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For the past eight years I have been asked to submit astronomical evidence to court cases across Australia.
Normally, when we think of evidence in court, we think of eyewitnesses, DNA, or police reports. Often this evidence requires an expert to explain it – to communicate the findings and data to the members of the court in order to make an informed decision. These experts are usually in medicine, engineering, psychology, or other fields.
Expert astronomers are not usually what one imagines in court, but that’s exactly what I do.
The first time I was asked by the police came as a surprise. I never thought of applying astronomy to the courtroom. Once the first group knew I could do it, more and more requests came in, from colleagues in the same police force or department, or detectives who had seen my evidence elsewhere.
Related: Whose is the moon? Law and space treaties
Now I am being asked to submit evidence for about 1-2 cases a week. Usually this requires filing a statement of evidence with the court. But sometimes I am asked to attend court and explain what the evidence means.
When I am needed as an expert in court, it is usually for important matters. My evidence is either crucial to part of the case, or the case itself is quite extensive and all details are checked and verified.
But what exactly am I providing evidence for?
Following the sun and moon
Most of an astronomer’s judicial evidence involves calculating the positions and illuminations of an astronomical body – the sun or the moon. Fortunately, the tools we use to calculate the positions of celestial objects are very accurate and can be calculated hundreds to thousands of years into the past or future.
An obvious example is when someone claims that the sun was in their eyes, making them sparkle, and they get into a car accident. Someone has to say where the sun was, its position and how it was aligned with the street and the direction of travel. At certain times and in certain directions, the sun can indeed obscure one’s view.
There is also the situation where someone sees something, but it happened around sunrise or sunset. It takes an expert to say what the illumination level was, as there are very clear definitions based on the sun’s position below the horizon and how much you can see. What if the event happened five minutes after sunset, for example? The light level depends on the time of year, location and other factors. It’s not a clear case of day versus night.
The moon can also appear in court evidence. Especially in dark locations, away from city lights, an astronomer can prove how much light the moon has given on any given night.
There are also historical instances or times when people notice the view or phase of the moon as a way of determining when something happened. The full moon has a precise definition, but the day before or after can resemble a full moon, despite not technically being full.
The limitations of expertise
Of course, like any part of science, there are limits to what I can say. If someone looked through a window – how breaking was the window? Were there clouds blocking the moon or sun? It is up to other experts and other parts of the legal system to resolve these factors.
Like many fields, space technology is changing, and so is its impact on law and crime. Satellites are increasingly being used in cases to track things as they happen. For example, the space technology company Maxar operates some of the highest-resolution commercial satellites to image the Earth. For a small fee, people can command these satellites to look at certain areas and/or times.
Lately we’ve seen the impact of satellites on Russia’s war in Ukraine, and how they’ve played a role in watching troop movements, and even providing evidence of some of the alleged war crimes.
Satellite images have been used for various criminal investigations, such as people smuggling or illegal mining.
They are also used in criminal cases in Australia. This is yet another situation where an expert is needed to explain the satellite imagery and what it might mean, or even how to access it.
Experts are vital
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Working as an expert witness has given me hope be
cause I see how far the justice system sometimes goes to get all the details right – like taking into account the position of the moon or the position of the sun. It is also the perfect example of the importance of experts in our society.
In science, we actively encourage people to turn to sources of accurate and reliable information, especially in an era of widespread misinformation.
Through experts, fields such as space travel and astronomy can directly impact people’s lives – even in court.
