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The Newsletter of the Ottawa Centre, RASC
Volume 58 – No. 11 – December 2019
Here we are in December with the Holidays rapidly approaching and Orion on the rise.
December of course brings our Annual General Meeting and the election of your new council. There are not many changes this time around though with all incumbents acclaimed. However, there are a couple of changes to note. The
most visible one is our meeting chair.
As you are aware, Oscar Echeverri has been our meeting chair for most of the past two years. His wife gave birth to their lovely daughter, Isabella, in August. Naturally enough, Oscar is finding that she is tugging at his heartstrings more than we are! So, he has decided to step down. A familiar face, Dave Chisholm will be taking over. Dave has been and will continue to do “Ottawa Skies”. Dave has asked that anyone with speaker or presentation ideas please contact him at firstname.lastname@example.org with your suggestions. The second change is at Oscar’s other position, Treasurer. We are fortunate to have David Parfett step forward. David has acted as our Auditor for the past several years so we will remain in good hands.
I wanted to take this opportunity to thank Oscar for all he has done for our Centre Centre Information over the past many years. He has done a great job as Treasurer and as Meeting Chair he has provided us with entertaining and informative speakers. He brought back the Monthly Challenge Object which has become a focus for many of us, especially our imagers. Oscar’s contributions have been so numerous it has taken two people to replace him! Thank you, Oscar.
Happy Holidays, all the best for the New Year and Clear Skies,
2019 Ottawa Centre President’s Report
We have had another busy year in the Ottawa Centre with numerous outreach events, developments at Centre facilities, and member programs. Let me share with you the highlights.
We are proud of our association with the Canada Aviation and Space Museum (CASM). The partnership allows us to participate at numerous public events that often attract large crowds. The recent International Astronomy Day (IAD) event in October was especially memorable and worth noting. CASM invited us to celebrate World Space Week which coincided with IAD on October 5 th . CASM provided a series of planetarium shows, special demonstrations and tours, while Ottawa Centre volunteers set up telescopes for solar observing and evening public stargazing. Due to some excellent promotions by CASM and the Ottawa Centre, over 1,500 people joined us to look through our telescopes during the evening, including many people who had returned after daytime solar observing. Thanks to Chris Teron who organized volunteers at this event and also participated with his telescope.
We also participated in a Learn to Camp event in August with CASM that was jointly sponsored by Parks Canada. Dave Chisholm rallied 7 RASC volunteers with telescopes to participate in this event that touched 75 participants. CASM was grateful to the RASC for our support. Thank you Dave.
Other events we held with CASM included sidewalk observing during the Ontario and Quebec student March breaks, Canada Day solar observing events (with large crowds all day!), and solar observing at the Spring IAD. We are developing plans with CASM to offer more programs in 2020 to build on the public interest in astronomy that is clearly evident.
Our Ottawa Centre Public Stargazing program is one of our flagship programs. For the last two years it has been organized by Paul Sadler, an exceptionally organized and gifted communicator. Paul has fully embraced the public star party coordinator role and has frequently solicited ideas from Ottawa Centre members to continuously improve it. He even reached out to other RASC Centres with a survey on their public star party programs. To say that Paul is inclusive would be an understatement. Thanks to Paul’s organization, the Ottawa Centre typically attracts 300+ people at public star parties, along with 30 telescopes. These are big events. As a result of his dedication, Paul was recognized recently with a 2019
Ottawa RASC Service award.
I am especially grateful for Jean-Sebastien Gaudet for stepping forward to be our new Outreach Co- ordinator. JS recently organized 10 Ottawa Centre members to participate in an event titled “Nature Nocturne” at the Canada Museum of Nature. He organized a large exhibit that included astro-sketching, indoor telescope observing, live stargazing through a remote observatory and several displays. Easily 1,000 mostly young adults stopped at our exhibit, many staying for 20 mins. The Canada Museum of Nature organizers thanked us profusely.
JS also recently organized a group of volunteers to offer observing of the Transit of Mercury at Marion Dewar plaza at City Hall on November 11 th , but unfortunately the event was cancelled due to clouds. If this event had proceeded, we could have had thousands of people look through our telescopes on their way to, and returning from, the Remembrance Day ceremonies.
Many thanks to Gordon Webster who organized several monthly members-only star parties at the Ottawa Centre’s Fred Lossing Observatory site. At FLO star parties, members bring their telescopes or look through the 18-inch Dobsonian that was donated by Mike Wirths. Great conversation always ensues. On several evenings we have been entertained by Ottawa Centre member Ghislain Serise who plays his guitar and sings. These are wonderful, tranquil evenings. Ghislain’s music brings a magical quality to the evenings.
Also at FLO, Rick Scholes has been offering a series of training programs for members on the use of the 18 inch Dobsonian. The observatory and the observing site is a major Centre asset, because of the dedication and contributions of Rick and other volunteers.
