical day for an astronomer on a university campus will have her start her work by looking at a list of science papers that have been intelligently selected by a software tool that surfed the Internet overnight. She clicks on an object in an online science paper and the Virtual Observatory database delivers views in X-ray, visible light, and infrared and radio observations. She queries the archive to perform an intelligent search, pulling up information relevant to the questions she’s asking about the object.

She never goes to a mountain top observatory to do follow-up observations of the object. Instead this is all carried out autonomously, following acceptance of her observing proposal. Automatically processed and calibrated observations are quickly delivered for high-level analysis after the observation. This online pipeline processing of data is a procedure pioneered on the Hubble Space Telescope mission, which has amassed 60 terabytes of observations to date.

Her observation goes into the Virtual Observatory archive after a brief proprietary period. Her unrefereed science results are soon published online. Peers and lay readers comment on the results, which are disseminated through social media. Her formally accepted paper is next published freely in an open-access online journal. Students in impoverished third-world universities have the same access to her results as a Harvard astrophysicist does.

Armchair astronomers will focus on complex and innovative queries of the Virtual Observatory to automatically search and extract precise sets of observations made by a variety of telescopes. Researchers will make new discoveries purely by being able to cleverly combine data from different wavelengths, spectra, and transient changes in space.

Many thousands more inquiring minds will be able to explore the databases, too. A prototype for this is the Galaxy Zoo project, where members of the public classify galaxies found in astronomical data. In 2007, Dutch schoolteacher Hanny van Arkel was participating in the Galaxy Zoo project when she found a huge, ghostly, glowing blob of gas, an oddity illuminated by a beam of light from a black hole in the core of a nearby galaxy.

We are just beginning to ride the wave of incredible new insights into our universe.

In this frame from the movie "Hubble 3D," the viewer enters the central region of the Orion Nebula. CREDIT: "Hubble 3D" © 2010 Warner Bros. Courtesy Warner Bros. and IMAX Corporation

Within our Office of Public Outreach, I lead a team that produces three-dimensional visualizations based on Hubble images and data. Most notably, our team worked on the IMAX film “Hubble 3D.” In collaboration with our partners at the National Center for Supercomputing Applications (NCSA) and the Spitzer Science Center, we worked on 12 minutes of scientific visualizations for the movie.

At a conference last week, I was invited to speak about our work on the project. I began with a reference to the old adage of “truth and beauty” as twin goals of artistry that both complement and conflict with each other. I noted that our documentary work must grow out of the truth side, while commercial (and fictional) films develop more from the beauty side. In fact, the incredible sophistication of movie computer graphics has raised audience expectations to a level that make standard scientific presentations look antiquated.

Taking Hubble to the big screen required many months of exacting work. I detailed the transformation of raw data into images, the variety of methods employed to create three-dimensional computer models, and the intensive computational requirements for these giant-screen, stereo 3D visualizations. I wanted to emphasize both the scientific underpinnings as well as the artistic effort necessary to produce the shots and sequences.

After my talk, one audience member sheepishly admitted that, when he saw the film, he had assumed the all of the sequences were fantasy Hollywood computer graphics. I was at first taken aback that our painstaking scientific basis was not recognized, but later I felt complemented that the sophistication of our work had risen enough to be considered “too good to be true.”

Donna Cox, my counterpart at NCSA, and I developed the phrase “cinematic scientific visualizations” to describe what our teams strive to produce. In that pursuit, we use not only the same software as used in astronomy research, but also the same software used in producing Hollywood blockbusters. Our goal is an elusive balance of accuracy and aesthetics.

While our artistry is well above the standard of science, we have neither the money, the manpower, nor the time to achieve the amazing complexity and detail that Hollywood routinely produces. In the end, however, that doesn’t matter.

The connection back to the underlying science is the crucial element that elevates our work. The knowledge that there is truth behind the beauty is what makes Hubble imagery all that more powerful.

The asteroid Eros

Last week, a new company entered the increasingly crowded market for private space exploration and exploitation. Planetary Resources‘ goal is to “establish a new paradigm for resource discovery and utilization that will bring the solar system into humanity’s sphere of influence.” This ambitious mission statement is backed up by “visionaries, pioneers, rocket scientists and industry leaders with proven track records on — and off — this planet.”

