Connecting Solar Physics to Space Weather in Sunspot

NSO's two main telescopes at Sunspot, New Mexico.

This week I'm attending the National Solar Observatory's 26th workshop at the aptly-named town of Sunspot, New Mexico.  The NSO has observing facilities at Big Bear, California, Kitt Peak, Arizona, here in New Mexico, and soon will have the world's most advanced telescope in the Advanced Technology Solar Telescope on Haleakala in Hawaii.  Sunspot facility has been around since the 1950's when the Air Force created it to study the Sun's activity.  The military had realized the usefulness of monitoring solar activity as early as the start of World War 2 when it was realized that solar storms had a negative impact on the effective range of short-wave radios, which were then the only means of long-range wireless communication.  By the 1950's the mechanism for this disturbance had been explained by connecting the x-rays and energetic particles emitted by solar storms to the ionization state of the upper atmosphere.  The purpose of the solar observing facilities established here at Sunspot was two-fold: monitor the Sun and alert the military of conditions that might impact them, as well as to conduct basic research on the Sun.

The NSO facility here at Sunspot long ago transitioned from an Air Force facility to a National Science Foundation lab, but it's two-fold mandate remains the same: predict what the Sun is going to do and explain why.  The conference I'm attending is focused on connecting those two missions.  But more broadly, this gets at an interesting concept in basic science, namely why do we do basic science?

One answer which we generally sell to the public is that we do science in order to produce tangible benefits - cure cancer, make faster computers, reduce pollution, etc.  The other answer is that we are exploring the natural world and this is the one that researchers prefer when talking to other researchers.  As far as I know nobody is opposed to either of those motivations, but there is a, of course, a question of balance.

In solar physics that balance is particularly sensitive.  There is a lot of funding available for space weather monitoring from an operational standpoint.  Commercial and military satellite operators, power grid controllers, those that rely heavily on GPS, and the manned space program need accurate and timely predictions about space weather. As with many complex systems sometimes it's easier and even more accurate to simply fit phenomenological models to the data rather than try to build physics-based models.  In the long run, understanding the physics will provide the most accurate forecasts, but often there's a lot more short-term payoff by simply looking for patterns in the data without trying to understand them.

So this week we're trying to bridge the gap a little bit in solar physics at a place that embodies the balance.  And it doesn't hurt that it's a beautiful place to visit.

View of White Sands National Monument from Sunspot.

Great Videos of Solar Storms

As you may have read the Sun had a bit of a temper tantrum earlier this month.  Here's a great video of the flares (there are actually two of them in rapid succession) from NASA's Solar Dynamics Observatory.


And here is a time-lapse movie of the strong northern lights the storm generated when it hit Earth's magnetosphere.


With the solar cycle just heating up, it may be a stormy couple years.

Kepler Finds A Possibly Live One

The Kepler mission has been looking for planets that might have liquid water (and therefore life as we know it) and it looks like they have their first confirmed candidate - the oh-so-memorably-named Kepler 22b.  Kepler 22b, or just 22b for short, has a radius 2.4 times as big as the Earth's and orbits a star that has roughly 2% less mass than the Sun every 289 days. That places it right at the inner edge of that star's habitable zone (the range of distances from their star where planets might have liquid water), as illustrated by this lovely NASA graphic.

If you assume an Earth-like greenhouse effect for 22b (which is a big assumption considering Venus and Mars have drastically different atmospheres than Earth), the mean surface temperature (assuming it has a surface) would be a balmy but not unreasonable 22 degrees Celsius compared to Earth's mean surface temperature of about 14 degrees Celsius.

NASA likes to call this type of planet a "Super-Earth", however that's something of a misnomer as planets with more than twice the radius of Earth probably aren't primarily rocky planets like Earth, Venus, and Mars but rather more like smaller, defrosted versions of our solar system's ice giants, Neptune and Uranus.  Using planetary structure models, one can map out the range of possible compositions for a planet of a given radius (remember with Kepler's transit data they know the planet's size but not it's mass).

