Date: March 11, 2009

Title History by Starlight

Podcaster: Colin Stuart

Description: Two subjects more than any others capture my attention and fire up my over-active imagination. Join me as I bring together history and astronomy to celebrate IYA 2009. The fact that the speed of light is finite means you aren’t looking at the stars as they are now but as they were in the past. How far in the past depends on how far away those stars are. In this episode we take a tour of tonight’s night sky and are transported into the past, exploring what was happening on Earth when light left these cosmic time machines.

Bio: Colin Stuart is a freelance science communicator from the UK. Having spent 3 years in rainy Manchester taming the strange beast that is astrophysics, he now lives in London where he spends a lot of his time presenting astronomy shows in The Peter Harrison Planetarium, at The Royal Observatory, Greenwich. He also regularly appears across the internet and in podcasts and radio shows including The Jodcast, Science Made Fun and Capital Science.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by Charles Van Orden on behalf of his favorite future astronauts, Colt and Dakota Worley.

Transcript:

Hello Everyone. My name is Colin Stuart.

As a child two subjects more than any others captured my attention and fired up my over-active imagination. Both could transport me to places physically unreachable but yet places that offered so much. These pillars of my childhood were astronomy with its shear scale and grandeur and history with its tales of kings, queens, wars, exploration and fascinating people.

In today’s 365DaysofAstronomy podcast I am going to join the two subjects together to weave a historical tale into a guided tour of tonight’s night sky. If you are able, download this podcast to an MP3 player, take me outside with you and enjoy the historical wonders the night sky has to offer. The tour is based on the night sky from England on 11^th March 2009. If you can’t do this or you live in the an area of the world where these stars aren’t visible then I hope you can still enjoy the story and feel inspired to think about the historical tales hidden behind your night sky.

Here’s the thinking behind it. The fact that the speed of light is finite means you aren’t looking at the stars as they are now but as they were in the past. How far in the past depends on how far away those stars are. So stargazing transports us into the past, back to the time when the light left these cosmic time machines in the sky.

Tonight the Moon dominates the sky. Light, the fastest thing in the universe, takes just over a second to traverse the quarter of a million miles to the Earth. In just the time it takes for a human heartbeat light from the Sun bounces off the Moon and into your eyes.

Let your eyes wander away from the spectacle of the moment and drift your gaze up and to the right until you rest upon the first bright object that you see. Whilst this may look like a star it is in fact a planet, perhaps the most famous planet in our Solar System, Saturn. The light reaching your eyes from this majestic planet has taken around about an hour and a half hurtling past Jupiter and Mars for us to see. What were you doing an hour and half ago? In the time it takes for Saturn’s light to reach us you could watch a soccer match or even fly from London to Amsterdam.

Now head back to Moon and follow almost a straight line across to the right. Shortly, you’ll stumble upon a very bright star that seems to be twinkling more violently than almost any other. You have found Sirius, the brightest star in the sky. Sirius is around eight and a half light years away. When light left the Sirian star system September the 11^th was just another day of the year, Vladimir Putin and George W Bush were elected presidents of their countries and astronomers enjoyed a rare conjunction of seven astronomical objects.

Move your stare upwards and to the right and stop when you find a bright star. This is Procyon. The light from Procyon reaches your eyes with echoes of 1998; a year when President Clinton denied having sexual relations with that woman and in April the Good Friday agreement brought a peace plan to the troubles in Northern Ireland.

With Bill’s words still ringing in your ears, trace a path in the sky straight up from Procyon until you reach the next bright sun with its hidden historical secrets. This is Pollox, one of the heads of Gemini, the twins. Then keeping Pollox in mind transfer your view about 45 degrees up to the right until your eyes dwell upon the next bright star you see, Capella. Pollux and Capella are almost the same distance from the Earth, however, in the window between light leaving one and the other Neil Armstrong planted his foot into the lunar dust and became the first human to set foot on another world. Oh and Barack Obama was just seven years old.

Head straight down from Capella and you’ll spot a cluster of stars in the shape of the letter V. This V makes up the head of Taurus the Bull. The brightest star, the Bull’s Eye, is Aldebaran. This transports us back now into the first half of the 20^th Century to 1949 when the horrors of World War Two were still fresh in the memory. In the last year of the forties, NATO was created, 1984 was published and the de Havilland comet became the first jet powered airliner to take to the skies.

Lets leap back to the 18^th century. To the left of Taurus is perhaps the most famous constellation of them all and he dominates the sky. Orion the Hunter is recognisable by the three stars all neatly lined up that make up Orion’s Belt. Move from the belt up to the right as you look to what is actually Orion’s left shoulder. This is Bellatrix. The light now dancing on your retina is 243 years old. In 1766 the Solar System in our minds had only 6 planets with Uranus still 15 years away from being discovered, George III sat on the throne of England and Napoleon Bonaparte was still three years away from entering the world.

Inch your pupils left, across Orion’s collarbone, move them around his neck and rest your gaze upon his right shoulder, the red giant star that is Betelgeuse. The year in which light left the cool surface of this bloated star was just 355 days long; ten days had to be cut out of the calendar which the adoption of the Gregorian calendar. 1582 was also the year that an eighteen year old William Shakespeare took his wedding vows.

Wrench your eyes away from Betelgeuse and cut your way across Orion’s belt down to the star that is Orion’s left boot. This gorgeous twinkling fireball is Rigel. In the century that the photons streaming through your eyes were hurtling away from this star some of the most famous figures in history were doing their thing. The twelve hundreds were the years of Genghis Khan, Marco Polo and William Wallace. In 1215 just a couple of miles downriver from the town where I was born King John was forced to scribble his name on the Magna Carta.

And it is with birth that we are going to finish our tour of history by starlight. Unless you are in an area with lots of light pollution you should be able to spot a smudge lurking beneath Orion’s Belt. Astronomers call this fuzzy patch M42 or The Great Nebula in Orion. This region of space covering no more than a fingernail in the sky is a vast star nursery, a place where brand new stars are igniting out of the cosmic dust. Some of the stars in this sun factory are just a few million years old, some of the youngest stars around. When those stars awoke into existence from their dusty beginnings dinosaurs still ruled the planet and the Earth had no intelligent life to gaze up into the heavens and marvel at the beauty and wonder stored within.

I hope your have enjoyed history by starlight. I will be back in a month’s time with the tale of Subrahmanyan Chandrasekhar’s fifty year journey from the sweltering heat of Madras to the esteemed Nobel Prize ceremony in Stockholm. Until then, enjoy IYA 2009!

365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.