December 30, 2010

Exobiology, Astrobiology and Exoplanets

So I tried Google's Ngram viewer on Exobiology, Astrobiology and Exoplanet, and came up with the chart shown above. As an added perk, I overlayed the yearly count of exoplanet discoveries on the graph.

As you can see, the term Exobiology was more popular than Astrobiology back then. And the word "Exoplanet" never occurred in any books prior to the 80's. But it all changed when the first confirmed exoplanet was announced in 1992. It was then that the trend of the exoplanet began, and propelled a sudden surge of interest in Astrobiology.

As new exoplanet discoveries continued to pile up, so did the field of Astrobiology continue to grow, evident in the increasing usage of the term in published books. By 1997, a few years after the discovery of 51 Pegasi b, the word astrobiology overtook exobiology.

Suddenly, Astrobiology was hip. It became increasingly more popular overnight, as if riding on the wave of exoplanets.

But what happened with the word Exobiology? Why didn't it pick up as much as Astrobiology did? It's a curious historical note, and the answer could be anyone's guess. And I'll give it a try.

The term Exobiology was coined by a Nobel Prize-winning scientist named Joshua Lederberg. I do not know exactly when the word Astrobiology was adopted to replace Exobiology but all we know is that it specifically means the "study of life beyond the Earth". But since there's no known life beyond the Earth (yet!), people said it's a field with no subject matter. That may well be a plausible reason why the term didn't catch on, no matter how cool the prefix "exo" is.

And since the term Astrobiology already picked up the momentum, it also locked on as the bastion to the science of "Life elsewhere in the universe"--a phrase that makes it seem a wider field than by just saying "Life outside earth".

Now here are questions to entice the next generation. Will exobiology make a comeback? Do you think the word exoplanet will skyrocket in the next decade? And what about...ahem...Exoplanetology?

Only time will tell.

December 29, 2010


I woke up one day wondering what kind of "gasm" I would describe for that ecstatic feeling about exoplanets. I toyed around with "exogasm". And I liked the fun suggestions from the twitters. But never did I realize that on that same day (December 1) my mind would be blown by a kind of cerebral experience brought about by the prospect of new worlds. Lots of them!

Several "foreplay" news items came into view through my twitter stream. First was that news of the first time a super-earth's atmosphere was ever examined.

But nothing would prepare me for a gasm that is truly mind-blowing: The number of stars in universe were more numerous than previously thought--so much more that the total number of stars in the universe is likely three times bigger than realized!

The tidbits below says it all in one word: Exogasm!

"There are about 20 times more red dwarfs in elliptical galaxies than in the Milky Way. In addition to boosting the total number of stars in the universe, the discovery also increases the number of planets orbiting those stars, which in turn elevates the number of planets that might harbor life."

"There are possibly trillions of Earths orbiting these stars."

Latest Star Census Increases Number of Exoplanets
Atmosphere Around Super-earth analysed for the first time

December 22, 2010

Exoplanet is the new Planet

I try to stay away from the debate about Pluto. My issue is not about Pluto. It's about the Planet. One can mock Pluto a thousand times over, and the best (or worst) it could do is annoy people. Sometimes it does get to me, so i have to remind myself that I am more concerned about the concept of the planet, and the idea it represents, and the ideal it imparts to the human psyche.

Let me begin by saying that I think I am falling in love with planets. I don’t know how, but during the course of following the saga of exoplanets it must have been inevitable (after all, the ‘exoplanet’ bears the name of ‘planet’).

With new discoveries that pour in almost daily about planets in other star systems, Exoplanets are a constant source of amazement. They continue to remind me that I can never know enough, that this fascinating universe is an endless source of wonder.

But...something keeps getting in the way. Something mind-numbing creeps in when I read something about what a ‘planet’ is defined to be. It has bothered me so much that I had to use “worlds” as an alternative keyword to hook me back in wonder about these spherical objects in space.

Why? What happened with the term “planet”? What happened with the magical and mythical concept that the Greeks once started with, saying that these mysterious points of light are ‘wanderers’?

The problem began when mankind started to *define* the Planet. We relentlessly squished the concept of a planet with words so that it could fit within our tiny skulls.

I looked into the two sides of the debate, learning as much as I can to understand, but the mandated definition of the Planet really does not appeal to me. In the spirit of freethinking, I humbly decline to subscribe in the 'official' definition of the planet.

Why? What have humans done to the concept of the planet?

There is nothing inherently wrong with classifying things, and certainly nothing wrong with identifying the boundaries in order to characterize objects, but I think we had the wrong attitude when we made up the criteria for planets.

And that is the sad thing about it. Instead of trying to widen the concept of the Planet, we tried to limit it. The kind of thinking that is promoted by the current definition of the planet is a divisive mode of mentality. You see, in our world, much strife is borne out of a discriminating mindset--a way of thinking that focuses on the differences and not on the similarites.

"The major problems in the world are the result of the difference between how nature works and the way people think." ~Gregory Bateson

Today, dwarf planets are not considered planets at all, despite calling them 'dwarf planets'. Is it a matter of linguistic fallacy that makes it all nonsensical? (Dwarf galaxies are galaxies, and dwarf stars are stars, but dwarf planets are not planets?)

Or is it just the mode of thinking? Why deny dwarf planets of being planets? Such judgement mirrors a way of thinking that is alienating and divisive.

It is certainly valid if you consider dwarf planets as a subset or variation of the wide scope of planets. This alternative method of classification exemplifies a way of thinking that respects differences and yet aims to see things as One.

You can choose a mindset that seeks to see all kinds of planets in a wholistic fashion, and delight in their diversity. Or you could choose a discriminating mentality, segregating a class of planet-worlds that don’t fit in your limited notion based on one star system alone--yours.

