Forecasting the End: The Science of Rogue Planets

21 03 2013

ftefbook2I’m pleased to report that I had the opportunity to consult on (and occasionally appear in) an astronomy/geoscience/climate science crossover project for the Weather Channel this past year, entitled, Forecasting the End.

The show, which premiers this evening, uses extremely-low-probability astronomical or geophysical disasters as a hook to explore and present astronomy, geology, meteorology, and physics concepts in a novel (and admittedly fantastic) way.

Of the six-episode series, the first deals with the concept of so-called “rogue” planets, a timely subject of recent research.

What is a Rogue Planet?

Many astrophysicists, astronomers, and exoplanetologists have set their research sights on puzzling out exactly how it is that new star systems go about forming planets, (in this case “exoplanets,” or planets outside our solar system).  Interestingly, the fruits of their labor have in recent years led to the realization that the process is a frequently violent one.  -So violent, in fact, that during the gravity tango performed between a fledgling solar system’s new planets, one of these “dancers” is thrown right off of the dance floor.

In other words, it seems that planets are often ejected from their home star system in the chaos surrounding a newly-formed star.  This actually serves to help the “dance” between the rest of the worlds calm into a more stable, final set of orbits, perhaps turning it into more of a “march.”

Any one of these escaped exoplanets, then, becomes a “rogue” planet – left to wander the cosmos along its lonely escape trajectory for billions of years.

-And to confirm that this knowledge is more than just theoretical, astronomers revealed last November that they captured what looks for all the world to be a rogue planet in the flesh a mere 75 light-years away:

Infrared image of rogue planet CFBDSIR2149. (Credit: CFHT/P. Delorme)

Infrared image of rogue planet CFBDSIR2149. (Credit: CFHT/P. Delorme)

Rogue Planet as Cosmic Bard

Astronomy-savvy readers may recall a splash last year when researchers reported calculating that there may be billions of these dark, lonely worlds wandering the galaxy.  However, as the “giggle-check” champion astronomer Phil Plait of “Bad Astronomy” fame was quick to point out, compared to the amount of free space in the galaxy, the odds of a collision with these seemingly innumerable rogue planets – any collision – are mind-bendingly slim.

Hence, while the Forecasting’s exercise deals with a disaster that is legitimately statistically possible, it is a threat far less likely than, say, being hit by a meteorite.  Or winning the lottery three times in a row.

Instead, the rogue planet has a different, more sublime function.  It can help us tell a story, and in the telling, learn a little bit more about the Earth.

By exploring the “What if?” scenario provided by the idea of a rogue planet breezing through our solar system, we have the opportunity to illuminate a seemingly-unrelated and often misunderstood phenomena at work much closer to home (and – for the “aha” moment – much more relevant to traditional weather):  Seasons.

Wherefore Art Thou Seasons?

The cosmic roots of our annual swing between months spent shoveling snow and sunning on sandy beaches may not be at all intuitive.  However, this reality becomes much easier to grasp in terms of a cosmic disaster.

Allow me to explain.

Many (intuitively) misunderstand why it is that the seasons exist at all, believing logically that summer is when the Earth is closest to the Sun, and winter is when we’re farthest away.  This is actually not the case.

Why not?  Simply, because the Earth’s orbit is almost perfectly circular, there really isn’t that much difference between the heat received by the Earth at closest and farthest approach to and from the Sun.

Instead, the seasons are caused by the fact that the Earth is tilted as it goes around the Sun.  This means that the Earth doesn’t stand “upright” as it goes round, but rather, it leans:

Illustration that weather seasons are related to the Earth's axis tilt; Summer on the hemisphere pointed toward the sun (northern or southern), and winter for the hemisphere pointed away. (Credit: Ben McGee)

Illustration that weather seasons are related to the Earth’s axis tilt; Summer on the hemisphere (northern or southern) pointed toward the sun, and winter for the hemisphere pointed away. (Credit: Ben McGee)

Consequently, summer is when your side of the Earth (northern or southern hemisphere) is pointed toward the Sun, and winter is when your side of the planet is pointed away.

This is also why, at the equator, the temperature is so consistent throughout the year – at the geographic middle of the planet, straddling the line between hemispheres, you’re neither pointed toward or away during any time of year and experience sunny temperatures year-round.  In contrast, if the “near-and-far” season misconception were true, one would expect snowy winters in Barbados, which simply never occurs…

Playing with Weather via Orbital Dynamics

All of this having been said, the reality explained above – the current cause of our seasons – goes completely out the window in the scenario explored in Forecasting’s rogue planet episode.  There, the orbits of Jupiter and the inner planets are enlongated by a rogue planet flyby (ignoring for the sake of brevity orbital resonances that might make such a shift even more catastrophic than advertised), which has a surprising result:

Such an event turns the previously-mentioned misconception (that seasons are caused by distance with respect to the Sun) into fact for life on Earth!

