Those in the vicinity of Manlius, NY are no doubt aware of the presence of Sno-Top (home of the best soft black raspberry in the area, IMHO) and the duck pond at town center(-ish). Those continuing just a tad further along Fayette Street (92, DeWitt-to-Cazenovia direction) also know that the swan population is localized to the higher pond near the Saucy Swan Restaurant (they do make for loquacious patrons). These facts, combined with the oppressive CNY heat of early July, made the choice of Cygnus the Swan obvious for this month’s constellation. Fittingly, Cygnus is an astronomical feast for naked eye, binocular, and telescope observers alike and, as it is half-way between horizon and zenith in early July in the early evening, it is strategically placed for accessibility with all manner of optics.
Cygnus is surrounded by several dangerous Constellations. The animal Constellations Draco, Velpecula, and Lacerta might enjoy freshly killed what the king Cepheus would otherwise enjoy glazed. The massive Constellation Pegasus is a problem in its own right. Trampled by horse is bad enough on the ground, but to have to avoid trampling by a flying one is another matter altogether. Lyra may be the only reminder to Cygnus of its terrestrial past, having been the instrument of choice for one of Cygnus’ human attributions (that man being Orpheus. See below). For those using only their free pair of 1×7 binoculars (that is, your pair of eyes), the cross that makes up the body and elbows of the wings of Cygnus are most obvious. The bright stars Deneb, Sadr, and Gienah (and the nearby Vega in Lyra, the easiest of the stars in this part of the sky to find starting at sunset) are perhaps most obvious, but the rest of the body is pronounced. As the evening progresses (and on reasonably clear nights), the most striking feature of Cygnus is the river of stars and interstellar dust that is our view of the Milky Way (as if Cygnus is flying above it).
As a collection of prominent stars within the body of the Milky Way, you can guess that the Constellation we know as Cygnus has a long and distinguished history. The Greeks (“Give me a Constellation, any Constellation, and I show you that the history of that Constellation is Greek”) have many swans in their mythology, from Zeus (who fathered Gemini and Helen of Troy disguised as a swan, or so the story goes) to Orpheus (turned into a swan upon his death and placed next to his lyre (Lyra) to characters in Ovid’s Metamorphoses. Cygnus is a member of the “Famed 48,” the 48 original Constellations contained within Ptolemy’s Almagest.
At the head of Cygnus is the star Alberio which, upon inspection with even low-magnification optics, resolves into two stars that make up quite possibly the best color contrast in the northern hemisphere (above, from wikipedia). Alberio A (the orange-ish one), is actually itself a true binary, meaning its two stars are gravitationally bound to one another. It is possible, with scopes larger than 20″ and under excellent conditions, to resolve the two stars, Alberio B (the blue-ish one), is a single star that is not gravitationally bound to Alberio A, making this most famous binary an “optical binary,” one where the two stars look very close but only because of our perspective from Earth. If Cygnus is out, this star always makes its way into the eyepiece of the 16″ scope at Darling Hill. Further, for those who like to get their scopes perfectly focused (especially large binoculars), this combination is an excellent test.
As is the case with all of the Constellations within the band of the Milky Way, Cygnus is host to several binocular and telescope objects. The two pronounced Messier Objects are M29 and M39, both open clusters. M29 (above, from wikipedia) is famous (to me) for being the one Messier Object that does NOT appear in the index of the Peterson Field Guide To Stars And Planets. Believe me, I have tried several times to find it (just assuming the dark conditions kept me from seeing it. It does appear in the Constellation map, though). This object appears within the binocular field of view of Sadr and is small but worth scanning in dark skies. M39 (below, from seds.org) is similarly nondescript, residing between Deneb and the stars of Lacerta.
