Citizen Science is where a single citizen or a croud of people do take part in science. They are no professional in the field they take part in.
The citizen scienitsts do either take data or they analyse the data. One single citizen scientist cannot take a lot of data or analyse it, but the croud is powerful in doing so.
While citizen scientist were in the past individuals, like William Herschel, in the present a large croud of people do take part in science whenever a large amount of data is needed or needs to be analysed.
To take data a certain amount of effort is needed. Amateur astronomers need the right place, right time and right equipment to succsessfully take data. On the other hand to analyse the data, a certain amount of knowledge is needed.
Saturn image taken by an amateur astronomer (Ian Griffin)
I did often analyse data in different Zooniverse projects. So I know how the projects work. I think there are two kind of projects. There are projects where you only classify and projects where you search&map.
The projects where you only classify are for example Galaxy Zoo (GZ) or Supernova Hunters. Both already did pre-classify objects that are now in the centre of the image and you only have to say what it is.
The search&map projects do not have a narrow pre-classification and you have to search inside the image the position of the objects and mark them. Examples are the Milky Way Project (MWP) or Backyard Worlds.
Left: Galaxy Zoo image/ Right: Milky Way Project image
The galaxy in GZ is in the centre, while the bubbles in MWP are not in the centre
Other analyse-projects work within the two type of projects, also non-zooniverse projects, which are large in number. A good website to search for citizen science projects is SciStarter. For example: Ther is currently no project that includes archeology in the Zooniverse, but the project GlobalXplorer does help archeology to identify looting.
Many projects also have the goal to find new and unusual objects. The past of citizen science does show many examples of successful findings of new and exciting discoveries by volunteers:
Hanny’s Voorwerp in Galaxy Zoo by Hanny van Arkel:
Green Pea Galaxies in Galaxy Zoo by volunteers:
Paired Doves in Gravity Spy by Barbara Téglás:
The Coffee Ring in the Milky Way Project by ZUCCO66 and volunteers of the first MWP:
Aurora documentation of the USS Jeanette in Old Weather by Julia Wilkinson: