Article written by: Heather Alexander, Education Officer
Space is always changing. New objects are discovered frequently, and the latest discovery was made inside our own Solar System. Jupiter, the largest planet in the Solar System, now has a staggering 79 moons in its orbit. Compare this to Earth’s lonely, singular moon and this shows you just how monstrous the gas giant planet is in size.
The cloud-covered face of Jupiter (Image credit: NASA)
The discovery was made last year by a team of astronomers (The Carnegie Team) who were on the look out for planets lying beyond Pluto. While observing a particular area of the sky, Jupiter just so happened to be in the same sightline and so they turned their attention to the gas giant, as well as continuing their search for other planets on the fringe of our solar system. It took a whole year to confirm the objects they discovered are actually orbiting around Jupiter, but now that confirmation has come about, the total number of moons has risen to an impressive 79!
Initially the astronomers thought that some of these moons could be a cluster of asteroids passing by the gas planet, however they were upgraded to moons. They orbit Jupiter in the opposite direction, or retrograde, to its spin rotation and are nine in total. It is speculated that these small moons are the remnants of three massive moons which were broken apart by collisions with other bodies in space.
Two of the new moons are much closer to Jupiter and orbit in the same direction as the planet’s rotation, or prograde. They are also believed to be part of a larger moon, which had broken apart.
Image depiciting the prograde orbits of the strange moon “Valetudo”, which is found amongst the retrograde moons. (Image Credit: Carnegie Institute of Science/Roberto Molar Candanosa)
The final moon is the one that has astronomers really excited. This strange, oddball moon, which has so far been named Valetudo, is found orbiting with the retrograde moons, but it itself is orbiting in a prograde orbit. Highly unusual, and very exciting. The best way to think about it is to imagine driving a car the wrong way up a motorway. There are lots of objects in its way and eventually it is likely it will have a head on collision with one of them. The name Valetudo comes from the great-granddaughter of the Roman God Jupiter. She was the goddess of Health and Hygiene.
We still don’t know an awful lot about these new moons, like what they look like or what they’re made of. NASA’s Juno spacecraft, which is currently orbiting Jupiter, is not in a position to image them. It will take a future mission to Jupiter to get a clearer view of them. The only things we know right now are their approximate sizes and the shape of their orbits.
Article written by: Heather Alexander
This article has been inspired by the many questions we get asked here at the Armagh Observatory and Planetarium. We love being asked questions but we thought it would be funny to have a look at the questions you really should never ask an Astronomer. We hope this gives you a bit of a laugh!
Can you name every star in the sky?
This is a silly question to ask anyone, not just an astronomer. Yes, we know a lot of star names, but to know all of them is impossible. You have to realise that some stars have names such as VY Canis Majoris, which is easy to remember, but others have names that are just a series of letters and numbers, which is not so easy to remember.
M13. Observed through binoculars this ‘fuzzy ball’ contains approximately 100 000 stars held together by their own gravity. Where open clusters contain mostly young stars and are more difficult to spot due to their loose structure, denser globular clusters like this one are composed primarily of different kinds of giant stars that are ‘in their old age’ and that have already completed their main sequence. Credit: Copyright: Martin Pugh/NASA
Can I have a look through your telescope?
Common question and the answer is no. A lot of the time people think astronomers are sitting on chairs actually looking through telescopes, however that is not how it is done now. We have to gain access to the telescopes we require and then you remotely observe. You then get the results on your computer screen and you then have to decipher the data. It’s not as simple as looking through a telescope and seeing a star. Also do you know how long we’ve waited to get access to remotely observe? We’re going to be selfish and keep that to yourselves!
The 22m diameter Mopra radio telescope, sited at the foot of Siding Spring Observatory in New South Wales, Australia. The author is pointing to the telescope, and provides a sense of scale for the size of the dish. (Image credit: Michael Burton)
Is the Earth flat?
You can ask this question but we’ll just walk away. Okay, we won’t just walk away, we will tell you why the Earth is definitely not flat, and then walk away.
Big Blue: Earth photographed by the crew of Apollo 15 (Image credit: NASA)
What have you discovered lately?