As you can see, 22b likely has a composition with significant amounts of hydrogen and helium, which means it may have a very thick, deep atmosphere. Alternatively it could have very large amounts of water, but at this point there's just no way to tell what it's made of as the planet is too far from it's star to be detected using the radial velocity technique, which can determine a planet's mass.  It's possible that space telescopes like Hubble and Spitzer might be able to get some information on the composition of the planet's atmosphere, but most likely this one is going to have to wait for new telescopes and instruments to be characterized more fully.

The best part is that 22b is not alone.  The Kepler team only officially announces a planet as discovered when they can confirm it using another telescope (here they used Spitzer to verify a transit), but the list of "planet candidates" in habitable zones is growing.  As of the now, there are about a half-dozen planet candidates in habitable zones that are smaller than 22b. 

As Kepler approaches it's third anniversary, expect those numbers to increase dramatically.  You can already see the trend by comparing the numbers of planets from the June 2010 (in blue), February 2011 (in red), and December 2011 (in yellow) data releases.

You can find the official NASA press release here and the slides from that press release (which are the source of these lovely images) here.

Yahoo! Makes Black Holes Hip

Disclaimer:  As a certified nerd in high school, I never really knew what the kids were saying even when I was one of them, so "hip" may not be the right word.  Whatever the appropriate vernacular, Yahoo! is doing it for news about black holes - complete with pop culture analogies.  You can see the video here (curse you Yahoo! and your lack of embedding options).  The specific "discovery" they reference was an observation of a peculiar gamma ray burst by the SWIFT satellite, which is a pretty amazing bit of science and certainly worthy of mention.  Besides, everybody likes black holes due to their position on the top of the cosmic sexiness ladder.

As someone who once hoped to model almost exactly what was observed, I have to say that Yahoo! did a decent job with the science.  Sure, they make it sound like we have close-up video of the event rather than a brief gamma ray point source and they think astrophysicists wear lab-coats and write "science" on glass plates, but those are forgivable mistakes in my book.  My only two questions are how can we get more videos like this and why for the love of everything holy don't they have an embed option?

The Cosmic Sexiness Ladder

Nobody gets into astrophysics because they want to study the Sun.  Usually we start out wanting to find exoplanets or black holes, and then at some point get hooked into solar physics because there is such a wealth of data on the sun.  It turns out this effect can be quantified by measuring a quantity known as "cosmic sexiness", which is defined as "relative visceral appeal of different fields of astrophysics".  From Jeremy Drake, solar physicist:

He then notes that below the Sun would go atomic physics, followed by the weather.

Dynamos in Physics Today

One of the standard jokes in astrophysical modeling is that if there is ever a discrepancy between your model and observations you simply attribute it to some combination magnetic fields and turbulence.  Let's say your model of star formation fails miserably to reproduce the observed initial mass function in our galaxy.  What do you do?  Blame turbulence and magnetic fields, present some overly simplistic explanation of why turbulence and magnetic fields would give you the right answer if you could just capture them properly, and then promise to include them in some ill-defined future simulation.

These two phenomena have a fundamental link  - dynamo action.  In the words of a very well-written article by two of the top researchers in the field of laboratory dynamos, Cary Forest and Daniel Lathrop, "[a]ll astrophysical plasmas are, as far as we know, magnetized and turbulent" and thus ripe for dynamo action.  The problem is that we are orders of magnitude removed in both simulations and experiments from some of the physical regimes where dynamo action takes place, even within our own solar system (see the graph on the right).

Check out the article over at Physics Today for a great explanation of why dynamos are so ubiquitous, why they are so hard to predict, and what is being done with theory, modeling, and laboratory experiments to unravel the mystery.

Summer Conference Travels

You may have noticed that things have gotten a little quiet around here and while I can't say exactly what everyone else is doing, I can guess the it has something to do with the summer conference season (and possibly also babies in one or two instances). Since this really isn't a blog about babies, let's do a quick check of where everyone is headed this summer.  Post your dream summer vacation to Austin, Texas in August where you'll spend 14 hours a day in a dimly lit room watching poorly prepared PowerPoint presentations in the comments.