In such a scenario, the shape of Earth’s orbit becomes more oval (ellipse) than circle, and it travels much closer to and farther away from the Sun during its yearly course (aphelion and perihelion) than it does now.  As a result, seasonal changes due to the Earth’s axial tilt are totally overwhelmed by the global swing in temperatures based just on proximity to the Sun.

NOTE: These effects were actually scientifically modeled on Earth by Penn State astronomer Darren Williams and paleoclimatologist David Pollard in an effort to explore the habitability of worlds with more elliptical orbits around other stars and were published in the International Journal of Astrobiology in 2002.  This paper, which formed the conceptual basis for the effects depicted in this episode, can be found here.

So now, on a post-rogue-planet-soon-to-be-apocalyptic Earth, everyone on the planet experiences summer and winter globally, which leads to a rapid sort of climate change completely disruptive to our way of life:

With an elliptical orbit, (where during half the year the Earth is much closer to the Sun than the other), Earth's seasons are global and driven by proximity to the Sun. (Credit: Ben McGee)

With an elliptical orbit, (where during half the year the Earth is much closer to the Sun than the other), Earth’s seasons are global and driven by proximity to the Sun. (Credit: Ben McGee)

Earthly Take-Home in an Exoplanetary Context

Aside from the tantalizing (for space scientists) or terrifying (for everyone else) infinitesimally-remote specter of some sort of  interaction with a rogue planet, this episode provides a a roundabout and extreme way to drive home a simple truth:  Astronomy relates directly to weather.

The knowledge that the study of the universe beyond can help us understand life at home is a powerful one, and the take-home truth (to me) of the rogue planet episode is that orbit shapes and axis tilts work to define the temperature (weather) for any world orbiting a star.

-And today, because our orbit is not elliptical, it is the tilt of our axis that dominates our climate and causes our seasons.

________________________________________
Stay tuned for more, and I’ll try and have one of these out for each episode!





Pluto’s Pain: The Unsung Story of Ceres

20 07 2012

Pluto is once again in the press, astronomers having recently discovered a fifth moon about the tiny, icy world.  -And, again, Pluto’s official designation as a “dwarf planet” is coming under fire.

However, Pluto’s pain really hearkens back to a much older story – one of an unsung planet that stood proudly in the rightful lineup alongside Earth, Venus, Mars, and the rest of the household-name kin of the Solar System for nearly a half-century, yet today nearly no one knows its name:

This is the oft-overlooked story of the scrappy planet Ceres [planet symbol:], which ultimately becomes the story of Pluto.

A Persistent Pattern

The story begins in the late 1700s, when the maturing discipline of astronomy discovered what was believed to be a pattern in the orbital semi-major axes (read: distances between) the planets.  The Cliff’s Notes version of the orbital mechanics here is that there appeared to be a gap between Mars and Jupiter where another planet should have been.

Thus at the turn of the 19th Century began a concerted effort to find this missing world, bringing to bear a contingent of respected astronomers and an arsenal of the most advanced telescopes the science of the time had to offer.

It wasn’t long before they hit paydirt.

(In an ironic turn, I should note that the subsequent discovery was made despite the fact that the ultimate logic of this proposition – the Titius-Bode Law – turned out to be wrong!)

 A Group Effort

In an unbelievable stroke of serendipity, one of the astronomers selected for the search won the race before he’d even entered.  Before Giuseppe Piazzi at the Academy of Palermo, Sicily had even been approached to join the strike team of planet-hunters, he pegged what would turn out to be Ceres while making separate astronomical observations on New Year’s Day, 1801.

A flurry of activity followed during the next year, with the observations changing hands multiple times before a young mathematician named Carl Friedrich Gauss (of differential geometry and magnetism fame), only 24 at the time, predicted the small world’s position to within a half-degree.

Gauss’s calculations led astronomers to the definitive discovery on December 31, 1801, nearly a year to the day of Piazzi’s initial discovery.

The Rise and Fall of Ceres

The discovery of a new world made waves through the astronomical community, with Piazzi naming the planet after the Roman goddess of agriculture, Ceres.  (The names Hera and Demeter have also been bounced about in different cultures, but the current generally-accepted name is Ceres.)

With a diameter of just over 600 miles, (almost exactly the same size of the peninsula of Korea), the world is something of a planetary runt.  However, this did not stop the planet from being included in astronomy textbooks as a brother amongst the rest of the known planets for more than a half-century.  Unlike the asteroids with which it was eventually found to share its orbit, Ceres is a true differentiated astronomical body that has reached so-called hydrostatic equilibrium, becoming a spherical world.