Our question to you is “well…what have you discovered recently?” We don’t discover new things every day. Sometimes our research can take years upon years to complete, if we even can complete it. If we discover something along the way, that is absolutely fantastic, name it after us and we will keep working on what we’ve been doing.
Do you know (insert famous astronomer name here)?
The field of astronomy and astrophysics is a much bigger field than you think. We may have heard of the person you’re referring to, and appreciate the work they do, but there is a chance we may never have met them.
Brian Cox and Dara O Briain hosting the Sky at Night Show
Have you ever been to space?
We’re astronomers, not astronauts so sadly we have not been to space. It would be really cool though!
Magnificent Seven: The lucky first astronauts recruited by NASA. Image credit: NASA)
Do you only work at night?
You may be surprised to learn this but astronomers don’t only work at night! Some of us do, but most of the time we try and work a regular day, like everyone else.
Did people really walk on the moon?
You will get the same reaction to this question as you would to question 3. We will explain to you that people definitely did walk on the moon, and then walk away.
This interior view of the Apollo 11 Lunar Module shows Astronaut Edwin E. Aldrin, Jr., lunar module pilot, during the lunar landing mission. This picture was taken by Astronaut Neil A. Armstrong, commander, prior to the moon landing.
Can you name all the moons of Jupiter?
This is a bit like question 1. Jupiter has 69 moons. Knowing every single one is a bit tricky. Some of us might know them all, and it’s a great party trick, but we need to be focusing more on our research and our particular area of interest.
What was that thing is saw in the sky last night?
Please do ask us this! One thing we will advise though is either try and take a photograph, or make sure you know exactly which direction you’re looking. The more information you can give us, the more likely we are to be able to answer this question. If it had red blinking lights, it was an aeroplane.
Well what did you think? Was this article able to give you a bit of a chuckle? Is there anything you would really LOVE to ask us? Leave a comment below and we will try and answer as many questions as possible.
This July will be a very astronomically eventful month – full of eclipses, bright planets, meteor showers and bright satellite passes. If the weather permits, we will have the opportunity to witness a lot of interesting events in the night sky.
The Solar System
All five bright planets will be visible in the evenings/mornings of July. On 12th July Mercury will be at its Greatest Eastern Elongation.
Mercury is the closest planet to the Sun. This is why for observers here on Earth, Mercury never strays far from the Sun. This makes the planet very hard to spot low in the evening sky or in the minutes before sunrise. For the month of July 2018 it will be visible close to the North-West horizon in the minutes after sunset. This month Mercury will reach its Greatest Eastern Elongation of 26.4 degrees from the Sun. This means that Mercury will be at its furthest point from the Sun as seen on our evening sky. The small planet will be visible in the low North-West horizon and will set at 22:50pm or about 1 hour after sunset. If you want to observe it, find a place with clear North-West horizon and look for the bright dot in the minutes after sunset. If you want to observe Mercury with binoculars, do not use them before the Sun has completely set! Looking at the Sun with binoculars or a telescope can seriously damage your sight!
15th July – Conjunction of Venus and the crescent Moon
Venus can be seen in the western sky, just after sunset. It is hard to miss it, as it is the brightest object on the sky after the Sun and the Moon. Venus will be setting about one and a half hours after sunset. On the evening of the 15th July/early hours of the 16th, Venus will be in conjunction with the very thin crescent Moon, separated by less than 1 lunar diameter (at 04:30am on 16th July). This will not be visible for the observers in Northern Ireland, for them the Moon and Venus will set with about 4 degrees separation, with Mercury just a few degrees to the West.
The Moon, Venus and Mars. Credit: Yanina Metodiva
27th July – Mars at Opposition.
The red planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Mars. A medium-sized telescope will allow you to see some of the details on the planet’s orange surface. Currently there is a big dust storm on Mars, obscuring most of the surface features and making the planet look extra red.
