In collaboration with universities in England and Australia, Armagh Observatory is part of a team operating and commissioning the new Gravitational wave Optical Transient Observatory (GOTO) at the Roque de los Muchachos Observatory on the island of La Palma.
The observatory site as seen from the on site residence.
GOTO, once operational, will try to photograph the optical counterpart of gravitational wave events like the one detected last year, GW170817. It will do this by quickly photographing a large area of the sky in the region where a detected gravitational wave is thought to have come from. A large area of sky needs to be photographed as it is difficult to pinpoint where in the sky a gravitational wave has come from just from the detectors like LIGO and VIRGO. To accomplish this, GOTO will use two separate arrays of 40cm telescopes (relatively small by research standards) to cover 5 square degrees of sky per telescope. Each array is capable of holding 8 telescopes each to eventually cover 80 square degrees.
GOTO open while we checked it over.
As part of Armagh’s contribution, at the start of February I went out to La Palma to “babysit” GOTO while it’s robotic mode was being commissioned. GOTO is able to run in a fully robotic mode, meaning no astronomer needs to sit and manually operate the telescope on site. However while this feature is being tested, the telescope still needs someone to keep an eye on it to make sure it’s doing what it should be.
Unfortunately upon my arrival at the observatory there was an ice storm at the top of the 7,800ft mountain. This meant it wasn’t possible for several days to even leave the astronomers residence, let alone use the telescope! Eventually the thick fog cleared and the ice began to melt enough to get to the telescope and dome to see how they had fared in the icy conditions. Sadly while I was there the ice didn’t clear enough to allow any observations to be made.
The Nordic Optical Telescope perched on the edge of the mountain.
Due to the high humidity, low temperatures, and freezing temperatures, ice was forming on virtually any surface, from cars to vegetation to telescope buildings. In some of the most exposed places, such as the Nordic Optical Telescope (NOT), we measured ice up to a meter thick and deep.
The 10.4m GTC above the clouds.
While it wasn’t possible to do what I’d gone out there to do, I was fortunate to be able to explore the site and visit some of the telescopes there. The observatory has some of the best facilities in the world, including the world’s largest telescope, the Gran Telescopio Canarias (GTC).
I was also show around the 1.2m Belgian Mercator telescope by PhD students from KU Leuven, and around the 2.56m NOT by a post graduate researcher from Leiden University.
Fellow Armagh PhD student Erin Higgins and me at the summit.
We were also given a tour of the telescope with the largest single mirror at the observatory, the 4.2m William Herschel Telescope (WHT). While the GTC has a larger overall diameter at 10.4m, so achieve such a large aperture a segmented mirror is used. While the mirror for WHT is a single piece of glass, GTC utilizes 36 hexagonal segments positioned together to act as a single mirror.
While we weren’t able to do what we went out there to do because of the weather, it was an incredible experience where lots was learned.
Hopefully next time I’m off somewhere observing the weather will be more cooperative!
The highlight of my trip, flying my Leicester City Premier League Champions 2015/16.
NASA’s Hubble space telescope was launched on 24th April 1990. It was the first optical space telescope to be launched into orbit and has been one of the most productive scientific instruments ever built. It orbits the Earth every 95 minutes and has almost completed its 28th orbit of the Sun. So far in 2018 it has released a series of beautiful high resolution images and aided a number of scientific investigations which shall be reviewed.
Milky Way Bulge
High resolution image of the Milky Way bulge captured by the Hubble Space Telescope 11/01/2018. Image credit: NASA/STScI
The bulge of the Milky Way is a big, dense region of stars at the centre of our galaxy. Our Solar system is 26,000 light years away from the bulge in the disk of the Milky Way. The bright blue stars in the image are young hot stars in the disk between us and the bulge. The redder stars are the older more evolved giant stars with slow, scattered motions. The smaller white stars are younger and are more rapidly orbiting the galactic centre.
Hubble Parameter Measurements with NGC1015 and NGC3972
One of the HST’s recent scientific projects was to make distance measurements to 19 galaxies to help improve the precision of the measured Hubble parameter. Edwin Hubble, namesake of both the HST and the Hubble parameter, was the first astronomer to observe galaxies other than our own. He used these measurements to provide evidence that the universe is expanding and that everything is moving away from everything else. The Hubble parameter is a measure of this expansion. It is defined as the ratio of the distance to the object and the velocity which object is moving away with. The value of the parameter has varied substantially since Hubble’s first measurement due to improvements in measurement techniques.
The distances to galaxies can be measured by observing Cepheid variables or Type 1a Supernovae. Cepheid variables are a type of star which cyclically and periodically change in brightness. The time period over which the brightness changes over is related to its luminosity. Type 1a supernovae are explosions of white dwarf stars. All 1a supernovae have roughly the same luminosity. If the absolute magnitude of the star is known the distance to it can be calculated. Galaxies with both observable Cepheids and Type 1a Supernovae are best to make precise distance measurements.
Optical image of galaxy NGC 1015 used for making distance measurements to recalculate the Hubble parameter NASA/STScI
NGC 1015 is spiral galaxy located in the whale constellation Cetus.
