Galaxy Size Comparison Chart

This is bloody amazing so i had to share! Brilliant picture.

Richer Ramblings

Galaxy ChartJust how big is our galaxy, the Milky Way, compared to others?

Not very, actually. Above is a galaxy size comparison chart (by Rhys Taylor), showing, to the same scale, a selection of galaxies that we know about. It’s a visually stunning piece of work, and really shows how huge galaxies can be, as well as how diverse. Click the image to see it in full detail, or head over to for some zoomable images.

If you could pick one galaxy to live in, which would you choose? Onwards!

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Once Upon a Time and Space…

In my day job I teach history to teenagers.  On one side of my classroom Buzz Aldrin stands sentinel like on the surface moon, flanked by Darwin and the Solar System.  On the other, Georgians rub shoulders with Romans and maps of long dead empires compete for space with D-Day.  It’s a reflection of my mind and so it has been since I took up my binoculars almost three decades ago.  History and Astronomy.  Time and Space.

The history of astronomy (and indeed science) is one of the great, inspirational stories of humanity.  The long road to rational explanations, the search for our place in the universe, the discovery of laws to direct human endeavours.  Now it is a story you can follow through a compelling and beautiful series of books – Dr Stuart Clark’s The Sky’s Dark Labyrinth Trilogy.  If the name alone does not make you want to rush off to pick it up, then read on as I talk to the author about his work and tell you a little about each book.

Dr Stuart Clark's The Sky's Dark Labyrinth

‘The roads that lead man to knowledge are as wondrous as that knowledge itself.’ Johannes Kepler

Book one, ‘The Sky’s Dark Labyrinth’, opens in a Europe tumbling out of the deep superstition of the medieval into the turmoil of the 17th Century. Here we meet Kepler and Galileo about to do battle with Aristotelian physics, the church and even those closest to them in their pursuit of the Sky’s secrets.

What was your original inspiration for tackling this project?

These astronomers’ lives were so dramatic, set as they all were against backgrounds of great social change and turmoil that to write about them in story form would do them better justice than purely factual biographies. By dramatising, I could really show the impact of their work on society and the forces acting on them as individuals.

How did you decide on the great astronomers and eras that the three books focus on?

I consider the men in my books to have the greatest brains that thought around the accepted knowledge of their time and overturned it. Essentially, I looked at the development of gravitational theory: so, Kepler, Galileo, Newton and Einstein.

I considered all the names that people know and perhaps would be curious to learn more about.

Some of the great names you wrote about had various unsavoury traits or habits, did you find that difficult to include at times or were you keen for it to be warts and all?

I wanted to convey how human all these people were so I gravitated towards the second, ‘warts and all’. However I did not want the story telling to be lurid or exploitative so whenever there was historical doubt I erred on the side of caution. My aim was to paint plausible characters.

Do you feel that the great leaps in astronomy the books describe required great minds such as Kepler, Newton and Einstein to make them or were these discoveries inevitable?

I think the route science has taken has been driven by great minds. Without these exceptional astronomers, our understanding of the universe would have been arrested. Hopefully, we would have got there in the end but certainly less quickly.

Dr STuart Clark's The Sensorium of God

Sparks of genius – the momentous clash of Isaac Newton and Robert Hooke

Book two moves the reader to the end of the 17th Century and to England where a more rational and scientific world is being born in the aftermath of Civil War and Restoration, we join Halley, Newton and Hooke as Kepler and Galileo’s legacy begins to bare fruit.

Which of the ‘turning points’ in the astronomy story that you explore do you feel was the most important?

I think each and every one was equally important and none would have happened without its predecessor. But, if you press me then I would have to choose Newton’s work. The man was truly a genius in that he seemed to pluck his inspiration from the air. It still astonishes me that he did what he did on his own.

You explain that some events, people and conversations were inventions of your pen to help the stories along, what do you feel was your biggest fiction?

The spymaster Winslow in the second book: The Sensorium of God. I needed someone to represent authority and the throne changed hands so many times during Newton’s life that I couldn’t use the monarchy. So I Invented Wilnslow to work for each of the kings and queen in turn, in the same way a present day civil servant works for successive governments. Winslow provided continuity.

If you could choose to visit a character or event from your books where would you tell the time machine to go?

I would love to have known both Tycho Brahe and Edmund Halley. I imagine spending an evening with Halley over a glass of good red wine would be an entertaining few hours well spent.

What were the biggest surprises that came up in your research?

So many! A proper understanding of Galileo’s trial; Halley acting as a spy for the monarchy; and the extent of the work achieved by the relatively unsung Belgian cosmologist, Georges Lemaître. And the suffering they endured.