Gordon Webster helped organize something we have not done in a long time. He organized a visit to the Plevna dark sky site, that was well-received by members. This dark sky site is only a couple of hours drive from Ottawa. I am sure we will offer more of these events in the future. Thanks, Paul, for motivating us.
In the autumn, Brian McCullough organized a very successful astro-sketching workshop that attracted over 20 members, including 5 RASC members from the Montreal Centre. I had the privilege of attending myself and can tell you that every minute of the workshop was well-planned and executed. Feedback was entirely positive. Thank you, Brian.
Building on the success of Brian’s workshop, another workshop titled “Introduction to Astrophotography” will be held in January. Fifty-two people have enrolled. It will be run by Paul Klauninger, who has awed us for many years with his astroimages. (Please contact me if you are interested in attending this workshop).
Recently in November, we hosted our annual dinner at Algonquin College. Our guest speaker was Dr John Moores, the York University Research Chair in Space Exploration. Thanks to Ottawa Centre VP Stephen Nourse for organizing this event, which included a lovely dinner buffet and awards ceremony to recognize members who have contributed to the Ottawa Centre. I would also like to thank Gordon Webster for organizing the wonderful door prizes, as well as the donors for their generosity: Focus Scientific, O’Telescope, Brightstar Communications, Diffraction Limited, Canada Aviation and Space Museum and Mallincam.
Another member benefit that I look forward to is our Centre newsletter, AstroNotes, organized by Editor Gordon Webster. This Ottawa Centre publication contains information that is relevant to members, topical and always interesting. Thank you, Gordon, for caring, and to all the contributors to AstroNotes.
I would be remiss if I did not acknowledge our monthly meetings. They are very popular with members and help attract new members. Oscar Echeverri, our Meeting Chair, has created a perfect program that appeals to the wide interests of our member base. He has re-introduced an Observers’ Challenges program that includes challenges for members of all skill levels. It is very popular. Each meeting provides a wonderful opportunity to learn something new and socialize with members. In the background for each meeting, many of us know that Chris Teron is assembling slides and ensuring the smooth operation of the meetings.
At our meetings, members Art and Anne Fraser do something very special. They provide a table with coffee, soft drinks and cookies. They have been doing this for more years that I can remember. They do it for the sole purpose of making people happy and encouraging socialization. Because of their long-term service to the Ottawa Centre, Art and Anne were recently recognized with the 2019 Ottawa Centre
There are two other programs for members that are popular and well used by new members especially – the Stan Mott Astronomy Book Library and the Ted Bean Telescope Loan Library, run by Estelle Rother and Darren Weatherall, respectively. Our Centre regularly invests in these programs. We are also grateful for donations. Thanks to Estelle and Darren for their dedication. As a result of Estelle’s long-term service to the Ottawa Centre, she was recognized with a 2019 Ottawa Centre Service award. Finally, Mick Wilson deserves our thanks for maintaining our ‘virtual space’ – our website. Since Mick has become our webmaster, our website has been very stable and is kept current. Mick is also volunteering with the National IT Committee. Thanks Mick.
SmartScope Remote Telescope. After nearly 20 years, Ottawa Centre Council decided to decommission the SmartScope facility. There were several challenges to using this remote observatory on the grounds of the Shirley’s Bay Communications Research Centre (CRC). Internet access is vital for the remote operation of this facility. With the security restrictions at this site, and ownership of the site being transferred from CRC to DND, it became clear to us that we would likely not have Internet access again. It was time to discontinue operations.
The building and dome were donated to Defence Research & Development Canada, while Chris Teron is temporarily holding on to the mount, scope and accessories. The steel pier is being stored at FLO. We will find a home for this equipment in the future.
There are many volunteers who gave their heart and soul to the SmartScope. I can’t possibly name them all here, but on behalf of all Ottawa Centre members, thank you.
Fred Lossing Observatory Site. We continued to make enhancements to the FLO site this year. We added a SkyPod observatory on a large wooden deck. The observatory houses a 14-inch Meade Schmidt-Cassegrain telescope. Thanks to Chris Teron, Andrew Brown, Gordon Webster, Tim Cole, David Lauzon and others for assembling the deck. Chris was especially active in acquiring the dome and assembling it. We had problems with the telescope mount, so we replaced it with a mount that was donated from the family of late, prominent Ottawa Centre member Paul Comision. To honour Paul Comision, we will name the observatory The Paul Comison Memorial Observatory. Currently Tim Cole is developing a training program for members using the telescope. It will be introduced for use in early 2020. This is a wonderful addition to the FLO site.
Few members may be aware that we received a very generous donation from Rick Scholes. Rick acquired late Ottawa Centre member Rolf Meier’s observatory that includes a 6 inch Astrophysics refractor. Rick recently moved the entire observatory to the FLO site. We plan to erect the observatory in 2020. It will be named the Rolf Meier Observatory. Rick, thank you for your generosity. In summary, we will have three telescopes available for use by members, once they have received training: A Dob, an SCT and a refractor. This is a great combination and we hope members take full advantage of these wonderful Centre assets. We plan to make additional earth-grading improvements to the FLO site in 2020. We will keep members posted on developments.