Optical image of galaxy NGC 3972 used for making distance measurements to recalculate the Hubble parameter NASA/STScI
NGC 3972 is spiral galaxy in Ursa Major which is the constellation most famous for housing the dig dipper.
‘Red and Dead’ NGC1277
Wide view image of the old elliptical galaxy NGC 1277
NGC 1277 is an old elliptical galaxy which has had no star formation whatsoever in the last 10 billion years. Galaxies like this are often named red and dead and provide a good snap shot into the conditions of the early universe. Studies suggest this galaxy initially had intense burst of star formation, much higher than that of our own galaxy. It is mainly populated with metal rich stars. No galaxies or globular clusters are close enough for it to merge with and fuel further star formation.
Ghost Galaxy NGC1052-DF2
View through ‘ghost’ galaxy NGC 1052-DF2
NGC 1052-DF2 is an ultra diffuse ‘ghost’ galaxy. It is almost entirely see through and the galaxies behind it are clearly visible. It is so difficult to see that no one realized it was a galaxy for quite a long time after it had been observed. It is associated with NGC 1052 which is an elliptical galaxy in Cetus. It has star forming regions and young clusters so is still an active galaxy.
It is particularly peculiar in that it only has 1/400th of the regular amount of dark matter and 1//200 the amount of stars typically observed in galaxies. Dark matter is an essential building block of the universe and is an essential component for many galaxy formation theories. The lack of observed dark matter raises many questions, particularly regarding the galaxies formation. Interestingly it also suggests dark matter isn’t just an artifact of behavior of regular matter under gravity and that galaxies can exist without it.
March has certainly been an eventful month, and now we’re in to April. The Spring has definitely sprung and we’re enjoying the stretch in the evenings, even if it makes stargazing a little trickier. Sure we have to go out later and later at night, but as long as we still have a flask of hot chocolate with us we’re fine.
The Romans called this month Aprilis, which may derive from the verb aperire meaning “to open”, referring to flowers and fruits opening. April is the cruellest month or so says TS Elliot in the poem “The Waste Land,” but we beg to differ! We think April is great and we would like to share with you what is great in the April night sky.
On April 16th we will not see the moon in the sky, as it will be a new moon. This would be the best time to get the telescopes out and do a bit of stargazing, as there will be no moonlight in the sky to hinder your view. So what should you look out for?
Leo the Lion
The constellation of Leo the Lion will be prominent in the night sky, and the brightest star in this fierce constellation is called Regulus. Before I go into any detail about the star Regulus I would like to make a connection to pop-culture here. In the night sky we have the star Regulus, and the star Sirius (the Dog Star) will have just about gone below the horizon. If we look to the ever popular fiction books of Harry Potter, we can see where JK Rowling go some of her inspiration from. Sirius Black is Harry Potter’s godfather and in the book he is known for transforming into a giant black dog. Sirius the Dog star is found in the constellation of Canis Major, the Great Dog! In the book Sirius Black has a brother and his brother is called, none other than, Regulus! In the story Regulus does not transform into a lion or anything like that, however he is a bad guy that ends up turning good and sacrificing himself for the greater good. Some would say he had the heart of a lion.
Anyway I have digressed enough, the star Regulus is considered a blue-white “B” star that lies on the main sequence of stellar evolution. Like the sun, Regulus fuses hydrogen to helium in its centre, but it is more massive than the sun and therefore hotter and brighter.
Lurking nearby and unseen by the naked eye are two very faint companions to the much larger bright star. The binary pair (two dwarfs, orange and red) are about 4,200 AU away from Regulus. If you would like to see this particular star, make sure you look south on 16th April, and to make it even better, use your telescope for a better view.
Cancer The Crab
Sticking with our signs of the zodiac, another constellation in the sky during this time is Cancer the Crab. This constellation is the faintest of the zodiac signs and would be great for more advanced stargazers to spot. The brightest star in the constellation is Al Tarf, Beta Cancri. It is approximately 290 light years from earth, and has a visual apparent magnitude of +3.5. Its absolute magnitude is −1.2. Al Tarf is an orange K-type giant, about 61 times the radius of the Sun.
Turning your heads East in the evenings, you can spot the orange star Arcturus. This is the brightest star in the constellation Bootes The Heardsman, and the fourth brighest star in the night sky. Arcturus is an orange giant star, 133 times more luminous than our own Sun, but much farther away, about 37 light years away.
A few interesting events will occur this April – a double conjunction of Mars and Saturn with the Moon, and the Lyrid meteor shower.
In the first days of April, the planets Mars and Saturn will appear very close together in the night sky. Rising together around 3am, they will be separated by only 1 degree on the night of 2nd April. A few days later, on the 7th and 8th April, the waning Moon will join the party, forming a triangle with the two planets, separated around 4 degrees away from one another. Visible close to the Milky way, the trio will be very attractive for observations and astrophotography.
The Lyrid meteor shower is the first strong shower for this spring. The radiant of the Lyrids lies in the constellation Lyra, which means that the meteors will seem to shoot out of the constellation Lyra. The meteor shower will be active in the period 14-30 April, with a maximum on April 22nd 18:00 GMT. The Lyrids this year will have little moonlight interference from the waxing crescent Moon, and in good weather conditions you can see about 18-20 white meteors per hour. Occasionally the Lyrids have stronger maximum with up to 90 meteors per hour.
