ISF Talks – Island Universes

I’ve recently finished delivering two public lectures on Galaxies at this year’s Inverness Science Festival.

The theme of my talks was ‘Island Universes’, telling the tale of when and how we discovered our Milky Way isn’t the only galaxy, and how the teeming multitudes of spiral nebulae, hitherto believed to be collapsing dust clouds, were in fact individual galaxies.

The talk started with some observational astronomy, before discussing the great debate of 1920 between Harlow Shapley and Heber Curtis.  The main unresolved issue here was the distance to the spiral nebulae, particularly Andromeda, which was unknown.  This lead us into pulsating stars and the work of Henrietta Swan Leavitt, who systematically analysed and determined the period luminosity law for cepheid variable stars.

Finally we discussed Edwin Hubble and the ramifications of his observations on the red shift of distance galaxies, and how this has informed our current understanding of the history and future dynamics of the universe.

I’ll let some choice slides do the talking from here on.

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Our own galaxy ‘The Milky Way’ is big.  If you tried to travel from our position to the galactic nucleus at the speed of the Voyager spacecraft it would take you over 400 million years.

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A 1900s image of the Andromeda nebula.  Back then the consensus was these spirals were large collapsing dust clouds, a bit like the star forming Orion nebula.  The idea that they could be separate galaxies like our Milky Way seemed inconceivable, yet that’s where the evidence eventually lead in the 1920s.

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Determining the distance to spiral nebulae (as they were known pre 1900) required a new way of determining distance from so-called ‘standard candles’.  Leavitt’s law was invaluable when Hubble turned his attention to Andromeda in 1922.

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Hubble discovered the galaxies were all rushing away from us.  However this phenomena is actually a metric expansion of space itself, and therefore has no intrinsic centre.  Some of the most distant galaxies are receding away at faster than the speed of light – again due to the expansion of space itself, which has no speed limit imposed.

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There were lots of questions on M87, the giant elliptical galaxy whose black hole was recently imaged by the Event Horizon telescope.

Q&As are always lively after astronomy and space talks, and the younger audience members always surprise me with their amazing knowledge and frank curiosity.  Some choice sample from the two evenings below.  Answers on a postcard please .

1. Is the singularity at the end of a black hole the size of the Planck length?

2. If a giant hole suddenly appeared in the Earth how many Pluto’s could you fit inside it?

3. Do supermassive black holes continue to grow until they devour the host galaxy?

GSC On Tour

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Ross teaching us how to make a comet in a bin bag!

We had a great day of outdoor and indoor astronomy learning with our guests from Glasgow Science Centre on Saturday.

Ross and Andrew travelled all the way up to the A9 loaded with space and science kit to kick off this year’s first daytime event for the Star Stories programme.

Ross ran a fascinating hands-on Comet making workshop in one of the outdoor woodcraft sheds, demonstrating how Comets form and disintegrate as they travel round the Sun.

Meanwhile Andrew presented an indoor planetarium show using a projector and Stellarium software, taking audiences across the night sky and explaining some of the science and mythology surrounding the constellations.

Everyone seemed to have a great time and we’re looking forward to continuing the summer programme with our Summer Solstice event on the 21st June.  Please check my facebook page for booking details in the weeks ahead.

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Interactive exhibits kept the youngsters entertained between learning streams

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Outdoor astronomy learning

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Andrew’s star hopping presentation

 

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Stargazing at Roseisle

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Starry skies over the Moray coast

Amidst a very busy schedule last month I managed to head out to Roseisle (along the Moray coast) for some observing and a wild camp.  My original mission was to try and catch a geomagnetic storm predicted by the MET office space weather forecasts.  As it happened the promised aurora didn’t arrive but I did manage to get some photos of the starry skies that opened up on Saturday night, starting with the International Space Station.

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Not the most fantastic ISS shot but I only had about 20 seconds to set up after running down the dunes to capture the pass!.  The station is actually travelling from west to east here, towards Sirius (bright star on left)

From there I took a number of pictures hoping to capture some aurora, but instead imaging the crisp starry skies.  I’ll let the photos do the talking from here – please read the caption notes.