For the days around the 27th July, Mars will be rising shortly after sunset, or around 10:15pm. It will reach maximum altitude of about 10 degrees above the horizon (at around 2am), so if you want to observe it, you will need to find a place with clear East and South horizon. On the night of the closest approach, the full Moon will be about 7 degrees away from Mars, making it slightly harder to observe. However, on the 30-31 July and the first days of August, the waning moon will be rising later in the night and will allow a few hours of moonless observations.
20th July – Conjunction of Jupiter and the Moon.
In July Jupiter can be seen from sunset (when it will be in the South-Western sky) to 1:30am. When observed with binoculars or a small telescope, you can see the four Galilean moons and details on Jupiter’s surface such as the red spot and the darker bands on the planet. On the night of 20th /21st July, Jupiter will be in conjunction with the Moon.
25th July – Conjunction of Saturn and the Moon.
For the month of July Saturn will be rising with the sunset, so it will be visible the whole night. The ring planet will be in the constellation of Sagittarius, appearing in front of the band of the Milky way, making it very attractive for astrophotography. In the morning hours of the 25th July, Saturn will be in conjunction with the Moon.
27th July – total Lunar eclipse
The month of eclipses
Solar and Lunar eclipses occur when the Moon is between us and the Sun, casting a shadow on the Earth, or when the Moon passes through the shadow the Earth casts in space.
In the next few weeks there will be three eclipses visible from our planet – a partial Solar eclipse on the 13th July, a total Lunar eclipse on the 27th July, and another partial Solar eclipse on the 11th August. Normally eclipses come in pairs, a solar and a lunar one 14 days apart, but on rare occasions like this, there are three in the same Lunar month, or from New Moon to New Moon.
For all observers in Northern Ireland, only the lunar eclipse on the 27th July will be visible. This will be the longest eclipse for the 21st century with a totallity phase duration of 113 minutes. Beginning to end the eclipse will last for 6 hours and 14 minutes.
For Armagh the eclipsed Moon will be rising at 21:28 BST, just a few minutes before sunset. The full eclipse will end at 22:13 BST with the Moon just 4 degrees above the horizon. The Moon will come out of the thick shadow (umbra) of the Earth at 23:19 BST, and from the thin shadow (penumbra) at 00:28 BST. If the weather permits, the best place to observe this eclipse will be somewhere with a clear North-East.
Keep an eye out on our website for any events we might be hosting around this time and for more information on visibility and how the eclipse will look for observers in Armagh, visit: timeanddate.com
27th July – not just a Lunar eclipse
But the night of the 27th July will be extra special. Not only will we see a total eclipse of the Moon, which will be the longest eclipse for the 21st century, but it is also the exact date Mars will be closest to us for the last 15 years, and Mars and the eclipsed Moon will be in conjunction, making the view even more spectacular.
28th /29th July – Delta Aquarids Meteor Shower.
The Delta Aquarids meteor shower can produce up to 20-25 meteors per hour at its peak. The meteors will appear to be coming out of the constellation Aquarius The Water Carrier. They are caused by dust and small particles left behind by the comets Marsden and Kracht. Whenever one of these small particles falls towards the Earth, it burns in the upper layers of our atmosphere and the light coming from it is called a meteor. The Delta Aquarids can be seen from 12th July to the 23rd August. This year’s peak falls on the night of 28th/29th July just after midnight. Around this time the waxing gibbous Moon (1 day after Full Moon) will be rising and outshining the fainter meteors, making this shower hard to observe.
The International Space Station (ISS) returns!
After more than a month of no visible passes, the The International Space Station (ISS) returns. For the period from 07 July 2018 to 06 August 2018, the ISS will be visible from Northern Ireland in the evening and early mornings, making a few bright passes above us each night. The ISS always moves from West to East, opposite all planets, stars, the Moon and the Sun (which is also a star!), and it outshines all stars on the sky. It is the biggest man-made satellite, measuring more than 100 by 70 meters. It orbits the Earth once every 92.5 minutes, making it possible for the astronauts on board to see 15 sunrises and sunsets a day!
