Gazer News

Astronomy News for Bluewater Stargazers Vol 14 No.4 Jul/Aug 2020 Jul/Aug 2020 SGN Contents p 1: Messages from President and Editor p 2: Perseid Meteor Shower is back! Arecibo Observatory radar image of 2 km wide asteroid 1998 p 3: Mars may have had Rings! OR-2, which flew past Earth on April 29, 2020, seems to show p 4: More on Rings in our Solar System it wearing a coronavirus mask. But the asteroid’s uneven p 5: Four Major Greek Discoveries shape caused the illusion, scientists say. NASA/NSF image p 6: Greek Discoveries (cont’d) p 7: Two planets around Proxima Centauri From the Editor: p 8-9: Einstein Theory Confirmed Again p 10: Sky Sights: July/August ES Fox observing coming back slowly p 11: Jupiter and Saturn at Opposition in July After the Ontario government started slowly relaxing p 12: page: Leo, Major and Minor restrictions due to the Covid-19 pandemic, your BAS p 13: Miscellaneous Page and Classified executive contacted the Bluewater Education Foundation, p 14: Feature Image: Leo Triplet owners of the BOEC with a request to slowly re-start [Quetican Field of View will return next issue -ed] observing at the Fox Observatory. They agreed with our arguments about the Fox being a low-risk outdoor facility From “Pro Tem” President Eric: and our commitment to follow social distancing, hand Hi all. sanitization, etc., and have allowed BAS members (only) In this time of continuing change, we have all been isolating in hope that the tide will turn. It seems that we are now to start re-using the observatory. seeing some light, and with that there is the start of viewing from the ES Fox Observatory at the Bluewater Outdoor The first of those events, involving observing only from the Education Centre (BOEC). The Bluewater Education grounds around the Fox with no access to the interior Foundation has granted us access to the observatory for occurred on our scheduled viewing night June 20. viewing purposes. Being that we are still in the grips of the Notwithstanding the mosquitoes and late sunset (it was still Covid-19 pandemic, there are a few new procedures to not truly dark even at 10 pm) a small group of observers did follow when attending events at the Fox Observatory. take advantage of the dark sky site. The next viewing night will be July 18 for the oppositions of Jupiter and Saturn Access is still limited by provincial guidelines and the emergency act. That is to say as we are entering into Phase followed by Perseid meteor watching Tues Aug 11/12 (Note 2 of the reopening on Friday (June 12) the following can change of date). As we get into the summer, access to the occur. observatory will gradually be permitted as long as we follow simple health precautions. See the column by Eric I. on this Access to the outside of the Observatory is permitted and page explaining the protocols. the maximum number on the site is limited to 10.

You must bring your own equipment at this time to view. There will be no sharing of equipment or use of equipment On arrival the leader of the observing session will have a inside the Fox Observatory. Please bring your own hand sign in book. You must sign in. sanitizer, and we recommend a mask. You may also wish to use gloves. Note at this time there will be no access to the inside of the Fox Observatory or any BOEC buildings. This means that If viewing is desired an email needs to be sent to me there are no washroom facilities available. at [email protected] . If there is at least 2 people then viewing can occur. Of course the maximum number is 10. Remember it is mosquito season.

Self screening is essential. If you are not feeling well, have At the end of the session you must see the leader and sign a new cough, fever, or been asked to isolate, then please out. stay at home. Happy Observing and stay safe On arrival at the BOEC you need to go directly to the Eric Ingard Observatory as currently the rest of the site is off limits. S G N Astro News Jul/Aug 2020 pg 2

Disclaimer: SGN reports on the activities of the Bluewater BAS Executive 2020-2021 Astronomical Society (formerly Bruce County Astronomical President (interim): Eric Ingard [email protected] Society) but any opinions presented herein are not necessarily V-President (interim): Brett Tatton [email protected] endorsed by BAS. For up-to-date details relating to BAS Secretary: Lorraine Rodgers [email protected] Treasurer: Cheryl Dawson [email protected] events see the BAS website at www.bluewaterastronomy.com. Member-at-Large: Zoë Kessler [email protected] SGN is produced and edited by John Hlynialuk and I am solely Membership: Marian Ratcliffe [email protected] responsible for its content. I maintain a web presence at www.johns- Public Outreach: John Hlynialuk [email protected] astronomy.com. Your original articles, images, opinions, comments, observing Past Pres: John Hlynialuk [email protected] reports, etc., are welcome at SGN. I reserve the right to edit for brevity or clarity. Errors or omissions are entirely mine. I will not publish your emails or other materials without your specific permission. No part of this publication shall be reproduced in any form whatsoever without the editor’s consent. However, the Sky Events and Constellation pages are free to copy for non-commercial use. Feel free to forward this issue in its entirety to friends. You are welcome to email comments and/or submissions to [email protected]

From “Retiring” President John As was announced at our last physical meeting in March, I there are limits on the sizes of groups. have decided to step back from president duties as of That is not to say that the exec has not been busy. May 31 and BAS has appointed a temporary president Organizing on-line meetings has fallen on the shoulders of Eric Ingard, to take on those duties until the next election both secretary Lorraine as host and Eric as chair of those in March of 2021. Brett Tatton was also appointed to take meetings. Brett has been busy communicating with his on the vice-presidential job vacated by Eric. I am staying contact at the national park as they gradually try to re- on exec as Public Outreach Chair, responsible for open. Unfortunately, group size restrictions make it promoting public events. impossible to hold astronomical viewing events and so our To some extent the reasons I had for stepping down annual “dark-in-the-park” weekend at the Bruce National have been declared moot by the Covid-19 pandemic since Park for July has been cancelled until next . The post- many of the duties that would have been on the Labour Day Inverhuron weekend may or may not go ahead president’s plate have been cancelled or postponed. Even but it will be in modified form, and nothing is confirmed at the Public Outreach job is duty-free at this point since this point as staff gradually return to Ont. Provincial Parks. there are no public viewings (anywhere in Ontario) until Nothing, it seems is normal and I think we can expect possibly in September. In addition, astronomy programs more of the same until well into the fall. Hang in there for students at the Outdoor Ed Centre have been folks, stay safe! Enjoy the from your backyards! All cancelled as well. These may start up again in September, the best from the BAS exec and a sincere personal "Thank but we are not sure what form they will take, especially if you” for your support of this retiring president.