Note:  I have actually attended a conference in Austin, Texas in August.  I don't recommend it.

Does the PhD Need Fixing?

Many of you have probably seen the special edition of Nature that is devoted to "The Future of the PhD".  Much of the discussion centers on the career prospects of those with a PhD.  As most of those in graduate school know, there are far more eager 1st-year graduate students than tenure-track positions at R1 universities - and often to have a shot at the few positions available at R1 universities one has to slog through multiple low-paying post-docs after a median of 7 years in a PhD program.  Part of Nature's special feature includes an editorial entitled "Fix the PhD".  But here's my question to those of us in grad school: in your experience, does the PhD system need fixing?

Before we jump into the debate, let me share a little bit of data.  First, Nature has put together a few nice set of graphs showing three relevant tidbits on key aspects of the PhD experience - namely the number of PhDs awarded by field, the median time to completion for the hard sciences, and the employment of science and engineering PhDs 1-3 years after graduation.

Several things that stood out to me.  First, medial and life sciences saw a huge increase in PhD production and many of the anecdotal horror stories I have heard come from those fields.  Second, a median of 7 years in grad school seems high to me - using data from the past 15 years in my department I have personally computed a mean time to completion of 6 years for my program.  Finally, I was surprised not to see a growth in the number of non-tenured faculty.  Other sources have clearly indicated that the ranks of the non-tenured have been growing, but apparently not with new PhDs.

The second bit of data I would like to inject comes from my own department.  CU's Astrophysical and Planetary Sciences department is pretty good, but I would say that CU is somewhat average when it comes to the top-tier of the astrophysics world.  So in the hope that CU's PhDs are in some sense "average", I decided to track all 43 of the PhD recipients from my department between 2000 and 2005 using Google and ADS in order to see where they were now.  I sorted them into 7 categories (post-doc, tenure-track faculty at research institutions, tenure-track faculty at non-research institutions, non-tenure-track faculty, research staff, industry, or other).  The results are on your left.  Note that all of those that still post-docs graduated in 2005.  Interestingly, only 1 of the 43 PhDs is in a non-tenure track faculty position and a very large fraction (67.4%) are still publishing in peer-reviewed journals in astronomy, physics, or planetary science.  As a side-note, the "other" category has some great entries, including a fellow that works for Answers in Genesis, another that works for a foundation that advocates for manta rays in Hawaii, and another that does market research for Kaiser Permanente.

So, there's a bit of data - more is of course welcome - now what does it mean?  Is the PhD system in the US broken and if so, how does one fix it?

Solar Physics Jobs In A Recession

Solar physics enjoys the blessing/curse of being a small sub-field of in the physics and astronomy community.  The Solar Physics Division of the American Astronomical Society (AAS) has roughly 600 registered members out of over 7,000 registered members of the AAS.  For comparison, the Division of Condensed Matter of the American Physical Society has over 4,000 members.  My point is the that is if the physics world is Europe, solar physics is like Latvia.

One of the advantages of being a small field is that it is possible to track almost all of the post-docs and potentially permanent positions without too much trouble. I have been doing this for the past few years using the AAS Job Register and positions listed in the Solar News.  Generally I would like to know what sort of job market I'm going to be jumping into in a year or two, but I'm also interested to see the effect of the recent economic difficulties on the job market.  So here are the results:

I've sorted the positions by locations (US or everywhere else) and into post-docs or potentially permanent positions, although the line between the two is often a bit fuzzy.  Essentially post-docs include anything that looked like it was designed for someone coming right out of grad school, while the permanent positions include anything that might become something long term.

In the US there have been roughly equal numbers of post-docs and long-term positions, meaning that on average one should expect to hold one post-doc before getting something long term.  Roughly 60% of the permanent positions, however, are either research positions at national labs or observatories, or support staff (e.g., programming, education/public outreach, etc.).  The situation in the US is also exacerbated by the situation in Europe where there are nearly three times as many post-docs each year as long-term positions.  This leads to a net migration of foreign post-docs into US permanent positions, for which I have only anecdotal evidence.