It was only as telescope technology improved and astronomy advanced that the understanding of what Ceres was began to change.  A sudden flood of asteroid discoveries at roughly the same orbital distance began to cast doubt upon Ceres’s uniqueness in the solar system.  Eventually, it was realized that all of these many new, small bodies would either have to also be called planets in order to remain consistent, or the definition of Ceres would have to be changed.

And so, unceremoniously, Ceres was demoted to the ringleader of the asteroids in the latter half of the 19th Century.  This means that by the time our grandparents came on-scene, one would have been hard-pressed to find a modern book that included more than a passing reference to this once-celebrated world.  It had become merely an asteroid.

The 2006 Upheaval

More than a century passed after the discovery of Ceres, and in the 20th Century a familiar story then began to unfold:  Pluto, which was determined to be a tiny world beyond the orbit of Uranus, was discovered in 1930.  It was added to textbooks as the ninth planet, as many of us grew up with.  However, during the 20th and early 21st Centuries, a flood of discoveries of other small, icy bodies in the outer solar system began to cast doubt upon Pluto’s uniqueness.  All of these objects together made up what became known as the Kuiper Belt, a zone of remnant material left over from our star system’s formation and the reservoir from which comets are occasionally pulled.

So, everyone knows that the reclassification of what makes a “planet” resulted in Pluto’s demotion to a new class of worlds called “dwarf planets.”  What few realized, however, was that Pluto’s loss was another’s vindication!

Ceres – waiting patiently in the wings for nearly 150 years – was promoted as a result of the change.  Instead of being “just” an asteroid, it too became a dwarf planet alongside Pluto.  Each as a result of the change evolved into small but noteworthy masters of their respective belts of material – Ceres the dwarf planet of the asteroid belt, Pluto the dwarf planet of the Kuiper belt.

In a way, the controversy resulted in long-awaited justice for little Ceres.

Take-Away

Perhaps, when engaged in your own debate about whether or not Pluto should be called a planet, you might decide to frame the conversation in a larger context.

It really isn’t just about Pluto.  Remember Ceres.





Retrospective: The coolest orbital image of 2011

29 05 2012

Space shuttle Atlantis leaves a glowing trail from the heat of re-entering the Earth’s atmosphere on its way home. (Credit: NASA)

In case you missed it, nearly a year ago on July 21, 2011, the space shuttle Atlantis was imaged as it began its fiery descent toward Earth.  As the final flight of the shuttle fleet, this was truly the last opportunity to grab this sort of image, and somehow the International Space Station Expedition 28 crew managed to snap the hero shot.

This visual – a heroic, blazing return to our world from the abyss beyond – is something sci-fi has been showing us for decades but that reality had yet to provide. 

A great moment, visually and historically.





Airships: A century from prototype to spaceflight?

24 02 2012

An airship that might have been, from "Sky Captain and the World of Tomorrow." (Credit: Paramount)

Airships.  There’s a certain nostalgic thrill to the streamline, art deco aircraft heyday that nearly was.

To the point (and as illustrated above): the Empire State Building’s observation tower was originally intended to serve as a mooring point for airships.

Achieving the power of flight by harnessing a buoyant gas is simple, reliable, quiet, low-velocity, and (after shifting away from using an explosive gas) veritably safe.  -And to many’s surprise, it might soon take us to space.

USS Shenandoah, U.S. Navy ZR-1, under construction in 1923.

Early 20th Century

Many don’t realize that the United States had airships in military service, which were outgrowths of a German design reverse-engineered after World War I.

For example, from 1922-1923, the first rigid airship, ZR-1 USS Shenandoah was constructed.  Several subsequent military airships flew under the American flag prior to World War II until they became tactically obsolete.

Early 21st Cenury

Now, after decades of work, volunteer-based aerospace firm JP Aerospace has its eyes set on an orbital airship as a gateway to the stars.

Ascender airship being serviced. (Credit: JP Aerospace)

How does it work?  The system is essentially 180-degrees apart from the rocket-and-fanfare, minutes-to-space spaceflight that we’ve all become accustomed to.  Instead, two separate classes of airships and a transfer station in-between slowly loft cargo to orbit over a matter of days.

The process is something they call “Airship-to-Orbit,” or ATO.

Essentially, an airship-to-orbit spaceflight program represents finesse versus conventional rocketry’s brute force.

Though there are still engineering challenges ahead, JP Aerospace is powering through tests of their magnetohydrodynamic thrusters and are continuing toward a stunning run of 67 high-altitude balloon and sensor platform ascents.

So, a century from prototype to spaceflight?  It certainly looks possible.  And if there truly is merit to the airship-to-orbit concept, based on how quickly JP Aerospace has been able to achieve flight benchmarks on a volunteer basis, then just imagine what could happen with serious backing by a government space agency.

Food for thought.

Personally, I love the architecture.  There’s something about truly alien competition to conventional spaceflight providers that I think is sorely needed.