Another interesting event for this month is the launching of the TESS mission. Tess stands for Transiting Exoplanet Survey Satellite, and it’s a mission designed to look for Earth-sized planets around other stars. TESS will be launched on board a SpaceX Falcon 9 rocket and it is scheduled for 16th April this year.
Article by: Daragh Logue, Peter McCormick, Ciaran McCaffrey
Assisted By: Maria Buckland, Sarah Bell, Adam McAfee
The Observatory and Planetarium has welcomed school students to visit for work experience. A previous Astronotes article described our work with the Faulkes Telescope Project. Below is an account written by three of our work experience students in 2018 March, based on the work done at Armagh Observatory and Planetarium by them and three other students.
We observed asteroid 2017 VR12. This is a 100-160m wide asteroid which rotates once every 1.4 hours. Under certain conditions it is seen (based on its shape) to look like a cat. It is of great interest to astronomers as it crosses earth’s orbit making it a very near earth asteroid – its closest approach was four times the distance to the moon on the 7th of March 2018. It is believed to originate from one of the largest bodies in the asteroid belt, Vesta. Our results, in which we measured the change in position with time, were submitted to the Minor Planet Centre which is administrated by the International Astronomical Union.
Above is an image of the near-Earth asteroid 2017 VR12. The nature of its appearance is due to its speed of movement across the sky. Although the exposure time was only 30 seconds, the very fast moving asteroid travelled around 25 arcseconds across the sky. At the time of observation, the asteroid was around 4 times the distance from the Earth as the moon is. Image obtained using 0.4-m telescope at Haleakala in Hawaii and operated by Las Cumbres Observatory.
We also observed asteroid 1981 Midas. This is a large asteroid, believed to be about 2km across. It was discovered by American astronomer Charles Kowal in 1973, and is classed as a potentially hazardous asteroid. Although it is predicted that Midas can approach 1.5 times the distance to the Moon, it does not pose a threat to earth in the near future.
Using the European Space Agency’s GAIA satellite which alerted us to its presence, we observed Gaia18amc. According to the Gaia alerts page, 18amc is a candidate supernova. It was cross referenced with an older sky survey image and was found to have appeared recently. We estimated its brightness using the magnitude of nearby known stars and using astronomical software to determine its brightness by comparing its brightness with other stars. We estimated Gaia18amc had a magnitude of 18.5.
The image shows the before image on the right without the new source present, and the after image on the left in which a new source has clearly appeared. Left image obtained using 0.4-m telescope at Haleakala, operated by Las Cumbres Observatory. Right from Digitized Sky Survey.
Another transient Gaia object which we observed was Gaia18amd. We received the alert again from the GAIA satellite. Using the same software we pinpointed the location of the object and compared this image to a previous sky survey. It was not present in the older sky survey, proving that this was a transient object. We again calculated its brightness using the same method as we used in Gaia18amc. This information has led us to conclude that this is likely to be a new supernova.
Another object we observed was ASASSN-18dw which was announced as going into a 4 magnitude outburst in a The Astronomer’s Telegram. It also matched the position of an already known reddish source near the star forming region of Orion. We used a table of star locations and magnitudes to figure out the real brightnesses of nearby objects. Using the same software, we repeated the method that we used earlier to find the actual brightness of ASASSN-18dw to be 14.68 magnitude. We then found a previous image and found its magnitude to have been roughly 19. This confirms our findings and the reports as published by The Astronomer’s Telegram.
In the highlighted area ASASSN-18dw is clearly visible and shows up as being quite bright. This is in stark contrast with previous images of the transient which showed it as being very small and faint. Image obtained using 0.4-m telescope at Cerro Tololo, operated by Las Cumbres Observatory.
The final asteroid we observed was 2011 XO3. It is about 1.2km – 2.7km in diameter. This asteroid does not pose a danger to earth, as the closest it has approached in recent years was 40 million kilometres on the 8th of February 2018, passing at a velocity of 68,000km/h.
We would like to thank The Faulkes Telescope Project and the Las Cumbres Observatory for allowing us to use their telescopes to gain these valuable images. Without them, the data collection that we were able to perform would not have been possible.
Article by Aaron Golden, Visiting Astronomer at the Armagh Observatory and Planetarium
Stephen Bourke works at the Department of Space, Earth and Environment, Onsala Space Observatory in Sweden, and Aaron Golden at the School of Maths in NUI Galway, and is a visiting astronomer at the Armagh Observatory and Planetarium. The I-LOFAR observations were taken as part of LOFAR proposal LC9_040 “A search for aurora on nearby flare stars using LOFAR”.
I-LOFAR reached another milestone on the night of the 6th of March, when the entire LOFAR telescope network across the European continent including the Birr outstation was for the first time used by Irish astronomers Stephen Bourke and Aaron Golden to observe the nearby flare star CN Leonis. The team hope to ‘catch’ a stellar flare exploding in the star’s corona, and to use the radio observations taken at Birr and across the LOFAR network to understand how such flares evolve over time and how similar they are to the solar flares we experience here on Earth. CN Leo is a small, red dwarf star about 8 light years away in the constellation Leo, and is likely to possess a planetary system. In fact, we now know that the vast majority of stars in the galaxy that have planetary systems that could harbour habitable planets orbit red dwarf stars like CN Leo, so a really important question to answer is whether or not such planets could survive the really very powerful stellar flares we see from many of these red dwarfs. Studying the way in which such stellar flares occur and how they interact with their local environments using I-LOFAR offers a new window on this important area of astronomy.
