Ask an Astronomer
If you’ve ever had any burning questions you wanted to ask an astronomer, here is the place to do it! We’ve answered some common questions here, but if you have any more you’d like an answer to, comment on this post.
If you’ve ever had any burning questions you wanted to ask an astronomer, here is the place to do it! We’ve answered some common questions here, but if you have any more you’d like an answer to, comment on this post.
AOP’s Dr. Andreas Sander has been involved in a scientific first unravelling the mysteries of rare stars! Within the constellation Cygnus, an elderly star and its massive companion are having one last hurrah, flinging off mass at an incredible rate before they explode as supernovae and collapse into a black Read more
Chances are, if you’re interested in astronomy, that you’ve heard of William Herschel. A bit of a polymath, he was an accomplished musician, composer and even philosopher, but is best known for his discovery of Uranus, the first planet to be discovered with a telescope (one he’d built himself). Someone you might not be as familiar with, however, Read more
Written by Dr. Gavin Ramsay One of humankinds greatest achievements was made on 14th Sept 2015 when the first direct detection of a gravitational wave event was made using the aLIGO observatories in Washington State and Louisana in the USA. This event was the result of two Black Holes, each Read more
NGC stands for the New General Catalogue of Nebulae and Clusters of Stars, which is an astronomical catalogue of deep sky objects and was compiled in 1888 by the 4th director of the Armagh Observatory John Dreyer. To this day the NGC catalogue is still used by Astronomers all over the world and remains one of our many claims to fame! The catalogue contains 7840 objects Read more
Sunniest October at Armagh for 12 years, slightly wetter than average, roughly average temperature. Armagh Observatory reports that October 2020 was much sunnier than average, slightly wetter and with roughly average temperature. This was the sunniest October at Armagh for 12 years. The mean temperature was nearly 10.1 degrees Celsius Read more
by Apostolos Christou An international team of planetary scientists led by astronomers at AOP have found an asteroid trailing behind Mars with a composition very similar to the Moon’s. The asteroid could be an ancient piece of debris, dating back to the gigantic impacts that formed the Moon and the Read more
Mild, dry September and sunnier than average. Armagh Observatory reports that September 2020 was warmer and drier than average and with slightly more than average sunshine. This was the sunniest September at Armagh for five years. The mean temperature was nearly 13.7 degrees Celsius (56.6 Fahrenheit), which is approximately 1.2 Read more
AN INCLEMENT MONTH: WETTEST AUGUST FOR 12 YEARS, WARMER AND DULLER THAN AVERAGE. SUMMER 2020 THE DULLEST FOR 33 YEARS, WETTEST FOR 8 YEARS AND COOLEST FOR 5 YEARS Armagh Observatory reports that August 2020 was the wettest at Armagh for 12 years, that is, since August 2008, and both Read more
DULLEST JULY FOR 34 YEARS, COOLER AND WETTER THAN AVERAGE Armagh Observatory reports that July 2020 was the dullest July at Armagh since 1986, and cooler and wetter than average. The mean temperature was 14.65 degrees Celsius (58.4 Fahrenheit), approximately 0.2 C cooler than the long-term (1796–2010) average July temperature Read more
A breakthrough in deciphering birth of supermassive black holes – astronomers zoom in on black hole with one of the lowest masses ever observed in nearby “ghost” galaxy. A research team led by Cardiff University scientists say they are closer to understanding how a supermassive black hole (SMBH) is born thanks Read more
DULLEST JUNE AT ARMAGH FOR EIGHT YEARS, WARMER AND SLIGHTLY WETTER THAN AVERAGE Armagh Observatory reports that June 2020 was much duller than average, the dullest June for eight years and the sixth-dullest June on record at Armagh. It was also slightly wetter and warmer than average. Total precipitation was Read more
In a new paper, Simon Jeffery reports the discovery of standing waves on two small hot stars similar to the pattern of jet streams seen in the Earth’s atmosphere.
