GSI Seminar Series: Dr Raphaelle D. Haywood – There’s no place like home: Placing Earth in its astronomical and geological contexts

Blog written by Daneen Cowling

A new year and a new set of interesting seminars!

The first of 2022 was from Dr Raphaëlle Haywood, a Senior Lecturer in Physics and Astronomy at the University of Exeter. Dr Haywood gave an immense talk covering the hunt for exoplanets, how we find another Earth-like planet, and shared some important insights into why we should not assume there is a planet B.


On a finite world, a cosmic perspective is not a luxury, it’s a necessity

Caleb A. Scharf, 2014

Dr Haywood began with thought-provoking set of quotes and statistics that brought home the importance of why we need to have this astronomical view and appreciation of our position within it. To realise – like our humble blue planet – the existence of planets orbiting other stars is extremely common.

Particularly important – the occurrence of “Earth-like planets” are also common, potentially between 9-21% of suns have a planet like Earth. But what is a planet like Earth?

An Earth-like planet is similar to us in size – around a 1/2 to 1 radius of Earth. But importantly, it also sits within the habitable zone. This means it is a suitable distance from it’s sun to allow for 30-100% of heat received on Earth to permit liquid water.

Dr Haywood estimated that there could be 63 BILLION temperate Earth size planets in our galaxy.


How to find other Earths

Find Earth-like planets goes far beyond it’s size and sun distance – we have tools that help us find the signatures of Earth – of life.

Earth is a complex self-regulating system composed of interacting systems of the planets rocks, atmosphere, ocean and biosphere. We can use the biosphere and the signatures it produces to help in our exploration. But what does this look like?

Key components of our biosphere can be identified through their signature wavelengths. through the reflectance signatures, we can identify:

  • Water and Water Vapour
  • Oxygen and Methane – this tells us there is a chemical disequilibrium and therefore there is life, as oxygen and methane are the bi-products
  • Near-Infared (NIR) “red-edge” – a sharp rise at around 700nm on the reflectance spectrum tells us there is a prevalence of vegetation

This means, using these signatures and tools we can understand what might be on another planet.

This is an exciting time for planet search and discovery – as from this year (2022) a new TerraHunting project will kick off a 10-year survey of 40 sun-like stars, to explore the planets and their resemblance to Earth. From this project and the huge dataset it will create, NASA plan to use this data to strategically begin a direct-imaging project, able to measure actual temperatures and investigate the prevalence of atmosphere on these potential Earth-like planets, and ultimately contribute great strides to the search for extra-terrestrial life!


No Planet B

As exciting as finding another planet with life on, Dr Haywood set it straight that regardless, there is no planet B. Even if we wanted to set up camp on another planet, the distances involved are way beyond our technological capacities – our nearest Earth-like planet is 300 years away at the speed of light. Even our Mars neighbour is out of our technological capability to transform into a habitable planet for humans.

Dr Haywood then went onto remind us that our planet, through its geological history, has never been the same state – it has consistently shifted into new versions of itself. Even human civilisations have shifted the planet trajectory of Earth – in its appearance and its observable signatures from space. Our current state of Earth has electromagnetic signatures, masses of waste, chemical signatures in our atmosphere – but what would an Earth signature look like it if it was inhabited by only indigenous communities? Communities that are able to live harmoniously with the Earth and the complex systems that regulate it. Maybe, this sustainable way of life isn’t even detectable? What’s to say other occurrences of life won’t be living so sustainable they are undetectable?

Lots of questions and exciting developments taken to get closer to answer them will make the next decades of planetary exploration an exciting one.


To learn more about Dr Haywood’s work, see her profile here.

If you’re a member of staff or student of the University of Exeter, feel free to join a mini-module called “No Place Like Home”: https://vle.exeter.ac.uk/course/view.php?id=13080

It was created by Dr Arwen Nicholson, Federica Rescigno and Dr Haywood as part of last year’s Summer School on Sustainability that was organised by CEMPS.

To view the full seminar, you can watch the recording here.

For more GSI events, stay up to date on the GSI website.

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