I-LOFAR and its High Band Array at Birr Castle in County Offaly.
Variable stars in the night sky have been known since antiquity – some of you may have heard of the naked-eye star Algol, at the end of the slightly skewed ‘T’ that forms the constellation Perseus. It is an eclipsing binary, whereby the passage of the cooler, and dimmer, companion star passes in front of the larger, brighter primary star – in effect, making Algol looking perceptively dimmer, about 1.3 magnitudes every 3 days. Stars that dim through eclipses are extremely useful to us, as observations can be used to study stellar atmospheres, and most famously, if the dimming is caused by a planet crossing the stellar disk, we can measure that too – in fact this is how all of the exoplanets that are regularly announced by NASA using their Kepler/K2 orbiting observatory are made. Thanks to this technique, we now know that there are thousands of exoplanets orbiting nearby stars, which in many respects is almost as revolutionary a concept as Copernicus’ proposal that the planets go around the sun.
I-LOFAR with the Milky Way over head (Credit: I-LOFAR Intern Luis Alberto Canizares)
The most interesting thing about planets is the possibility that life could exist on them, and astronomers have already embarked on studies to try and determine if the ingredients for life as we know it are present on these exoplanets. There are many ways, both direct and indirect, to try and see if an exoplanet might fit the bill.
How close is an orbiting planet to a star? Too close, and the perpetual roasting heat will bake away any atmosphere, such as what we see with Mercury. Too far away, and the planet will exist in an endlessly freezing state, the star being too far away to allow a rocky world like ours to sustain a gaseous atmosphere, critically in the temperature regime that allows water to stably exist in liquid form. The distance bounded by this inner & outer limit is known as the habitable zone, and where it can be determined is almost entirely based on how hot the central star is, which can be determined from the colours of the star itself. But this is only half of the story – for our solar system, the planets Venus, Earth and Mars lie in the Sun’s habitable zone, yet we all know only one is actually habitable.
Direct observations can resolve whether an exoplanet is ‘habitable’ by studying the minuscule difference in the observed spectrum of a star as a planet passes in front of it. These changes come from light scattering through the planet’s thin atmosphere and using the largest of ground based telescopes, along with the Hubble Space Telescope, signatures of water have been found on other worlds. How can you determine directly what a ‘living planet’ looks like compared to an inert one? Remarkably enough, this is where the Moon is very useful. You might have noticed when the sky is sufficiently dark that you can still sort of see the other part of a bright crescent moon – the part of the moon supposed to be in shadow from the sun. Through binoculars or a telescope, this ‘ashen light’ is gloriously apparent. This the light of our planet reflecting off the dark side of the moon. Beautiful that it is, it’s also a signature of what reflected light is like from a ‘living’ planet, and astronomers can take a spectrum of the Sun’s normal light, and a spectrum of this ‘earthshine’, subtract one from the other, and hey-presto, have a spectrum of what Earth actually looks like. Its then easy to detect the interesting signatures associated with water, with various oxygen species, and the broad humps and bumps corresponding to the oceans or the forested landmasses. One day in the very near future, astronomers will be able to make these same types of observations for the nearest exoplanets.
The constellation of Leo the Lion, seen behind Armagh’s Robinson Memorial Loan.
So what has all this got to do with CN Leo, and the observations recently performed by I-LOFAR?
CN Leo is a cool M dwarf – its a lot cooler than our Sun, so its habitable zone is closer in. The galaxy has a lot more of these types of stars, than stars like our Sun, and perhaps more pertinently, the vast majority of exoplanets discovered to date orbit stars like CN Leo. The other thing about stars like CN Leo is that they are pretty old, so given what we know about our own ‘family history’ i.e. the billion or so years it took life to evolve, this would tend to ‘shorten the odds’ of habitability. That’s the good news.
An artist’s illustration of a flare from a red dwarf next to one of its nearby planets. Credit: Roberto Molar Candanosa/Carnegie Institution for Science, NASA/SDO, NASA/JPL.
The bad news is that stars like CN Leo undergo, for reasons we still don’t fully understand, frequent and at times very violent flare events – like the giant solar flares we occasionally hear about originating from our own Sun. When a stellar flare occurs, enormous amounts of energy are released as electromagnetic radiation and high energy particles, and this event can have devastating implications for anything nearby, such as a planet, as the impact of this energy can in effect strip away and evaporate any atmosphere, and bathe its surface in lethal ionizing radiation. On Earth we are incredibly fortunate that our planet possesses a magnetic field. Like iron filings sprinkled on top of a bar magnet, the torus like magnetic field lines create a cocoon, known as the magnetosphere, that shields us from the searing solar wind 24/7, and which buckles yet remains resilient when a solar flare’s particle bomb – a coronal mass ejection – hits, providing us with the beautiful light show that are the aurorae.