Recognizing Centre Members
I have already acknowledged the contributions of many Ottawa Centre members. There are a few more that deserve our thanks.
- Rick Wagner. Rick was awarded a National Service Award at the RASC General Assembly in Toronto this past summer for his contributions over several decades to the RASC in many roles, including his current role as the Kingston Centre President. Rick is always willing to share his knowledge and, as was stated in the award citation, he “represents the very best of the RASC”.
- Janet Tulloch. In Feb of this year, we received wonderful news about Janet Tulloch. She was a recipient of a top award in the RASC’s sesquicentennial (150 th year) Imagining the Skies contest. Her submission title “Twilight of the gods” won in the Creative Works Category, Experienced Level. The judging panel commented that her work had “Good balance of line, texture and form with rich coloration” and it was “A delight for the senses”. Chris Gainor, the RASC National President, summarized her award beautifully: “Congratulations to you for this fitting recognition of your efforts to celebrate the beautiful skies that for countless eons have inspired humans, including members of the RASC since our founding 150 years ago.”
- Dave Chisholm. Dave has been an active volunteer with the Ottawa Centre for many years now. He has been involved with outreach and is responsible for the Monthly Sky segment at the Ottawa Centre meetings, where he raises awareness of items of interest to observe each month. In 2019, Dave has gone into overdrive with his outreach. Here is the record of his outreach events in 2019. It is truly extraordinary
15-JAN-2019 - Girl Guide Astronomy Night - Manotick - 25 youth, 7 leaders.
29-JAN-2019 - Cub Scout Astronomy Night - Ottawa - 15 youth 2 leaders.
04-MAR-2019 - Seniors Introduction to Astronomy - Barrhaven - 18 seniors.
06-MAR-2019 - Solar Viewing March Break - CASM - 45 youth, 30 adults.
30-APR-2019 - Brownie Astronomy Night - Barrhaven - 25 youth, 5 leaders.
04-JUL-2019 - Vacation Bible School Astronomy Presentation - Lancaster - 100 youth, 20 adults.
10-AUG-2019 - Learn to Camp Event - CASM - 35 youth, 40 adults.
15-AUG-2019 - Seniors Introduction to Astronomy - Kanata - 15 seniors.
27-AUG-2019 - Seniors Introduction to Astronomy - Carlingwood - 30 seniors.
16-SEP-2019 - Seniors Introduction to Astronomy - Bells Corners - 35 seniors.
24-OCT-2019 - Cub Scout Astronomy Night - Rockcliffe - 16 youth, 3 leaders.
05-NOV-2019 - Cub Scout Astronomy Night - Barrhaven - 20 youth, 5 leaders.
12-NOV-2019 - Brownie Astronomy Night - Manotick - 21 youth, 5 leaders.
18-NOV-2019 - Sparks Astronomy Night - Manor Park - 19 youth, 4 leaders.
20-NOV-2019 - Sparks Astronomy Night - Barrhaven - 16 youth, 4 leaders.
25-NOV-2019 - Cub Scout Astronomy Night - South March - 23 youth, 4 leaders.
26-NOV-2019 - Beaver Astronomy Night - Ottawa - 15 youth, 3 leaders.
26-NOV-2019 - Joint Cub/Scout Astronomy Night - Ottawa - 15 youth, 5 leaders.
27-NOV-2019 - Brownie Astronomy Night - Kanata - 17 youth, 3 leaders.
In total, Dave touched 645 people in 2019. In recognition of Dave’s contributions, he was recently awarded a 2019 Ottawa Centre Service award. In case you are wondering, he already has bookings with two groups (Beavers and Cubs) in February 2020. Thank you Dave. You have created some beautiful, life-long memories for many people.
- Estelle Rother. For many years, Estelle has quietly served as the librarian for the Stan Mott Astronomy Book Library. Before we started recording our monthly meetings with videos, Estelle provided summaries to members in AstroNotes. For her many years of service and devotion, she was award recently a 2019 Ottawa Centre Service award.
- Taras Rabarskyi. Congratulations to Taras for receiving the Rolf Meier Award for Planetary Observing this year. I remember when Taras was just starting with astrophotography. Now, quite frankly, I am in awe of his work.
- Brian McCullough. Congratulations to Brian for receiving the Best Presentation award this year for his account of the 50 th anniversary of the Moon landing. His enthusiasm was palpable during his presentation. He transported all of us in the audience back to another time.
- Janet Tulloch. Congratulations to Janet for receiving the Best AstroNotes article this year for her archaeoastronomy article titled “Outstanding Standing Stones”. Janet’s work is always thorough and interesting. Congratulations Janet.
- Paul Klauninger. Well, he did it again. Paul won the Observer of the Year award again. Paul is widely recognized in the Ottawa Centre for his astroimages he shares at the monthly meetings, but his observing logs – for which this award is based on - set a very high standard for observers.