Perseid Meteor Shower -from IMO International Meteor Organization Active from July 17th to August 26th, 2020

The Perseids are particles released from comet 109P/Swift-Tuttle during its numerous returns to the inner solar system. They are called Perseids since the radiant (the area of the sky where the meteors seem to originate) is located near the prominent constellation of Perseus.

Shower details - Radiant: 03:12 +57.6° - ZHR: 100 - Velocity: (swift - 60km/s) Parent Object: 109P/Swift-Tuttle Peak - The Perseids will peak at 9 am EDT Aug 12, 2020 so Aug 11 or 12 are prime nights. The moon is LQ (43%). enough by 9:30 pm Aug 11 and the radiant is 16° above the NE horizon by then. Until the LQ moon rises at 12:30 am Perseid meteor viewing will be best on the nights of Aug Aug 12, there is a good 3 hour window to observe shooting 11-12, 2020. The official peak is 9 am EDT on Wed Aug 12 stars. The same applies the previous night, Aug 10-11 and in North America, so the previous night is closest to peak. also 12-13 (2.5 and 3.5 hour windows, respectively, before Aug 10/11 and 12/13 should be good as well. The RASC Moon rise). handbook gives 100 per hour as a peak rate but only under Make sure you give your camera a workout! Just mount it ideal conditions, -still you can expect about 50 to 60 per on a tripod, focus on infinity and set exposure to a minute hour around midnight on those nights. It should be dark or so, with a low ISO and fire away. S G N Mars with Rings? Jul/Aug 2020 pg 3 Mars May Have Had a Ring in Mars rings -artist the Past SETI Press Rel. June 2, 2020, concept: Kevin Gill Mountain View, CA – Scientists from the SETI Institute and Purdue University have found that the only way to produce Deimos’s unusually tilted orbit is for Mars to have had a ring billions of ago. While some of the more massive planets in our solar system have giant rings and numerous big moons, Mars only has two small, misshapen moons, Phobos and Deimos. Although these moons are small, their peculiar orbits hide important secrets about their past.

For a long time, scientists believed that Mars’s two moons, discovered in 1877, were captured asteroids. However, since their orbits are almost in the same plane as Mars’s equator, the moons must have formed at the same time as just over 3 billion years ago, which was followed by two Mars. But the orbit of the smaller, more distant moon more ring-moon cycles, with the latest moon being Phobos. Deimos is tilted by two degrees. This insight from a modest tilt of a humble moon’s orbit has “The fact that Deimos’s orbit is not exactly in plane with some significant consequences for our understanding of Mars’s equator was considered unimportant, and nobody Mars and its moons. The discovery of the past orbital cared to try to explain it,” says lead author Matija Ćuk, a resonance all but clinches the cyclic ring-moon theory for research scientist at the SETI Institute. “But once we had a Mars. It implies that for much of its history, Mars possessed big new idea and we looked at it with new eyes, Deimos’s a prominent ring. While Deimos is billions of years old, Ćuk orbital tilt revealed its big secret.” and collaborators believe Phobos is young as astronomical objects go, forming maybe only 200 million years ago, just This significant new idea was put forward in 2017 by Ćuk’s in time for the dinosaurs. co-author David Minton, professor at Purdue University and his then-graduate student Andrew Hesselbrock. These theories may be up for some serious testing in a few years, as Japanese space agency JAXA plans to send a Hesselbrock and Minton noted that Mars’s inner moon, spacecraft to Phobos in 2024, which would collect samples Phobos, is losing height as its tiny gravity is interacting with from the moon’s surface and bring them back to Earth. Ćuk the looming Martian globe. Soon, in astronomical terms, is hopeful that this will give us firm answers about the Phobos’s orbit will drop too low, and Mars’s gravity will pull murky past of the Martian moons: “I do theoretical it apart to make a ring around the planet. Hesselbrock and calculations for a living, and they are good, but getting them Minton proposed that over billions of years, generations of tested against the real world now and then is even better.” Martian moons were destroyed into rings. Each time, the ring would then give rise to a new, smaller moon to repeat This research is presented at the 236th Meeting of the the cycle over again. American Astronomical Society, held virtually on June 1-3, 2020, and is accepted for publication in the Astrophysical This cyclic Martian moon theory has one crucial element Journal Letters. that makes Deimos’s tilt possible: a newborn moon would move away from the ring and Mars. Which is in the opposite Link to Paper: https://arxiv.org/abs/2006.00645 direction from the inward spiral Phobos is experiencing due to gravitational interactions with Mars. An outward- migrating moon just outside the rings can encounter a so- called orbital resonance, in which Deimos’s orbital period is The Martian three times that of the other moon. moon Phobos may have played These orbital resonances are picky but predictable about a major role in the direction in which they are crossed. We can tell that only producing rings an outward-moving moon could have strongly affected around Mars in Deimos, which means that Mars must have had a ring the past. pushing the inner moon outward. Ćuk and collaborators deduce that this moon may have been 20 times as massive NASA photo as Phobos, and may have been its “grandparent” existing S G N Outer Planets -Rings Galore Jul/Aug 2020 pg 4

Scientists know that the ring process must be a common one in our solar system. After all there is Saturn with its magnificent set of rings that have enthralled astronomers from the first views made by Galileo in 1610. Recently other systems of rings have been discovered around the other gas giants, Jupiter, Uranus and Neptune.