Among the founders of Planetary Resources is Peter Diamandis, who is very well known is space circles for many ambitious and successful undertakings. Perhaps the most well-known is the $10 million Ansari X PRIZE for private-sector manned spaceflight, a prize won in October 2004 by Microsoft co-founder Paul Allen and famed aviation designer Burt Rutan for SpaceShipOne, the world’s first non-governmental, piloted spacecraft. However, it is perhaps not as well known that Peter is also the co-founder of the International Space University (ISU): “an international institution of higher learning, dedicated to the development of outer space for peaceful purposes through international and multidisciplinary education and research programs.”

I was privileged to be part of the ISU summer programs in Barcelona (1994) as a student, and in Stockholm (1995) as a teaching assistant. As one of the 180 or so students in Barcelona, I worked on an intense, nine-week course for postgraduate students and professionals. The course tackled space-related disciplines that covered astrophysics, space policy and law, life sciences and more. Our final product was a Solar System Exploration Design Project, in which we ran thought experiments on how we should colonize and explore our own solar system. We developed mission concepts for lunar probes, comet sample returns, missions to the outer planets, and even the search for life!

Of particular relevance to the announcement by Planetary Resources was our Near Earth Asteroid Mission. Our mission statement — remember this was 1994 — was to “affirm the relevance of solar system exploration to human society using a smaller, cheaper, and faster science mission to evaluate the resource and hazard potential of small near-Earth asteroids.” Even back then, young professionals thought that investigating Near-Earth Objects (NEOs) was a rather promising idea.

Scientifically, NEOs represent the remnants from the early formation of our own solar system. As such, their physical, chemical and geological properties hold clues to the origin and evolution of our solar system. However, from a resource potential, NEOs are truly remarkable. Unlike on Earth, where heavier metals sink to the core, metals in NEOs are distributed throughout their body, making them easier to extract. They contain valuable and useful materials like iron, nickel, water, and rare platinum group metals, often in significantly higher concentration than found in mines on Earth.

Some NEOs could even be the remnants of extinct comet nuclei and therefore contain large quantities of water ice and other volatiles under a thin shell of silicate dust.

So how would you built a mission to rendezvous and orbit an NEO in preparation for full-scale mining? In our project, we identified three possible mission scenarios, in order of increasing complexity:

• Flyby — short observation time, but ideal for quick reconnaissance
• Rendezvous — long observations time, ample opportunity to study composition and landing sites
• Contact/Penetrator Probe — direct sampling of internal composition

Each mission would be equipped with cameras for determining size, shape, rotation and surface features; X-ray and Gamma-ray spectrometers to inspect surface and near-surface elemental composition; infrared reflectance spectral mappers for detailed mineralogical composition; and a number of other desirable instruments such as magnetometers, altimeters, dust collectors, mass spectrometers, etc.

Our design was inspired by the Clementine mission, which flew in 1994, and tested advanced sensors and spacecraft components under extended exposure to the harsh space environment during observations of the Moon. (The project was named Clementine after the song “Oh My Darling, Clementine” as the spacecraft would be “lost and gone forever” following its mission.)

Clementine was only a partial success; its planned flyby of an NEO did not take place due to an instrument malfunction. However, many of the technologies and techniques used by Clementine to obtain high-resolution images of our Moon, using innovative ideas and with limited costs, helped the development of later solar system observatories.

It is now almost two decades later, and the landscape of space exploration has changed. NASA is starting to partner with the private sector to enable new initiatives in support of its 50-year-old mission. At the same time, innovative entrepreneurs are seeking to capitalize on the convergence of cheap and reliable technologies for mining operations, which, for the first time in our history, will be located on a different solar system body than our own.

The time seems to be favorable for the exploitation of resources well beyond our immediate atmosphere. This race will undoubtedly produce a cascade of products and ideas focused on enabling our species to explore our immediate planetary neighborhood.

Let the race begin!

None of those are true about me. I got a bicycle for my ninth birthday, and I’ve never owned either a white lab coat or a telescope (unless binoculars count).