For more information on when the ISS will be visible from your location, visit heavens-above.com and simply put in your coordinates. (The coordinates for the Armagh Planetarium are: Latitude: 54.3521, Longitude: -6.6485)
The International Space Station as seen in transit across the moon. Credit: Yanina Metodiva
Occasionally the path of the ISS in the sky crosses the disks of Sun or the Moon, and this is called an ISS transit. It is rare to see one of these events, but well worth it. As seen from the Armagh Observatory and Planetarium, the next ISS transit in front of the Moon will be on Saturday 21st July at 00:19:54 BST. These transits last only a second or two, and if you wish to photograph them you have to be prepared well in advance and use fast shutter speeds. You can miss an ISS transit in the blink of an eye.
More information on when the ISS will cross the Sun or the Moon from your location you can find here: transit-finder.com.
The Iridium satellites are a group 95 of communication satellites orbiting the Earth since 1997. Thanks to these, we can make phone calls to every place on Earth. For the last 21 years people have been seeing the bright flashes (called flares) caused by the reflection of sunlight from the satellites’ panels. The effect is exactly the same as catching sunlight with a small mirror. The Iridium flares occur in the hours after sunset and before sunrise, and can often outshine all stars and planets on the night sky. In the summer months the nights are very short and the Iridium flares can be seen from dusk to dawn. They make wonderful addition to any photos of the night sky.
Iridium flare as seen over the Armagh Observatory and Planetarium. Credit: Yanina Metodiva
Information on bright flares in your area you can visit heavens-above.com and don’t forget to put in your coordinates.
Where do meteorites come from? This question has been occupying the scientific community ever since it was realised that these “rocks from the sky” are, in fact, pieces of other worlds arriving on our planet from deep space. New research done by scientists at the Armagh Observatory and Planetarium in the UK, the University of Florida at Gainsville, the Florida Space Institute and the University of Pennsylvania in the US and published this week in Nature Astronomy now suggests that meteorites, as well as the larger objects that pose an ever-present hazard to civilization if they hit our planet, come from a few large, ancient asteroids between Mars and Jupiter that were destroyed by collisions.
Snapshot of known solar system objects within the orbit of Jupiter. The white dots correspond to asteroids in the Main Belt. Source: Wikipedia Commons
Some tens of thousands of meteorites now lie in laboratories and private or museum collections across the globe. The vast majority originate from the so-called Main Asteroid Belt (see above), a region between the orbits of Mars and Jupiter occupied by millions of rocky objects. The smallest of those barely survive entry into the Earth’s atmosphere to land on the surface as solid fragments, such as the Bovedy meteorite that fell near Portadown, Northern Ireland in 1969. Larger asteroids, such as the object that exploded above the city of Chelyabinsk in 2013, carry enough energy to do significant damage at ground level. The systematic study of these objects over decades has revealed a remarkable degree of diversity: no two meteorites are quite the same, even among groups that share a common characteristic such as a high abundance of metal or carbon-rich material. Scientists have been hard-pressed to come up with a credible scenario to reproduce this diversity from accretion of solids within the solar nebula.
In the new study, the team led by Professor Stanley Dermott of the University of Florida at Gainesville took a fresh approach to the problem by looking at the distribution of asteroid orbits and their sizes. Studying the asteroid belt is complicated by the fact that the orbits continuously change because of the gravitational influence of Jupiter and Saturn. But by taking time averages of the orbital properties, a significant amount of structure becomes apparent: some areas show concentrations of asteroids, elsewhere the Belt is relatively barren.
This is the result of asteroids colliding with one another over the 4 billion year history of the solar system (right). Collisions release myriads of fragments from the “parent” asteroids, which remain in much the same orbit. In fact, these asteroid “families” account for just under 50% of the known asteroids. The remaining non-family or “background” asteroids are more evenly spread across the Belt and it is not immediately clear where they come from: are they objects that formed independently as the solar system was forming or, are they themselves pieces of larger asteroids? The latter would imply a mechanism that changes the orbit, otherwise those asteroids would show concentrations just like the family asteroids.