In looking at the graph, one doesn't see any clear indication of the current economic turmoil aside from the fact that 2010 looks like a less-than-stellar year in all categories.  This may be the result of two factors:  first, it may take several years to see the effect of the poor economy propagate through the state and federal governments and the larger university community before it hits physics departments directly; second, the $865 million Solar Dynamics Observatory was launched in February 2010, so there has been a build up of hiring in related research positions and post-docs over the past couple years, which may partially offset a recession-related dip in hiring.

The bottom line is that solar physics, like all fields of basic science, is a tough career choice.  There are a lot of very smart people vying for few ideal permanent positions.  But trying to get into the field is not the career Russian-roulette that is seen in some fields.

Current Cosmology From Supernova Data.

Ariel Goobar and Bruno Leibundgu have recently submitted an article to Annual Review of Nuclear and Particle Science summing up our current understanding of physics from the current set of supernova data. We have accrued quite a lot of supernova data over the years and so it is interesting to take a look at how much we have learned. I will not report everything but will post a few interesting plots.

Above is the original diagram/scatter plot Hubble used to show the universe is expanding in a way that fits Hubble's law. This is that same diagram today using current supernova data (not a scatter plot any more!): (showing the distance modulous versus redshift.)

As you can see Hubble's law is confirmed by quite a few supernova today. :) Furthermore, the lower plot shows a blue line representing a universe containing cold dark matter and a cosmological constant and a flat dotted line assuming a universe empty of cold dark matter or dark energy/cosmological constant. As can be seen, the supernova data *strongly* favors a universe with dark matter and dark energy/cosmological constant.

The next plot above shows how well we can constrain the percentage of dark matter and dark energy in the universe using supernova, CMB and BAO data. (click on the image to see better.) As you can see the data fits a flat universe with an accelerated expansion very well

The last plot I want to display shows the current constrains we have on the type of beast dark energy is. As a reminder, the prediction we get from dark energy being the cosmological constant is w = -1. As you can see w = -1 still fits the data very well.

Conclusion: It is nice to see as more and more cosmological data pours in the standard flat universe containing dark energy, cold dark matter, accelerated expansion and dark energy best described by a cosmological constant is verified. Cosmology has truly become a precision science.

Ariel Goobar, & Bruno Leibundgut (2011). Supernova cosmology: legacy and future To Appear In Annual Review of Nuclear and Particle Science arXiv: 1102.1431v1

Gender, Physics, and the Wikipedia

For a long time people in physics have known that we have something funny going on in our field with respect to gender.  In 2006 only 6% of full professors at US physics departments were women.  In fact, there is a well-documented "leaky pipeline" for women in physics and astronomy that is summed up nicely by the following figure from the AIP's Statistical Research Center:

You'll note that while just under 50% of high school physics students are women, that number almost monotonically decreases as they move up the professional ranks (although there is a very slight bump between women with PhD's and those who are new tenure-track faculty).  So the question is why?  I have never seen any evidence for a gender-based discrepancy in fundamental ability, so I - like many others - would attribute this to something social rather than something biological.  But it's not like physics faculty hate women - in fact most physicists I know would be in the top few percent of people in terms of those concerned about making science more inclusive.

It turns out that we in physics and astronomy are not alone - the Wikipedia has a similar problem.  The New York Times reports that only 13% of Wikipedia contributors are women.  There are some proposals to actively encourage women to contribute, but that is exactly contrary to the idea Wikipedia espouses - namely that the best source of knowledge is one that is allowed to grow and expand naturally from a community rather than one that is mediated by some arbiter of truth.  As one of the women on Wikipedia's governing board stated:

“The big problem is that the current Wikipedia community is what came about by letting things develop naturally — trying to influence it in another direction is no longer the easiest path, and requires conscious effort to change.”

So while Wikipedia might not have many answers for the physics community, at least we know we're in good company.

Dark Matter Reconstruction From Radio Experiments.