For M dwarfs though, the flares are much more common, and much more violent – the repeat offenders make up a well studied group known as ‘flare stars’, and CN Leo is one of these. Just like our sun, the best way to try and understand the origin and evolution of a flare is to observe it happening, using many different types of observations – in X-rays, in the optical, using radio waves – as these all probe different physical components of the process, and so allow us to fit together the jigsaw of the underlying physics involved. Its only very recently that we have been able to study the Universe in the radio waves more normally associated with transistor radios, and using the LOFAR telescope we will be able for the first time have a critically important missing piece in that jigsaw puzzle. This is why our recent observations of CN Leo with LOFAR also involved Jodrell Bank’s e-MERLIN radiotelescope array, John Moore’s University’s robotic Liverpool Telescope at the Roque de los Muchachos Observatory in the Canary Islands, and NASA’s Neil Gehrels Swift Observatory.
Map showing the stations of LOFAR across Europe. With the addition of the Irish station at Birr the east-west baseline is increased, so improving the angular resolution of the images.
And there is the potential of a ‘bonus’. The beautiful colors we see in optical light from the aurorae also have a distinct signature in radio light, and frequency on the dial we need to set our receivers to so we can listen to the Earth’s aurorae are set by the Earth’s magnetic field. Fortuitously, radiotelescopes like LOFAR can be tuned to that set of ‘planetary’ frequencies, and so detect the distant dance of an aurora from an as yet undetected exoplanet orbiting CN Leo, an exoplanet that had a sufficiently strong magnetic field to protect it from CN Leo’s stellar flares. And if so for the CN Leo system, why not for many of the other exoplanetary systems orbiting other M dwarfs in our little corner of the galaxy?
No one undertakes research in physics with the intention of winning a prize. It is the joy of discovering something no one knew before. – Professor Stephen Hawking
Today, 14th March 2018, marks a very sad day in the world of physics and the world in general. One of the greatest mind’s of our time, Professor Stephen Hawking, has passed away.
The world of science and physics has lost one of its greatest champions. Professor Hawking inspired generations of people to start thinking beyond the planet they live on, to gaze further than we ever have, and ask those questions that need answers.
When people think of famous scientists, Professor Hawking is always one of the first people to be mentioned, alongside brilliant minds such as Albert Einstein and Sir Isaac Newton.
I was never top of the class at school, but my classmates must have seen potential in me, because my nickname was ‘Einstein.’ – Professor Stephen Hawking
His story is one of triumph. After being diagnosed with Motor Neurone Disease at the age of 21, doctors did not expect him to live longer than two years. The diagnosis seemed to give him an even stronger zest for life and the disease seemed to progress a little more slowly in Professor Hawking, and he lived to the age of 76.
He was known not only for his brilliance in science, but also for his wicked sense of humour. This is something his family and loved ones have stated that they will miss the most. It’s not everyday one can state that they have featured in The Simpsons and The Big Bang Theory, as well as having a film made about the early years of your life.
My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all. – Professor Stephen Hawking
He penned many books, some of the most famous being “A Brief History of Time,” “The Universe in a Nutshell,” and “A Briefer History of Time.” Along with his papers and research, these books articulated the physicist’s personal search for science’s Holy Grail: a single unifying theory that can combine cosmology (the study of the big) with quantum mechanics (the study of the small) to explain how the universe began.
When asking our staff members about their own personal memories of Professor Hawking, our colleague Nick Parke mentioned a brilliant documentary called Master of the Universe. He remembers watching this documentary and feeling awed by Professor Hawking’s story.
Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist. Be curious. – Professor Stephen Hawking
Michael Burton, now Director of the Observatory and Planetarium, while a student learning his mathematics at Cambridge, remembers Hawking’s presence about the Department of Applied Mathematics and Theoretical Physics (or DAMPT as it is fondly remembered!). Hawking was only famous then to a relatively small number of scientists, not the global figure he later became. There was a sense of awe when you saw him navigating his wheel chair about the narrow corridors of the Department. I particularly remember a seminar Hawking gave when I was in the final year of my studies, and thought I perhaps comprehended a little of what Physics was really about. The title of the seminar was “the wave function of the Universe” – only Hawking could be so bold as to try and solve Schrödinger’s equations for the entire universe, and not just a single atom as our U/G classes would have us tackle! The seminar room was, of course, absolutely packed, the only time I ever saw it so. And I understood barely a word of it! Not that Hawking was difficult to understand, but the concepts were just so far beyond me.
Not long before I left Australia to come to Armagh, Hawking gave the most amazing performance in the Sydney Opera House, again to a packed audience. He wasn’t there in person – it was too difficult for him to travel across the world by then – so he appeared in hologram! His daughter compered the performance from the Opera House, and Hawking replied to questions by tapping out the answers using his computer. We’d just seen extracts from the movie of his life. It was an amazing and touching occasion, a very special one for all who were there.
To scientists Hawking is perhaps best remembered for the concept of “Hawking radiation”, or what makes Black Holes not so black! Hawking made headway in tackling what is perhaps the greatest challenge of physics today, tying the large scale, as expressed through General Relativity, to the very small scale, as expressed through the language of Quantum Mechanics. Hawking’s great idea was to use the concept of pair production through virtual particles, with one entering into the black hole and the other escaping from it, to produce a flood of photons seemingly emitted from the event horizon, and giving rise to the concept of temperature for describing a Black Hole.
