A devastating cluster of tornadoes that hit the southern U.S. between April 25 and 28 left tracks large enough to be seen by satellite. This image, taken by NASA's Aqua satellite on April 28, shows two brown paths cleared of vegetation and cutting through Smithville, Miss., (bottom left) and northwestern Alabama (center).

The National Weather Service rated the Smithville storm at EF5, which means it was strong enough to collapse a concrete building, according to NASA Earth Observatory. That storm killed at least 14 people. The tornado in the Alabama track was rated at EF4 and killed more than 20 people. Its path is about 12 miles long.

The overall late April storm system created an estimated 305 tornadoes, the greatest number of tornadoes on record for one event, according to the National Oceanic and Atmospheric Administration. Tornadoes across seven states killed 342 people and several hundred are missing, according to MSNBC.

—Francie Diep