Ascender 6000 on approach. (Credit: JP Aerospace)





Red-Letter Day: NASA Astronauts wanted; NSRC spaceflight giveaway

15 11 2011

Today has been quite a big day for aspiring astronauts:

NASA Seeks New Wave of Astronauts

Prototypical astronauts Tom Stafford and Alan Shepard Jr. studying a mission chart, Dec 1965. (Credit: NASA)

On one hand, NASA finally opened another selection announcement for the next class of astronauts.  Until the end of January 2012, anyone with the grit, drive, and the moxie to put their hat in the ring will be stacked up against the best of the best for a handful of new astronaut positions.

Contrary to what many believe in the post-Shuttle NASA environment, what awaits these future spacefarers is more than just maintaining the International Space Station, showing up at press appearances, and performing (much needed) education public outreach.  …NASA is also hard at work, developing a new, Apollo-style spacecraft intended for deep space missions (Orion MPCV) while exploring the possibility of using it to visit and explore near-Earth asteroids.

-Not to mention that these new astronauts will also be on the cusp of helping to break open a new era of commercial spaceflight.  (For more information on the many developments there, see CCDev to get started.)

Not a bad time to get involved, all things considered.

Spaceflight Giveaway for Next-Generation Suborbital Researcher

The XCOR Lynx suborbital vehicle. (Credit: XCOR Aerospace)

As if that weren’t excitement enough for the day, on the commercial spaceflight front, the Southwest Research Institute announced a partnership with XCOR Aerospace to offer a free suborbital spaceflight to one exceedingly lucky attendee at the next Next-Generation Suborbital Researcher’s Conference (NSRC)!

That’s right, a research seat in a spacecraft may be yours for the cost of attending and participating in the conference, slated for the end of February 2012.  The only obligations of the winner are to find their own way to the waiting spacecraft and create and provide an experiment for the trip.

The NSRC, the third conference of its kind, brings together commercial spaceflight industry pioneers, regulators, and both private and federal researchers to explore the opportunities and possibilities presented by the many private suborbital spacecraft currently in development.

For more info, visit nsrc.swri.org – and sign up!  (I can speak from personal experience: the conference last year was thrilling to those for whom spaceflight and microgravity research holds an appeal.)





Room with a (global) view

3 11 2011

When you gaze outside of your spacecraft, what do you see?

What’s it really like to be there?

With the advent of digital photography in the hands of determined astronauts willing to make time to steal moments to snap images like the above, now we can know. 

Have a look.  Blow the image up with a click.  You’re really just sitting there, looking out the window; A perfectly mundane act performed from an extraordinary vantage.

This reality represents (to me, anyway) one of the most inspirational aspects of 21st-century human space exploration: for the first time, the human experience of spaceflight is being not just communicated but also shown to those of us on the planet surface in real-time (via Twitter, for example,) to great effect.

I believe it is the responsibility of those who support and/or are professionally involved in space exploration to promote imagery like the above, for I truly believe it will be via exposure to this media that the next generation of planetary explorers will be engaged to careers in the student-starved sectors of Science, Technology, Engineering, and Mathematics (see: STEM).
 
-And the more ordinary orbital space feels, not only will the goals of work off-world feel attainbale, perhaps the next generation will be even more compelled to see the world as a fragile, interconnected system and seek out the extraordinary in their experiences farther beyond…




Plans afoot for snaring a space rock

2 10 2011

Trajectory of 2008EA9 before and after orbit maneuver. (Credit: Hexi et al., 2011)

Researchers at the Tsinghua University in Beijing recently published a plan just daring enough to work/make people nervous.

After an extensive review of the orbits of thousands of candidate near-Earth objects, the research team headed by Associate Professor Baoyin Hexi identified a small asteroid that with a nudge at the opportune moment would settle into a temporary Earth orbit.

The 410-meter-per-second-boost required to snare 30-foot-wide asteroid 2008EA9 is but a fraction of the propulsion cost required, for instance, for our spacecraft to get to low Earth orbit, (8,000 meters-per-second).

Attempting such a technical feat would be a boon for space logistics and exploration research by providing a simple, local target for investigation by astronauts.  Further, the experience would exponentially improve our asteroid diversion know-how and spur the development of space resource/mining techniques.

Despite the terror-stoking hype that any asteroid-grab project is bound to inspire, the risks in this case are relatively low: few realize that asteroids of similar size (5-10 meters in diameter) hit the Earth’s atmosphere annually.  While still packing the punch of an mid-twentieth century atom-bomb, these objects are small enough to vaporize in the upper atmosphere, and typically no one is the wiser for it.

I say let’s go for it.  Any eccentric, research-minded philanthropists want to drop a fortune on lassoing a giant lump of primordial solar system?








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