- Ottawa Centre Council. We are fortunate to have a group of volunteers that help manage the operation of our Centre and think about its future. I have already mentioned the contribution of some of them. Let me recognize the others:
- Oscar Echeverri – he has served as both Meeting Chair and Treasurer. Oscar is stepping down from both these roles this year. Thank you for your contribution.
- Rick Scholes and David Lauzon – FLO Co-Directors who oversaw the biggest re-development of the FLO site in decades. Dave recently stepped down.
- Tim Cole – former President. Tim has provided more support and guidance to me than I think he realizes. Thank you, Tim.
- Carmen Rush, Gerry Shewan, Jim Sofia – As Councillors, their input is vitally important to the health and success of our Centre.
- Karen Finstad and Ingrid De Buda – as National Council representatives, and a vital interface to other Centres. The NC representative role is evolving. Thanks to Karen and Ingrid during this transition. Ingrid recently stepped down.
- Stephen Nourse. Stephen is a long-time RASC member who brings a lot of experience from within and outside the RASC to Council.
- Chris Teron. I mentioned Chris already a few times in this report. He is clearly an active member of the Ottawa Centre and is widely recognized to be a pillar of the Centre. He is our liaison to CASM and was responsible for the success of many events with CASM. Officially he is our Centre Secretary, but his helpful hand extends all throughout the Ottawa Centre.
In June of this year, we lost a friend of the Ottawa Centre. Michel Bois, our Centre Videographer, passed away suddenly. Michel was active at star parties, where his willingness to share his love of astronomy was evident. We also remember him for his beautiful smile.
On behalf of Ottawa Centre Council, I wish everyone a healthy and happy 2020 – and especially clear skies for all our star parties and outreach events.
RASC Ottawa Centre President
December 1, 2019
In last month’s issue we stated in error that there were 20 people who attended Brian McCullough’s Astro Sketching Workshop. In fact, there were 25. We apologize for the error.
Mercury Science in 2019
by Simon Hanmer
In July of this year the RASC Ottawa chapter celebrated the 50 th anniversary of the 1 st Moon Landing. My contribution to that meeting was to look beyond the hype and the politics and discuss where Lunar Science stands in 2019. It then occurred to me that perhaps this was a good time to review where planetary science stands today with respect to our Solar System in general, a significant undertaking that would require a series of presentations to do it justice. So, I want to start with a look at Mercury. As with the Moon, I’m going to look at what’s hot scientifically speaking: what are the key questions that planetary scientists are asking themselves about the innermost planet in our System, and what answers are they finding. As you’ll see as the presentation unfolds, the key question regarding Mercury is not difficult to identify.
After several fly-bys, beginning in 2008, the MESSENGER probe slipped into orbit around Mercury in 2011 and reported back until 2015. Data from MESSENGER have fundamentally upgraded our understanding of Mercury as both a planet and as a component of the history of our Solar System. To be blunt - if we don’t understand Mercury, then we don’t understand how Solar Systems work in general, either our own - or others around other stars.
MESSENGER imaged Mercury’s surface at the planet scale, imaging much of the surface we had never seen before. It mapped the entire surface of the planet, providing us with global maps of the distribution of rock units – such as this map of the smooth plains of volcanic origin that dominate the northern hemisphere and polar region (white) – as distinct from other lavas (grey).
One of the truly big surprises was how little iron (Fe) there is in the lavas that cover the entire surface of Mercury. On the other Rocky Planets, Fe and magnesium (Mg) go hand in hand, but not on Mercury. It turns out that this lack of Fe in the planet’s crust is going to be fundamental to understanding the planet, so bear it in mind. I’ll be coming back to this ...
MESSENGER clarified thematic aspects that we had already seen in the partial coverage provided by the earlier Mariner 10 probe that performed a series of fly-bys (1974-5), but never orbited Mercury.
This slide shows details of a lobate fault scarp that formed early in Mercury’s history as slabs of crust rode over each other when the once hot planet cooled and contracted.
Here is another example of the same thing where a coloured digital elevation model (red for high ground, blue for low ground) is draped over a photo of a lobate scarp cutting across an older impact crater. It gives a better impression of the topography in 3D.
Even Mercury, closest rock to the Sun, provided evidence for the presence of water in permanently shadowed parts of impact craters around the planetary poles. NASA simply can’t resist highlighting water!!
More detailed mapping from orbit has also revealed large erosional valleys (15-20 km across) that look very much like the Outwash Channels on Mars that I talked to you about in 2014 (https://www.simonhanmer52.ca/voyage-to-mars.html) with streamlined hills as evidence for erosion. Except that on Mercury the agent of erosion was very runny Mg-rich (Fe-poor) lava rather than water!! Even more detailed mapping has revealed strange features – apparently unique to Mercury – that may even be forming today: “Hollows”. These are small, flat bottomed pits with no rims, and they seem to be confined to the floors or rims of pre-existing impact craters. The pits are pretty small and have very steep sides. Chemical analysis by remote sensing from the MESSENGER orbiter suggests that these pits may result from the sublimation of volatiles localised just under the impact crater floors and the lack of impact damage to the pits suggests that they are very, very young, possibly even modern! As we’ll see shortly, the presence of volatiles in Mercury’s planetary crust was as unexpected as the low Fe content. Both require explanation: so now bear both in mind! I will explain them shortly.