Dr Stuart Clark's The Day without yesterday

Once we recognise our limits we can leap beyond them.

Book three, ‘The Day without Yesterday’, brings us into the more familiar territory of the early 20th century and the dark days of the Great War.  Here we meet Einstein and Lemaître puzzling over the Universe, a place that appears at odds with what general relativity is trying to tell them.  We are swept from Berlin to the hills above Los Angeles as the sky appears to be revealing the labyrinth and presenting a puzzle far deeper and complex than imagined.

Throughout the trilogy science and religion’s relationship is never far from the surface, did you feel that the religious view of the protagonists became more or less important to their view of the universe as you worked through to the 20th century?

My first three main characters: Kepler, Galileo, and Newton were devoutly religious men, albeit with different ways of interpreting the Bible. Halley I felt was more of a free thinker, less accepting of the doctrine of the time, but not overtly against it either. In many ways he was the model Anglican. When I came to Einstein, he clearly had atheistic tendencies but then Lemaître was not just devout but also a priest. Their religious views, for and against, shaped the way they studied the universe. I had to include all this and, when I did, I found I could perceive their individual motivations more clearly.

Were the similarities between the observatories of Tycho Brahe and Edwin Hubble a pleasing coincidence or one that you always had in mind?

Do you mean the way they were run as a ‘dictatorship’, with everyone eating together in the afternoon? I was always on the lookout for such similarities to help the trilogy to work as a whole. To have noticed such a subtle point conveys what a careful reader you are, Paul!

Which of the characters did you sympathise with the most?

In each book I found myself drawn to one character in particular. In the first it was Kepler, Halley in the second and Lemaître in the third. Each man seemed to embody an essential humanity as well as being a great scientist. I liked them all, but one always finished up being my favourite.

Where next for Dr Stuart Clark the author?

I think I will be revisiting non-fiction for my next couple of projects but I have a couple of ideas banging around in my head for more fiction based on science. I really enjoyed writing the trilogy and it has been warmly accepted. So I would like to continue but I don’t want to jump into the first idea I have. I would like to be convinced that it is something I can really do well. I’m keen to maintain the quality of everything I write. (Dr Stuart Clark March 2013)

Dr Stuart Clark

Dr Stuart Clark

My thanks to Dr Stuart Clark for taking part in this interview.  He is an astronomer, author and journalist with an extensive catalogue of work to enjoy, both fiction and non-fiction and his website can be found here He also writes about the cosmos for The guardian which can be seen here

Posted in Astronomy, Books, Halley, Kepler, Stuart Clark, The Astronomer's Den, Transit of Venus | Tagged , , , , , , , , , , , | Leave a comment

Giotto of Filton

It was an exciting moment for many people, but especially for a young boy.

It seemed such a daring mission and the fact the probe was not expected to survive made it all the more tantalising.  Which boy doesn’t relish the idea of a death and glory suicide mission?

And of course this was not just a European probe and Europe’s first deep space mission, the spacecraft was built in the UK and was visiting an object special to British scientific history.  But I skip ahead…


Giotto of Florence

Giotto di Bondone, Giotto of Florence, was perhaps the foremost artist and architect of his era.  He completed the painting Scrovegni Chapel in 1305, considered one of the masterpieces of western art.  A series of 37 frescos depict the life of Christ and as befits someone credited as the first artist of the renaissance, the detail, expression of human emotion and realism is still considered masterful.

Scrovegni Chapel, Giotto

Inside lies a masterpiece and a comet

One detail that stands out as a particularly renaissance touch is painted above the manger in a fresco entitled the ‘Adoration of the Magi’.  Kneeling before the Christ child the the Magi have been led from the east by a star, but not any star.  Inspired by his own observation in 1301, Giotto decided that the star of Bethlehem was a hairy star, a comet.

Adoration of the Magi, Giotto, Halleys Comet

The Adoration of the Magi by Giotto

As it would turn out not just any comet, but one that would be named over 400 years later after the astronomer who demonstrated that it wasn’t a passing phenomenon, but a frequent visitor on an elliptical orbit of 76 years- Halley.

Halley's Comet

Halley’s Comet. NASA

The Night of the 14th/13th March 1986.

Humans have witnessed the rise of the Renaissance, the Reformation, the Enlightenment. Outside the walls of the Scrovegni Chapel almost seven centuries of human progress have passed.  Steam Engines and man on the moon are as much part of history as those frescos.  Thousands of miles above, deep in space, a small probe hurtled towards Comet 1P/Halley.