As an astrophysicist with a keen interest in space from a young age, the opportunity to witness a rare astronomical phenomenon is naturally quite high on the ‘bucket list’. So when I was attending a research workshop in the United States in August 2017, just a few days before a solar eclipse passed through, I wasn’t going to let this opportunity pass me by! By the end of this article, I hope I’ll have convinced some of you that it’s worth trying to see a total eclipse at least once in your life if you haven’t already!
Eclipses have been observed for thousands of years and played a big role in influencing mythology around the world, such as the Chinese stories of the dragon that ate the Sun. A solar eclipse is an extraordinary event where the Moon passes directly between the Sun and the Earth, casting a shadow on the surface of the Earth. The Moon passes between the Earth and the Sun once a month, and this is why we get New Moons, as the Moon is in the same part of sky as the Sun, and we see no light being reflected off its surface. This might lead you to think that a New Moon will always result in a solar eclipse, however this is not the case.
The Moon orbits the Earth at an angle relative to the Earth’s orbit around the Sun. This means that in most months, the Moon is either higher or lower in the sky than the Sun when it reaches its New Moon phase. However, if the Moon is passing through the plane of the Solar System at the time of a New Moon, then the Sun, Moon and Earth lie in a straight line and a solar eclipse occurs.
Fig 1: Diagram illustrating the different shadows (umbra and penumbra) that the Moon casts on the Earth during an eclipse. The very small region within the umbra is where a total eclipse can be seen. (Credit: NASA)
The Moon happens to be about 400 times smaller than the Sun, but also 400 times closer, meaning that it’s just big enough to totally block out the Sun. This means that a total eclipse is generally only visible over a narrow area, while a much larger area of the Earth witnesses a partial eclipse. In the case of the 2017 eclipse, the path of totality (the region where the Sun gets fully obscured) passed across the US, while most of North America was treated to a partial eclipse. In fact, a barely noticeable 3% partial eclipse was visible from Armagh just before sunset on the day.
Fig 2: Path of the 2017 eclipse. The total eclipse started in Oregon in the northwest and moved across parts of 14 different states, ending in South Carolina about 90 minutes later. The partial eclipse was seen all across North America. (Credit: AAS)
Organising an eclipse viewing trip proved a tricky task. A former research student at the Observatory also expressed interest in viewing the eclipse so we put our brains together to come up with a plan. A lot of factors needed to be considered, first and foremost the places most likely to have good weather on the day. The last thing we wanted was clouds obscuring the view! Oregon and Idaho, west of the Rocky Mountains, had some of the driest weather for August, so this became our target area. However, this added its own complications. This part of the US is quite sparsely populated and accommodation options were few and expensive. Some hotels on or near the path of totality had apparently been booked out 12 months in advance! Eventually we found a reasonably priced hotel about a 90 minute drive from the eclipse path. This left us with a 4 and a half hour journey from the nearest major airport in Salt Lake City. And so our great American road trip began. I could write an entirely separate blog article on the trip, but I should probably stick to the astronomy!
We eagerly watched the weather forecast the night before the eclipse. Everything was looking good. We surveyed our maps and decided to aim for the city of Rexburg, Idaho. This city of 25,000 people would, for about 2 and half minutes, be the site of the most remarkable sight on Earth. We arrived in plenty of time to pick a good vantage point and were welcomed by clear blue skies. Now, all we had to do was wait for the Moon to get into position. The local radio station was, of course, playing ‘Total Eclipse of the Heart’ by Bonnie Tyler for the occasion!
Fig 3: Various stages of the solar eclipse as the Moon obscures progressively more of the Sun. (Credit: Conor Byrne)
There are a lot of environmental changes can be observed during a solar eclipse. The most apparent one is that it starts to get darker. This confuses both animals and machines. The birds stopped singing, thinking that night was falling, while the street lighting thought likewise!
Fig 4: Compare these two images from the same location. The one on the left was taken at 10:30 am around the start of the eclipse, the other taken moments before totality. The amount of light being obscured by the Moon gives a distinct twilight feel even though it is the middle of the day. (Credit: Conor Byrne)
But another thing you notice as the eclipse progresses is that the temperature begins to drop. Without the energy from our nearest star shining down on us, the air begins to cool. The crowds fell silent as the anticipation built up. What followed was a moment of pure magic.
Fig 5: The moment everyone had been waiting for, the total solar eclipse! If there was a point in my life where I wished I had invested more in camera equipment, this was it! Looks incredible nonetheless. (Credit: Conor Byrne)
We stood in awe as the Sun was fully obscured, revealing the glow of the solar corona (the hot, faint material that stretches millions of kilometres from the Sun’s surface). I found the experience quite emotional. Months of planning, thousands of miles travelled and perfect weather conditions had all come together for these 2 minutes and 20 seconds. I was lucky enough to see some of the 2015 partial solar eclipse through the clouds in Dublin, but it was totally eclipsed by what I saw on the 21 August 2017.
