A citizen scientist is anyone who contributes to real scientific research without being a professional scientist. You don’t need a degree, a lab, or special training. If you’ve ever counted birds in your backyard for a wildlife survey, classified galaxy shapes on your laptop, or reported unusual lights in the sky to a research team, you’ve done citizen science. The concept is flexible and spans nearly every scientific discipline, from astronomy to ecology to public health.
What Citizen Scientists Actually Do
Citizen science covers a wide range of activities. At its simplest, you might collect observations: photographing plants, recording rainfall, or logging the species you spot on a hike. At a more involved level, you could be analyzing satellite images, sorting through telescope data, or transcribing historical field notes from museum archives.
The common thread is that nonprofessionals contribute work that feeds into legitimate research. Sometimes that means gathering data scientists couldn’t collect alone because of sheer geographic scale. Other times it means lending human pattern recognition to tasks that computers still struggle with, like distinguishing one bird call from another in thousands of hours of audio recordings. Some citizen scientists go further, helping to design research questions or interpret findings alongside professional teams.
Discoveries That Changed What We Know
Citizen scientists aren’t just doing busywork. Their contributions have led to findings that professional researchers missed or couldn’t have made alone.
In 2017, volunteers using data from NASA’s Kepler space telescope discovered a system of at least five exoplanets through a project called Exoplanet Explorers on the Zooniverse platform. It was the first multiplanet system discovered entirely through crowdsourcing. Researchers later confirmed the system, called K2-138, may even contain a sixth planet.
A year later, amateur astronomer Scott Tilley contacted NASA with an unusual claim: he believed he’d found a lost spacecraft. He was right. Tilley had picked up signals from IMAGE, a NASA satellite that had gone silent years earlier.
Volunteers scanning Kepler data through the Planet Hunters project also flagged an object whose light pattern was so unusual that researchers labeled it “bizarre.” That turned out to be Tabby’s Star, one of the most debated objects in modern astronomy.
Between 2015 and 2016, citizen scientists in online forums reported mysterious lights in the night sky to a project called Aurorasaurus. They nicknamed the phenomenon “Steve.” Scientists eventually confirmed it was a distinct atmospheric feature, not a traditional aurora, and gave it the formal name Strong Thermal Emission Velocity Enhancement. And since 1995, amateur comet hunters using real-time data from the SOHO solar observatory have found more than 3,400 comets, more than doubling the number of comets with known orbits over the previous 300 years.
The Scale of Participation Today
Citizen science has grown far beyond a niche hobby. iNaturalist, one of the largest biodiversity platforms, held over 200 million unique observations from 3.3 million observers worldwide as of September 2024. That volume of data, spread across every continent, would be impossible for any professional research team to collect on its own.
Zooniverse hosts over 100 active projects at any given time, spanning galaxy classification, wildlife monitoring, and historical document transcription. SciStarter, a hub that connects volunteers with opportunities, lists more than 3,000 searchable projects from universities, government agencies, and nonprofits. The Smithsonian and National Geographic also run their own citizen science programs, from climate research involving ginkgo trees to ecological monitoring through frog call recordings.
How This Data Shapes Published Science
Citizen science data doesn’t just sit in a database. A systematic review of 1,240 citizen science studies found that about half were empirical scientific articles, and roughly 20% used citizen-collected data directly to answer research questions. In ecology, for example, around 275 citizen scientists monitored coral transects over a decade, producing data that revealed significant coral decline. In ornithology, nearly 4,000 audio recordings collected by volunteers over six years formed the basis of published research. In astronomy, one analysis examined citations from 143 citizen science publications in that field alone.
These aren’t side projects. Citizen-collected data feeds into peer-reviewed journals and influences conservation policy, species monitoring programs, and our understanding of space.
How to Get Involved
Most citizen science projects require nothing more than a smartphone, an internet connection, and curiosity. Zooniverse projects, for instance, need no prior experience. You can start classifying galaxies, identifying kelp forests in satellite imagery, or locating structures in aerial photographs within minutes of signing up.
If you prefer fieldwork, iNaturalist lets you photograph any organism you encounter and upload it for community identification. Your observation becomes part of a global biodiversity dataset used by researchers worldwide. For something more structured, SciStarter lets you filter projects by location, topic, and age level, so you can find something that matches your interests and availability.
Some projects ask for more specialized effort. Monitoring water quality might require a simple test kit. Recording bird songs needs a quiet morning and a microphone. But the barrier to entry across most projects is intentionally low, because the whole model depends on broad participation.
Ethics and Credit
As citizen science has scaled up, questions about fairness have followed. Who owns the data you collect? Who gets credit when your observation leads to a published discovery? If you contribute personal health information to a biomedical study, what control do you retain over that data?
These aren’t hypothetical concerns. Ownership of research outputs has been identified as a significant practical, legal, and ethical issue across many citizen science projects. In biomedical citizen science especially, where participants sometimes share personal health data, volunteers may reasonably expect to access, control, or benefit from whatever comes out of the research. Some projects restrict participants from receiving interpretations of their own contributed data, which can feel paternalistic.
The ethical framework emerging around citizen science emphasizes respect for participants, inclusivity, and a fair balance of power between professional researchers and volunteers. That includes minimizing barriers to participation so the opportunity to contribute isn’t limited by income, geography, or education. Well-run projects are transparent about how data will be used, who benefits, and how contributors are acknowledged.