Radio Astronomy Reveals a Long and Winding Road in Space

Radio/optical composite of the Orion Molecular Cloud Complex showing the OMC-2/3 star-forming filament. GBT data is shown in orange. Uncommonly large dust grains there may kick-start planet formation. Credit: S. Schnee, et al.; B. Saxton, B. Kent (NRAO/AUI/NSF); We acknowledge the use of NASA’s SkyView Facility located at NASA Goddard Space Flight Center.

Wow!  Check out this latest image of the Orion Nebula!

Just when you think astronomy can’t get any cooler, something like this comes out: radio astronomers using the Green Bank Telescope (a radio telescope in West Virginia) have found filaments of star-forming gas near the Orion Nebula. Embedded in those filaments are what they think could be large grains of rocky material, the building blocks of planets.

If this discovery is held up through further observations, it would be the first time large particles — perhaps the size of a Lego-type building block — have been detected in such a dense super-nurturing star- and planet-forming nursery. Prior to this, regions of star birth were understood to be thick with dust-sized grains.  The existence of larger grains could change the dynamic of planet formation in this and other regions where larger particles exist.

Scott Schnee, an astronomer at the National Radio Astronomy Observatory (NRAO) and lead on the team doing the work, pointed out that the availability of large-enough (pebble or Lego-sized) planetary building blocks would encourage the formation of planets around newborn stars in the region. “If you want to build a house, it’s best to start with bricks rather than gravel,” he said, implying that it would lead to faster building rates than normal.

Planet formation, similar to building a house, needs material to get started. Most planet nurseries start out with grains of material perhaps no larger than dust specks or maybe sand bits. Over time, those materials stick together to form larger and larger planetesimals, which collide to form planets. If you can start with bigger pieces, that might shorten the planet formation time.

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The Issue is NOT Just Planetary Status

Artists’ concept of the New Horizons spacecraft as it flies by Pluto in July, 2015. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

I recently got into a fascinating late-evening computer chat with someone who is really incensed that Pluto is no longer a planet. He seemed pretty upset about it, and although not a planetary scientist, seemed cognizant of the IAU’s role in the supposed “demotion” of Pluto a few years ago. Since we just passed the anniversary of that silly vote that led to all the commotion, and in light of my conversational partner’s concerns about this distant world, I thought it a good time to talk about Pluto again.

Essentially, there are two issues:  the definition of planet (and where Pluto fits) and the IAU vote. People get upset about the second issue without understanding the scientific implications of the first. And, whether or not the IAU voted the way it did, there was and is still a healthy conversation going on in the planetary science community about just how we define solar system objects, particularly planets.

In less than a year, we’ll know more about Pluto than at any other time in human history. The New Horizons spacecraft will have just completed a successful flyby of Pluto, looked at Charon (its companion), and its moons (and maybe will have found a few more!). It will be exciting, and as Alan Stern (PI of the New Horizons mission put it on a recent NASA press conference), ” A year from now, we’ll write the textbooks on Pluto.”

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