The reason I became an astronomer is that I am obsessive about solving puzzles. As a child in the 1970s, I loved playing with the Soma cube puzzle. When the Rubik’s Cube went on sale in 1980, I bought one the first day I heard about it. I twiddled, solved, and created patterns on it for many moons. I own every size cube up to a 7×7x7 — that’s seven squares in each row — including a 1×1x1 that a friend made for me, and dozens of other 3D rotating, flipping, and/or sliding puzzles.

Beyond those physical manipulation puzzles, I also love the intellectual challenge that many math students fear most: word problems. To me, equations are only really interesting when applied to a situation. Give me a description, let me deduce both the method and the solution, and I‘m hooked. In addition to baseball, I played at recreational math. I felt I lost a bit of my childhood when Martin Gardner, math and science writer best known for his Scientific American math puzzles, passed away a couple years ago.

So I came to astrophysics in a sideways fashion. I was brilliant at math, and the best math problems came from physics. As I progressed through college physics, the most interesting situations were in astronomy. What could be a greater puzzling challenge than to deduce all the physics of a situation trillions of miles away simply by examining the light it emits? And the answers described possibilities not only unheard of, but also impossible to reproduce here on Earth.

When speaking to students, I tell them it’s OK not to know what you want to be when you grow up. At one time, I dreamt of being a baseball pitcher. My experience says that if you work hard and follow your passion, you never know where it might take you.

It may say “astrophysicist” on my business cards, but really, I’m just a cosmic puzzle junkie.

My new blog, “A Curious Mind,” is intended — you guessed it — for curious minds. I will be writing mostly about science, occasionally about art, sometimes about the connections between the two. These will be somewhat longer pieces, discussing topics at the forefront of science, and at the intersection of science and general culture. I will augment the blog postings with Tweets – you can follow me on Twitter, at Mario_Livio.

As you can imagine, as an astrophysicist at the Space Telescope Science Institute, Hubble and the upcoming James Webb Space Telescope continue to be front and center in my mind. Consequently, these topics will, no doubt, feature frequently in my postings and Tweets.

I am looking forward to this new literary adventure, and I can only hope that the readers will share my passion for science and art.

Super-Earth GJ1214b orbits a red dwarf star (artist’s view).

Over the past year there has been a string of breathless news stories about astronomers finding extrasolar planets in the habitable zone around their star. This is the “Goldilocks zone” where temperatures are not too hot, and not too cold, but just right for surface water to remain liquid and presumably nurture life as we know it.

Astronomers with the Search for Extraterrestrial Intelligence (SETI) are firing up their Allen Array telescope to check out these worlds for signs of intelligent life.

But using the term Earth-like for these planets is stretch at best, and misleading at worst. We don’t have a clue about the physical nature or processes on these worlds, any more than an air traffic control radar blip tells you what meals are being served on a commercial flight.

Saying that water could exist is OK, but to imply it does exist with the phrase “Earth-like planet” is very presumptive.

The bottom line is that we don’t know how Earth got tanked-up with its water supply. So how might we guess what’s happening on worlds thousands of light-years away?

“If we need exotic mechanisms to get water onto Earth, then maybe it suggests life is not prevalent in these exoplanetary systems,” says astrobiologist Karen Meech of the University of Hawaii.

The oceans account for merely one-quarter of one percent of Earth’s mass. Another one-tenth of a percent of water may be in Earth’s mantle. If we could probe deeper, down into the core, Earth could conceivably have 50 oceans worth of water locked away from the days of our planet’s formation. (This is somewhat bemusing, considering Jules Vern wrote about a great subterranean ocean in the 1864 “A Journey to the Center of the Earth.”)

With water potentially so locked away, “we may never know how much water Earth really has,” says Meech.

This complicates several competing theories for how Earth got its water supply in the first place. We know water is everywhere in the solar system, especially among the planets and moons of the outer solar system. They lie beyond the “frost line” where water can remain a solid. By comparison, the baked, rocky planets Mercury and Venus seem bone-dry, and Mars looks arid at best.

From the geologic record we do know that oceans were here on Earth just a few hundred million years after our planet’s formation 4.6 billion years ago.