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This image of the Plough (minus Alkaid) was snapped while I was still under the trees, on my approach to the beach.  You can clearly see the naked eye double star Mizar-Alcor at the bottom of the image.  The main stars in the Plough are roughly 100 lights years away.  Our Sun would not be visible naked eye if placed this far away which tells us something about the scale and luminosity of these titan stars.

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Looking north towards Burghead where I hoped to capture some aurora.  Instead I picked up the rich star fields within the Milky Way near Cassiopeia.

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One of many passing satellites.

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An interesting shot looking north west.  The bright white light is the Portmahomack lighthouse and the orange light pollution on the right is likely from Helmsdale.  Perhaps the most interesting feature in this photo is the faint smudge of light in the top left.  That’s the Andromeda galaxy – a separate spiral galaxy (larger than our Milky Way) over 2.5 million light years away.

Urban Astronomy Inverness

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The formation of a young protostar following the collapse of a previously inert dust cloud

We had a great turnout for March’s Urban Astronomy session last week at the Sea Cadet’s Hall in Inverness.  The indoor presentation massively benefited from our new giant screen, expertly erected by Robbie (pictured below).  Here’s a selection of slides from my presentation on naked eye observing and the life of giant stars.

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Robbie putting the final touches to our new giant screen for indoor astronomy presentations and virtual sky guiding

Topics covered:

– Naked eye and binocular observing
– Satellites: Iridium Flares and ISS
– Colour, temperature and mass of stars
– The Hertzsprung-Russell diagram
– Protostar formation from dark nebulae
– Main sequence burning and final fate of stars
– White dwarfs, supernovae, neutron stars and black holes.

As ever there were some superb questions during and after the talk.  Stay tuned for upcoming events as myself and Caroline roll out the program.

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In the simplest terms stars behave like black body radiators with colour linked to their surface temperatures.

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The brightest stars in the night sky can be close – like Sirius – or giant stars very far away (eg. Betelgeuse, Rigel, Deneb).

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The HR diagram.  An elegant and reliable tool for describing the evolution of stars from main sequence burning into their final stages of life

Island Universes – Inverness Science Festival

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Face-on spiral galaxy NGC 6814

I’m looking forward to presenting another astronomy talk for the 2019 Inverness Science Festival.  Talk details below:

Astronomer Stephen Mackintosh from Highland Astronomy will take you on a journey through space and time, looking at the massive stellar structures that make up the observable universe – Galaxies.

How did we discover them, how many are there and what do they tell us about the immense scale and dynamics of the universe?

Plus tips and advice on observing galaxies and other faint deep sky objects for yourself.

Time:  7pm – 8pm,  8th May 2019

Venue:  Main Lecture Theatre, UHI Campus

Booking links:  Eventbrite

 

Upcoming Astronomy Outreach

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Here’s an updated list of events I’ll be hosting with Abriachan Forest, the Merkinch Nature Reserve in Inverness and others.  Tickets can be picked up via eventbrite (linked) or email contact.  Please follow the links below.

Saturday February 9th – Star Stories Aurora special with special guest Graham Bradshaw of Graham Bradshaw Photography.  Almost sold out, only a couple of adult and child tickets left.  Eventbrite link here.

Saturday 9th March – Star Stories Dark Sky Observing.  70% of tickets already allocated for this one.  Eventbrite link here.

Thursday February 28th – Stargazing and Guide to Deep Sky Observing at the Inverness Sea Cadet Hall and in partnership with the Merkinch Nature Reserve.  Event details here.

Thursday 28th March – The Life of Stars at the Inverness Sea Cadet Hall and in partnership with the Merkinch Nature Reserve.   Event details to be added.

I’ll also be involved in outreach at some festivals this year.  So far I can confirm my attendance at SCAPA Festival at Loch Fyne on the 3rd to 5th May  Details on the festival and booking info here.