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?

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

 

ISS Returns

The International Space Station returns to Scotland’s skies on January 25th.  I’ve put together a short informative video on the station linked below.  Please also find the first few flyby times.  I’ll be posting live prompts on my Highland Astronomy FB page when I can.

List of the first few bright ISS passes:

  • Friday 25th Jan at 19.07pm
  • Saturday 26th Jan 18.19pm
  • Sunday 27th Jan 19.00pm
  • Monday 28th Jan 18.09pm

 

 

The Quadrantids Meteor Shower 2019

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The Quadrantids meteor shower will peak on the night of Jan 3rd/4th

Although not normally singled out as a major meteor shower, the 2019 Quadrantids will peak under the darkness of a new Moon, offering the best chances of seeing an abundance of shooting stars if you can get away to a suitably dark location under favourable skies.

Like the Geminids, the Quadrantids are not produced by the debris from a comet, but by a large asteroid.  In this case asteroid 2003EH1 which orbits the Sun every five and a half years.

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An asteroid – 2003EH1 was discovered by Peter Jenniskens and astronomers of the LONEOS programme in Arizona

The time to begin looking up will run from January 1st until the 6th.  However rates will be low in general over this wide period.  For the best spectacle try and head out over the narrow peak of the shower, after midnight on January 3rd, when for a few hours the shower can theoretically produce between 50-100 meteors per hour, but only under ideal conditions.

If you’re observing close to midnight at Inverness latitudes (57 degrees) the radiant will be about 22 degrees high.  Therefore a more realistic estimate would be 20-30 per hour.  Stay out later and the radiant will rise higher increasing the theoretical rate.  If you’d like to know more about the technical considerations when estimating visible meteor rates check out this excellent blog post by Steve Owens.

The rough radiant for the Quadrantids is the constellation Bootes, although you don’t need to look in this direction to see them.

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Remember you don’t need to look at the radiant when viewing a meteor shower

Observing the Quadrantids

You don’t need any special equipment to view a meteor shower, in fact binoculars or telescopes will just narrow your field of view. Grab a deck chair or camping mat and a warm blanket, prepare a hot drink, wrap up warm and lay out under the darkest conditions you can find. It’s an excellent activity to do alone or if you have children they’ll love an excuse to get outside for some after dark play.

Put away any lights or bright mobile phone screens and simply look up and wait. Remember it takes up to 30 minutes for your eyes to fully dark adapt and any exposure to bright lights will start the process all over again. If you need a light, red leds or touches are best for preserving you night vision.

For optimal viewing, head out late at night after the Moon sets or in the darkness of the pre dawn sky., when the radiant is highest in the sky.

Photographing the Quadrantids

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If your have a DSLR camera and tripod, or a suitable phone app like NightCap, you could try capturing some meteors with this rough guide.

  1. Firmly attach you camera to the tripod.
  2. Disable autofocus and manually focus at some bright stars (make them as small and pin point as possible in your viewing screen)
  3. Set an ISO range somewhere between 1000-3000 depending on the capabilities of the sensor.  Mid 1000s is a good middle road.
  4. Turn off noise reduction or you’ll get big delays between each shot.
  5. Point your camera at a high and clear part of the sky.
  6. Shoot long exposures ranging from 10s to 30s, or simply use a remote shutter to take manual exposures.  Note:  don’t go crazy with very long exposures or you’ll get amp glow from the sensor.
  7. Take lots and lots of shots and be patient!

If your camera has a time-lapse feature you can automate the shooting process and tell the camera to automatically take 30 second exposures over a long interval.  Just watch out for dew forming on the lens if conditions are cold.  Some hand warmers stuffed into a sock wrapped around the lens will solve this particular issue.

Good luck and clear skies!

 

Bespoke Stargazing Experiences at the Torridon

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After the success of the first weekend stargazing experience I’m very pleased to be working with the Torridon to deliver bespoke evening stargazing experiences.  These evenings would make a very special treat for someone.

The skies around the Torridon are exceptionally dark with minimal skyglow.  Perfect for Moonless excursions under the stars.

Full details on the experience can be found here:

https://www.thetorridon.com/experiences/torridon-stargazing-experience/