The Pluto debate is a clash of mentalities. And it has marred the concept of the planet. I hope that the next generation never inherits the discriminating mentality that is present in that conflict.

I rest my case in the lessons that exoplanets are teaching us. They continue to challenge our pre-defined notions of what a planet truly is. They continue to be a source of wonder, in the same way that the Ancient Greeks felt about their ‘wanderers’. In our modern era, only the Exoplanet can conjure that feeling of mystery and discovery ascribed to such mysterious objects.

For me, Exoplanet is the new Planet.

I wish we never end up defining the Exoplanet in the same way we did for the Planet, for I wish to keep the concept of the Exoplanet with awesomeness and wonder.

December 14, 2010

Exoplanetary Bow Shocks

Exoplanetary Bow Shock
We've heard of stellar bow shocks before. But I bet no one has heard of bow shocks of planets just yet! Exoplanetary Bow Shocks would be an amazing sight to see. I am surprised by the lack of pictures that I can find on the web on how it would look like. So I made one of my own.

Now here's an unusual trivia about exoplanetary bow shocks which caught my attention: Exoplanetary Bow Shocks can also appear from behind the planet! Astrophysicists call them "behind-shocks".

Another case, is when the shock trails the planet. In the “behind-shock” case, the planet orbits the star beyond the Keplerian co-rotation radius, so that the coronal plasma lags behind the planetary motion. In order to develop a behind-shock, the planet must be in a prograde orbit.

Now, of course I wanted to imagine how a bow shock would look like when viewed from the surface of the planet. A question brewed in my mind: Would an exoplanetary bow shock look like the Aurora? Yes. But you would not be around long enough to see much of it, for the bow shocks described in the paper are stellar plasma emanating from the star that interacts with the magnetic fields of both the planet and star itself. Imagine yourself being burnt to a crisp while watching a beautiful 'Aurora' show.

The planetary magnetic field is believed to be responsible for shielding the planet against the erosion of the planetary atmosphere by the host star’s wind or the impact of energetic cosmic particles. Such effects could harm creation and development of life in the planet.
Furthermore, the presence of a planetary magnetic field may induce star-planet interactions, e.g., through reconnection between stellar and planetary magnetic field lines.

But of course, planets farther away from the star would have a more gentler bow shock, and a milder shower of stellar material. I would assume different kinds of beauty and variety that one would see if one were to look up from the surface of an exoplanet with a faint bow shock. And it hit me! We have those here on earth! We know them as Aurora Borealis and Aurora Australis!

And that whole visual imagining is the whole reason why the arxiv paper inspired me to write a story, entitled “Worlds Hopper”. The ArXiV paper is rich with information. It contains lists and data tables of exoplanets which may possibly have bow shocks. Some of them are WASP-12b, OGLE-TR-56b, WASP-19b, SWEEPS-11,WASP-4b,WASP-18b, CoRoT-7b, CoRoT-14b, HAT-P-7b, OGLE-TR-132b, CoRoT-1b, TrES-3, and WASP-5b.

Well, these bow shocked exoplanets are quite a handful, eh? Go check out the paper and tell me what you think.

Prospects for Detection of Exoplanet Magnetic Fields Through Bow-Shock Observations During Transits
Transit Variability in Bow Shock-Hosting Exoplanets (PDF)
Short Story: Worlds Hopper

December 2, 2010

Other Platforms of Life

Mono Lake, where the arsenic-loving GFAJ-1 was found.
Life as we know it appears to have a common base. All of us, from the smallest amoeba, to the largest whale, share the same platform of life: Carbon.

And we think that life can only occur in one way, in one place and at one time in the history of the earth.

Today, all that is about to change.

NASA scientists have found a bacteria whose biochemical make-up is quite different from the carbon-based life that we know of.

A bacteria called GFAJ-1 has been found in Mono Lake that eats arsenic, and also incorporates arsenic in its DNA as replacement for phosphorus--one of the usual set of components of "CHNOPS" (carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur) that form the basis of all life on earth.

I’ve always believed that our form of life is the only possible configuration. And now there is direct scientific evidence that it is possible for life to occur in other platforms.

This finding is mindblowing. It gives a preview of a "shadow biosphere" that could exist on our planet, and may strengthen the idea that life may be rampant elsewhere in the universe. All the more that this fascinating discovery was announced a day after astronomers revealed that the number of stars is 3 times more numerous than previously known--which means that there are gazillions more of exoplanets exist!

If we just found a hint of “shadow life” on our very own planet, then one can imagine the richness of life originating on other conditions and other chemicals on other planets.

Arsenic-eating microbe may redefine chemistry of life
Arsenic-Eating Bacteria Opens New Possibilities

The Exoplanet Generation

Image credit: ESO
I asked my seven-year-old daughter, "What do you call a planet outside our solar sys..." I didn't even finish my question when she excitedly exclaimed, "EXOPLANET!!!"

I laughed. She smiled. And then I realized: I am talking to a child of the "Exoplanet Generation", the young ones that were born from 1992 and onwards. It's the year when the first discovered exoplanet (orbiting a pulsar called PSR B1257+12) was announced. From then onwards, the accelerating rate of discovery defined the pulse of the Exoplanet Generation.

These "ExoGen" kids will grow up in a world very different from our own. When I was seven, i had no idea about other worlds. But the children of the exoplanet generation will bask in the weekly or daily news about the new exoplanet discoveries. They will wake up hearing new discoveries about how other lifeforms in platforms other than carbon may be able to thrive, or how life is possible on planets and moons outside our solar system.

Perhaps, in their lifetime they will witness the discovery of exolife, or be the ones to make the discovery itself, of life on other worlds!

And so, ExoGen kids...Welcome to brave New Worlds!