Cygnus becomes quite interesting for its wealth of interesting New General Catalogue (NGC) Objects. The four most prominent objects are the North America Nebula (NGC 7000), the Pelican Nebula (IC 5070), the Veil Nebula (NGC 6960, 6962, 6979, 6992, and 6995), and the Crescent Nebula (NGC 6888). The North America (not American) Nebula (below, with the Pelican Nebula to its right, from wikipedia) is a testament to the only mild imagination of the working observational astronomer. Like many nebulae, details can be pulled out of this object with the use of filters. Depending on the conditions, the best way to confirm this structure exists in your scope is, frankly, to move the scope ever so slightly in the field of view of nearby stars and confirm for yourself that some slightly darkened patch of sky is staying put with respect to the background of stars. This approach, combined with averted vision, is definitely my method of choice for finding the locations of objects I may otherwise miss completely (and we’ve all had the experience of NOT seeing something in a scope that another person can even make detail out of). The very low surface brightness of the nebula makes it an at-least binocular object to observe, but it is noteworthy that this entire North America Nebula is reportedly four times the size of the full Moon. The Pelican Nebula (lower right of the image above) looks more like a Teradactyl to me, but there is some similarity in both (in case you do not see it, the pair of eyes are at upper left (with a bright star in each marking the pupils), the beak extends to the left (and is narrower than a typical pelican), and the body extends to some less structured arrangement down to the lower right).
The North America and Pelican Nebulae, photo by Jason Ware. From wikipedia.org.
The Veil Nebula is a collection of nebulae that make for haunting photos. I am very pleased to have a greyscale image of the Eastern Veil provided by our own Stu Forster (below and in the member gallery). This object is very difficult to observe without an OIII filter, but even an 8″ scope will resolve the detail of this nebula with the filter (it is reported that in excellent sky locations, simply holding this filter to one’s eye will make the Veil Nebula stand out). The Veil Nebula has also been the focus of some considerable Hubble imaging time and a web search for these images is definitely worth one’s time.
The Crescent Nebula. Photo by Stu Forster.
Finally, the Crescent Nebula has also been the focus of some astrophotography time by the good Dr. Forster (below (The Crescent, not Dr. Forster)), appearing to me more like a floating brain than a boring crescent. The Nebula is formed by a Wolf-Rayet star, a type of very hot, massive star with a strong stellar wind. This nebula is actually a double-whammy, as the fast-moving stellar wind from this WR star is colliding with the slower stellar wind from this same star when it was a red giant some 400,000 years earlier.
In press, in the journal Molecular Biosystems. A first official foray into molecular dynamics-only (MD-only) computational work and I am pleased to report that the computational results not only make sense with respect to the experimental results, they also indicate a possible new way to use vitamin B12 for the oral delivery of bio-active molecules more complicated than the binary bioconjugates considered to date.
The Interesting Result
The conclusion from the previous study was that the insulin B Chain (figure below) acts as a tether to separate the structured region of insulin (the region with the largest inflexible steric bulk, see below) from the region of the transcobalamin II (TCII) that bind vitamin B12. It was then determined that the approach employed for the B12-insulin bioconjugate, simply linking one biomolecule onto another with known binding and transport properties (this is a common theme in all bioconjugate design), worked because the last 10 residues in the insulin B Chain (B22 to B30) are flexible in solution (they, in fact, cover the insulin binding region in the crystal form, then uncover this region in the biologically active form).
As a general procedure for B12 bioconjugate design, one of the key requirements for a functional product is a tether length that provides sufficient separation between B12 and any molecular structure large enough to affect B12 binding within its transport proteins (makes sense, as a tethered structure that does not enable B12 binding in its transport proteins will find the B12 bioconjugate delivered to the gut where acids and digestive enzymes will hide the failed binding). This leads to the question, “How long must a tether be to meet this rather general criterion?” This is, partly, the correct question, as the retention of B12 binding within its transport proteins is a function of both proper tether length and [transport protein]-["other molecule"] interaction (in this first case, “other molecule” = insulin).
Saving the exhaustive analysis for the paper, this new study used this flexible region of human insulin (that is, B22 to B30, with the B12 linkage occurring on the B29 lysine side chain) as a proxy for any arbitrary tether, then used MD simulations to consider how the flexibility of this tether might lead to changes in B12 binding within its TCII pocket (the transport protein for which we have the best crystal structure). The result of these simulations was the identification of the side chain of lysine itself being just long enough to separate the B Chain tether region from the TCII protein surface. This does not mean that lysine will always serve as a perfect linkage. This means that, if the tether structure is effectively non-interacting with TCII (so not sterically demanding by itself), the lysine side chain is long enough to span the solvent-accessible hole produced by the encapsulation of B12 in (in this case) TCII.