A probe named Giotto.

It will take the first close pictures of a cometary body and with a package of sensors start to settle the questions of what these objects are.

It was a tense night. European science held it’s breath.

Death and glory.

Giotto, Halley's Comet

Giotto of Filton (Andrzej Mirecki)

Water. 80% water.  But blacker than coal.

And shaped like a peanut.  A 15km long peanut.

The tail formed by just 10% of the surface, three active jets releasing material as it was hit by the solar wind.

4.5 Billion years old and with the same ratio of constituents as the Sun.

Here was one of the most primitive bodies in the Solar System, almost unchanged since the formation of our star.

Methane, Ammonia, hydrocarbons, organics.

Halley's Comet, Giotto

The Hairy Star revealed (ESA)

It was a giant dirty snowball with many of the ingredients of a star and planetary system. Lots of data, many answers and lots more questions.

Without all the science the series of pictures taken on approach were worth the cost of the mission alone. (Do watch this!)

Then little Giotto was hit.  It started to spin, contact lost, regained, lost, regained; the antenna was no longer pointing directly at Earth.  Then the camera was lost.  Death after glory.

But not quite.  Giotto stabilised after half an hour and lived to do it all again 6 years later with Comet Grigg-skjellerup in 1992.  Today the little probe from Filton orbits in quiet retirement, switched off by it’s creators after revealing the first secrets of hairy stars.

Join me in part 3 for an exploration of where comets come from.

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Hairy Stars

Galileo agreed with Aristotle and thought them to be high atmospheric phenomenon.

Burning gas or some such.

Comet of 1618

1618. Bringer of plague and the end of the world.

Ancient texts saw them filled with evil intent or foreboding, a sight unpredictable.

In 1066 the appearance of one foretold the fall of Saxon England.

Comet of 1066

The doom of Harold

The artist Giotto, first of the renaissance painters, was so taken with his sighting of one that he placed it in one of the frescos of Scrovegni Chapel.

Adoration of the Magi, Giotto, Halleys Comet

The adoration of the Magi by Giotto

Kepler, the decoder of planetary orbits, rejected the possibility that they could follow his ellipses as they did not conform to the ecliptic, so could not be a solar system body.

Comet 1882 pyramids

Mysterious and Captivating

Hairy Stars.


Halley's Comet

Halley’s Comet. NASA

In our age of warm houses, indoor entertainment and light pollution so few in the world have seen them or are even aware of their existence. Indeed in the UK the word Comet is more likely to illicit the image of a now defunct electrical store.

In the past though these were objects of fascination and mystery, feared, misunderstood and admired. They have played a key part in our histories and cultures, references to them appear throughout literature from Gilgamesh to Arthur C. Clarke.

It was the 17th Century that saw some questions answered. While the big name of renaissance science, had passed them off as meteorological, others had begun to peer more closely. It was in Stuart England that reason would start to be applied to our hairy visitors.

William Lower

Sir William Lower, National Portrait Gallery

William Lower began the process in 1607 when he suggested, from his observations, that Comets did indeed follow a curved ellipse like path that would fit Kepler’s model. Lower like his friend and contemporary Thomas Harriot , is one of the forgotten names of Astronomy, even within England. Overshadowed by the celebrity of the Tuscan, eclipsed in England by the scientific giants that followed at the dawn of the enlightenment, Lower and Harriot were drawing the moon through a telescope before Galileo made it cool.

But it was the bewigged experimenters and observers of the later half of the century that would confirm what Lower suspected.

Many suggested and argued that comets followed an eliptical path, others stuck fast to the notion of a linear course.  The comet of 1680 seemed to answer the issue when the astronomer Gottfreid Kirch deomstrated that it followed a parabolic path around the sun.  Newton used the same comet in his as evidence for his new gravity.

Newton, Comet, Principia Mathmatica

The Comet of 1680 in Principia Mathmatica

But it was another man who sealed the idea and showed that Comets were a recurring phenomenon and not one off objects, by combining Newton’s new gravitational theory with Kepler’s laws to plot 23 histroical comets and crucially make a prediction – a key part of the new scientific method.  Edmund Halley, playboy astronomer, spy, inventor of the diving bell, meteorologist, atheist and sometime naval captain showed that Comets were indeed solar system bodies, adhering to the mechanics and clockwork of the enlightenment universe.

Edmund Halley, Halley's Comet

Edmund Halley

But confirmation of Halley’s work would have to wait.