And, in 2014, astronomers found an asteroid – named Chariklo – had two dense and narrow rings orbiting it. This was the first time that rings were found around any solar system object smaller than the gas or ice giant planets. Chariklo is a member of a group of asteroids called Centaurs that orbit between Jupiter and Neptune.

Uffe Gråe Jørgensen at Niels Bohr Institute, University of Copenhagen in Denmark, said of Chariklo:

For me, it was quite amazing to realize that we were able not only to detect a ring system, but also pinpoint that it consists of two clearly distinct rings. I try to imagine how it would be to stand on the surface of this icy object – small enough that a fast sports car could reach escape velocity and drive off into space – and stare up at a 20-kilometer (12-mile) wide ring system 1,000 times closer than the moon. Ring systems around Saturn (top); Jupiter (backlit In 2017, a ring was also discovered around Galileo image); Uranus the asteroid-like dwarf planet Haumea, which (right) with a “new” ring orbits beyond Neptune in the Kuiper Belt. imaged in 2005 by Keck Telescope; and Neptune Artist’s concept of asteroid Chariklo, (lower right) as seen by which, in 2014, was the first object in Voyager 2 with the planet the solar system smaller than the gas backlit by the Sun. Up to or ice giant planets found to have rings. 2014, no rings had been observed around the smaller rocky or icy bodies, but rings around Charillo (2014) and Haumea (2017) have changed that. Four Major Greek Discoveries S G N Jul/Aug 2020 pg 5 Four Major Discoveries of the Greeks Unfortunately, the original text in which he makes this The Histories by Herodotus (484 BC to 425 BC) offers a argument has been lost to history, so we cannot know for remarkable window into the world as it was known to the certain how he worked it out. Aristarchus knew the Sun was ancient Greeks in the mid fifth century BC. Almost as much bigger than the Earth or the Moon, and he may have interesting as what they knew, however, is what they did not surmised that it should therefore have the central position in know. This sets the baseline for the remarkable advances in the solar system. their understanding over the next few centuries – simply relying on what they could observe with their own eyes. Nevertheless it is a jawdropping finding, especially when you consider that it wasn’t rediscovered until the 16th century, Herodotus claimed that Africa was surrounded almost by Nicolaus Copernicus, who even acknowledged entirely by sea. How did he know this? He recounts the story Aristarchus during the development of his own work. of Phoenician sailors who were dispatched by King Neco II of Egypt (about 600 BC), to sail around continental Africa, in 2. The size of the Moon a clockwise fashion, starting in the Red Sea. This story, if One of Aristarchus’ books that did survive is about the sizes true, recounts the earliest known circumnavigation of Africa, and distances of the Sun and Moon. In this remarkable but also contains an interesting insight into the astronomical treatise, Aristarchus laid out the earliest known attempted knowledge of the ancient world. calculations of the relative sizes and distances to the Sun and Moon. It had long been observed that the Sun and The voyage took several years. Having rounded the Moon appeared to be of the same apparent size in the sky, southern tip of Africa, and following a westerly course, the and that the Sun was further away. They realised this from sailors observed the Sun as being on their right hand side, solar eclipses, caused by the Moon passing in front of the above the northern horizon. This observation simply did not Sun. make sense at the time because they didn’t yet know that the Earth has a spherical shape, and that there is a southern Also, at the instant when the Moon is at first or third quarter, hemisphere. Aristarchus reasoned that the Sun, Earth, and Moon would form a right-angled triangle. As Pythagoras had determined 1. The planets orbit the Sun how the lengths of triangle’s sides were related a couple of A few centuries later, there had been a lot of progress. centuries earlier, Aristarchus used the triangle to estimate Aristarchus of Samos (310 BC to 230 BC) argued that the that the distance to the Sun was between 18 and 20 times Sun was the “central fire” of the cosmos and he placed all of the distance to the Moon. He also estimated that the size of the then known planets in their correct order of distance the Moon was approximately one-third that of Earth, based around it. This is the earliest known heliocentric theory of the on careful timing of lunar eclipses. solar system.

Above: A 10th century reproduction of a diagram by Aristarchus showing some of the geometry he used in his calculations. wikipedia, CC BY-SA

While his estimated distance to the Sun was too low (the actual ratio is 390), on account of the lack of telescopic precision available at the time, the value for the ratio of the size of the Earth to the Moon is surprisingly accurate (the Moon has a diameter 0.27 times that of Earth).

Image above: To explain the retrograde motion of planets Today, we know the moon parameters accurately by precise like Mars and Jupiter, the (incorrect) Earth-centered theory telescope measurements, radar observations and laser resorted to dozens of epicycles in an unwieldy geometry as reflectors left on the surface by Apollo astronauts. shown above. Four Major Greek Discoveries Jul/Aug 2020 pg 6 S G N 3. The Earth’s circumference Eratosthenes (276 BC to 195 BC) was chief librarian at the Great Library of Alexandria, and a keen experimentalist. Among his many achievements was the earliest known calculation of the circumference of the Earth. Pythagoras is generally regarded as the earliest proponent of a spherical Earth, although apparently not its size. Eratosthenes’ famous and yet simple method relied on measuring the different lengths of shadows cast by poles stuck vertically into the ground, at midday on the summer solstice, at different latitudes.

The Sun is sufficiently far away (diagram right) that, wherever Eratosthenes assumed the Sun’s rays would be parallel if the its rays arrive at Earth, they are effectively parallel, as had Sun were far enough away and so shadows cast at different previously been shown by Aristarchus. So the difference in the shadows demonstrated how much the Earth’s surface locations would give an indication of the angle labelled α in curved. Eratosthenes used this to estimate the Earth’s the diagram above. The distance along the arc from Syene circumference as approximately 40,000 km. This is within a to Alexandria, would be that fraction of a complete circle, couple of percent of the actual value, as established by the Earth’s circumference. modern geodesy (the science of the Earth’s shape).