The result is a design constraint when using lysine that is quite fortuitous! If the target peptide (insulin or whatnot) has a surface-accessible lysine side chain within a region that is flexible in solution, some simple amide chemistry may produce a viable B12 bioconjugate for delivering that peptide orally (thereby avoiding complete peptide degradation in the G.I. tract).
The More Interesting Result
Buried deep within the bottom of the Discussion section. If you watch the dynamics simulation of the TCII-[B12-tether] complex (shown below for a 300 K 50 ns simulation with 1.5 fs time steps in 14,000 waters (not shown)), you see that the binding of B12 within TCII and the geometry of the encapsulation complex are strongly linked. That is, TCII (and, presumably, its cohorts in the B12 transport pathway) can be thought of as two quite rigid fragments (Red and Blue in the animation) connected by a long tether (Green) that are separated in solution but brought into contact by the binding of vitamin B12 (Gold). The B12 is a glue that holds the fragments together, and a simple tabulation of hydrogen-bonding interactions in the crystal structure reveal that the B12 has more interactions to the A and B fragments of TCII individually than A and B have with each other (which is to say, the B12-A Segment interaction and B12-B Segment interaction are stronger than the A-B Segment interaction). From a biological perspective, this should make perfect sense. B12 is a large, extremely important biomolecule that, since we do not make it ourselves, is to be captured and transported as effectively as possible. The best way to bind this molecule is not to wait for it to burrow into a binding pocket, but rather to encapsulate it in a “clam shell” maneuver that provides “maximum embedding.” The tether between the A and B Segments technically would not have to be present if the A and B fragments were present in large quantities (although, as you might expect, the A-B tether does considerably reduce the time to complete encapsulation by forcing these fragments within close proximity).
According to the crystal structure, the B12 is entirely embedded within TCII, with only the solvent-accessible hole at the 5′-ribose position readily accessible for bioconjugate formation. If the overall structure were as rigid as a crystal structure might lead one to believe, functionalization at the cobalt position in the corrin ring would be out of the question.
As I just stated that such a binding mode would otherwise be unlikely, you can guess that there are B12 bioconjugates linked at the cobalt ring that are bio-active.
If you watch the dynamics simulation of the TCII-[B12-tether] complex, you see that the clam shell binding mode of TCII is one with a “loose hinge.” This loose hinge is really a result of the flexibility of the two protein fragments (typical protein motion) and flexibility in the short propionamide side chains of vitamin B12 that provide a bit of “spring” in the complete complex. In effect, the flexibility within the structure provides a means for cobalt to be coordinated to something without loss of B12 binding provided that the tether linking the cobalt and the “other” molecule is small enough that it does not require a large change in the A-B binding arrangement (that is, does not affect B12-A and B12-B binding).
And Then There Were Three…
The expectation/prediction/untested hypothesis is that vitamin B12 may be able to happily accommodate two additional molecules at the 5’-ribose and cobalt positions (properly designed) that then provide for the transport of two molecules and/or the delivery of three molecules (one being vitamin B12). This opens the door to a wealth of possibilities, from trinary delivery to combined drug delivery + radiopharma characterization. This is the possibility I’m most interested in pursuing in the next rounds of calculations, with the theory (presumably) providing a very good initial guess about the ideal tether designs to use with B12 for enabling delivery and bio-activity.
And Now For The Hard Work
Stepping back from the theoretical analysis for a moment, the most difficult obstacles to overcome in this study were the generation AND incorporation of force field parameters for vitamin B12 and a B12-Lysine mini-bioconjugate into GROMACS, a problem that I’ve addressed only in passing in several previous posts. What I won’t do in this post is explain the procedure (a single blog post will not do the procedure justice given the complexity of force field parameter generation). What I will do is provide the files for the topology for these systems and a short list of the modifications one needs to make in order to get these systems working. For additional reference, the same topology files are provided in the Supplemental Material for the paper (so, if you find yourself using these, obviously cite the paper and not my humble blog).