The comet that bares his name was also his experimental legacy.  Predicted in Synopsis Astronomia Cometicae, Halley asserted that the comets seen in 1456, 1531, 1607 (the one Lower measured), and 1682 were one and the same and that it would return (If he was correct) in 1758. He died in 1742 leaving, in the spirit of the age, his experiment running. It did indeed return in 1758 and Halley was immortalised in the heavens.

Comets followed highly eccentric elliptical orbits that varied in orbital period. They did not always follow the ecliptic, indeed comets appeared to come from all angles of the sky. But they appeared to be predictable and part of the Solar Sytem’s very make up.

Comets had been tamed, no longer harbingers of doom from the gods, but the mystery of their make up and origin remained.

What exactly were comets?

Join me in Part 2 “Giotto of Filton”

Posted in Astronomy, Comets, Greenwich, Halley, History, Kepler, Telescope, Weather | Tagged , , , , , , , , , | 1 Comment

Asteroid Day


Well I didn’t see it.  Well it was briefly in my scope but the gap in the clouds was so short that I didn’t get a chance to confirm which of the faint white dots was the one.  Oh well.  That’s astronomy.

But what a day.  The Urals meteorite was incredible and an amazing cosmic coincidence.  Really demonstrated the way the cosmos reaches out and gives us a shake sometimes.  A future blog post on the full story will follow.

BBC world News impact

Cosmic Jumper. Me on the BBC.

I was fortunate to be able to give an interview for BBC World News alongside Cosmologist Marcus Chown.  Hope you enjoy it and no comments about my jumper!


Posted in Astronomy, Baker Street Irregular Astronomers, Binoculars, End Of World, meteor shower, Meteorite, The Astronomer's Den, Weather | Tagged , , , , , , , | 1 Comment

Where, oh where is the Great Big Bear?

When I was a small astronomer one of the highlights of my early interest was the London Planetarium.  It is one of those trips with my parents that I remember very fondly and still feel the edge of excitement from the start of the show, can still hear the narrator talking about “a bright star shining over the heads of shoppers on a busy London street – Venus”.  The amazing projector like something from the space program.  I still have the guide book three decades later.

London planetarium

Cultural wasteland – The Old London Planetarium.

It’s gone now. Purchased by Madame Tussauds next door, emaciated, gutted and then destroyed by an organisation with a penchant for cultural destruction (you bet I’m angry! Don’t even get me started on Warwick Castle…)

So here I am, now a father to a budding astro-nut in the shape of a big-bang obsessed, ‘Mars is my favourite pink planet’ almost four year old and while the site of the London Planetarium is a mere 20 minute tube ride away it is many years in the past and the Bakerloo Line has no worm-hole.

Which is why today I was with my daughter in Greenwich.  Up on a hill, looking down on the faded Georgian splendour of Britain’s maritime heritage is the Royal Observatory.  This is the home of the Prime Meridian, home of time keeping, spiritual home of British Astronomy and tucked away between the old telescope domes is the Peter Harrison Planetarium.  Opened in 2007 this is The London Planetarium reborn.

Peter Harrison Planetarium

Peter Harrison Planetarium, Greenwich

11am and we are here for “Space Safari” a show aimed specifically at the under 5s.  I will admit to being apprehensive.  If you are a parent you will know the feeling of dread regarding any sort of educational presentation. “Will it be too advanced? Will it be too dumbed down – or worse – patronising?”  My daughter was excitement itself, the driverless DLR had already started her day well and she could not get me up that hill quick enough for her liking.

Royal Observatory

The Royal Observatory, Greenwich

We got comfy and clutching her ‘space rhino’ (don’t ask) and her copy of ‘Fancy Nancy Sees Stars’ (great book highly recommend!) she began to listen carefully to our Astronomer for the show, Dr Edward Bloomer and she didn’t stop listening to his every word for the next 30 minutes.

Peter Harrison Planetarium

Entranced by the Space Safari.

The show was beautifully simple, involving a teddy bear leaving his bedroom and exploring the Solar System for “The Great Big Bear”, which of course, you may have guessed was Ursa Major.  There was music and songs, fantastic narration and questioning by our host and everything was pitched perfectly.  My daughter was so taken with it all that when the offer of meeting Dr Bloomer to ask a question was presented, Daddy was left gathering the coats and bags while she interrogated him about craters on Mars.

Prime Meridian, Greenwich

East meets west in Greenwich,

Well done Royal Observatory (the rest of the visit was an equal success) and thank you Dr Bloomer.  My daughter was buzzing all day and wanted to stargaze the moment it got dark (defeated by cloud).  I hope and I am pretty sure that my daughter will remember her first planetarium visit in three decades time as I do mine.