Friday 26th June is Digital Takeover Day and we want children and young people to takeover our blog. What do you have to do? Write about which planet in our solar system is your favourite one and why! You can write about any reasons why you love the planet – Read more
When Thomas Romney Robinson, director of the Armagh Observatory, invented the cup anemometer in 1846, little did he know that one day his invention would be recording the alien breeze on the surface of another world. Fast forward 130 years: On 20 October 1975, a small capsule detached from the Read more
By Gavin Ramsay, AOP Research Astronomer In previous AstroNotes we have highlighted the Gravitational-wave Optical Transient Observer (GOTO) project of which AOP is a partner. Although its main aim is to detect the optical counterparts of cosmic explosions, it has been used to observe some Comets. Last week GOTO observed Read more
How astronomy can help us understand the spread of a pandemic Article by Michael Burton, Director of the Armagh Observatory and Planetarium The Hill of Infinity of Armagh, in the Astropark of the Observatory and Planetarium, contains a scale model of the universe, illustrating the place of planet Earth in Read more
By Simon Jeffery, AOP Research Astronomer In 1930, Dorrit Hoffleit reported that star number #4749 in the Harvard List of variables had faded four times between 1897 and 1929, and identified it as an R Coronae Borealis (RCB) variable. RCB stars are luminous low-mass stars (red giants) with surfaces around Read more
Research Astronomer Dr Apostolos Christou reports on a new model to explain the two “oddball’’ moons of Neptune: Triton, a >2000 km diameter satellite that circles Neptune in the opposite direction that the planet rotates; and 300-km Nereid, the planetary moon with the most elongated orbit in the solar system. Read more
Armagh Observatory reports that April 2020 was much sunnier than average at Armagh, much warmer and much drier. This was the sunniest April at Armagh for 118 years, the second-sunniest April at Armagh since sunshine records began in 1880, and the equal fourth-warmest on record. Total precipitation was 16.6 mm Read more
By Christopher Duffy Studies of the sun, our closest star, have shown that sun spot activity and solar eruptions, also known as solar flares, are strongly correlated – regions of the sun with many sun spots are found to be the typical point of origin for most solar flares. This Read more
Data has been collected daily through famine and world wars They have continued through famine and world wars and now staff at Armagh Observatory and Planetarium (AOP) are determined the daily weather recordings which have been taken for over 200 years will not fall foul to the Covid-19 pandemic. Meteorological Read more
COOL MARCH, SUNNIER AND DRIER THAN AVERAGE. EXCEPTIONAL HIGH PRESSURE ON THE 29TH Armagh Observatory reports that March 2020 was cool, sunnier and drier than average. The highest pressure recorded during the late morning of the 29th March, namely 1050.0 mbar (corrected to mean sea level), equalled or nearly equalled Read more
One of our Astronomers, Dr Gavin Ramsay, reflects on his memories of some of the amazing telescopes he has travelled to throughout his career! When the telescope was invented in early 17th century, they were generally used in the urban environment. Gradually they were housed in quite grand purpose-built buildings Read more
March 2020: The clocks go forward on Sunday for what could be the penultimate British Summer Time (BST) observed on the island of Ireland. The European Parliament has voted to scrap daylight saving time (the practise of moving the clocks forward one hour during the summer months) from the end Read more
Have you ever wondered about the impact that you may have as an amateur astronomer? How much can amateur and professional astronomers gain from each other? Can amateur astronomers impact research? Please listen below to a short audio piece by Lucie Affronti and Neasa Cumiskey; two Postgraduate Media students at Read more
The 2019 Nobel prize for physics has been awarded to three scientists: James Peebles, Michel Mayor and Didier Queloz. This blog post will briefly outline why Mayor and Queloz were awarded their prize. In 1995 these Swiss astronomers announced the discovery of the first planet orbiting another ‘solar type’ star. Read more
MILD, WET SEPTEMBER WITH ABOUT AVERAGE SUNSHINE Armagh Observatory, 1st October 2019: Armagh Observatory reports that September 2019 was warmer and wetter than average, with about average sunshine. This was the sunniest September at Armagh for four years, the warmest for three years and the wettest for two years. The Read more