Files And Contents:
These are not files to be placed in a single directory, but are segments of file that are going to be placed directly into pre-existing topology files. This is not the best way to do it but is the procedure I began with and will not be changing without finding a very simple tutorial on how-to (which, if you have, I’d be happy to read).
The contents of the topology file (which I assume for you will be ffG53a6 but should work generally) are provided below:
The topology specifications for vitamin B12 (nothing bound to the cobalt in the corrin ring), cyanocobalamin (CN-B12, with a cyanide bound to the cobalt), B12 with a lysine residue attached to the 5’-ribose hydroxyl position (the tether linkage for the GROMACS prep programs), and CN-B12 with a lysine residue attached to the 5’-ribose hydroxyl position.
I am assuming that you’re using the ffG53a6 force field, meaning you add the topology sets to the bottom of the ffG53a6.rtp file.
GROMACS Modifications:
GROMACS force field and topology files must be modified slightly in order to read the topologies generated above and, depending on where you got the B12 structure, add/correct the hydrogen atoms in the B12 molecule.
In a typical UNIX/Linux installation (which I have provided compilation instructions for in a previous post), the files to be modified can be found in /usr/local/gromacs. And, if you’re using Ubuntu like I am, you’ll need to “sudo” these modifications.
1. aminoacids.dat
If you open this file, you see a list of three- and four-letter codes in the format:
50
ABU
ACE
...
VAL
PGLU
The “50” refers to the number of codes. As we’re going to be adding the codes B12, BCN, LYB, and LCB into GROMACS, we first change 50 to 54, then just list the four codes at the bottom of the file:
54
ABU
ACE
...
VAL
PGLU
B12
BCN
LYB
LCB
You’ll note that B12 and BCN aren’t like the others, LYB is not LYS, and LCB is also nowhere to be seen. The codes in this file are STANDARD and make sure you don’t inadvertently name your inserted structure one of the structures in the list.
2. ffG53a6.hdb
I specifically used the ffG53a6 force field for the TCII-B12 work, meaning I only made modifications to these force field files. The ffG53a6.hdb file is responsible for adding/correcting hydrogen atoms in your structure (just because the crystallographers do not see them does not mean they aren’t there) and contains hydrogen-beautification information for all of the three/four-letter codes recognized in aminoacids.dat. The content below is the hydrogen-correcting data for the B12, BCN, LYB, and LCB structures. Simply paste this into the bottom of the ffG53a6.hdb file.
As brief explanation, the three-letter code is followed by the number of Hydrogen atoms that are to be added. Each line can be read:
First Column – The number of hydrogen atoms added (so all of these entries on the far left mean “add ONE hydrogen”)
Second Column – The manner by which the hydrogen atom is to be added (this is listed in section 5.5 of the GROMACS 3.3 Manual (page 93))
Third Column – The name of the Hydrogen atom to be added
Fourth Column – The atom to which the H is going to be directly linked in the topology file
Fifth – Seventh Columns – atoms that define how the Hydrogen is added with respect to (1) the code in Column 2 and (2) the atom to which the Hydrogen is added.
3. ffG53a6bon.itp
There are a few subtle tweaks to the force constants for a few bonds that I perform here right within the file and that proper MD people likely would scream at. I note that, when you do this, you are making changes to numbers that will affect the results if you somehow start doing heme MD simulations.
Change the gb_NN values to those provided below.
#define gb_34 0.198 0.6400e+06
; NR - FE 120
#define gb_4 0.1142 3.7000e+07
; C - O (CO in heme) 2220
#define gb_14 0.1340 1.1000e+07
; C - NR (heme) 1000
#define gb_30 0.1880 2.7200e+06
; FE - C (Heme)
You will note that I have not done anything to make cobalt appear in the topology or force field files. For the sake of running a simulation, Fe and Co are close enough that simply replacing CO for FE in the PDB file is sufficient. You can do the completely proper job of adding cobalt to the force field to get the mass right.