As photons move through the universe they get gravitationally lensed as the pass by large clumps of matter. (As shown in the image above.) Dark matter, being the dominant form of matter, lenses these photons more than anything.  Therefore, by studying the lensing properties of incoming photons, in principle we can reconstruct what the profiles of the dark matter doing that lensing.

Now, put (hopefully) more simply: we can't directly see dark matter.  But taking the statistical lensing properties of the incoming photons we can hopefully reconstruct what the dark matter looks like.  In this way we can "see" the clumps of dark matter in the universe directly.

Recently, Brown and Battye have proposed a new method for reconstructing the projected dark matter distribution using radio surveys like SKA and e-MERLIN. They then test their method on simulated data as discussed below.

The plot above shows a mock initial dark matter distribution from which they make simulations of the kind of data e-MERLIN would see coming from such a distribution of dark matter.  If their method works, this is the distribution they will reconstruct.

This next plot above shows how well they are able to reconstruct the input dark matter distribution.  As can be seen, the main features, especially the two dominant clusters, can be resolved fairly well.  (Especially given the input data is smoothed by the beam of the instrument and so this at some level is approaching as good as things get for a single experiment.)

Punchline: So, using this lensing reconstruction technique for be can begin to "see" what the underlying dark matter clumps look like.

I for one am excited about where lensing is headed.  Utilizing a variety of lensing techniques, including the method for radio sources done here, we may one day reconstruct the dark matter throughout the universe with great precision, especially when we combine the data from many experiments at many wavelengths.  Again, in this way we can visually "see" the dark matter that comprises our universe.


Michael L. Brown, & Richard A. Battye (2011). Mapping the dark matter with polarized radio surveys E-Print arXiv: 1101.5157v1

Evidence Against The Universe Being Fine Tuned For Life.

Many people will tell you that the universe appears fine tuned for life.  Don Page has decided to address this issue scientifically by calculating the best value for the cosmological constant needed to support life in the universe and then comparing it to our own.  His conclusion is that the cosmological constant is actually an example that our universe is not fine tuned for life.

The cosmological constant is like a knob that affects how quickly the universe's expansion is accelerating or decelerating.  As a rule of thumb, the more positive the constant is the faster the expansion accelerates and the more negative the more it decelerates.  If it is zero, and there is just the right amount of matter, the universe just stays flat and we never experience a rapid acceleration or deceleration in expansion.

First, all positive values are bad.  Now, what does this have to do with life?  It turns out a positive cosmological constant, like our own, actually dilutes matter and prevents a lot of gravitational collapse making our universe less likely for life than if the constant were not positive.  From the paper:

The reason is that a positive cosmological constant gives a repulsion between separate particles that reduce the ordinary gravitational attraction and leads to less gravitational condensation of matter. Therefore, other factors being equal, any positive cosmological constant decreases the fraction of baryons that condense to form galaxies and other structures that eventually form living substructures.

As an immediate consequence, no positive value of the cosmological constant (such as the observed value Λ) can maximize the fraction of baryons in life 

But wouldn't a negative value also be bad? Yes, because if the value is too negative the universe recollapses and life doesn't have time to form.  Page keeps this in mind while calculating the best value to find that Goldilocks region that is most optimal for life.  That said, he does find that the optimal values for life in the universe are slightly negative on the order of Λ ~ -10^-120.

So God created a Multiverse?  Interestingly enough Page is very religious and so does not conclude this is evidence against God but actually evidence that God must have created a multiverse where each pocket universe has a different cosmological constant like most modern cosmology theories predict.  From the paper:

It might be appropriate to note that although this paper has focused on the scientifically testable question of whether the constants of physics maximize a particular measure for life, it obviously also has theological implications. It could be taken as negative evidence for theists who expect God to fine tune the constants of physics optimally for life. However, for other theists, such as myself, it may simply support the hypothesis that God might prefer a multiverse as the most elegant way to create life and the other purposes He has for His Creation.

I for one am a big fan of the multiverse because all modern cosmological theories with inflation lead to a multiverse.