Following from last week’s introduction to our climate change series, this week we have an article explaining how climate change actually works and why it happens. Firstly, we will be drawing on our sister planet Venus as an example. Earth’s Evil Twin Earth and Venus are, on the face of Read more
Article by Professor Michael Burton, Director of the Armagh Observatory and Planetarium July 20, 2019 marks 50 years from the day Neil Armstrong stepped onto the Moon, humanity’s first foot steps on another world. As much an awe inspiring feat then as it remains today. Indeed, despite the revolution in Read more
Our final piece in our Astronomy & You series is a fascinating piece on lab astrophysics and the discovery of buckminsterfullerene (c60) by Armagh Observatory and Planetarium’s own Michael Burton. He is our Director and before coming to Armagh was the Director of Teaching at the School of Physics in Read more
To follow on from last week’s post on grid computing in our series on the technological applications of astronomy to society we have an article on spectroscopy and the discovery of a new element in the cosmos – helium – by Armagh Observatory and Planetarium’s Michael Burton. He is our Read more
Apollo 10 was the mission that almost made it to the Moon. Designed as the full dress rehearsal for Apollo 11, the lunar module “Snoopy” approached to just under 15 km from the Moon’s surface with astronauts Thomas Stafford and Eugene Cernan aboard. It was May 22, 1969 – 50 Read more
There’s lots to look forward to in the Month of May: the evenings are brighter, there’s the promise of good weather and most importantly – not one, but two bank holiday weekends! There’s also lots to look forward to and look out for in May’s night sky. There’s the chance Read more
To kick off our new weekly series on the Technical Applications of Astronomy to Society, inspired by a recent publication of the IAU (The International Astronomical Union), our Director Michael Burton has written a brief summary of the history and purpose of the IAU, as well as outlining some of Read more
While you may be familiar with black holes from sci-fi and many artists’ renditions of the phenomenon, our first actual view of the event horizon of the supermassive black hole which is at the centre of a neighbouring galaxy, Messier 87, was released 4 weeks ago to the day. What Read more
In celebration of the 50th Anniversary of The Bovedy Meteorite falling in Northern Ireland on Friday 25th April 1969, Artist Noel Connor has compiled some thoughts and reflections on his experience with Bovedy. The sky always seemed low over our street in Andersonstown, with the Black Mountain looming behind the Read more
To celebrate the 50th Anniversary of The Bovedy Meteorite falling in Northern Ireland, some of The Education Team at Armagh Observatory and Planetarium have written pieces about their favourite meteorites and craters from across the globe. The Mysterious Mbozi by Helen McLoughlin The Mbozi meteorite is the eighth largest meteorite Read more
Article by: Gavin Ramsay Unlike our Sun, around half of all stars have another stellar companion. The closest stars to the Sun are two bright southern stars, alpha Centauri A and B, which orbit each other every 80 years and Proxima Centauri which orbits A and B every few tens Read more
Before addressing Black Hole sizes, we should first go back to see what astronomers mean when they use the term “Black Hole”. This may be easiest to understand when considering the end products of stars.
The hottest February day ever in Armagh.
Michael Burton, Director of the Armagh Observatory and Planaterium Monday January 21, 2019 – the last chance to watch a total eclipse of the Moon from Armagh for over a decade. Should we hold a special viewing session to give people the chance of seeing this celestial wonder?! Easy question, Read more
Our view of the cosmos is biased by the vista that is apparent to our eyes. This is what the view in what we call the optically visible portion of the spectrum. To the unaided eye it is a view of a universe full of stars, together with five planets, one Moon and of course the Sun. When augmented with a telescope, our eyes can then see a universe full of galaxies – giant cities of stars.
Christmas Eve of 1968 saw the arrival of the first humans at the Moon – the crew of Apollo 8. A truly momentous event in history, the arrival of humans to another world for the very first time.
With Space Exploration comes theories and conspiracies. In our latest blog we debunk some of the more infamous ones.
