The scientific legacy of 'undiscovering' an island
The 'undiscovery' of an island by a team of scientists led by the University of Sydney resulted in worldwide scientific debate, the correction of databases and a re-evaluation of the infallibility of certain information.
"The mystery of Sandy Island called into question how well humanity really knows our own planet," said Dr Maria Seton, from the University's School of Geoscience.
During the trip the team of Australian and international scientists 'undiscovered' Sandy Island, a 25km long and 5km wide feature, that appeared in numerous scientific data sets and in Google Earth but was absent from the hydrographic charts used onboard ship for navigation.
"The island was not there. The data we collected on the voyage and subsequently obtained from the Australian Hydrographic Service confirmed what we suspected - data sets showing the island were wrong."
There was intense global interest from traditional and social media and in Australia it became the most read story of 2012 on the Sydney Morning Herald's news website.
Extensive scientific debate followed, as the undiscovery appeared to contradict some of the most fundamental data sets used by the scientific community, including global coastlines, water depths and products from satellite imagery including Google Earth.
"The response to the 'Sandy Island' story highlighted the strength and enthusiasm of the scientific community in coming together to resolve a controversy through crowd‐sourced research," Dr Seton said.
The outcome was that databases on which the scientific community rely are being updated and others are in the process of being corrected.
In a recent 'obituary' for Sandy Island written for the journal EOS, Dr Seton and her colleagues explain that Sandy Island was first sighted by the whaling ship Velocity in 1876 and first appears on a British admiralty map in 1908. Over the years a failure to spot the charted island resulted in its removal from hydrographic charts.
The answer to why it persisted in other data sets lies in the freely accessible World Vector Shoreline Database, originally developed by the American military and widely used by the scientific community.
"During the conversion from hard-copy charts to digital formats the 'Sandy Island' error was entrenched," said Dr Seton. "Inconsistencies in this data set exist in some of the least explored parts of our planet, a result of both human digitising errors and errors in the original maps from which the digitising took place."
Dr Seton reflects that the experience demonstrated the genuine interest the general public has in marine science and Earth exploration.
"It also underscores that although global data sets are an invaluable resource, users must be aware of the uncertainties of raw data inputs and it points to the invaluable contribution of marine scientific research voyages for accurately mapping the oceans."
As to the origin of the non-existent island first sighted by Velocity one possibility is that the crew may have sighted a vast pumice raft, large areas of floating pumice formed as result of volcanic eruptions.
"Whether originally pumice or a figment of a whaling crew's imagination 'Sandy Island' has been a valuable mythbusting adventure for all involved," Dr Seton said.