Recent computer simulations show that all hell would have broken loose in our solar system if the outer planets had ever migrated in their orbits – a phenomenon commonly seen in exoplanetary systems that may also have happened here. Earth would have been pelted with water-bearing asteroids that were thrown into Earth-crossing elliptical orbits. This would explain a late, heavy asteroid bombardment 3.9 billion years ago, as recorded on the moon and other solar system bodies.

Or perhaps water was transported to the early Earth by a class of object that no longer exists? And did the water appear late, early or in intermediate episodes in Earth’s formative years?

The picture is so complicated that it’s safest to say that water came to Earth from many sources: comets, hydrated asteroids, solar nebula gasses, and chemical processing on Earth’s surface.

Because we don’t even know how much water Earth has, we don’t know if our planet is a comparatively dry or wet planet. Now astronomers using Hubble have found a new class of planet that may truly be a water world. Zachory Berta of the Harvard-Smithsonian Center for Astrophysics (CfA) and colleagues have uncovered a new class of planet where a very large fraction of its mass is water. A thick, steamy atmosphere enshrouds it. But don’t plan on going surfing; the surface temperature is 450 degree Fahrenheit.

The waterworld, called GJ1214b, is 2.7 times Earth’s diameter and orbits a red dwarf star every 38 hours at a distance of 1.3 million miles.

In 2010, CfA scientist Jacob Bean and colleagues reported that they had measured the atmosphere of GJ1214b, finding it likely that the atmosphere was composed mainly of water. However, a hazy atmosphere could also explain their observations.

The infrared capabilities of Hubble’s Wide Field Camera 3 were used to study the planet at infrared wavelengths when it passed in front of its star. The team essentially used Hubble to measure the infrared color of sunset on this world. Hazes are more transparent to infrared light than to visible light, so the Hubble observations help tell the difference between a steamy and a hazy atmosphere.

The astronomers found the spectrum of GJ1214b to be featureless over a wide range of colors. The atmospheric model most consistent with the Hubble data is a dense atmosphere of water vapor.

The planet could only have amassed so much water if the planet had formed farther away from its star, beyond the frost line where water ice would be abundant. The planet then migrated inward toward the star, either through friction with gas in the disk or by gravitational interactions with other planetary bodies.

In the process, the wandering planet would have passed through the star’s habitable zone. Therefore, long ago it would have had a balmy ocean like Earth’s. But was the planet there long enough for life to start? The water planet is a prime candidate for further observations with the infrared capabilities of the upcoming James Webb Space Telescope.

The Hubble Deep Field (HDF) unveiled a myriad galaxies in 1995.

Scientists in general, and astronomers in particular, have been at the forefront when it comes to dealing with large amounts of data. These days, the “Big Data” community, as it is known, includes almost every scientific endeavor — and even you.

In fact, Big Data is not just about extremely large collections of information hidden in databases inside archives like the Barbara A. Mikulski Archive for Space Telescopes. Big Data includes the hidden data you carry with you all the time in now-ubiquitous smart phones: calendars, photographs, SMS messages, usage information and records of our current and past locations. As we live our lives, we leave behind us a “data exhaust” that tells something about ourselves.

Does the universe contain some hidden data, data that is there in plain sight but has yet to be investigated? If so, what’s in the cosmos’ data exhaust?

In late 1995, the Hubble Space Telescope took hundreds of exposures of a seemingly empty patch of sky near the constellation of Ursa Major (the Big Dipper). The Hubble Deep Field (HDF), as it is known, uncovered a mystifying collection of about 3,000 galaxies at various stages of their evolution. Most of the galaxies were faint, and from them we began to learn a story about our Universe that had not been told before.

At the time, I was a young graduate student at the Ohio State University. I still remember very vividly how mesmerized I was by what our universe was telling us with just one image. I remember calculating the approximate total number of galaxies in the visible universe, assuming that the HDF was a representative patch of our universe: 100 billion. I ended up using that image for my first paper as a graduate student, looking for distant quasars in the HDF.

The HDF represented a tremendous achievement for science in ways that are still reverberating today. It initiated one of the many legacies of the Hubble Telescope: deep images showing infant galaxies in the early universe.