Some seven months ago, a NASA spacecraft called InSight was launched atop an Atlas 5 rocket and headed to Mars (Figure 1). If all goes well, the spacecraft will land on the Martian surface at around 8pm UK time this Monday 26th November and begin its science investigation. InSight is a fixed lander (see Figure 2 below), a much simpler affair than the Curiosity rover that arrived in 2012 and continues its trek across the floor of Gale crater to this day. Mobility, is however, not required for the specific aim of the mission.
NASA has announced the retirement of the Kepler spacecraft. After launch in March 2009, it began a continuous observation of a 115 square degree field of view (the diameter of the moon is 1/2 a degree) between the constellations Cygnus and Lyra.
As had been reported on in an earlier Astronotes blog article, the International Astronomical Union was putting to the vote whether to change the name of the law relating to the expansion of the universe. Of the 11,000 professional astronomers entitled to vote on the motion, over 4,000 did. The Read more
An interview with resident PhD Student Rok Nezic about his recent adventure to the European Planetary Science Congress 2018, held in Berlin, Germany.
As an earlier Astronotes article reported on, during its XXX General Assembly in Vienna, held in August 2018, the International Astronomical Union (IAU) put forward a draft resolution to rename the Hubble law as the “Hubble–Lemaître law”. The resolution was proposed to recognise Lemaître’s research on the expansion of the Universe, and to pay tribute to both Lemaître and Hubble for their fundamental contributions to the development of modern cosmology.
The discovery of planets orbiting around other stars has been one of humankinds greatest achievements. The existance of these ‘exo-planets’ can challenge our perception of our place in the universe. Since the first confirmed detection of a planet around another normal star (51 Peg) in 1995, many thousands of planets have been discovered. Indeed, it is likely that most stars will have their own system of planets. It is important in answering the question – is there intelligent life out there?
The Daniel K. Inouye Solar Telescope (DKIST) is under construction on the summit of Haleakalā on Maui, Hawaii. Since DKIST will be observing the Sun’s corona, the sky above the telescope needs to be as free of dust, aerosols and pollutants. The isolated islands of Hawaii provide optimal conditions for clear, “coronal skies”.
Have you ever been worried about the impact of an asteroid wiping out human life? Well, I have some disturbing news for you: there is another possibility involving the explosion of a massive star that gives rise to a gamma-ray burst (called by astronomers simply a GRB), when the star ends its life producing a black hole.
After a special vote in the IAu General Assembly, we interview Armagh Observatory and Planetarium Director. Professor MIchael Burton, on the renaming of the Hubble Law.
The Armagh Observatory has been a staple feature along the Armagh skyline since its creation in 1790. Astronomical research has been undertaken within the organisation since the 1790s and to this day it has seen several different Directors and numerous astronomers walk through its historical doors.
September 2018 will see over 50 astronomers from around the world gather at the Armagh Observatory and Planetarium to discuss the latest news about hydrogen-deficient stars. These stars have lost nearly all the hydrogen from which they were made, to leave only nuclear ash. Astronomers want to learn how these rare and short-lived remnants formed, and what drives their spectacular changes in brightness.
Armagh Observatory, 3rd August 2018: Armagh Observatory reports that July 2018 was much warmer and sunnier than average, with only slightly less than average total rainfall. The mean temperature was 17.0 degrees Celsius (62.6 Fahrenheit), approximately 2.2 C warmer than the long-term (1796–2010) average July temperature at Armagh and 1.2 C warmer than the most recent (1981–2010) 30- year average. This was the warmest July at Armagh for five years. The warmest day (highest maximum air temperature) was 27.1 C, which occurred on the 4th, followed by 26.7 C on the 22nd. Both these maxima wereslightly more than 80 degrees Fahrenheit. The coldest day (lowest maximum air temperature) was 14.4 C on the 11th. The coolest night (lowest minimum air
temperature) was 7.6 C on the 10th, and the warmest night (highest minimum air temperature) was 16.6 C on the 27th followed closely by 16.5 C on the 23rd. The minimum grass temperature was 0.3 C on the 10th, so there were no ground or air frosts.
It’s the beginning of a new month, filled with new exciting events in the night sky. Here is a brief summary of what to expect in the next few weeks.