Octogan room, Greenwich

About time we had a woman as Astronomer Royal….

Do visit the Peter Harrison Planetarium and the Royal Observatory.  The planetarium has a range of shows and the Royal Observatory has a stated aim of giving the public access to a qualified astronomer and I was delighted to discover that this extended down to even the under-5s.

Posted in Astronomy, Greenwich, Planetarium, Telescope, The Astronomer's Den | Tagged , , , , , , , | 4 Comments


45 metres long.  About the size of a Boeing 757.

130,000 tons.  Heavier than a fully loaded Nimitz class carrier.

2.5 Megatonnes of tnt equivalent if it hit.  That’s six Polaris missiles worth of bang.

everyday representation of 2012DA14

A 757 sized, super carrier massed, very destructive lump of asteroid. 2012DA14

Right now it’s heading our way.  2012DA14 Near Earth Asteroid.  It was spotted last year a week after it had sailed by Earth, missing us by a well over a million miles.  It’s orbital period of 366 days has brought it right back to us and on Friday 15th February 2013, while people are hurrying home from a hard week at work 2012DA14 will be silently overhead, a mere 21,200 miles away.  That’s well within the orbit of the moon and inside the geostationary satellite network.


2012DA14 passing Earth 15th February 2013. NASA

But it is not going to hit.  In fact after the initial scare and some early maths that showed it had a chance of collision after its pass in 2026, it looks pretty unlikely to be ever hitting us in the forseeable future (never say never) with the chance of a collision in 2110 being a staggering  1 in 7,692,308,000.  I think i’ll sleep easy for now.

So what is it?

Well it was discovered by the OAM Observatory at La Sagra in Spain on 23rd February last year.  It is an Apollo Near-Earth asteroid, which is a type of asteroid that has an orbit that crosses that of Earth’s, more specifically it belongs to a class of asteroid that have a semi-major axis  slightly larger than Earth’s.

Orbit of 2012DA14

Orbit of 2012DA14 via OAM.

2012DA14 is also a spectral class L asteroid, a ‘stony’ class of asteroid that are quite rare and appear very red in spectral analysis.  In terms of Earth hitting potential stony is better than predominantly metallic, which would have far more mass per volume and make a far larger dent in our little planet.

Can I see it?

If the clouds play ball and your sky is dark and pointing the right way then you can find it in binoculars or a small scope.  It will be around Magnitude 7 at it’s brightest so will rank as one of the brightest if not the brightest asteroids to pass near Earth in recorded astronomy.  In the UK it will pass over the East-North-East horizon about 19.30 (depending on exact location) and then it will climb though the constellations of Coma Berenicies, Canes Venatici then into Ursa Major about 2100, passing through the ‘handle of the plough’ just after 2130.  Below are two excellent maps from the British Astronomical Association’s Asteroid section.  (Please do visit their site and see more of the information for yourself!)

BAA chart for 2012DA14

Chart compiled by Richard Miles. 1950-2100 GMT BAA

BAA chart for 2012DA14

Chart compiled by Richard Miles. 2100-0100 GMT BAA

For those with AZ mounts some co-ordinates have been compiled by a friend of mine (thanks Eric!) from The Baker Street Irregular Astronomers, based on observing from West London.

For those with Az-ALT mounts these are the co-ordinates (and magnitude) between 20:00 and 00:00
2013-Feb-15 20:00 m 76.5190 5.4035 7.62
2013-Feb-15 21:00 m 59.8424 36.6396 8.62
2013-Feb-15 22:00 m 44.0305 50.8595 9.69
2013-Feb-15 23:00 m 30.1030 56.4436 10.51
2013-Feb-16 00:00 19.3666 58.1381 11.13
For those wishing RA DEC co-ordinates, they are
2013-Feb-15 20:00 m 12 12 26.88 +12 36 06.7 7.62
2013-Feb-15 21:00 m 12 25 10.84 +45 53 18.9 8.62
2013-Feb-15 22:00 m 12 38 55.26 +62 48 41.2 9.69
2013-Feb-15 23:00 m 12 53 50.82 +71 46 52.4 10.51
2013-Feb-16 00:00 13 10 21.29 +77 05 05.6 11.13

Of course contact your local Astro society (list can be found at Active Astronomy) and find out if they are having an observing event on 15th February 2013 and if not get out there and enjoy from your own garden.

Good hunting and remember it’s NOT going to hit!

Posted in Asteroid, Astronomy, Baker Street Irregular Astronomers, Binoculars, End Of World, Telescope, The Astronomer's Den | Tagged , , , , , , , , | 4 Comments