In the last portion of _Sidereus Nuncius_, Galileo reported his discovery of FOUR OBJECTS that appeared to form a straight line of stars near JUPITER. The first night, he witnessed a line of three little stars close to Jupiter parallel to the ecliptic; the following nights brought different arrangements and another star into his view, totaling four stars around Jupiter. Throughout the text, Galileo gave illustrations of the relative positions of Jupiter and its apparent companion stars as they appeared nightly from late January through early March 1610. The fact that they changed their positions relative to Jupiter from night to night, but always appeared in the same straight line near Jupiter, brought Galileo to deduce that they were four bodies in orbit around Jupiter. On January 11 after 4 nights of observation he wrote: “I therefore concluded and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury round the Sun; which at length was established as clear as daylight by numerous subsequent observations. These observations also established that there are not only three, but four, erratic sidereal bodies performing their revolutions round Jupiter...the revolutions are so swift that an observer may generally get differences of position every hour.”

ABSTRACT The very long, thin infrared dark cloud Nessie is even longer than had been previously claimed, and an analysis of its Galactic location suggests that it lies directly in the Milky Way’s mid-plane, tracing out a highly elongated bone-like feature within the prominent Scutum-Centaurus spiral arm. Re-analysis of mid-infrared imagery from the Spitzer Space Telescope shows that this IRDC is at least 2, and possibly as many as 8 times longer than had originally been claimed by Nessie’s discoverers, ; its aspect ratio is therefore at least 150:1, and possibly as large as 800:1. A careful accounting for both the Sun’s offset from the Galactic plane (∼25 pc) and the Galactic center’s offset from the (lII, bII)=(0, 0) position defined by the IAU in 1959 shows that the latitude of the true Galactic mid-plane at the 3.1 kpc distance to the Scutum-Centaurus Arm is not b = 0, but instead closer to b = −0.5, which is the latitude of Nessie to within a few pc. Apparently, Nessie lies _in_ the Galactic mid-plane. An analysis of the radial velocities of low-density (CO) and high-density (${\rm NH}_3$) gas associated with the Nessie dust feature suggests that Nessie runs along the Scutum-Centaurus Arm in position-position-velocity space, which means it likely forms a dense ‘spine’ of the arm in real space as well. No galaxy-scale simulation to date has the spatial resolution to predict a Nessie-like feature, but extant simulations do suggest that highly elongated over-dense filaments should be associated with a galaxy’s spiral arms. Nessie is situated in the closest major spiral arm to the Sun toward the inner Galaxy, and appears almost perpendicular to our line of sight, making it the easiest feature of its kind to detect from our location (a shadow of an Arm’s bone, illuminated by the Galaxy beyond). Although the Sun’s (∼25 pc) offset from the Galactic plane is not large in comparison with the half-thickness of the plane as traced by Population I objects such as GMCs and HII regions (∼200 pc; ), it may be significant compared with an extremely thin layer that might be traced out by Nessie-like “bones” of the Milky Way. Future high-resolution extinction and molecular line data may therefore allow us to exploit the Sun’s position above the plane to gain a (very foreshortened) view “from above" of dense gas in Milky Way’s disk and its structure.

Instructions for Co-Authors The full file repository for this paper is at a shared Google Drive directory, https://drive.google.com/#folders/0BxIRxiTe1u6BcGlnUGt2ckU1Vms, shared with all co-authors. NOTE: THE “AAS” (PRESS CONFERENCE) SLIDES AT HTTPS://DRIVE.GOOGLE.COM/#FOLDERS/0BXIRXITE1U6BRKLQRZLUAUNUUUU GIVE A BETTER IDEA OF WHERE THIS DRAFT IS GOING THAN THE TEXT/FIGURES HERE AS OF NOW... AG WILL UPDATE ALL BY C.1/1/13! The Mendeley Library “Nessie and Friends” used to house references used in this work, at: http://www.mendeley.com/groups/2505711/nessie-and-friends/, but since Authorea works more directly with ADS links, we’ll use the ADS Private Library at http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?library&libname=Nessie+and+Friends&libid=488e32b08b instead. The Mendeley library is the source of the nessie.bib file in the “Bibliography” folder here on Authorea, but I am not sure how to get the ADS references out as a .bib file. xxAlberto?xx The Glue software used to intercompare data sets used in this work is online through: http://glue-viz.readthedocs.org/en/latest/ We are using Authorea.com as an experimental platform to compile this paper. The manual steps we will need to take before submission include: - download LaTeX file - modify LaTeX file to use aas macros - insert needed information (e.g. about authors, running header) into was version of LaTeX manuscript - extract needed figures from relevant folders here & bundle them with LaTeX manuscript & macros - create .bib file from ADS Private Library - add .bib file to folder with manuscript & figures - fix in-line referencing so that $\citet$ and $\citep$ commands work

_A 5-minute video demonstration of this paper is available at this YouTube link._ PREAMBLE A variety of research on human cognition demonstrates that humans learn and communicate best when more than one processing system (e.g. visual, auditory, touch) is used. And, related research also shows that, no matter how technical the material, most humans also retain and process information best when they can put a narrative "story" to it. So, when considering the future of scholarly communication, we should be careful not to do blithely away with the linear narrative format that articles and books have followed for centuries: instead, we should enrich it. Much more than text is used to commuicate in Science. Figures, which include images, diagrams, graphs, charts, and more, have enriched scholarly articles since the time of Galileo, and ever-growing volumes of data underpin most scientific papers. When scientists communicate face-to-face, as in talks or small discussions, these figures are often the focus of the conversation. In the best discussions, scientists have the ability to manipulate the figures, and to access underlying data, in real-time, so as to test out various what-if scenarios, and to explain findings more clearly. THIS SHORT ARTICLE EXPLAINS—AND SHOWS WITH DEMONSTRATIONS—HOW SCHOLARLY "PAPERS" CAN MORPH INTO LONG-LASTING RICH RECORDS OF SCIENTIFIC DISCOURSE, enriched with deep data and code linkages, interactive figures, audio, video, and commenting.

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