And that is the bare basics for getting a run to happen. A proper tutorial on how to generate force field parameters and topologies may be forthcoming, depending largely on interest and my ability to find time to do it.
Damian G. Allis1, Timothy J. Fairchild2 and Robert P. Doyle1
1. Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA
2. School of Chiropractic and Sports Science, Murdoch University, Murdoch, WA 6150, Australia
As part of ongoing research into the use of vitamin B12 (B12; cobalamin; Cbl)-based bioconjugate approaches for the oral delivery of peptides/proteins, a molecular dynamics (MD) study of the binding of a cyanocobalamin–insulin (CN–Cbl–insulin) conjugate to human transcobalamin(II) (TCII) was recently reported that provides a qualitative picture of how the human insulin protein in its open T-state geometry affects CN–Cbl binding to TCII. This initial analysis revealed that the B22–B30 segment of the insulin B-chain acts as a long tether that connects the larger combined insulin A/B region to CN–Cbl when this conjugation is performed at the CN–Cbl ribose 5-hydroxy position. The experimental support for this model of the binding interaction is provided by the consequences of the successful delivery of the CN–Cbl–insulin conjugate in the production of significantly decreased blood glucose levels in diabetic STZ-rat models. In efforts to provide a more detailed description of the (CN–Cbl)–TCII complex for modeling Cbl-based bioconjugate designs, the (CN–Cbl)–TCII system and a CN–Cbl conjugate incorporating a flexible tether composed of only the B22–B30 segment of human insulin have been examined by MD simulations. The implications of these simulations are discussed in terms of successful conjugate positioning on Cbl, especially when such sites are not apparent from the diffraction studies alone, and the possibilities, as yet not reported, for dual-tethered Cbl bioconjugates for multi-component drug delivery applications.
Details: The ISS made an early evening fly-by during the last official Public Viewing session for 2009 of the Syracuse Astronomical Society in Vesper, NY. The 6:36 p.m. EST fly-by made it as far as Alcor and Mizar before passing into Earth’s shadow (the Big Dipper is just entering the tree line to our North). Details: Canon SD780 IS, 15″ exposure, 400 ISO.
Now enjoying the benefits of dispersion-corrected solid-state density functional theory (and a proper MPICH2 implementation for infrared intensity calculations, although this now a problem for reasons to be addressed in an upcoming post) in Crystal09, three issues in recent calculations caused me to think hard enough about keyword formats and job runs that I have opted to post briefly about what to do in case google and bing are your preferred methods of manual searching.
1. How To Run Only A Single-Point Energy Calculation In Crystal06/Crystal09
This had never come up before and, by the time I needed to find an input file to see what do to, the first google search provided Civalleri’s Total Energy Calculation page that currently has broken links to .zip files. There is quite a bit about the different geometry optimization approaches in the manual, but a search for “single-point” provides no information about what to do for only single-point energy calculations.
The solution, it should be obvious after, is simply to not include the geometry optimization section in the input file. What would otherwise be the following (with arbitrary geometry optimization-like info between [COORDINATES] and [BASIS SETS]…
[COORDINATES]
OPTGEOM
TOLDEG
0.000005
TOLDEX
0.000020
END
END
[BASIS SETS]
becomes…
[COORDINATES]
[BASIS SETS]
One problem solved by simply not having any optimization parameters (again, makes sense and is now google-able).
2. Proper GRIMME Input Format For Long-Range Dispersion Contributions In Crystal09
This is another example where one’s first efforts in translating the manual into calculations may lead to considerable confusion until the proper format is finally identified (by which time you’ve run many pruned-down input tests).
