European space scientists ask the public for help to spot signs of activity on a comet.
For two years, between 2014 and 2016, the European Space Agency Rosetta spacecraft overtaken by comet 67P/Churyumav-Gerasimenko, also known as simply 67P. This ambitious mission was the first to meet a comet and stay with it as it swung past the sun. It was the first opportunity to observe closely how a comet produces its distinctive tail.
Comets are extremely ancient objects in the solar system, made of a combination of rock and ice, loosely cobbled together into oddly shaped objects just a few miles in diameter. 67P is about three by five kilometers and is shaped like a rubber duck.
Most comets are found in the cold depths of space beyond Neptune, where they remain still and frozen. But every now and then one of them wanders inward toward the sun. As it approaches the inner solar system, the sun’s heat evaporates its ice, and water vapor and dust rise from the surface to form the long, beautiful tails we occasionally see draped across our heavens on Earth.
67P has an orbit that only takes it to Jupiter. As a result, it makes repeated visits to the inner solar system every 6.5 years, making it a good target for study. Other known visiting comets have much longer orbits. The most famous – Halley’s Comet – takes about 75 years to travel around the sun and takes it as far as Pluto.
During her mission, Rosetta almost 100,000 images of the entire surface of the comet. Now the space agency is asking for the public’s help to sift through them to track down any changes that took place as it tracked the comet around the sun.
It turns out that the human eye is the best tool for discerning subtle changes in images of the spacecraft. Images of the comet are variable due to the ever-changing point of view and illumination of the comet. This makes it difficult to automate the process of observing the comet, since computers cannot tell the difference between changing lighting and perspective and actual changes to the comet. The human eye and brain are still unrivaled in these types of pattern recognition tasks.
Using a program called soniversepeople can view before-and-after images of a region on the comet and notice any differences.
Some changes are minor. A new crack may appear, or a rock may change position because material has eroded beneath it. Volunteers will need to look closely and carefully, such as those challenges in magazines that instruct the reader to identify the differences between two nearly identical photographs or drawings.
The goal of the project is to determine exactly how a comet loses ice and dust, where the material comes from — whether it comes directly from the surface or through vents — and how much the comet is affected by the sun’s heat.
Scientists hope this will provide information about the life cycle of a comet, especially a comet like 67P that returns regularly. Those visits will eventually erode all the ice from the comet’s mass, reducing it to a flying mess that no longer develops a tail.
Comets have been the subject of lore for centuries and arouse both fear and fascination. Now is your chance to contribute to real science and get up close and personal with one of these dazzling celestial visitors from deep space.
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