However, the HDF was also instrumental for a generation of young astronomers in another significant way. For the first time, an observation was deemed so important in order to address basic questions about the structure and evolution of the universe that it needed to be made available immediately to the astronomical community around the world. This, as well as the underlying science, was a game changer. Typically observations are released to the astronomical community after a proprietary period — typically 6 months or a year. This gives the astronomers who requested the observation time to perform their investigations. In this case, the HDF team took the unusual step of both swiftly preparing the observations for scientific study and releasing them without delay, thus allowing students and researchers alike to dive immediately into the science of the observation. The success of this decision paved the way for future observations to be released with similar speed.

So was the HDF unique? Were we just lucky to observe a crowded but faint patch of sky? To address this question, and determine if indeed the HDF was a “lucky shot,” in 2004  Hubble took a million-second-long exposure in a similarly “empty” patch of sky: The Hubble Ultra Deep Field (HUDF). The result was even more breathtaking. Containing an estimated 10,000 galaxies, the HUDF revealed glimpses of the first galaxies as they emerge from the so-called “dark ages” — the time shortly after the Big Bang when the first stars reheated the cold, dark universe. As with the HDF, the HUDF data was made immediately available to the community, and has spawned hundreds of publications and several follow-up observations.

Many more examples exist of “deep fields,” and in all cases it seems that if we look closely at an unobserved portion of our universe we discover more and more of its “data exhaust,” pointing us to the signatures of its origin.

The Hubble Deep Field started a revolution in the way we look at our universe but also in the way we access information. This trend exists to this day. Just a few days ago the European Southern Observatory (ESO) released the widest deep view of the sky ever made using infrared light. Once again an unremarkable patch of sky comes to life and reveals more than 200,000 galaxies!

This trend is not about to end. Over the next decade, astronomy will undergo dramatic changes. Missions like the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) and the Large Synoptic Survey Telescope (LSST) will be able to survey the whole sky in just a few days, creating a 3D map of the universe. I personally cannot wait to see what we will find!

Hubble's sharp vision uncovered white dwarf stars in the ancient globular cluster NGC 6397.

As you stargaze over the next few weeks, keep in mind that most of those tiny points of light scattered across the sky are burning infernos of gas. These stars are very much like the Sun. Some are bigger and more powerful, and some smaller. But they are not constant. Stars change over time, and evolve into different states. Understanding this process of “stellar evolution” is my primary passion in astronomy, and was the focus of a meeting we just held at the Space Telescope Science Institute, “The Mass Loss Return from Stars to Galaxies.”

Stars are sort of like humans … They are energetic when young, “cool” when old, and kind of boring in the middle years. The most important property of a star that defines how it will evolve over time is its mass. A low-mass star, like our Sun, will slowly burn its hydrogen into helium, and remain in a state of equilibrium for billions of years. This is great for us on Earth, since it provides us with a stable environment. But in about 4 billion years, the Sun will expand and begin to lose its outer layers. During this stage, called the red giant phase, the Sun will be so large that it will encompass the Earth’s orbit around it, crisping our planet!

Unlike our Sun, more massive stars – about 10 times the Sun’s mass – will suffer a very different fate. These stars burn through their gas very quickly, like sports cars, and then blow up as supernova explosions. In doing so, the star experiences a very energetic death and sprays 90% of its material into its surroundings. Why does this matter to us if our Sun will never meet this fate? Because this spewed-out material from exploding stars is very important in the cosmic cycle of star and planet formation. All the elements heavier than hydrogen and helium are produced in the cores of these massive exploding stars. That includes everything you see around you, from the computer you’re reading this on to the skin on your body. Yes, you are made of “star stuff.” Our Sun and its planets formed in a region of space that had already been polluted by previous supernovae, and so these heavy elements exist here.