By comparing the mean orbits of asteroids in families with the means for the background asteroids, Dermott et al found that families and background are quite similar and that this is true for asteroids of all sizes down to a few km across. The exception is asteroids in the most extreme orbits; these objects may also have derived from the families, but their orbits been so radically modified that any memory of their origin has been effectively wiped out. But even if one excludes these latter asteroids, that still leaves 85% of the asteroids studied by Dermott et al that are probably derived from the families.
The finding has important implications for scientists who study our solar system’s history. As Prof Dermott explains: “Rather than sampling numerous objects that formed independently in orbit around the sun, our findings suggest that the diversity observed in the meteorite record is more likely to represent a comparatively few large parent asteroids.”
Still, much work remains to be done. One question left unanswered is the nature of the mechanism that transports the asteroids out of the families. Dermott et al suggest that a subtle effect called chaotic diffusion may be the culprit. According to Dr Apostolos Christou, an astronomer at the Armagh Observatory and Planetarium and co-author of the paper, the combined gravity of Mars, Jupiter and Saturn acting over hundreds of millions of years would cause orbits to become more elongated and more tilted to the plane of the solar system so that finally the asteroid no longer lies within the family.
This idea also finds resonance with a theory, proposed a decade ago by a team led by Dr Alessandro Morbidelli and colleagues at the Observatoire de la Cote d’Azur in France and the Southern Research Institute in the US, whereby all the objects that originally populated the asteroid belt were quite big, hundreds or thousands of km across. According to that paper, all the smaller asteroids we now see are fragments of the larger objects being whittled down to smaller and smaller sizes by mutual collisions. Most of these objects have been completely destroyed but we are lucky enough that some, like the asteroid (4) Vesta visited by the Dawn spacecraft a few years ago (Fig), have survived to give testament to the violent early history of our solar system.
Reference to the paper: “The common origin of family and non-family asteroids”, by Dermott, Stanley F., Christou, Apostolos A., Li, Dan, Kehoe, Thomas. J. J., Robinson, J. Malcolm, Nature Astronomy, Vol. 7 (2018), DOI: 10.1038/s41550-018-0482-4
Armagh Planetarium: It’s out of this world this summer!
This summer experience our world and beyond as you sit back and relax in the Planetarium’s 360-degree dome theatre. With six different shows running Monday-Saturday throughout July and August there is so much to choose from, including a brand new film. “Solar Superstorms”, narrated by Benedict Cumberbatch, will take viewers into the tangle of magnetic fields and superhot plasma that vent the Sun’s rage in dramatic flares, violent solar tornadoes, and the largest eruptions in the Solar System: Coronal Mass Ejections. The film links to research carried out by the Armagh Observatory and Planetarium on the Sun. Best suited for adults and children over the age of six, “Solar Superstorms” launches at 2pm on Monday 2 July. Check out our website www.armaghplanet.com for show information and times. This summer you can also book your tickets online!
A Coronal Mass Ejection in the making: magnetic loops pushing up from solar sunspots. Credit: CME simulation by Yuhong Fan; solar surface simulation by Matthias Rempel, both from National Center for Atmospheric Research. Visualization by Advanced Visualization Lab, National Center for Supercomputing Applications, U. of Illinois.
Solar Superstorms describes rare but extremely powerful eruptions from our Sun that appear to occur about every 100 years. It discusses the last such event to affect the Earth, the Carrington Event of 1859. Amazingly, the auroral storms that were seen over much of our planet during this event are recorded in the Armagh Observatory weather record. (look at the entries for September 2, 3 & 4, 1859 in the entry in the log book below). If such a Solar Superstorm were to strike the Earth today it would likely lead to wide scale break downs in the electrical power grid and global communications.
The Carrington Solar Storm, recorded in Armagh’s daily weather record. Look at the entries for September 2-4, 1859 for the sighting of a bright aurora (click image to see at full size).
A turbulent pulse of solar plasma interacts with Earth’s magnetic field. Credit: Simulation by Homa Karimabadi, University of California, San Diego. Visualization by Advanced Visualization Lab, National Center for Supercomputing Applications, U. of Illinois.
