Big universities have staff members whose jobs it is to help professors get grants — whether by finding the right programs for their research, introducing researchers to potential partners, or sorting out the seemingly-endless paperwork. These folks often have graduate degrees and research backgrounds, so they know what research is. Like most people, they have a general idea of what astronomers study: stars and planets and stuff like that. But we often have to try to explain what astronomers do when we’re doing research, and what that research is good for. This is my attempt at such a general description.

Astronomical research is the same as other kinds of research in that our goal is to understand the world. We want to explain why the universe is the way it is and how it will change in the future. We work under the assumption that the laws of physics apply everywhere in the universe, although there are conditions found elsewhere in the universe that are not replicated on Earth. One major difference between research in astronomy and most other fields is that there’s little expectation that our results can be applied directly to our objects of study. We don’t expect to make new planets or galaxies in the same way that a botanist might be trying to breed a better tomato or a chemist create a new polymer.

Research in astronomy can be broken down into three categories. Researchers specialize in one or sometimes two of these, and there is plenty of crosstalk between them.

  • Observation: measuring emission from objects beyond the Earth. Mostly this is electromagnetic radiation, but gravitational waves and particles like neutrinos or cosmic rays are also important. We measure where the emission is coming from, how much energy it contains in different parts of the spectrum, its polarization, and how these change with time. We measure these properties for many objects so that we can understand the statistics of their populations. We interpret these properties and statistics using our understanding of gravitation, electromagnetism, quantum mechanics, and more: virtually every branch of physics has some application in astrophysics.

  • Instrumentation: we’re observing objects that are very faint or far away or both, and in most cases we can’t get closer to them. So we need very clever, sophisticated technology to detect and measure the tiny amount of energy that reaches us. Developing telescopes to collect light, and the complex instruments and software that analyze it, is an often under-appreciated specialty that bridges science and engineering.

  • Theory: theoretical astrophysicists attempt to understand the universe using physical principles. This involves solving physics equations to construct idealized models of astronomical objects like stars. Sometimes these equations are too complicated to be solved: instead we have to simulate astrophysical objects with computers to understand how they behave. Astrophysical theory makes predictions that can be tested by observations and in turn is used to interpret observations.

Astronomy’s goal is to understand the origins and fate of the universe in which we find ourselves. Many consider this a worthwhile goal in and of itself. But if you want applications, where to look? If you are reading this, you most likely live on Earth. Both the Sun’s energy output and the risk of impact by asteroids or comets are important for life on Earth. Predicting the future behaviour of objects in our solar system clearly has practical implications.

Knowing where things are in the sky is helpful if you want to know where you are on Earth or which way your satellite is pointing. It’s also useful for timekeeping, and the sky provided humans’ earliest external clock. The spatial reference frame provided by the Sun, Moon and stars has been used for millennia for navigation, and is still relevant in the GPS age. It seems to me that people in charge of detecting incoming missiles would want to know what things in the sky aren’t missiles (in the same way that Charles Messier cataloged things that weren’t comets) but I don’t know if this is actually important.

The direct applications of astronomy are relatively few, but there are numerous indirect applications. Astronomy was important in the early development of statistics; the relationship between the two lagged for a while but astronomy is once again driving innovation in understanding complex data. Spin-offs and technology transfer from astronomical instrumentation include devices and algorithms used in medical imaging as well as the CCD light sensor and Wi-Fi in your cell phone. Astronomers push the limits of computation and have since the days when computers were people. Would these advances have occurred without astronomy? It’s impossible to say, but sometimes an oblique approach to problems is really important: I’m reminded of the quote that “you don’t get the light bulb by funding research in candle technology.”

Astronomy has broad effects on society beyond technology. Like other sciences, it can help us place the state of our planet and society in a broader persective beyond the everyday. As the International Astronomical Union points out, the need to observe the whole sky has been a driver of peaceful international collaboration. I’ve argued that astronomy can provide a model for other sciences in its approach to data sharing.

It’s often stated that astronomy is a “gateway science”, drawing people into economically important careers. (I’m not aware of any empirical studies that support this, however.) People trained through astronomy research have a broad skillset including quantitative problem-solving, programming, statistics, data management, and communication of complex technical concepts. These skills are applicable to many fields beyond astronomy. While it be seem more straightforward just to directly train people to be data scientists or financial researchers rather than having them switch over from astronomy, those fields probably benefit from an outside perspective. (Again, I’d love to know of any research that addresses this question!)

What is astronomy good for? Knowing where and when we are and how we got here. Developing tools that might not otherwise exist and people who can solve problems with them. And inspiring us to think bigger and look beyond.

For more reading on this topic, see the “Astronomy and Society” chapter of the 2015 mid-term review of the ong-range plan for Canadian astronomy and the “Benefits to the Nation” chapter of the 2001 US decadal survey on astronomy.