To TEDx Speaking and Beyond!

Back in April I received an invitation to speak at the ‘One Step Beyond’ TEDx event organised at the National Space Centre in Leicester, with my focus on the Blue Economy and Earth Observation (EO).

We’ve been to a few TEDx events in the past and they’ve always been great, and so I was excited to have the opportunity to join this community. Normally, I’m pretty relaxed about public speaking. I spend a lot of time thinking about what I’m going to say, but don’t assemble my slides until a couple of days beforehand. This approach has developed in part because I used to lecture – where I got used to talking for a while with a few slides – but also because I always like to take some inspiration from the overall mood of the event I’m talking at. This can be through hearing other speakers, attending workshops or even just walking around the local area.

TEDx, however, was different. There was a need to have the talk ready early for previewing and feedback, alongside producing stunning visuals and having a key single message. So, for a change, I started with a storyboard.

My key idea was to get across the sense of wonder I and many other scientists share in observing the oceans from space, whilst also emphasising that anyone can get involved in protecting this natural resource. I echoed the event title by calling my talk “Beyond the blue ocean” as many people think of the ocean as just a blue waterbody. However, especially from space, we can see the beauty, and complexity, of colour variations influenced by the microscopic life and substances dissolved and suspended within it.

I began with an with an image called the ‘Pale Blue Dot’ that was taken by Voyager 1 at a distance of more than 4 billion miles from Earth, and then went with well-known ‘Blue Marble’ image before zooming into what we see from more conventional EO satellites. I also wanted to take the audience beyond just optical wavelengths and so displayed microwave imagery from Sentinel-1 that’s at a similar spatial resolution to my processed 15 m resolution Sentinel-2 data that was also shown.

Dr Samantha Lavender speaking at the One Step Beyond TEDx event in Leicester. Photo courtesy of TEDxLeicester

The satellite imagery included features such as wind farms, boats and phytoplankton blooms I intended to discuss. However, this didn’t quite to go to plan on my practice run through! The talk was in the planetarium at the National Space Centre, which meant the screen was absolutely huge – as you can see in the image to the right. However, with the lights on in the room the detail in the images was really difficult to see. The solution for the talk itself was to have the planetarium in darkness and myself picked out by two large spotlights, meaning that the image details were visible to the audience but I couldn’t see the audience myself.

The evening itself took place on the 21st September, and with almost two hundred in the audience I was up first. I was very happy with how it went and the people who spoke to me afterwards said they were inspired by what they’d seen. You can see for yourself, as the talk can be found here on the TEDx library. Let me know what you think!

I was followed by two other fantastic speakers who gave inspiring presentations and these are also up on the TEDx Library. Firstly, Dr Emily Shuckburgh, Deputy Head of Polar Oceans team at British Antarctic Survey discussed “How to conduct a planetary health check”; and she was followed by Corentin Guillo, CEO and Founder of Bird.i, who spoke about “Space entrepreneurship, when thinking outside the box is not enough”.

The whole event was hugely enjoyable and the team at TEDx Leicester did an amazing job of organising it. It was good to talk to people after the event, and it was fantastic that seventy percent of the audience were aged between 16 and 18. We need to do much more of this type of outreach activities to educate and inspire the next generation of scientists. Of course, for me, the day also means that I can now add TEDx Speaker to my biography!

Can You See The Great Wall of China From Space?

Area north of Beijing, China, showing the Great Wall of China running through the centre. Image acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

Dating back over two thousand three hundred years, the Great Wall of China winds its way from east to west across the northern part of the country. The current remains were built during Ming Dynasty and have a length of 8 851.8 km according to 2009 work by the Chinese State Administration of Cultural Heritage and National Bureau of Surveying and Mapping Agency. However, if you take into account the different parts of the wall built by other dynasties, its length is almost twenty two thousand kilometres.

The average height of the wall is between six and seven metres, and its width is between four to five metres. This width would allow five horses, or ten men, to walk side by side. The sheer size of the structure has led people to believe that it could be seen from space. This was first described by William Stukeley in 1754, when he wrote in reference to Hadrian’s Wall that ‘This mighty wall of four score miles in length is only exceeded by the Chinese Wall, which makes a considerable figure upon the terrestrial globe, and may be discerned at the Moon.’

Despite Stukeley’s personal opinion not having any scientific basis, it has been repeated many times since. By the time humans began to go into space, it was considered a fact. Unfortunately, astronauts such as Buzz Aldrin, Chris Hatfield and even China’s first astronaut, Yang Liwei, have all confirmed that the Great Wall is not visible from space by the naked eye. Even Pixalytics has got a little involved in this debate. Two years ago we wrote a blog saying that we couldn’t see the wall on Landsat imagery as the spatial resolution was not small enough to be able to distinguish it from its surroundings.

Anyone who is familiar with the QI television series on the BBC will know that they occasionally ask the same question in different shows and give different answers when new information comes to light. This time it’s our turn!

Last week Sam was a speaker at the TEDx One Step Beyond event at the National Space Centre in Leicester – you’ll hear more of that in a week or two. However, in exploring some imagery for the event we looked for the Great Wall of China within Sentinel-2 imagery. And guess what? We found it! In the image at the top, the Great Wall can be seen cutting down the centre from the top left.

Screenshot of SNAP showing area north of Beijing, China. Data acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

It was difficult to spot. The first challenge was getting a cloud free image of northern China, and we only found one covering our area of interest north of Beijing! Despite Sentinel-2 having 10 m spatial resolution for its visible wavelengths, as noted above, the wall is generally narrower. This means it is difficult to see the actual wall itself, but it is possible to see its path on the image. This ability to see very small things from space by their influence on their surroundings is similar to how we are able to spot microscopic phytoplankton blooms. The image on the right is a screenshot from Sentinel Application Platform tool (SNAP) which shows the original Sentinel-2 image of China on the top left and the zoomed section identifying the wall.

So whilst the Great Wall of China might not be visible from space with the naked eye, it is visible from our artificial eyes in the skies, like Sentinel-2.