Should Pluto Be Returned to the Family of Planets?

Should we still be having this argument about whether or not Pluto is a planet? Is this a scientific duel, or more the earlier generation complaining that they still want to use the mislabeled name brontosaurus rather than Apatosaurus? I am fine with the 2006 decision to make Pluto a dwarf planet, but some at Harvard-Smithsonian Center for Astrophysics are still debating the topic. Last month, after hearing a debate among three leading experts in planetary science, the audience voted and decided that Pluto is still a Planet.  While this settles nothing, it was still a good debate (you can see it on YouTube at https://www.youtube.com/user/ObsNights).

I am more interested in labeling exoplanets rather than relabeling our neighbors, but I do not expect this issue to die anytime soon.  So while the local debate continues, I hope the telescopes will be trained on much more distant matters as we ponder the wild and strange universe. 

Looking for that Next Earth

A lot of attention is being paid to the newly discovered Kepler 10c, a planet twice as large as Earth and 17 times heavier.  About 560 light years from Earth, this planet takes 45 days to orbit its sun.  In the Harvard-Smithsonian Center for Astrophysics press release announcing the finding, researcher Dimitar Sasselov, director of the Harvard Origins of Life Initiatives, stated "This is the Godzilla of Earths!" But unlike the movie monster, Kepler-10c has positive implications for life."

What I find even more interesting is the age of  the solar system hosting Kepler-10.  It is about 11 billion years old, having formed less than 3 billion years after the Big Bang.  So in addition to a planet more than twice the size of Earth, it is also more than twice as old.  What does this rocky world tell us about the available elements for planet building.  And what has been happening on that planet all this time? 

Estimates on the number of Earth-like planets and the likelihood of life continue to abound.  One recent paper, Assessing the Possibility of Biological Complexity on Other Worlds, with an Estimate of the Occurrence of Complex Life in the Milky Way Galaxy, put the estimated number of Earth-like planets about about 100 million in the Milky Way alone.  The paper concludes, "It supports the view that the evolution of complex life on other worlds is rare in frequency but large in absolute number." That provides ample ammunition for many more stories about new worlds. 

The Beginning of the Universe...

If you want to see how the universe expanded into what we see today, or at least see a computer simulation of this process, you should visit the Illustris project.  Here is how the site defiines the project:

The Illustris project is a set of large-scale cosmological simulations, including the most ambitious simulation of galaxy formation yet performed. The calculation tracks the expansion of the universe, the gravitational pull of matter onto itself, the motion or "hydrodynamics" of cosmic gas, as well as the formation of stars and black holes. These physical components and processes are all modeled starting from initial conditions resembling the very young universe 300,000 years after the Big Bang and until the present day, spanning over 13.8 billion years of cosmic evolution. The simulated volume contains tens of thousands of galaxies captured in high-detail, covering a wide range of masses, rates of star formation, shapes, sizes, and with properties that agree well with the galaxy population observed in the real universe. We are currently working to make detailed comparisons of our simulation box to these observed galaxy populations, and some exciting promising results have already been published.

In an MIT press release, we learn about how this simulation is the first successful attempt to account for our current universe:

“For the past two decades, cosmologists have been unable to produce galaxies like the Milky Way in their simulations,” says David Spergel, a professor of astronomy at Princeton University. “We have long debated whether this failure was due to complex dark matter physics, unknown stellar feedbacks, or the difficulties in simulating the highly non-linear multi-scale process of galaxy formation … With their simulations, [the researchers] finally produce galaxies that look like our own.”

And this is quite a project in terms of the scientists, computer resources, and sources of funding.  The MIT press release noted that the paper, “Properties of galaxies reproduced by a hydrodynamic simulation,” was co-written by 10 authors at several institutions: the Harvard-Smithsonian Center for Astrophysics (CfA); the Heidelberg Institute for Theoretical Studies in Germany; the University of Heidelberg; the Kavli Institute for Cosmology and the Institute of Astronomy, both in Cambridge, England; the Space Telescope Science Institute in Baltimore; and the Institute for Advanced Study in Princeton, N.J.

The computing centers used to run the simulation were the Harvard Odyssey and CfA/ITC cluster; the Ranger and Stampede supercomputers at the Texas Advanced Computing Center; the CURIE supercomputer at CEA/France; and the SuperMUC computer at the Leibniz Computing Centre in Germany.

Support for the research came from the German Research Foundation, the European Research Council, NASA, and the Alexander von Humboldt Foundation in Germany.

Image Credit:  Illustris project

Away from the Politics: More on the Big Bang

While the U.S. and Russia have been tussling on a variety of issues, some solid science has been going on unabated.  For instance, last month the Harvard-Smithsonian Center for Astrophysics announced the discovery of gravitational waves formed when the universe was a trillionth of a trillionth of a second old.  While I cannot really wrap my head around the particulars, this discovery (if successfully duplicated by others) could further confirm the theory of cosmic inflation, or the idea of rapid expansion of the universe in the first 380,000 years of its existence.  I found a nice scientific cartoon (really) that walks us through these ideas at PhD Comics.  And here is the March 17th video from the Center with the scientific announcement.

The research itself involved scientists from the Harvard-Smithsonian Center for Astrophysics (CfA), Stanford University, the California Institute of Technology (Caltech), and the University of Minnesota, while the observations themselves were made at the BICEP2 telescope near the South Pole.