Slide #10: Much as all this new observational data is fascinating, and there’s lots more I haven’t even mentioned (see my 2008 RASC presentation https://www.simonhanmer52.ca/messenger.html), they don’t address the primary problem facing planetary scientists with respect to Mercury: a problem so important - and until now so intractable - that most scientific publications dealing with Mercury don’t seem to want to address it directly, even when they have appropriate evidence to contribute to the debate. That fundamental issue is this: Mercury doesn’t look like any other Rocky planet in the Solar System. Its planetary Fe-Ni core is way too big to be explained by the standard model of planetary accretion, heating, melting and differentiation, such that Mercury is sometimes called the Iron Planet.
So, the fundamental issue for planetary scientists is: how did Mercury form? For us as amateur astronomers, the question is: how do we (they) know? What is running through the minds of planetary scientists as they tackle this issue? There have been many attempts to explain Mercury’s internal structure ever since Mariner 10 in the 1970s, but we can group them into three main themes:
#1: Erosion of the primordial crust and much of the planetary mantle by the solar wind during the very early history of the Solar System, thereby leaving a disproportionately large Fe-Ni core.
#2: Erosion of the primordial crust and planetary mantle by a giant collision, or hit-and-run, “near-miss” style of gravitational interaction with another planetary body – potentially Venus or the Earth according to some. Both of these hypotheses create problems: if the primordial crust and upper planetary mantle have been removed, then where do the volatiles identified on Mercury come from? We’ll come back to this.
#3 None of the above: maybe Mercury just formed the way we find it. Maybe the innermost part of the Solar System was very different to the rest of the accretionary disk.
In order to understand what this third hypothesis says, we have to delve a little into some chemistry. Now I know that some folks think that chemistry is difficult to understand, but it’s not, if it’s explained appropriately. In addition, we don’t need to know much more than the chemistry of pencil lead (graphite) in order to understand what planetary scientists are thinking with respect to the origins of Mercury - and why it’s is so different from the other Rocky Planets. The magazine Elements is published by the national Mineralogical Societies of a whole slate of countries, and in February 2019 they put out a special issue on Mercury, with an emphasis on its origins as determined from its chemistry based on data from the MESSENGER probe. I hope that you’ve already noticed the blue tint in the insets of Mercury on the slides in this talk, shown even better in the blow-up of the planet ...
... and even better in this wrap-around global map. The blue colour is due to NASA’s processing, but it accurately reflects the distribution of graphite at the planetary surface. Graphite is a naturally occurring mineral, and it’s made of pure carbon. As we’re about to see, carbon is the key to the chemistry of the formation of Mercury. Have a good look at this map: can you see the impact craters surrounded by well-defined rings of blue carbon? It’s pretty obvious that the carbon is in the ejecta thrown out from the transient cavities that formed due to the impacts, which means that the carbon was located at shallow crustal depths all over the planet.
Here’s a more detailed image of craters with their associated blue carbon located within the impact crater ejecta rings. So, what’s carbon doing sitting in significant quantities in the shallow crust of Mercury? No other Rocky Planet shows so much carbon in its crust: it’s unique to Mercury. Planetary scientists interpret the graphite as the “scum” that floated on top of a primordial global magma ocean that formed from the heat of accretion +/- heat from short-lived radioactive isotopes such as Al 26 . But why “graphite scum”, and why is it unique to Mercury? After all, a similar global magma ocean “scum” on the Moon gave us the plagioclase feldspar of the white lunar highlands! It’s all to do with the role of carbon in the chemistry of that global magma ocean, and I’ll explain that in just a minute.
Meanwhile – think about the significance of a primordial crust containing graphite “scum”. Even if impact events have to dig it up from a few km down, it is still a crustal component. It’s simple presence in the present crust can only mean one thing: the primordial crust and planetary mantle of Mercury were never removed from the planet. If this is true, then we are left with no choice: we have to assume that Mercury formed as we find it, with a disproportionately large Fe-Ni core: and that requires explanation.
