You may be wondering how volcanic ash from Iceland erupting from underneath the Eyjafjallajokull glacier could be shutting down airports across northern Europe. Here’s 18 hours of satellite footage from April 14-15, 2010 that shows just how much ash is being produced and spread over European skies.

Thousands of flights have already been canceled due to this second eruption of the volcano. Apparently volcanic ash, which being mostly invisible to the naked eye from the ground in Europe, can disrupt jet engines. Scientists aren’t sure how long the eruptions will last but the last time in 1821, the volcano was active for over a year.

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