Later, another scientist called Posidonius (135 BC to 51 BC) Below: The Antikythera Mechanism found in 1900 in a used a slightly different method and arrived at almost exactly shipwreck off the Greek island of the same name.The device the same answer. Posidonius lived on the island of Rhodes is thought to be an early sophisticated astronomical for much of his life. There he observed the bright star calculator. A video of the internal structure is available here: Canopus would lie very close to the horizon. However, when https://youtu.be/6Wp3wL8g2Eg in Alexandria, in Egypt, he noted Canopus would ascend to some 7.5 degrees above the horizon.

Given that 7.5 degrees is 1/48th of a circle, he multiplied the distance from Rhodes to Alexandria by 48, and arrived at a value also of approximately 40,000 km.

4. The first astronomical calculator The world’s oldest surviving mechanical calculator is the Antikythera Mechanism. The amazing device was discovered in an ancient shipwreck off the Greek island of Antikythera in 1900.

The device is now fragmented by the passage of time, but when intact it would have appeared as a box housing dozens of finely machined bronze gear wheels. When manually rotated by a handle, the gears spun dials on the exterior showing the phases of the Moon, the timing of lunar eclipses, and the positions of the five planets then known (Mercury, Venus, Mars, Jupiter, and Saturn) at different times of the year. This even accounted for their retrograde motion – an illusionary change in the movement of planets through the special equipment, allowing those just beginning their interest sky. in science to understand by doing, experimenting and, ultimately, following in the footsteps of some of the first We don’t know who built it, but it dates to some time scientists. between the 3rd and 1st centuries BC, and may even have been the work of Archimedes. Gearing technology with the One can but speculate where our civilisation might be now if sophistication of the Antikythera mechanism was not seen this ancient science had continued unabated. again for a thousand years. This article appeared in The Conversation, a publication of Sadly, the vast majority of these works were lost to history the Academic Journalism Society and our scientific awakening was delayed by millennia. As a https://theconversation.com tool for introducing scientific measurement, the techniques of Eratosthenes are relatively easy to perform and require no S G N Two planets around Proxima Centauri Jul/Aug 2020 pg 7 25-yr-old Hubble Data Confirms Shortly afterward, a team led by Raffaele Gratton of INAF published images of the planet at several points along its orbit 2nd Planet around Proxima Centauri that they had made with the SPHERE instrument on the Very 2 June 2020 Press release U of T at A Large Telescope in Chile. Click here for more. AUSTIN — Fritz Benedict has used data he took over two decades ago with to confirm the existence of another planet [the 2nd one! -ed] around the Sun’s nearest neighbour, Proxima Centauri, and to pin down the planet’s orbit and mass. Benedict, an emeritus Senior Research Scientist with McDonald Observatory at The University of Texas at Austin, presented his findings June 2 in a scientific session and then in a press conference at a meeting of the American Astronomical Society.

Proxima Centauri has been in the news frequently since 2016, when scientists including McDonald Observatory’s Michael Endl found its first planet, Proxima Centauri b. [See Naming below.] The discovery incited speculation on the types of in-depth studies that could done on an extrasolar planet so close to our own solar system. Benedict then combined the findings of all three studies: his own Hubble , Damasso’s studies, Adding to the excitement, earlier this year a group led by and Gratton’s images to greatly refine the mass of Proxima Mario Damasso of Italy’s National Institute for Astrophysics Centauri c. He found that the planet is about 7 times as (INAF) announced they might have found another planet massive as Earth. orbiting Proxima Centauri farther out. This analysis shows the power of combining several This group used radial velocity observations, that is, independent methods of studying an . Each measurements of the star’s motion on the sky toward and approach has its strengths and weaknesses, but together away from Earth, to deduce the possible planet (dubbed they serve to confirm the existence of Proxima Centauri c. Proxima Centauri c) orbits the star every 1,907 days at distance of 1.5 AU (that is, 1.5 times the distance at which “Basically, this is a story of how old data can be very useful Earth orbits the Sun). when you get new information,” Benedict said. “It’s also a story of how hard it is to retire if you’re an astronomer, Still, the existence of planet c was far from certain. Thus because this is fun stuff to do!” Benedict decided to re-visit his studies of Proxima Centauri from the 1990s made with Hubble Space Telescope. For that study, he had used Hubble’s Fine Guidance Sensors (FGS). Naming Exoplanets Though their primary role is to ensure accurate pointing of the telescope, Benedict and others routinely used FGS for a type Exoplanets around named stars are named “Starname” of research called astrometry: the precise measurement of plus b, c, d, etc. The letter a is not used. The alpha the positions and motions of celestial bodies. In this case, he (brightest) star of the Centaur is, in fact, a triple star used FGS to search for Proxima Centauri’s motion on sky designated α-Centauri A, α-Centauri B and α-Centauri C. caused by tugging from its surrounding — and unseen — Multiple stars in gravitationally bound systems are planets. designated with capital letters starting with A for the primary, B for the secondary, etc. When Benedict and research partner Barbara MacArthur originally studied Proxima Centauri in the 1990s, he said, α-Centauri C was discovered in 1915 and given its own they only checked for planets with orbital periods of 1,000 name, Proxima Centauri, when it was found to be closer Earth days or fewer. They found none. He now revisited that to us than the AB pair. Respective distances are 4.24 data to check for signs of a planet with a longer orbital period. light-years (Proxima) and 4.37 LY for the α-Centauri-AB binary pair. The other stars of the system have names as Indeed, Benedict found a planet with an orbital period of well, and α-Centauri A is often called Rigel Kentaurus, α- about 1,907 days buried in the 25-year-old Hubble data. This Centauri B was recently named Toliman but this is was an independent confirmation of Proxima Centauri c. relatively unused. S G N Einstein Theory Confirmed Yet Again Jul/Aug 2020 pg 8 Pulsars Confirm One of Einstein’s Best Ideas, That Freefall Really Feels Like You’re Experiencing a Lack of Gravity Six and a half decades after he passed away, famed theoretical physicist Albert Einstein is still being proven right! In addition to General Relativity (GR) being tested under the most extreme conditions, lesser-known aspects of his theories are still being validated as well. For example, GR predicts that gravity and inertia are often indistinguishable, in what is known as the gravitational Strong Equivalence Principle (SEP).