If Mercury formed as we find it - and where we find it - then there had to be something special about the innermost part of the accretionary disk from which the Solar System formed ... and this is where chemistry comes in. It turns out that chemistry can explain a lot about Mercury - if the planet formed in a highly “reducing” environment. So now we need to know something about “reduction” and its opposite number: oxidation – commonly abbreviated as REDOX. Common sense tells us that oxidation is the addition of oxygen to something: think of the case of a rusty nail. So common sense must also tell us that reduction is the removal of oxygen from something. However, while this may make common sense, it’s a limited way of understanding what really happens – especially when we get to carbon! In order for the oxygen to hitch or unhitch itself from other elements, something must happen at the level of electrical charges to facilitate this. Take a look at the second example here (CuO + Mg = Cu + MgO), which is also presented in terms of electrical charge: in this case just positive and neutral). The Cu 2+ that’s hitched to the oxygen has 2 protons that are NOT balanced by negative electrons: hence the double positive charge. To make it neutral (Cu) we need to unhitch the oxygen, and to do that we need to find two spare negative electrons in order to balance the protons in the atomic nucleus. The opposite applies to the Mg, which is neutral: to hitch it to the oxygen we just unhitched from the Cu we need to remove two electrons to make the Mg positive, or the oxygen simply won’t play ball. So the reaction runs from left to right because the Mg donates 2 electrons to the Cu, which we express as Mg reduces the Cu (or we could say that the Cu oxidises the Mg: it comes to the same thing). The key thing to retain here is that something (A) is reduced when something else (B) donates electrons to A.
Slide #17: So, now that we know that what “reduction” means, where does carbon fit into all this? For reasons we’re not going to get into here, it turns out that carbon is a great electron donor. It just loves giving up electrons to other elements, and thereby reducing them! Having carbon (graphite) around is a great way to produce a reducing environment. So, what does this have to do with Mercury and how it formed as a planet? What if the innermost part of the accretionary disk of our early Solar System had a significant carbon content? So far, I haven’t read an explanation of why that might be the case, but we do have observations that point in that direction!
I’m going to show you two slides of diagrams that I have redrawn from one of the papers in the Mercury issue of Elements magazine. Here’s the first. On the left is a diagram showing the degree of reduction vs oxidation (REDOX state or oxygen fugacity) measured for the Rocky Planets and meteorites. As planets go, Mercury stands out as sitting entirely within the reduced field (negative values). On the right is a diagram showing oxidised Fe vs reduced Fe, and again, Mercury stands out as being made of way more strongly reduced Fe than the other planets. The red ellipses indicate the redox states for different groups of meteorites, and Mercury clearly stands apart from all of the rocky components of the Solar System, including the meteorites.
Now we are equipped to look at what planetary scientists think they have found that allows them to explain the formation of Mercury. It turns out that many elements modify their chemical behaviour depending on whether they find themselves in an oxidising or a reducing environment. This change in behaviour is dramatic, as these diagrams on the left show. Note that the redox environment illustrated here goes from “average” on the right (0: think Goldilocks - not too oxidising, and not too reducing) to highly reducing on the left (negative values). The vertical red bar represents the values measured for Mercury. The top diagram is for Sulphur (which normally prefers to form Sulphide minerals in a
planetary core), while the lower diagram is for silicon (which normally prefers to form silicate minerals in a planetary crust or mantle).
We’ve just seen that in most of the inner Solar System, the chemical environment where the other Rocky Planets formed was pretty much average: Goldilocks! In such an environment, your standard accreting Rocky Planet – such as the Earth, Venus or Mars - heats up and differentiates such that elements that tend to prefer to bond with metals (Sulphur - Fe-Ni : siderophile) end up in the core, while other elements that tend to prefer to bond with rock-forming silicate minerals (Silicon-Al-Ca-K-Na-Oxygen : lithophile) end up in the planetary mantle or the crust - and that’s where we get our standard model of a differentiated Rocky Planet from. However, when an accreting Rocky Planet differentiates in a highly reduced environment, something remarkable happens.
Elements that normally prefer to bond with the planetary core end-up preferring to bond with silicate minerals, and most importantly those that normally bond with the planetary crust and mantle prefer to segregate into the core. A diagram for the behaviour of Fe would look somewhat like the diagram for silicon, but more complicated because Fe comes in all kinds of states of oxidation. The oxidised states tend to end up in silicate rocks, while the reduced state prefers to go into the planetary core. However, in a highly reducing environment, much more of the planetary iron is reduced and so much more of it goes into the planetary core, and that core becomes abnormally large! Remember what I told you at the beginning of the presentation: Mercury’s crust is abnormally poor in Fe compared with the other rocky planets and is unexpectedly rich in volatile elements. As we’ve just seen, both of these observations
support the hypothesis of Mercury forming in a highly reducing environment.
So, what’s the explanation for all that carbon in Mercury’s crust? It so happens that an Fe-poor (Mg-rich) global magma ocean has too low a density to allow silicate minerals to float and form a surface scum (not even light-weight plagioclase, the dominant lunar surface mineral). The only element that could have floated to form a surface scum would have been carbon, which we find as graphite.
Now - the next question is: why was the innermost part of the Solar System a highly reducing environment, potentially rich in carbon? But that’s a question for another day. Meanwhile, what’s my take-home message here? Well, it’s somewhat philosophical. The identification of carbon as a relic of Mercury’s primordial crust is not new: we’ve been hearing this for quite a while. Yet, even recent papers continue to entertain the hypotheses that require removal of the planetary crust and outer mantle to explain the origin of Mercury. Even the papers in the Mercury edition of Elements magazine do not explicitly state that the crustal-removal hypotheses must be wrong, even though they are delivering explicit support for the existence of primordial crust. Why is this? It’s certainly not limited to Mercury.