And religion aside, given our cosmological constant is such a bizarre value and currently seems to be best explained by multiverse models I will agree with Page that the cosmological constant seems to hint at a multiverse. (Which is why many respected theoretical physicists suggest the peculiar value for the cosmological constant is the best evidence so far for crazy multiverse models like the string landscape.)

Thoughts?

Don N. Page (2011). Evidence Against Fine Tuning for Life E-Print arXiv: 1101.2444v1

Live From Seattle - ADS Gets an Update

Today the big talks at the AAS were mostly about cosmology, pulsars, and other things that as far as I know were not hot news, but I did find out about one great new thing:  ADS is getting a facelift.  For those of you that don't use it religiously, NASA and the Smithsonian Astrophysical Observatory have for the past 20 years run the Astrophysical Data System, which is an online library for publications in astronomy and astrophysics.  ADS is an invaluable resource for those of us in the astrophysical community, but it also has had the same search interface for the past 20 years.  For those of you that remember searching online in the 90's, the search interface may cause post-traumatic flashbacks.

If you just had a flashback to Lycos, click here and take a good hard look.

So what does the new ADS look like?  Here's the search interface:

Note that like almost all search engines of the past decade they've gone to a single entry box capable of accepting anything from keywords to author names to publication dates.  They've also added six default search modes.  Three just make sense (sort by date, relevance, or citation count) and three are new and very handy (sort by popularity, most referenced, and those most instructive).  The popular option returns those entries with the most recent traffic, the most referenced returns the papers most cited by the most relevant papers, and the most instructive option returns those papers that are most cited by the most cited papers - which is a clever way to favor review articles.

Let's try searching for review articles about the solar dynamo and see how it does.

The results look great.  I have read and highly recommend all but entry #5 as quality reviews of the source of solar magnetic fields - and even though I wasn't previously familiar with entry #5 a quick look leads me to think the problem is with me and not ADS.

Overall, I give the new version of ADS two big thumbs up.  Check it out.

Live From Seattle - Kepler Rocks

The big news from the first day of the AAS can be summed up with "Kepler 10b", which is the first confirmed Kepler planet that's mostly made of rock.  It's also the smallest exoplanet ever found at 4.6 earth masses.  Talks today by many of the Kepler science team focused on this little ball of burning hot rock which orbits its parent star roughly every 12 hours.  This suicidally close orbit leads to surface temperatures in the ballpark of 2500 K, which means it probably looks a lot more like a super-Mercury than a super-Earth.  One scientist compared the newly discovered planet to Dante's Inferno.  You can read the media articles here, here, and here.

From a planet formation standpoint this little guy is also a big deal because it is significantly more dense than Earth, Venus, or Mars, meaning that it is either 75% iron or it contains some material in its core that is so dense it doesn't exist in our solar system.  Laboratory experiments are starting to show that at the ridiculously high pressures one might find in a planet like this one you can get some really funky phases of common materials - things like metallic hydrogen or super-dense ice at 2000 degrees.  It turns out that rocky exoplanets might help us understand high-pressure physics in ways that are really tough to do here on earth.

Live From Seattle - It's the AAS!

Today is the start of the scientific program here at the 217th meeting of the American Astronomical Society and somewhere in days of scheduled talks, posters, receptions, and informal chats we'll try to bring you some of the highlights of the biggest meeting in astronomy and astrophysics.

Also, for those of you in Seattle, the first ever Eternal Universe Nerdfest is going to happen.  Possible days and times include lunch Tuesday, Wednesday, or Thursday, or dinner on Tuesday.  I vote for some seafood (it's Seattle), but the location is up for discussion as well.  If you're interested vote for a time and place in the comments and we'll see what works best for everyone.

It's Astro-physics not Astro-recipes

The other day my adviser said something interesting. We were talking about the current state of theoretical astrophysics papers out there and he said, "All these papers just give recipes. They say, do this and do that and you will get this. They don't talk about the physics. They don't try to look into the different physics that could cause what we see. It's supposed to be Astro-physics not Astro-recipes."