Thanks to an inter national team of researchers, it has been proven under the strongest conditions to date. By precisely tracking the motion of a pulsar, the team demonstrated that gravity causes neutron stars and white dwarf stars to fall with equal accelerations. This confirms Einstein’s prediction that freefall accurately simulates zero-gravity conditions in all inertial reference frames. Above: Artist’s illustration of Pulsar PSR J0337+1715, part of Their study, which recently appeared in the journal a triple star system located 4,200 light-years away in the Astronomy & Astrophysics, was led by Dr. Guillaume Voisin. constellation Taurus. a research associate from Manchester University’s Jodrell Bank Centre for Astrophysics. He was joined by researchers was incompatible with relativity. By 1907, he theorized that from the Observatoire de Paris, the Max-Planck-Institute for an object in freefall behaves exactly as it would in zero-g Radio Astronomy (MPIR), and the Centre National de la since gravity causes everything to accelerate at the same Recherche Scientifique (CNRS). rate – i.e. the “universality of freefall”.

For the sake of their study, the team relied on a rigorous new This insight led Einstein to realize that gravity is a method that combined radio telescope observations with the manifestation of curved space-time and acts on all masses more recent data obtained by gravitational wave detectors. the same way (which lies at the heart of GR). In the case of This allowed them to precisely track the motion of a pulsar neutron stars, their intense gravity alters the curvature of known as PSR J0337+1715, which is part of a triple star spacetime in a way that is many trillion times stronger than system located 4,200 light-years away in the constellation what the planets or even the Sun are capable of. Taurus. This is what makes pulsars (a rapidly-rotating neutron star) PSR J0337+1715 is a millisecond pulsar, a type of rapidly- like PSR J0337+1715 – discovered in 2014 by radio rotating neutron star that emits regular radio pulses as it astronomers – an ideal testbed for testing GR and SEP. rotates 366 times per second. Its companions are both white Using the Nançay radio telescope located in the Sologne dwarfs, stellar remnants that remain after stars exhaust their region of France, Dr. Voisin and his colleagues observed this nuclear fuel and undergo gravitational collapse (aka. “go pulsar for eight years and precisely measured its motion by supernova”). Neutron stars are even more extreme due to monitoring the arrival times of its radio pulses. their greater density and gravitational force. What this showed was that PSR J0337+1715 falls with the This makes them fitting candidates to test General Relativity, same rate of acceleration as the nearby white dwarf in the which Einstein eventually arrived at thanks to his work with gravitational field of the outer white dwarf. the equivalence principle – which Einstein referred to as “the most fortunate thought in my life.” Einstein began to These results confirm the universality of freefall with the contemplate this after the publication of his Theory of greatest precision and under the most extreme conditions to Special Relativity in 1905, which stated that the speed of date. Previously, the most precise test was carried out by a light is constant and the same in all reference frames. mini-satellite developed by the French Centre National d’Études Spatiales (CNES). Shortly thereafter, he began working on unifying this theory with gravity, since Newton’s theory of Universal Gravitation S G N Einstein Theory Confirmed Yet Again Jul/Aug 2020 pg 9

This was known as the Micro-Satellite à traînée Compensée pour l’Observation du Principe d’Equivalence (MICROSCOPE) (Image right), which operated from April of 2016 to Oct of 2018. This satellite carried small masses within its frame to show how they experienced identical accelerations while being exposed to the gravitational field of Earth while in Low Earth Orbit (LEO).

This is not the first time that SEP has been tested using this system, but it does improve over previous results in two ways. First, it provides tighter contraints of the differences in acceleration between the pulsar and the inner white dwarf. Second, it relies on a better understanding of the properties of neutron stars, which is the result of the LIGO/Virgo observatories detecting collisions between them. As Dr. Voisin put it:

“Confirming it to this precision constitutes one of the most stringent tests of Einstein’s theory ever made – and the theory passes the test with flying colors. Moreover, the results also provide very stringent constraints on alternative theories of gravity, which compete with Einstein’s general relativity to explain gravity and, for example, dark energy.”

The study is also significant because of how it lends further credence to GR over alternative theories of gravity. To be fair, most theories of gravity incorporate Einstein’s insights regarding SEP and describe gravity as a geometric phenomenon – in that it arises from the curvature of spacetime. What sets them apart from GR is how the curvature of spacetime is altered by the masses of large bodies.

While these alternative theories predict that small and large objects fall with the same acceleration in the same gravitational field, things become different when describing astronomical objects (which are held together by gravity itself). Here, alternative theories predict that deviations from universal acceleration will occur, whereas GR predicts that astronomical objects abide by the same rules as small objects.