The highly respected senior planetary scientist William Hartmann has just published a comprehensive review of the history of the concept of the Late Heavy Bombardment and the purported Lunar Cataclysm: History of the Terminal Cataclysm Paradigm: Epistemology of a Planetary Bombardment That Never (?) Happened : https://www.mdpi.com/2076-3263/9/7/285. See also my 2016 RASC presentation: https://www.simonhanmer52.ca/lunar-cataclysm.html, as well as my 2004 review of Hartmann’s book on Mars “ https://www.simonhanmer52.ca/mars--travelers-guide.html In his paper Hartmann is strongly critical of how science evolves in the real world : “As science gels into paradigms, human culture, by definition, begins to influence the paradigm along with the science ... as a paradigm becomes influential, new research begins to become influential not only for the quality of the work, but also because it fits within the paradigm.” In short, he is saying that scientists tend hear what they want to hear and tend to ignore what doesn’t fit with their favoured or current model. It would appear that this is now endemic in planetary science: for example, see my 2016 RASC presentation on Pluto : https://www.simonhanmer52.ca/pluto-update-2016.html.
Hubble's Cepheid Variable V1 in M31 V1
by Stephen J McIntyre
The image below is a close up of the Andromeda galaxy core i took with a Celestron EdgeHD 11 and a modified DSLR. The area photographed includes the Cepheid variable star - M31_V1 – the star that Hubble used to calculate the first reliable distance to the "Andromeda Nebula". His result proved conclusively that "nebula" were distant objects that were not part of the Milky Way.
M31 - Andromeda with Hubble V1 (Stephen J McIntyre 2017-01-15)
The wide field view of the Andromeda galaxy below shows the section captured in the closeup image as well as locators for M31_V1. The insert at the top left is the original plate H335H taken with the Hooker telescope in 1923.
M31 Hubble V1 Locator (Wide field by Stephen J McIntyre 2010-11-08)
Hubble used the recently commissioned 100" Hooker telescope on top of Mount Wilson to capture a 1hr photographic plate of M31 on October 5/6, 1923. A crop from the original glass plate H335H (Hooker 335 Hubble) is shown below along with the same area from my image. Perhaps the plate has faded over the years or the technicians had keen eyes, but M31_V1 is barely visible.
Hubble V1 Comparison - H335H plate and my Image
Hubble had originally identified the star as a Super Nova and marked it "N". Nova had been seen on plates before, so it was reasonable to assume that a star that had not been seen before was a super nova. However, he later decided it was a variable star and marked it 'VAR!" (presumably by examining other plates and finding a star of different brightness in the same location). Finding a variable star was significant because Henrietta Leavitt had earlier discovered a method for accurately calculating distances to Cepheid variable stars. Hubble's discovery of M31_V1 was the first time a variable star had been observed in a nebula.
Cepheid variables are a class of variable stars that can be used as a "standard candle". That is, their absolute (actual) brightness can be calculated, so their apparent brightness is then a measure of their distance (the dimmer the star, the further away it is). Today, Cepheid variables are still an important tool for determining distances to galaxies.
Naked Eye Observing of M31
As engaging as the background story is, the Andromeda galaxy is also interesting for another reason. At a distance of 2.5 million light-years, the Andromeda galaxy is the furthest object that can be seen without a telescope or binoculars and only requires a moderately dark sky to see it. During November/December, it's high in the sky facing south in the evening and appears as a faint, but distinct oval smudge. The darker the skies, the more obvious it is. The Andromeda galaxy is located in the constellation Andromeda. Which is more easily identified as the “V” shaped arrangement of stars attached to the corner of Pegasus. Pegasus is due south in the November/December evening sky and is identified by the large square (or diamond) shape which is as wide as your hand stretched from thumb to baby finger. The Andromeda constellation is to the east and they share the corner star Alpheratz.
The chart below provides some tips on how to find M31 once you’ve found Pegasus.
Step 1: Start with Alpheratz in the upper left corner of Pegasus. Count three stars up to the left heading to Mirach (with Alpheratz being star No 1).
Step 2: Again, count three stars this time up to the right (Mirach as No 1). These stars are fainter than the first set, so may be harder to find.
Step 3: M31 will be 4deg to the right of the last star (about 2 finger widths) and elongated as shown.
