SOLVE magazine Issue 03 2021 | Page 26

Sloan was the first real digital view of the whole sky , and the universe came to life with digital camera technology – technology that astronomy helped to develop . – Professor Bob Nichol
it of seabirds or in the discovery of new exoplanets . These citizen scientists have since provided almost 600 million classifications and contributed to more than 100 peer-reviewed science papers .
Strong advocacy for the scientific usefulness of Zooniverse comes from internationally prominent astronomers who helped mastermind Galaxy Zoo in the first place . Included are Daniel Thomas , Portsmouth Professor of Astrophysics and Head of the School of Mathematics and Physics , and Professor Bob Nichol , Portsmouth Pro Vice-Chancellor of Research , Innovation and External Relations , and previously Co-director of the Institute of Cosmology and Gravitation .
They say the turning point for this extraordinary community collaboration was the digital revolution in how data is captured . The Sloan Digital Sky Survey ( SDSS ) that was launched in 1992 and commenced regular survey operations in 2000 played a pivotal role in the decision to engage the general public .
Digital window opens “ Sloan was the first real digital view of the whole sky , and the universe came to life with digital camera technology – technology that astronomy helped to develop ,” Professor Nichol says .
“ Digital imaging meant we could scan the sky with a level of depth and sharpness that was
Galaxy categories
Astronomers classify galaxies into three major categories : elliptical , spiral and irregular . These galaxies cover a wide range of sizes , from dwarf galaxies containing as few as 100 million stars to giant galaxies with more than a trillion stars .
Ellipticals , which account for about one-third of all galaxies , vary from nearly circular to elongated . They possess comparatively little gas and dust , contain older stars and are not actively forming stars anymore . The largest and rarest of these , called giant ellipticals , are about 300,000 light-years across . Astronomers theorise that these are formed by the mergers of smaller galaxies . More common are dwarf ellipticals , which are only a few thousand light-years wide .
Spiral galaxies appear as flat , blue – white discs of stars , gas and dust with yellowish bulges in their centres . Spirals are actively forming stars and comprise a large fraction of all the galaxies in the local universe .
Irregular galaxies , which have very little dust , are neither disc-like nor elliptical . Astronomers often see irregular galaxies as they peer deeply into the universe , which is equivalent to looking back in time . These galaxies are abundant in the early universe , before spirals and ellipticals developed .
Aside from these three classic categories , astronomers have also identified many unusually shaped galaxies that seem to be in a transitory phase of development . These include those in the process of colliding or interacting , and those with active nuclei ejecting jets of gas . revolutionary . And for the first time , in colour . “ But it gave us more data than we knew what to do with .” At stake was the opportunity to record and study millions of galaxies seen for the first time in such detail using all parts of the visible spectrum , from ultraviolet through to the reddest part of the spectrum . That onslaught of data has continued unabated , with SDSS still collecting spectral data today .
Professor Nichol describes the data collected by the SDSS as one of its greatest legacies : “ I ’ m very proud we realised early on that the data belonged to everybody and we made our archive available publicly .”
Professor Thomas suspected the images themselves contained valuable information and he made the seemingly irrational decision , given the sheer volume of data at hand , to attempt to classify galaxies into different types – for example , elliptical , spiral and irregular – manually , with the help of a student . The pair managed 50,000 – a herculean task that couldn ’ t even be called the tip of the data iceberg .
But it did prove an important point : the classifications were scientifically valuable . The structure of galaxies and their distribution contain clues about how galaxies form and evolve . It was a galling situation for Professor Thomas and his assistant that they lacked the means to classify more of the images .
At Oxford University , Professor Chris Lintott then made a radical suggestion to Professor Thomas : why not involve the public ?
“ It was one of those lightbulb moments , a great idea , and was the genesis of Galaxy Zoo ,” says Professor Nichol , who was asked to validate the idea and joined in because of his expertise in the SDSS .
Enthusiasm off the scale None of the academics , however , anticipated the public ’ s reaction … a reaction so enthusiastic that it crashed the server when Galaxy Zoo went live for the first time in 2007 .
Professor Thomas recalls being simply awed by the response . He watched , stunned , as the public achieved a staggering 70,000 classifications in just one hour on day two . Eight million were submitted in the first 10 days .
“ I really think it represented a new era in citizen science that was international in scope ,” Professor Thomas says .
With the platform allowing for two-way engagement with scientists , and forums for open discussions , the academics now better understand people ’ s motivation . And it was the same as theirs . People liked contributing to science and being part of scientific discovery .
ISSUE 03 / 2021