Image right: The orbit of S2, a star orbiting the SMBH at the center of the Milky Way, is just as Einstein predicted with his theory of GR. Credit: ESO

By testing Einstein’s theories in an extreme environment like a neutron star, the universality of freefall has been shown to truly be universal. This is perhaps the most significant takeaway from this test, which is the way it demonstrates how GR – as inspired by the simplicity of Einstein’s “most fortunate thought” – truly captures something fundamental about gravity and the inner workings of Nature. S G N Sky Sights Jul/Aug 2020 pg 10 July 2020 July 4/5: Penumbral Lunar Eclipse The full moon rises on July 4 at 9:05 pm for local Date GMT Event moon gazers, and just after midnight will be 01 03:00 Mercury at Inferior Conjunction (not vis.) about 20 degrees high above the southern 05 04:30 Pen. Lunar Eclipse; magn. = 0.355 (visible in N. Amer.) horizon in Sagittarius. At 12:30 am July 5, it will Greatest Eclipse at 12:30 am (just after midnight) July 4/5. be experiencing the maximum shading where 05 04:44 FM rises locally at 9:58 pm EDT the faint penumbral shadow of the Earth cuts 05 21:37 Jupiter 1.9°N of Moon across the top quarter or so of the Moon’s face. 06 08:45 Saturn 2.5°N of Moon You will need to look very carefully, as this is not 11 12:10 Venus 1.0°N of Aldebaran very perceptible to the naked eye. A light meter 11 19:36 Mars 2.0°N of Moon at the eyepiece of a scope may be able to detect 12 19:27 Moon at Apogee: 404 201 km the subtle drop-off, but don’t count on seeing it 12 23:29 LQ Moon rises locally at 12:53 am EDT by eye. It may be possible to record the slight change photographically. Try a full moon shot at 14 07:00 Jupiter at Opposition (magn.= -2.8, disk = 47.6” across) 11 pm or so on July 4, and then use the identical 17 01:21 Aldebaran 3.8°S of Moon settings for another shot at 12:30 am. You may 17 07:26 Venus 3.1°S of Moon see a subtle difference in the brightness at the 19 03:54 Mercury 3.9°S of Moon top of the Moon. Good luck! 20 17:33 NM rises locally at 5:33 am EDT 20 22:00 Saturn Opposition (magn.= 0.1, disk = 18.5”, ring tilt = 21.9°) 22 15:00 Mercury at Greatest Elong: 20.1°W 22 20:50 Regulus 4.3°S of Moon 25 04:54 Moon at Perigee: 368 367 km 27 12:32 FQ Moon rises locally at 2:11 pm EDT 27 21:00 Delta-Aquarid Meteors (20/h, peak 5 pm EDT, Moon 66%)

August 2020 Date GMT Event 01 20:14 Mercury 6.6°S of Pollux 01 23:30 Jupiter 1.5°N of Moon 02 13:17 Saturn 2.3°N of Moon 03 15:59 FM rises locally at 9:15 pm EDT 09 07:57 Mars 0.8°N of Moon: Occn. (S. Amer., Antarctica) (Moon-Mars 1° apart 3 am locally) P4 = 1:52 am EDT (July 5) P1 = 11:07 pm July 4 09 13:51 Moon at Apogee: 404 658 km Maximum Eclipse = 12:29 am July 5 (Subtract 4 hours from UT times for local EDT) 11 16:45 LQ Moon rises locally at 12:01 am EDT 12 13:00 Perseid Meteor Shower (90/h, peak 8 am EDT, Moon 43%) https://www.timeanddate.com/eclipse/ 13 01:00 Venus at Greatest Elongation West: 45.8°W magnitude.html 13 10:06 Aldebaran 4.0°S of Moon 15 13:01 Venus 4.0°S of Moon 16 19:10 Pollux 4.5°N of Moon 17 15:00 Mercury at Superior Conjunction (not vis.) 19 02:41 NM BAS “Zooms” again July 8 21 10:59 Moon at Perigee: 363 513 km 25 17:58 FQ Moon rises locally at 2:32 pm EDT BAS will continue with a Zoom meeting for the 26 04:04 Antares 6.2°S of Moon July 8 regular club session. Note that we have 29 01:33 Jupiter 1.4°N of Moon and16:40 Saturn 2.2°N of Moon moved the first Wed meeting of July to the second Wednesday of the month since July 1 is Canada Day. It helps to download Zoom from BAS Events in July/August this site https://zoom.us Viewing events for July and August are gradually opening up at the Fox Lorraine will alert you as usual by email shortly Observatory and meetings will continue via Zoom until further notice. ahead of time with a link and password to use Check the BAS website at www.bluewaterastronmy.com for updates on events. Notifications for future Dark-of-the-Moon viewing nights/other to join the meeting. events will come to members by email. Note that for Fox Observatory viewing nights, there are restrictions as outlined on page 1 of this issue. Sky Sights Jul/Aug 2020 pg 11 July 14, July 20, 2020: Oppositions of Jupiter and Saturn MERCURY is a morning “star” in July (GEW on The two most interesting gas giant planets reach opposition in Planets 22nd) and by the third week of August is back our sky only a few days apart this summer. There is nothing again in the Sun’s glare. Catch it this summer, special about their visibility on those dates, however, and they Mercury will not be in good viewing position as an evening star in will be in good viewing position for several weeks, even a September and October. VENUS, is “the” Morning Star to watch in month or more, before and after their respective July July and August and brightest on July 10 at -4.7 magnitude! On July 12, Venus is farthest from the Sun (GEW) at 46° and oppositions. True, at opposition they are actually the closest coincidentally closest to Aldebaran that morning. MARS, (-0.5 to they can get to Earth, but the viewing window is pretty wide -1.8) rises by midnight in July and is visible for half the night as it since these planets move so slowly across the sky. dominates the sky in Pisces with its brightness. JUPITER, -2.7 and SATURN, (0.13) reach opposition in early July and are in prime The geometry of opposition (diagram below), shows that they viewing location all night. The two planets grow in separation from are lined up on the same side of the Sun as Earth. The view 6° to 8° this summer. URANUS, (5.7) in Aries and NEPTUNE, (7.8) from above the Sun however is not how we see them in the in Aquarius straddle Mars in midnight skies this summer. Dwarf sky, of course. From our perspective, both planets are in the planet, Ceres (8.6) stays in Aquarius east of Saturn and Mars all sky in front of Sagittarius and appear to rise at sunset and set summer long. Asteroid, Vesta (7.9) is too close to the Sun to at sunrise, so they are in the sky all night long. Jupiter being observe. PLUTO (mag. 14.3) stays close to Jupiter in Jul/Aug near Saturn in the sky this year is a happy coincidence, -in 5 skies. Finder charts for Pluto in 2020 are on the BAS website. years or so, Jupiter’s apparent motion (3x that of Saturn The table below gives the sunrise/sunset times and the Sun’s across the sky) will carry it to the opposite side of the sky. altitude for dates in July and August. The moon phase dates and For 2020, the two are in the same constellation, Sagittarius, moonrise times for Owen Sound are in the Astronomy Events and will stay near each other for several years into the future - listing on pg. 11. Check https://www.timeanddate.com for Moon a nice arrangement for Earthly observers. By 2025 or so, and precise Sun rise and set times for your location. Jupiter will have moved to the evening sky while Saturn is a dawn planet and vice versa, so not so convenient for viewing Sunrise/set times: Owen Sound 44°35‘N 80°55’W both. Times in Eastern Daylight Time (EDT) Vernal Equinox is due at 9:30 am EDT Sep 22 Jupiter reaches opposition first on July 14 and shines at Date Rise Noon altitude Set magnitude -2.8 with a surface disk of 47.6" of arc. Only Venus July 10 5:49 am 67.5° 9:08 pm at inferior conjunction (last June 3) can be larger at 58"or so. July 20 5:58 am 65.9° 9:00 pm Saturn reaches opposition on July 20, magnitude of 0.13 and July 30 6:08 am 63.7° 8:50 pm a disk diameter of 18.5 arc-seconds. The rings are about as Aug 10 6:21 am 60.7° 8:36 pm wide as Jupiter's disk, 42" of arc across, so Saturn still Aug 20 8:32 am 57.6° 8:20 pm presents a large target for telescopes! The ring plane is nicely Aug 30 8:44 am 53.7° 8:02 pm tilted our way as well, 21.9°. Data from www.timeanddate.com