This struck me as a particularly good criticism because the vast majority of papers I have been reading all have a lot of recipes for how to recreate their simulations, but very few actually look at the different physics involved. They focus more on the number of grid points in their simulation than on whether or not their physics produces something we see through a telescope. Perhaps this is a problem more for my particular sub-field, but it does seem to pop up everywhere.

Why Study This Stuff?: An Example

Last week at a church social activity my wife and I were sitting with some friends - highly educated people - and the discussion turned to my profession.  I explained what it is that I do and then came the question that always comes after I explain that I'm trying to understand dynamo action in sun-like stars, "so why does the government give you money to do that?"  I tried to explain that there are economic benefits to funding basic research and then moved the conversation to something else.  Today, however, I was reading about proposals to cut funding of the NSF is some of the latest debt-reduction proposals and I again thought of that conversation.  Then I thought about some work that a good friend is doing trying to build compact, low-cost, reliable ways to diagnose exactly what strain of viral infection someone has, and I came up with an alternate idea.  So I'm going to try it out on you guys.

Here it is:  we should fund basic science because Issac Newton playing with prisms in the 1660's has led to knowledge that prevents cancer, allows you to microwave your food, and protects us from terrorists.  Here's why.

Most US Physics PhD's Don't Go On To a Post-Doc

When those of us crazy enough to pass-up more lucrative, less demanding career paths entered graduate school most of thought we'd get our PhD's, do a post-doc or two, and then become a tenure-track professor somewhere.  At some point most of us realized that most of us were not going to end up as professors at large research universities, but for me at least a post-doc seemed like a necessary step in the whatever career path I envisioned.  It turns out that piece of the Physics Career Path™ isn't as ironclad as I once thought.  From the excellent folks at the Statistical Research Center at the American Institute of Physics, below is the break-down of what those who earned PhD's in 2007 and 2008 were doing one year later.

Note that for Americans only 49% go on to a Post-Doc, meaning that there is something to do with a doctorate other than take a low-paying temporary research position in the hopes of getting a long-term research position with moderate pay.

Here's the trends over the past 30 years for all physics PhD's. 

And here is the breakdown by sub-field. 

Note that over 60% of astrophysicists end up in post-docs, so maybe the Physics Career Path™ is my destiny after all.

We Might Have A Live One: First Possibly Habitable Extrasolar Planet Found

People have been freaking out of the possibility of finding habitable extra-solar planets for close to a decade now.  It looks like they might just have their first candidate:  Gliese 581g  or Gg to it's friends.  You can see the press release or the 50 page preprint for those of you that want the gory details.

The Lick-Carnegie collaboration used over 11 years of continuous radial velocity measurement of the star Gliese 581, a nearby red dwarf star with about 30% of the mass of the sun (type M3V for you astronomers out there) that is already known to have two other small planets right on the inner and outer edges of the star's habitable zone - effectively jumbo-sized versions of Venus and Mars.  Gg, however is right smack dab in the middle of the habitable zone with an estimated average surface temperature of 228 K - chilly but not "lifeless chunk of ice" cold.  Also helping things out is the fact that planetary evolution models indicate that Gg is probably tidally locked to its sun, meaning that one side is in eternal day and the other in eternal night.  This might allow the planet to have a wide range of temperatures - from scorching hot at eternal noon to extremely cold at eternal midnight.  Gg is also about 30% more massive than the earth, meaning it's gravity is probably something like 10% stronger than ours, which might be helpful in holding on to an atmosphere.

So when do we send tourists?  Probably not for a very long time.  Gliese 581 is about 20 light-years away and our current fastest moving spacecraft (Voyager 2) is only going about 0.001% of the speed of light, so it'll be a very long time before we get a probe there to check it out, much less a person to write a travel review.  And it gets worse.  Since Gg's orbit doesn't happen to line up with our line of sight its sun, we can't even use satellites like CoRoT or Kepler to watch Gg transit across its sun.  It looks like more information on Gg is going to have to wait for the next generations of missions like SIM-lite or New World Explorer which should be able to directly image it.