I’m not even sure where the final ,’Rvdw comes from. Your .out file may terminate with the following error (or something similar)…
rank 7 in job 8 korterquad_51438 caused collective abort of all ranks
exit status of rank 7: killed by signal 9
And the ERROR.peN file with any content will show the following, clearly pointing to a GRIMME-specific error…
ERROR **** GRIMME_INPUT **** ELEMENT NOT DEFINED: 1
The problem is the additional content within the manual pages for the GRIMME keyword that require pruning (or, at least, some identifier to show what is and what is not needed). The proper GRIMME section above is properly provided in the INPUT file as…
GRIMME <- keyword is called
1.05 20. 25. <- scaling factor, steepness, cutoff distance
5 <- number of elements in the list (not the total number of atoms)
1 0.14 1.001 <- atomic number, dispersion coefficient, van der Waals radius
...
When all is properly run, the bottom of your output file will look something like the following:
CYC 43 ETOT(AU) -5.784662098123E+03 DETOT 1.18E-11 tst 8.17E-15 PX 6.73E-08
== SCF ENDED - CONVERGENCE ON ENERGY E(AU) -5.7846620981229E+03 CYCLES 43
ENERGY EXPRESSION=HARTREE+FOCK EXCH*0.20000+(BECKE EXCH)*0.80000+LYP CORR
TOTAL ENERGY(DFT)(AU)( 43) -5.7846620981229E+03 DE 1.2E-11 tester 8.2E-15
TTTTTTTTTTTTTTTTTTTTTTTTTTTTTT EDFT TELAPSE 4705.82 TCPU 4651.41
*******************************************************************************
GRIMME DISPERSION ENERGY CORRECTION
SCALE FACTOR (S6): 1.0500
GRIMME DISPERSION ENERGY (AU) -1.9723347118951E-01
TOTAL ENERGY + DISP (AU) -5.7848593315941E+03
*******************************************************************************
The Crystal09 manual refers you to Table 1 of the Stefan Grimme paper, “Semiempirical GGA-type density functional constructed with a long-range dispersion correction” (Journal of Computational Chemistry, Volume 27, Issue 15, Pages 1787 – 1799), which I’ve put together into the proper format below. Be sure to (1) delete the elements in parentheses ( -> get rid of the (H) <- ), (2) remove those atoms you do not need, (3) be sure to change the “number of elements” number for your structure, and (4) get and reference the Grimme paper so you have the proper C6 parameters and van der Waals radii accounted for (you’ll be the right nitwit if I mis-copied something and you ran with it (although I trust my input), and you should have the reference regardless).
Note that the d-block is identical for each row (so no atom numbers provided).
3. Removing The MPICH2 Content From The Output File In Pcrystal(/09)
This final issue does not occur in Pcrystal(/06) but does in Pcrystal(/09), with the reason being (I assume) the new use of MPICH2 in Pcrystal(/09) instead of MPICH in Pcrystal(/06). The problem comes from running the following set of commands at the terminal window in MPICH2:
mpiexec -machinefile machine -np N /path/to/Pcrystal &>FILENAME.out &
Embedded within the FILENAME.out file will be all flavors of MPI-specific output, perhaps such as the following (in this case errors, but it happens in proper output as well):
application called MPI_Abort(MPI_COMM_WORLD, 1) - process 4
application called MPI_Abort(MPI_COMM_WORLD, 1) - process 7
rank 7 in job 9 korterquad_51438 caused collective abort of all ranks
exit status of rank 7: return code 1
rank 4 in job 9 korterquad_51438 caused collective abort of all ranks
exit status of rank 4: killed by signal 9
or…
mpiexec_machine (handle_stdin_input 1089): stdin problem; if pgm is run in background...
mpiexec_machine (handle_stdin_input 1090): e.g.: mpiexec -n 4 a.out < /dev/null &
The solution is to break up the mpiexec output from the Pcrystal output, performed by directing the mpiexec-specific content to, in this case, /dev/null (because it is not necessary except for diagnostic purposes).
mpiexec -machinefile machine -np N /path/to/Pcrystal < /dev/null &>FILENAME.out &
Which removes all traces of mpi-specific output from FILENAME.out.
It is only fitting that, as we approach Summer and the unbelievable wealth of binocular and telescope objects that reside within the central region of the Milky Way, we spend at least one article on an otherwise mundane (to the amateur astronomer, anyway) Constellation. We endeavor this act of balance in the presentation of night sky viewing (and in the interest of accounting for all of the sky by the time these articles are done) by featuring Libra, The Scales.