July 20 1969 saw, arguably, the most famous event in all of human history when Neil Armstrong stepped onto the surface of the Moon and left his footprints there – a mark still indelibly framed in the lunar dust today, some 49 years later. It may seem almost as incredible that it is indeed nearly half a century ago that this epochal event occurred, one that united all of humanity for a short while, as we stared at that yellow orb in our night skies to know that one of our species was walking on it surface.
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!
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.
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.
Approximately every other star in the Milky Way galaxy is in a ‘binary’ system. These binaries are made up of two stars orbiting around a common centre of gravity. The time taken for the stars in the binary to make one revolution is called the ‘orbital period’. Binaries have a wide range of orbital period. The closest stellar system to the Sun is alpha Centauri which has two stars not unlike our Sun orbiting around one another every 80 years. A third member of the system, Proxima Centauri, which is much smaller red dwarf star, orbits around these two stars once every 10,000 years.
Article by Michael Burton, Director of the Armagh Observatory and Planetarium NASA’s Curiosity Mars rover recently discovered organic molecules in 3 billion year old Martian rocks. This material may have been delivered by meteorites and comets to the young planet. Deep space is full of organic matter. Organic matter contains Read more
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 Read more
Article by: Tom Watts In collaboration with universities in England, Australia and Thailand, the Armagh Observatory and Planetarium 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. GOTO, once operational, Read more
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 Read more
Article written by: Conor Byrne 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 Read more
Article written by: Professor Michael Burton, Director of Armagh Observatory and Planetarium 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 Read more
Article written by: Phil Hall 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’, Read more
Recent observations of the helium star HD144941 have been obtained from space. Armagh astronomers Professor Simon Jeffery and Dr Gavin Ramsay have discovered that they show a light curve best explained by darker and lighter patches on the star’s surface coming into view as the star rotates with a period Read more
Since the beginning of the space age, humanity has been sending robotic emissaries to all corners of the solar system. These represent some of the most complex technological undertakings ever conceived. Travelling for years and even decades to their destinations, they have helped form a modern picture of the solar Read more
Some good news folks! If you fancy a few free ‘sparklers’ to get you celebrating, you could fill a bag with the number of fabulous looking stars that will appear their prettiest again this month against the darkest seasonal drape of the year as it stretches in all directions above Read more
Comets are small icy and rocky objects flying around our Solar System on elliptical orbits, as opposed to near-circular ones the planets are enjoying. They are strange and fantastic enough as it is: bright comets with their tails spanning across the sky have been marvelled at, recorded, and often feared Read more
In a paper entitled ‘GALEX J184559.8−413827: a new extreme helium star identified using SALT’, Armagh astronomer Simon Jeffery reports the first new extreme helium star to be discovered in nearly 40 years. Extreme helium stars represent a small group of low-mass supergiant stars. They have spectral types equivalent to A Read more
After telling us about the Sun, in part two of this posting Armagh astronomer Gerry Doyle takes us through the telescopes and satellites being used to study the Sun. The Solar Physics community needs continued access to state-of-the-art observational facilities (both space- and ground-based) that cover a broad range of wavelengths and Read more
October is over, and November is now upon us. The days are definitely getting colder, the night are definitely longer, which means the time for gazing into the night sky is now! One of the best things about November is the fact that there is not one, but two meteor Read more
Armagh Observatory and Planetarium’s Robinson Lecture this year will be about the Sun. To lead into this here is the first of two articles about why astronomers study our Sun, and the range of telescopes and satellites co-opted to the the task. Solar physics is the branch of astrophysics that Read more
The 2018 Robinson Lecture will be given by Professor Louise Harra of University College London. Her topic is about the Solar Orbiter, a new spacecraft to be launched to study the Sun. It will be held in the Archbishop’s Palace in Armagh on Wednesday 22 November, 2017, starting at 7pm. Read more