Diagram below shows the position of Jupiter and Saturn on the part of the Earth as it catches up to the gas giants. July 17 (Happy Birthday Rebecca!) at opposition time. Earth, From Jan to July, for ex. while Earth moved 50% of a Jupiter and Saturn are almost lined up exactly and all three are complete orbit, Jupiter performed only 4% of its trip around on the same side of the Sun. Most of the motion has been on the Sun and Saturn did less, 1.7% of a complete orbit.

11.17 AU to Earth 1.68 Billion km

7.51 AU to Earth 1.13 Billion km SGN : Leo, Jul/Aug 2020 pg 12 Leo (Leo) α−Leonis - Regulus β−Leonis - Denebola γ−Leonis - Algieba δ−Leonis - Zosma Leo Minor (LMi) ε−Leonis - Asad Australis ζ− Leonis-Aldhafera θ− Leonis - Chort Leo Minor is a small constellation between Ursa Major and Leo with λ− Leonis - Alterf μ−Leonis - Rasalas only 3 first magnitude stars. The brightest, 46 Leonis Minoris, has a magnitude of 3.9. is a long period variable (372 Leo is a zodiacal constellation lying south of Ursa Major. It is one of days) with a maximum magnitude of 7.1. the most beautiful of the constellations and is easily recognized; the stars forming the head of the lion are arranged in the shape of a The following information is from Wikipedia: sickle, or reversed "?." Regulus, its brightest star, has a magnitude DOUBLE STARS of 1.3 and is 19th among the 20 brightest stars in the sky. It lies almost exactly on the plane of the ecliptic and is therefore eclipsed Mag. Sep (s) Remarks by the sun once a year (on about August 23). τ Leonis, a double β Leonis Minoris 4.4-6.1 11 star, can be separated with binoculars. A meteor shower, the Leonids, radiates from the head of the lion every year about the Other Objects of Interest in Leo Minor 14th or 15th of November. Hanny's Voorwerp, Dutch for "Hanny's Object", is enormous, about the DOUBLE STARS size of our own Milky Way . Glowing strongly in the greenish light Mag. Sep (s) Remarks produced by ionized oxygen atoms, the mysterious voorwerp is below IC 2497 in this view from the Hubble Space Telescope. α 1.5-8.0 177 Pale Blue-White. Both are about 650 γ 2.3-3.5 4 Yellow-Green; one million light-years in Leo of the most beautiful doubles in the sky. Minor. The green cloud is 6 5.3-9.0 37 now suspected to be part 7 6.2-9.3 42 of a tidal tail of material 54 4.5-6.3 6 Greenish Wh-Blue; beaut. illuminated by a 88 6.2-8.2 15 inhabiting the center of 90 6.0-7.3 3 IC 2497. Powered by a MESSIER OBJECTS massive black hole, the Mag Remarks quasar suddenly turned M65 9.3 Spiral Galaxy. off, leaving only galaxy M66 8.4 Spiral Galaxy. and glowing voorwerp M95 10.4 Spiral Galaxy. visible in telescopes at M96 9.1 Spiral Galaxy. optical wavelengths. The M105 9.2 Spiral Galaxy. sharp Hubble image also resolves a star forming Other Objects of Interest in Leo region in the voorwerp, R Leonis - Long period (313 days) variable, magnitude range seen in yellow on the side 5-11. This star is red in color and is visible to the naked eye at near IC 2497. That region maximum. was likely compressed by an outflow of gas driven from the galaxy's core. The remarkable mystery object was discovered by Dutch schoolteacher Hanny van Arkel in 2007 while participating online in the Galaxy Zoo project. Galaxy Zoo enlists the public to help classify found in the Sloan Digital Sky Survey, and more recently in deep Hubble imagery.