Our amazing water rocket workshop (weather permitting) will run throughout the summer and we have a fantastic event programme planned. If you think you have “The Force” then join us on Saturday 7 July and Saturday 18 August when the Emerald Garrison will be training future Jedi Knights. Don’t miss this film-inspired StarWars treat for all young Padawans. Young visitors will have the opportunity to don the famous brown robe, pick up a lightsabre, and learn a few Force skills from an Emerald Garrison Jedi Master!
Launching Rockets from the Planetarium towards the weather station by the Observatory.
To celebrate our 50th Anniversary of opening this year, we have a special “50 Years of Sci-Fi” event on Saturday 28 and Sunday 29 July. This stunning family event is one not to be missed. Meet and have your picture taken with some iconic costumed characters and see the amazing fan built sets and props from some of the biggest movies and television series.
To end the Summer fun we have our popular Minecraft workshop returning on Friday 24 and Saturday 25 August. In conjunction with STEM Aware, children taking part in this workshop will have the chance to explore the International Space Station and beyond using the platform of Minecraft. Each child will have their own laptop gaming station and will be set team challenges in these workshops.
Remember that on those sunny summer days we also have a lovely outside trip through the Universe. Our Astropark is a scale model of the Cosmos where visitors can walk through the Solar System, into the Milky Way and beyond. The landscaped grounds are dotted with stainless steel scale models of the planets demonstrating how small our planet Earth is compared with some of its neighbouring worlds. At the top stand in our stone circle and admire the view across the city of Armagh and the surrounding countryside.
Article by Jorick Vink , Astronomer at the Armagh Observatory and Planetarium
When you are fortunate enough to have a clear view of the night sky, and you start wondering about the properties of all these sources of light, you might be amazed to find out all these stars have different colours, distances, and sizes.
Most stars in our Milky Way have masses like that of our nearest stars, the Sun, but there are also huge, massive beasts out there , some with masses as big as 300 times that of the Sun. These objects shine brilliantly, up to 10 million times more intensely than the Sun.
Stars more massive than 8 times the Sun are called “massive stars”, with lifetimes of just 2 million years, and thus much shorter than the 10 billion years of our Sun. Therefore, they are sometimes called the Rockstars of Astronomy, as they live fast and they die young!
Black Hole Collision from LIGO
Their ferocious nuclear burning, ultimately leads to an Iron core that collapses into a very compact object. For the most massive stars, about 25 times the mass of the Sun, the compact object that is left behind is a Black Hole. From such a super-heavy compact object, even light cannot escape. For those stars in between 8 and 25 times the mass of the Sun, the object becomes a neutron star. Both neutron stars and Black Holes have recently been detected by gravitational waves, proving the theory of relativity by Albert Einstein some 100 years ago.
Up until this year, astronomers believed that although most of the light is produced by massive stars, it was thought that most of the stellar mass was held together by lower mass stars like the Sun.
However, this paradigm has recently been overturned. Astronomers in Armagh in the massive star group lead by Prof Jorick Vink have studied the most massive stars known in our Local Universe, in the giant Starburst “Tarantula” region of the nearby galaxy the Large Magellanic Cloud (or LMC) (See figure). Taking into account the mass determinations from these most massive stars analysed in Armagh with more normal looking massive O-type stars studied by a large European Consortium, the VLT-FLames Tarantula Survey team, we found that the stellar mass function of stars is tilted in favour of the massive stars in the Universe (Schneider et al. 2018).
Where the life of massive stars is mentioned a picture of the Grand star forming region R136 in the Tarantula nebula.
This dramatic shift in our knowledge will have significant consequences for the numbers of Black Holes predicted to have formed in our Universe, and this will be tested in the next decade by thousands of detections of Black Holes with gravitational waves. Moreover, the light contribution of these most massive stars is expect to strongly dominate the light of the first Galaxies in our Cosmos, that are anticipated to be detected for the first time by NASA’s James Webb Space Telescope (JWST) and the European Extremely Large Telescope.
This will mean that this author and his team cannot relax, but instead the burning of calories will need to increase, just like the burning of the chemical elements in a massive star..!
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.