Why this astronomer prefers ‘pristine’ 4.5bn-year-old asteroids


20 Feb 2024

Image: Dr Apostolos Christou

Dr Apostolos Christou is proud to work with interested amateur astronomers to further people’s knowledge of the wonders of this celestial field.

Research astronomer Dr Apostolos Christou has been interested in astronomy for as long as he can remember. He studied applied maths at the National and Kapodistrian University of Athens, before heading to the UK to undertake an MSc at the University of Edinburgh and a PhD in solar system dynamics at Queen Mary University of London.

His PhD research focused on modelling the changes in the orbits of the major planets and their satellites to understand whether these orbits are stable in the long term. “[We] discovered that no planet is stable forever!” Christou said.

He has worked at Armagh Observatory and Planetarium for more than 23 years.

Tell us about your current research.

I consider myself a planetary scientist interested in asteroids, comets and dust. These objects witnessed the birth and later evolution of our planetary system to the present date. By means of the telescope and of scientific analysis, we are getting better and better at reading back their testimony to ultimately understand where the planets, the Earth and even ourselves came from.

The vast majority of these first asteroids are not directly available for us to study, as they have been broken up by collisions. The few that are left relatively unscathed since their formation 4.5bn years ago are, scientifically speaking, extremely valuable and my work aims to distinguish between those pristine objects and the second-or third-generation fragments of their less fortunate brethren.

I am also excited about the idea of meteors streaking through not just Earth’s skies but those of other planets as well. Meteors are possible on any celestial body with an atmosphere: Mars, Venus, Jupiter, also some moons like Saturn’s Titan or Neptune’s Triton.

I think that Mars is special because of the possibility of people living there and I like to imagine that future human settlers on the planet will record these meteors on a regular basis either for scientific research or for leisure.

In your opinion, why is your research important?

This question can be asked and answered at different levels. Research is significant from a reputational standpoint. Having one’s scientific work published in peer-reviewed publications, or presenting your latest findings to a conference of world-leading experts is very important.

As the public face of space and astronomy in Northern Ireland (NI), Armagh Observatory and Planetarium delivers internationally recognised research in astronomy and related sciences and having our work published helps to present NI and the organisation in a positive light on the world stage.

What inspired you to become a researcher?

I’ve been interested in astronomy for as long as I can remember! I got my first telescope when I was about nine years old. It was a 40mm refractor, just barely able to show the planets as discs and the craters on the moon, but it felt magical, and we had some marvellous adventures together!

And I’ve always been good at mathematics, so looking for something that combines these disciplines seemed sensible.

Fortunately, I also encountered a string of inspiring mentors throughout every stage of my education and early career, from schoolteachers to university lecturers, project advisors and finally employers.

Most of all, I am thankful for my parents’ support and encouragement through both the good and the bad, and for giving me the space that I needed to discover my path.

What are some of the biggest challenges or misconceptions you face as a researcher in your field?

Modern astronomy research is extremely specialised, and each field of the discipline comes with its own bespoke terminology that can be difficult to penetrate.

In some cases, even the set of core competencies may vary. There are for example, many differences between astrophysics and planetary science. As a mathematician by training, I find my fellow planetary scientists to be receptive to concepts and ideas that may at first be unfamiliar to them.

I think that is because of the diverse nature of planetary science – you might say we have learned to talk to each other by virtue of necessity!

Do you think public engagement with science has changed in recent years?

Modern society is science-enabled but also somewhat science-illiterate. I think that the Covid-19 pandemic showed us what a potentially dangerous combination this can be.

Public engagement with science is one way to mitigate that risk. As a social activity, astronomy is a great way to bring out latent curiosity in people. I do not need to sell the view of Saturn’s rings or the craters on the moon through a telescope, as many people tend to find that interesting.

The hard part has always been to get them near a telescope under a (mostly) clear sky.

I have always strived to facilitate partnerships between the professional community and the public, usually through participation in hybrid professional and amateur activities, like international observing campaigns.

In my experience, amateur astronomers are generally highly driven, technically competent and capable of making important contributions to research-grade astronomy. Usually all that is needed is some guidance from professionals to point them in the right direction.

It is a source of personal pride to me that many of my publications in academic peer-reviewed literature feature amateur scientist authors.

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