So what about the death of our own star? During one of the breaks at the meeting, I spoke with a colleague of mine about the end fate of the Sun. When we look at the nearby galaxy, we see beautiful stars in the “planetary nebula” phase of their life cycle. This phase only lasts for a short amount of time, during which the outer layers shed by the star – the “mass loss” of the meeting’s title – are illuminated by the hot and exposed core of the dying star, the white dwarf. The resulting pictures of these objects are among the most beautiful sights in the universe. My colleague and I asked ourselves whether the Sun would end its life in one of these states, but we concluded that it would be unlikely.

The Sun has a couple things working against it. First, it doesn’t have as much mass as some of the other stars that become planetary nebulae, so the stellar ejecta will be less dense. Second, because it has less mass, it will evolve more slowly than larger stars. By the time the core of the dying Sun is ready to light up the material around it, that material will be more dispersed. Both of these effects lead to an unlikely case for a bright illumination of the gas.

Eventually, after the outer layers have been shed, the remnant star of the Sun – the stellar cinder – will cool and dim as time passes. This type of white dwarf star is the final resting state of 98% of all stars. These dead stars are littered all across our galaxy, and they have incredible properties. First, having no nuclear fuel, they are extremely faint and hard to detect. Powerful telescopes like Hubble have, however, revealed large populations of these stars in the nearby galaxy. Second, these stars are very dense. Although the progenitor lost half (or more) of its mass, the core is very small – about the size of the Earth. The density of the star is therefore about a million times higher than the density of ordinary matter on Earth. A tablespoon of material from a white dwarf would “weigh” as much as a school bus. Finally, the composition of that core is largely carbon, an end product of helium burning in the progenitor star. So, a white dwarf is essentially highly compressed carbon. In other words, our Sun will end its life as a giant natural diamond!

A white box indicates Fomalhaut b's suspected location (top). A magnified view of the planet in question shows different positions in its orbit (bottom).

One of Hubble’s most celebrated discoveries is the November 2008 announcement of the first visible-light image of a planet orbiting another star. Along with several infrared observations announced by other observatories, that month marked the historic beginning of direct detections of extrasolar planets. Previous discoveries were indirect, deduced from the way the gravity, size, or motion of the planet affects the light from its host (or another) star. Since then, we’ve also been able to see infrared images of a few planets in other solar systems.

Hubble’s discovery, however, has been literally clouded from the start. The star Fomalhaut is 25 light-years away from Earth. The planet, dubbed “Fomalhaut b,” has an orbit more than 100 times larger than Earth’s orbit, and a size estimated to be about three times the mass of Jupiter. Considering the star’s brightness and distance, as well as the planet’s orbit and size, the object Hubble sees is too bright to be just the planet. The explanation has been that a huge ring of ice and dust around the planet is reflecting the extra starlight.

Observers using the Spitzer Space Telescope have recently questioned that explanation. As reported by Universe Today, a paper will appear in the “Astrophysicial Journal” that argues a better interpretation of the image is a “transient or semi-transient dust cloud.” This conclusion is based on infrared observations that fail to show the expected emission from a planet. Because planets are brighter at infrared wavelengths, the astronomers concluded that the visible-light observation is only from dust and not from a planet. While the gravitational argument for a planet remains solid, the research team found that the observed light source is “highly unlikely” to be a giant planet.

As one might expect, the original researchers disagree with these findings. They considered the dust cloud idea, but ruled it out. In their opinion, the resolution and sensitivity of Spitzer is too low to warrant such conclusions, and their postulated ring around the planet fits with the infrared observations.

One could promote this as the NASA Great Observatories in a scientific smackdown. Hubble punches with a planet. Spitzer counterattacks with a dust cloud. It’s an astronomical battle royale for extrasolar supremacy! But that would be silly.

This discussion is just the natural progress of science. Results, especially the really significant ones, must be checked and re-checked by many astronomers at many observatories before they become fully accepted. The original paper clearly identified the discrepancy of the extra light observed. The follow-up paper does a great service for everyone by providing more data to examine. Neither explanation is completely convincing at this time.

Eventually, more data will reveal what is truly being observed. In particular, the James Webb Space Telescope has the resolution of Hubble in the infrared wavelengths of Spitzer. JWST is slated for launch in 2018, and its observations should be able to distinguish between the two hypotheses. Or, more dramatically, JWST will be the ultimate referee of this cosmic clash of telescopic titans.