Here are some top tips and information on observing a total solar eclipse:
Don’t look at the Sun! This one goes without saying really, only look at the Sun if you’re using special eclipse glasses that have strong filters to block out almost all the light from the Sun. Once the Sun is totally eclipsed, it is safe to take off your glasses, but be ready to put your glasses on before the Sun starts to reappear. Alternatively, you can make a pinhole camera and use this to look at a projection of the Sun’s image onto a piece of paper.
Plan well in advance: Hotels in/near the path of totality will be booked out well in advance, so one idea would be to look for a major city on the path as they will have more accommodation options.
Have a ‘Plan B’: Depending on the location, it may be important to consider the weather. It helps to have flexible plans/a backup observing site in case it is cloudy.
OK, I’m interested, when/where can I see one?
The next total solar eclipse is on 2nd July 2019 and will be visible from parts of Chile and Argentina.
The next total solar eclipse visible from Europe is on 12 August 2026 and will be seen in northern Spain. A 94% partial eclipse will be visible in Armagh.
If you want to wait to see one in the UK or Ireland, you’ll have to wait until 23 September 2090 (totality in West Cork and Cornwall).
On 14 April 2200, Armagh will be the centre of attention as the path of totality will pass right over us!
Article written by: Professor Michael Burton, Director of Armagh Observatory and Planetarium
Armagh Planetarium 1968 Opening Year
The city of Armagh lays claim to a remarkable history that belies its small size. A history stretching from the neolithic era, and the mythology of Emain Macha (the ancient capital of Ulster), through the City’s Christian foundation with Patrick and the two cathedrals named after the famous Saint. Then there is the Observatory founded in the Georgian era, and its offshoot the Planetarium, symbol of the space age. It is of a story underpinned by a theme of wonder about our place in the cosmos.
The Observatory and the Planetarium are the oldest institutions of their kind in the UK and Ireland, still operating under the ethos of their founding legislation, of 1791, for “settling and preserving a public Observatory and Museum in the City of Armagh, forever”. This year, 2018, we celebrate the Planetarium’s 50th anniversary, having been formally opened on May the 1st, 1968 by the Prime Minister, Terence O’Neil. Here we tell a little of the story of the founding of the Planetarium.
Built in troubled times in Northern Ireland, the Planetarium was the vision of the Observatory’s 7th Director, Eric Lindsay. He recognised the need for a facility able to meet the public’s fascination about the planets and the stars, and desire to know more about our understanding of the cosmos, in ways that a research institution like the Observatory simply was unable to provide.
Dr Eric Lindsay Founder of the Planetarium
Yet from first vision to opening took a quarter of a century, and is a story of determination in the face of adversity, of continually telling exciting stories of astronomy and eliciting interest in the concept of a Planetarium, and slowly, ever-slowly, raising funds to build it.
Lindsay’s first efforts to build the Planetarium started in 1943, following on from plaques being erected commemorating the stay of US troops in Northern Ireland due the War. He too sought the support of Americans in NI. Much enthusiasm was evidenced, and subscriptions in the City elicited £3,000 in donations, but ultimately stronger claims from Belfast resulted in the project stalling.
The next effort came in 1950, when Lindsay sought to build on the success of getting the two Governments in Ireland to come together to fund the Armagh-Dunsink-Harvard (ADH) telescope in South Africa (an amazing story that needs to be told separately) to then build a planetarium. He established an all-Ireland Board for the project, jointly chaired by the two Archbishops of Armagh, the heads of the leading universities across the island, and even Eamon de Valera as the Chancellor of the National University! Given the subsequent history in these lands, this was quite an achievement of itself. Lindsay was granted funds to embark on a fund raising tour of the US, again seeking the Irish-American connection for their help.
Lindsay details the travails of his efforts in New York and Boston over the next year, living effectively as a pauper with barely sufficient to feed himself, let alone clothe against the harsh winters! But despite being well received, the funding brought in amounted to just $1,500. It seemed that Lindsay’s dream would remain no more than that.
Efforts continued on and off over the next decade, while Lindsay applied most of his energy to furthering the ADH telescope project in South Africa. Through the Armagh Chamber of Commerce some further funds were raised, but the total fell far short of the then £30,000 that had been estimated to cost. This even included representations to the Goto Optical Works company in Tokyo to provide one of their projectors for free. But by 1964 success seemed as far away as it was 20 years earlier. Though when it did it was with a Goto projector.
Ulster Gazette Official Planetarium Opening
But then success came quickly. Growth in cultural activities in Northern Ireland had been significant, such as the Ulster Folk Museum and the Ulster Museum, all made possible through Government moral and financial support. Lindsay approached Government once more and made progress by seeking support for a Tourist Development Project. The two councils of Armagh (as there were at the same; city + county) came on board. Agreement was reached to split the project 60-40 between Government and Councils, with the Councils splitting their share 60-40 between City and County.
Armagh Planetarium 1966 Construction Begins
An announcement was made at a press conference was held on March 4th 1965 and the project was off! Three years later came the formal opening, and a new era in science communication and public outreach was born. Now, 50 years on, we are gathering again to celebrate Lindsay’s great achievement and the successes that followed. And also to discuss where our future lies so that there can be an even bigger celebration for the centenary, another 50 years hence!