The Leo Triplet (image pg 14): A nice group of galaxies located just under the rear feet of Leo are a suitable target for all sizes of telescopes. M65, M66 and NGC3628 form this classic group of spiral galaxies. M65 and 66 are above 9th magnitude and only about 0.33° apart. Both are edge-on. The third member of this group NGC3628 is fainter but larger and in medium scopes shows a prominent dust lane across its length. Starry Night gives this description: “The sight of this lovely trio is a delight under low power in telescopes. M65 is quite large and oval shaped and M66 has a noticeably bright star-like nucleus. A moderate aperture telescope begins to reveal subtle detail.” The Leo Galaxy Group The other galaxy group in Leo is a pair of spirals, M95 and M96 and an elliptical galaxy, M105. The first two are 42 min of arc apart, twice the separation of M65 and M66. The brighter is M95 but M96 is more interesting with a bright core and hints of a bar crossing it, since it is a barred spiral. All three are fainter that the Leo Triplet, being 10.5, 11 and 11th magnitudes respectively. This is an interesting challenge for moderate sized telescopes and will give you an opportunity to test your scope’s ability to pick out faint details in these spiral galaxies. These two groups are a nice half dozen to add to your list of observed objects. S G N The Miscellaneous Page Jul/Aug 2020 pg 13 BAS Member Loaner Scopes Solar H-alpha scope now available. SGN Our Lunt solar scope can be borrowed by BAS members for an extended period. Contact John H. if you wish to book it. We Classified now have a suitable mount for it as well. A short training session will be provided on pickup. Ads Section

Several Dobs available. See For Sale page One 12-inch dobsonian loaner telescope is available for free www.johns-astronomy.com loan to members. Other telescopes are also available. Contact John H. or Brett T. for availability. Scopes come in and out so keep checking with John or Brett if you are interested in borrowing a telescope.

Contact [email protected] for any of these items. FOR SALE: NEW PRICE! 12.5 inch f/6 Dobsonian See the complete list on Homebuilt by experienced telescope maker in 1980. See Sep 2014 www.johns-astronomy.com For Sale page. SGN pg 9 for build details. Truss tube design with full thickness Coulter mirror -one of their best, recently re-aluminized. Focuser and secondary mirror/spider is a Novak unit. Alt-azimuth mount (3/4-inch Tirion Sky Atlas 2000.0 contains 26 ply) is a nice wood grain finish with coating of Varathane. This is a charts covering the whole sky and large telescope and probably would be happy in a relatively showing 81,312 single, multiple, and permanent location, but is portable if you have lots of trunk space. variable stars of magnitude 8.5 and Loading into and out of a car trunk is easier with two people. Can be up with 2,700 deep-sky objects. seen at the Fox Observatory. Asking $759 but willing to negotiate. Asking $60 Contact John H. at 519-371-0670 or [email protected].

Two-inch mirror diagonal plus adapter for C-8’ or Meade SCTs $80

Logitech QuickCam Express USB Rack&Pinion Focuser 1-½” video cam. suitable for dobsonian Model V-UB2 reflector. Long focus range. (video res Asking $30. 640x480, asking $10. Celestron Zoom eyepiece Meade full aperture glass 24-8 mm for 1.25” focuser Meade 2x-3x variable (9.25” ID) - Tube rings. Two sizes avail. solar filter new $120, asking $80 One to fit 5” and one for 6 Barlow (1.25”) asking $20 orange/yellow image inch tubes. Clamshell-type (equivalent to Thousand that open up and clamp Oaks Type 2 Glass filter) down with knurled knobs. asking $40 Asking $20 either set. Meade illum. reticle (double cross-hair) 1.5 V req’d $25

More Thanksgiving Aurora S G N Feature Image: Leo Triplet Jul/Aug 2020 pg 14 This Frank Williams image was taken May 2016 with a with interesting galaxy in the group is NGC 3628, an edge-on spiral TEC 140 refractor from Allenford using SBIG STL11000 mono with a prominent dust lane. Upper left, is galaxy M66 and CCD 60 (20x3) minutes , 50 minutes (10x2, 10x3) of below is M65, both relatively normal spirals. A (fainter) group of Red, Green and Blue filters. The image shows more detail than three galaxies in Leo, M95, M96 and M105, about halfway the visual telescopic appearance of these galaxies. The most between Regulus and the Leo Triplet are also worth a look.

From https://www.messier-objects.com NGC 3628 is an unbarred spiral galaxy with a visual magnitude of 10.2. Seen edge-on, the galaxy occupies an The Leo Triplet, or the M66 Group, consists of the galaxies area of 15 by 3.6 arc minutes and appears transected by a Messier 65, Messier 66 and NGC 3628, also known as the broad band of dust that stretches along its outer edge, Hamburger Galaxy. The Leo Triplet lies at an approximate hiding the young stars in the galaxy’s spiral arms. distance of 35 million light years from Earth. The three galaxies in the M66 Group have all been affected The three large spiral galaxies can be seen in a single field of by gravitational interactions with each other. This is evident view and are well viewed even in small telescopes. Their in the deformed, drawn out spiral arms of M66 that are galactic disks are tilted at different angles when seen from experiencing a high rate of star forming activity and in the Earth. NGC 3628 appears edge-on, while M65 and M66 are warped, inflated disk of NGC 3628. With a prominent tidal inclined enough to reveal their spiral arms. tail consisting mainly of young blue stars, NGC 3628 seems to be the most affected of the three, while M65 appears to Messier 66, the largest and brightest member of the Leo have suffered the least damage from the interaction. The Triplet, is roughly 95 000 light years across. It has an tidal tail of NGC 3628 spans over 300,000 light years, but is apparent size of 9.1 by 4.2 minutes of arc and an apparent very faint and does not always appear in images. magnitude of 8.9. Messier 65 has a visual magnitude of 10.25 and occupies an The disk of M65 appears a bit warped and there is evidence area of 8.7 by 2.4 arc minutes of apparent sky. It is an of a relatively recent burst of star forming activity within the intermediate spiral galaxy, poor in dust and gas, and shows galaxy, indicating that M65, too, is tidally interacting with the little evidence of star formation. other galaxies in the M66 Group.