The history of Libra in Western culture is one of science, religion, theft, imminent domain, here-say, and whatever existed as copyright in the Roman days (it is tough to make a Constellation associated with the Law interesting enough for prime time TV, as the only thing there is to murder is the presentation of any historical interpretation attributed to it). The reference to this collection of stars as a balance is reported to go as far back as the Sumerians (approximately 2000 B.C.), where this collection was known as “ZIBBA AN-NA”, or the “balance of heaven.” It is of particularly humorous irony this month that the Greeks were responsible for the disappearance of “the balance” from the night sky in favor of over-inflating the magnitude of the already important constellation Scorpius (for historical perspective, this article is being written as Greek economic infrastructure is falling apart faster than the Parthenon during the Siege of Athens in 1687 by Francesco Morosini, the Doge of Venice [as a good Greek, I shake my fist at the Gods in anger]).
The Romans saw fit to either return to the Sumerian tradition or simply declaw Scorpius, as Libra once again became a set of Scales. It is fate that the pinchers of an arthropod would be returned to the type of covering for reptiles. With the first publications of Libra-friendly star groupings and names upon the demotion of the now more diminutive Scorpius, one might even argue that the pen is mightier than the claws.
When not being visually accosted by rock n’ roll advertisements for lawyers behind cheap bookcase backdrops offering beaucoup bucks for your injury settlements, the legal profession often seems quite dull and arcane in its own right (sorry, Ray). Libra is equally subdued in its presentation, offering no Messier Objects within its official borders and no other really “interesting” things observable through binoculars or small telescopes. Perhaps the most interesting aspect about the constellation itself is its identification as the only inanimate object of the Zodiac, the ring of Constellations that encompass the ecliptic, or the apparent path of the Sun throughout the year.
That is not, however, to say that there isn’t anything worth its weight in hydrogen residing within the Libra boundaries. If we perform a considerable zooming in just above Zubeneschamali (phew! That translates to the “northern claw,” just as its counterpart Zubenelgenubi translates to the “southern claw.” These names would indicate that Arab astronomers opted to use both Greek and Roman sources despite the obvious conflict in the star groupings), we can see (with very good scopes) the star Gliese 581 (shown below), home of one of the most populated planetary systems yet discovered (although it is important to remember that this number is only of those planets we can detect, which means those with significant gravitational influence on their stellar anchor). This is marked “1” in the opening image. To date, there are four detected stars around Gliese 581 (note that the star name is always first, followed by a letter designation), including Gliese 581 b, a Neptune-sized object with a 5.4 day orbit, c, a rocky Earth-like planet within the Gliese 581 Habitable Zone 1.5 times wider and 5 times more dense than our own, d, a planet 1/2 as massive as Uranus and still within in the Habitable Zone, and e, a planet 1.6 times as massive as Earth and the smallest yet identified. the star Gliese 581 not only represents a feat of mathematical prowess on the part of Terran researchers, but is also of specific interest because of the number of planets within its Habitable Zone, the region within which conditions are believed to be similar to our own (specifically, liquid water on the surface). Some even refer to this as the “Goldilocks Zone,” where it’s not too cold and not too hot. One might say that this region is where a proper balance of hot and cold is reached…
Of all of the asterisms (groups of stars that are not designated as Constellations but that still have specific meaning. For instance, the Big Dipper is an asterism within the Constellation Ursa Major) that have jumped out at me during my binocular viewing adventures, the one marked by the “2″ is perhaps the one that most stood out to my eyes. It is one of the most perfect isosceles triangles in the nighttime sky and is reasonably clear around it such that only this shape stands out in low-power optics. When it’s out, I always look for this small golden nugget residing within the Zubeneschamali-side of the scales, tipping the balance towards the arrival of the Summer constellations Scorpius and Sagittarius, the pair that mark the inside of our own galaxy and where a disproportionate number of Messier riches abound.