On October 31, 2017, the world will celebrate the international hunt for dark matter. Armagh Observatory and Planetarium will be having a special showing of the “Phantom of the Universe” at 2pm, a Full Dome show which discusses our understanding (or lack thereof) Dark Matter, and the search to find Read more
On Aug 14th 2017 LIGO and the Virgo Gravitational Wave detectors based in the USA and Italy detected the fourth merging Black Hole event. This was a triumph for both groups, but especially the Virgo group which had only started taking regular data earlier that month. It did leave many Read more
The Sun is a constant presence in everyday life from rising in the morning signifying the beginning of the day, to setting at night representing the time to rest. With the human race ever more dependent on technology it is important to monitor solar activity and the potential harm it Read more
Gaia is a satellite launched by the European Space Agency (ESA) on 19 December 2013. It is essentially a census gathering information on over one billion stars, totalling an amazing 1% of the galaxy’s total population, measuring their positions, motion, brightness and colour. Gaia’s primary objective is to create the Read more
As the summer draws to a close September is a perfect time for stargazing before the cold nights of winter finally creep in. With sunset around 9pm and a forecasted heatwave, fingers crossed for some clear skies with some lovely mild temperatures. A key feature of the summer night sky Read more
Michael Burton, Director, AOP On 27th July 2017, the RoI Minister John Halligan switched on I-LOFAR telescope, the largest radio telescope in the world, at Birr Castle in Co. Offaly. The Armagh Observatory and Planetarium is a member of the 8 institutions across the island of Ireland that came together to build I-LOFAR. Read more
Michael Burton, Director of Armagh Observatory and Planetarium Have you been enthralled by the BBC’s Stargazing Live Australia, hosted by Brian Cox and Dara O Briain and shown over three nights at the end March this year? A spectacular show, hosted from Siding Spring Observatory in the Warrumbungles National Park Read more
The discovery of the TRAPPIST-1 exo-planetary system is a truly remarkable event in science. It is an exemplar of how an armada of telescopes – some located on the ground and some in space, and collectively owned by a league of nations – can work together to chart new frontiers Read more
It’s that time of the year again for the third annual Northern Ireland Science Festival and this year is bigger and better! The Armagh planetarium has been holding events under NISF from the beginning so we could not miss the opportunity to be part of this inspiring event. We Read more
1 September 2016 saw the first full meeting of all of the staff of Armagh Observatory and Planetarium. We are looking forward to carrying Armagh’s impressive heritage of astronomical research and public education forward into an exciting future together! You can follow AOP’s work through our websites and Read more
We are delighted to welcome Michael G. Burton as Director of Armagh Observatory and Planetarium. Professor Burton is an internationally renowned researcher who specialises in using infrared and millimetre-wave astronomy to study how stars form in the interstellar medium (the tenuous matter between the stars in our galaxy, the Read more
Pokémon Go has taken the world by storm; it seems that everyone is playing it. If you see someone walking in circles with their head down and looking at their phone, you know they’re on the game…and maybe part of you wants to rush over and see what they’ve found. Read more
At the end of Part Two our Galactic explorers had produced the first true maps of our Galaxy, showing its shape and extent, by using radio telescopes to map the distribution of atomic hydrogen, so revealing the spiral arm structure. In the concluding portion of this article we turn to Read more
In March 2016, Armagh Planetarium debuted a new workshop for schools ‘Robotics in Space’. This interactive workshop highlighted the roles of robots and robotics in space missions, discussed what robots are currently in space as well as how can they be programmed and controlled. This new workshop was made possible Read more
At the end of part one of this article we left our galactic explorers uncovering the first hints of the existence of spiral structure within our Milky Way. In part two we see how the new field of radio astronomy opened up the Galaxy for viewing to our explorers. Read more
Picking books for children can be difficult, not only are we adults battling with TV, game consoles, tablets and toys, it’s hard to fit the old-fashioned entertainment of a book into a child’s life. There’s no doubt children have a great imagination and at a young age nothing is impossible Read more
We live in a galaxy – a star city with several hundred billion residents. Moreover, we know our Milky Way is a spiral galaxy, with prominent arms of bright young stars that spiral outwards from a central bar that is dominated by old stars. These arms are so prominent as Read more