Every year at the Annual Dinner Meeting we recognize members for their service to the Ottawa Centre and also for their accomplishments. This year’s award winners are:
President’s Award - Anne & Art Fraser
Service Awards - Dave Chisholm, Estelle Rother, Paul Sadler
Best Presentation - Brian McCullough for “Apollo 8 - Liftoff of My 50-year Journey to the Moon” in December 2018
Best AstroNotes Article - Janet Tulloch for “Outstanding Standing Stones” in the July 2019 issue
Paul Comision Observer of the Year - Paul Klauninger
Rolf Meier Award for Planetary Observing - Taras Rabarskyi
Introduction to AstroPhotography Workshop
A few months ago, we announced an Astrophotography workshop. To date, 53 people have registered to attend. Dates have now been set for the two-part workshop: Saturday Jan 11 and Saturday Jan 25th from 1 - 4 pm on both days. It will be held in a large meeting room in Carleton University. We have space in the meeting room to accommodate more people. If you wish to attend, please send an email to Mike Moghadam ( email@example.com ) before Friday December 20th. After registering, you will receive more info including the meeting room.
The Workshop will be offered by Ottawa RASC Centre member Paul Klauninger, who has wowed us for many years with his astrophotos at our monthly meetings. Paul's talks have always been interesting and educational. He is a gifted speaker who has delivered classes on astrophotography many times in the past to various groups.
Workshop price: Free for Ottawa RASC members. There is a charge for parking at Carleton University. The workshop is only open to Ottawa RASC members.
This beginner level workshop will introduce participants to imaging the night sky. A surprising number of different objects and phenomenon can be captured with relatively modest equipment, and that will be the primary focus of this beginner’s level workshop. However, a broad overview of the entire field of astro-imaging is also provided. This is essential to understanding how today’s amazing celestial imagery is being created by amateur astronomers around the world. It also gives a glimpse of the path going forward, should a participant wish to pursue astrophotography at a deeper level.
The workshop is divided into three broad segments:
- The basic concepts of astrophotography will be discussed, including the nature of the objects that can be imaged and the challenges they pose compared to conventional daytime photography. This discussion will provide an overview of the various levels of astrophotography, ranging from the simplest forms to the most complex, and the type of images each can produce. Celestial motion and observing site considerations will also be examined.
- Equipment configurations and techniques will be explained to show what is involved in the various types of astro-imaging. Some of the basic equipment configurations will also be demonstrated in class.
- Image processing software and techniques will also be examined. Virtually all astronomical imagery requires a degree of photo editing to bring out all of the details contained in a captured `scene. The final session of this workshop will include hands-on processing of a couple of sample images using some freely available software.
Students must have their own notebook computer if they wish to participate in the hands-on processing segment, or they may choose to just watch. Familiarity with photo-editing software such as Photoshop, Lightroom, GIMP, etc. is an asset, but not a requirement.
Carp Star Parties
Closed for the season. See you in the spring.
FLO Star Party Dates for 2020
Our Ottawa Centre’s Members’ Star Parties at the FLO will continue this summer. If you haven’t attended before, be sure to mark at least one of these dates on your calendar. You are welcome to bring family members or a guest. The GO/NO GO call will be made on the Centre mailing list, about noon the day of the star party
WINTER & SPRING DATES
Saturday January 25 – Waxing Crescent Moon, 1.1% illumination
Friday February 21 – Waning Crescent Moon, 2.8% illumination
Friday March 20 – Waning Crescent Moon, 10.8% illumination
Saturday April 25 – Waxing Crescent Moon, 7.3% illumination
Saturday May 23 – Waxing Crescent Moon, 1.4% illumination
Saturday June 20 – Day before New Moon, 0.2% illumination
7:30 PM Friday January 3, 2020 at the Canada Aviation and Space Museum (directions). Note there is a $4.00 parking fee for museum parking. The meeting runs until 9:30 pm
PLUS: all our regular meeting features: Ottawa Skies, 10-minute Astronomy News Update, Observation Reports and, of course, the beloved Door Prizes!
All RASC monthly meetings are free and open to members and non-members alike. Refreshments will be available, and this will be a wonderful opportunity to meet new friends who share a common interest and chat in a relaxed, stimulating and fun environment. Please join us!
The Ottawa Centre 2020 Council
President: Mike Moghadam (firstname.lastname@example.org)
Vice President: Stephen Nourse
Secretary: Chris Teron (email@example.com)
Treasurer: David Parfett (firstname.lastname@example.org)
Centre Meeting Chair: Dave Chisholm (email@example.com)
Councillors: Carmen Rush, Gerry Shewan, Jim Sofia
National Council Representatives: Karen Finstad, OPEN
Past President: Tim Cole
2018 Appointed Positions
Membership: Art Fraser
Star Parties: Paul Sadler
Fred Lossing Observatory: Rick Scholes (firstname.lastname@example.org)
Light Pollution Abatement: OPEN
Public Outreach Coordinator: Jean-Sebastien (JS) Gaudet
Hospitality: Art & Anne Fraser
Stan Mott Astronomy Library: Estelle Rother
Ted Bean Telescope Library: Darren Weatherall
Webmaster: Mick Wilson (email@example.com)
AstroNotes Editors: Gordon Webster & Douglas Fleming (firstname.lastname@example.org)