Two weeks ago, a space-suited mannequin was strapped inside a cherry red car, the car was strapped inside a rocket, and the whole lot was launched into space. Although the shiny convertible might be the first of its kind in space, the mannequin, dubbed ‘Spaceman’, is most definitely not. That title belongs to a Russian-made dummy who left Earth’s atmosphere weeks before the first human.
Spaceman in space (SpaceX)
The dummy cosmonaut, nicknamed Ivan Ivanovich, was manufactured by the Moscow Prosthetic Appliances Works. To test the spacesuit and ejection processes that would be used in the first human spaceflight, he was rigged up with various sensors, as well as being filled with live mice and literal guinea pigs.
Ivan Ivanovich on display at the Smithsonian National Air and Space Museum (SI 97-16252-3 / Owner: Smithsonian Institution / Source: National Air and Space Museum, Smithsonian Institution / Photographer: Eric Long)
His first flight was on 9 March 1961. Before takeoff, he was dressed in a bright orange spacesuit and white helmet and secured in the ejector seat of the Korabl-Sputnik 4 spacecraft. After a successful launch and a single orbit around the Earth, the spacecraft’s re-entry module re-entered the atmosphere. Soon after, Ivan was ejected and a parachute deployed to soften his landing –- in this case, back in Russia, in a region covered in snow. The freezing conditions delayed his recovery. Fortunately, his helmet contained a sign with the word ‘Maket’ (Russian for ‘dummy’) so that anyone who discovered him in the meantime did not mistake him for a corpse.
After completing another successful launch, orbit, landing and recovery on 25 March 1961, Ivan was seemingly retired in favour of human cosmonauts. He was auctioned for $187,500 in 1993 and since 1997 has been on show at the Smithsonian Space and Air Museum in Washington, DC.
The flights undertaken by Ivan were essential to testing key systems and gave the USSR the confidence to launch the first human spaceflight. The significance of the SpaceX mannequin Spaceman is yet to be seen.
Comets have been known for millennia with Halley’s Comet famously being shown in the Bayeux Tapestry illustrating events which took place in 1066. They were also thought to foretell catastrophic events. Today we know them as having a small nucleus made up of ice and dust and when they near the Sun some of this material is vaporised forming a ‘Coma’ around the nucleus and a tail facing away from the Sun. More than 4000 comets have been discovered. Some, such as Comet West, which was seen in 1976, are unlikely to be seen again. In contrast, Comet Halley famously returns approximately every 76 years with its next visit expected in 2061.
The European Space Agency (ESA) sent the Giotto spacecraft to Comet Halley approaching within 600 km before encountering Comet Grigg-Skjellerup six years later. In 2003 the Japanese Space Agency launched the satellite Hayabusa to closely study the near-Earth asteroid Itokawa. These missions helped determine the physical characteristics of these small solar system bodies. However, the most famous recent mission was ESA’s Rosetta mission to Comet Churyumov– Gerasimenko in which they deployed the probe Philae on to the surface of the Comet. Because of the orientation of the probe its solar cells couldn’t see the Sun and its battery eventually failed. A mission highlight was showing that much of the water on the Earth was unlikely to have originated from Comets.
Image of GOTO in La Palma. Credit: Gavin Ramsay
Despite these missions which were able to examine Comets up and close, there are still great opportunities for astronomers to study Comets with binoculars and small telescopes. Using the GOTO group of telescopes on the island of La Palma in the Canaries, four work experience students have been studying images of three comets made on three consecutive nights at Armagh Observatory and Planetarium. Comet 2017o1 was discovered using the ‘ASASSN’ survey based in Hawaii and Chile in 2017, while Comet Schaumasse was discovered in 1911 and orbits the Sun every 8.2 years and Comet Tsuchinshan was discovered in 1965 and takes 6.6 years to orbit the Sun.
The students, Glen Chambers (Enniskillen Royal Grammar School), Caoimhe Hillen (St Paul’s High School, Bessbrook), Jake Walsh (Banbridge Academy) and Shane Ferris (Wellington College, Belfast) were able to measure the position of the Comets on the three nights and measure their brightness by comparing with the brightness of nearby stars which had known magnitudes. They were also able to make false colour images of the Comets since we had images taken in blue, green and red light. However, since the Comet moves across the sky at a slow but detectable rate, the Comet is not at the same position in the sky in each of the three frames, so a ‘rainbow’ type effect is seen. The position and brightness of the Comets have been reported to the Minor Planet Center in the USA.
Three images of comets 2017o1, Comet 24/P Schaumasse and Comet 62/P Tsuchinshan made using Blue, Green and Red images taken using the GOTO UT2 0.4 m telescope on La Palma. The ‘rainbow’ effect on two images is due to the Comet moving relative to the stars over the time it took to make the each image.
The Gravitational-wave Optical Transient Observer (GOTO) project is supported by the Monash-Warwick Alliance; Warwick University, Monash University and Sheffield University, Leicester University and Armagh Observatory and Planetarium. See GOTO Observatory for more details.
Read Full Article
Read for later
Articles marked as Favorite are saved for later viewing.
Scroll to Top
Separate tags by commas
To access this feature, please upgrade your account.