Green Fireball Lights Up Midwestern Night Skies


Meteor Spotted over the Midwest Carousel image: Screenshot from Lisle, Illinois, police video; Video: CNN
Meteor Spotted over the Midwest Carousel image: Screenshot from Lisle, Illinois, police video; Video: CNN

At about 1:30 in the morning on Feb. 6, 2017, a ball of flame shot across the dark skies above the Midwestern United States.

Because we live in a world filled with video cameras, even in the wee hours of the morning, there are several recordings of the event. You can see one above. It was pretty spectacular.

Three-hundred fifty-seven people (and counting at the time of publication) reported seeing the green fireball, according to the American Meteor Society. The cause of the fireball? A meteor falling through the atmosphere. As for the meteor, scientists aren't sure yet if any pieces landed or if the pressure the meteor encountered in the atmosphere reduced it to dust.

And why was it a lovely shade of green? The folks at the American Meteor Society explain that the color is related to the meteor's composition. An element will produce a specific color when it's vaporized. So, for instance, sodium will generate a bright yellow light, while nickel will produce a green light. The meteor's speed also factors into the color perceived by humans.

Whenever there's a story like this, it's a good time to review the categories of stuff in space. Here's a quick refresher course:

A meteoroid is a piece of a comet or asteroid orbiting the sun. Meteoroids aren't necessarily a threat to Earth unless the orbital paths grow close enough for Earth's orbit to pull the meteoroid toward it.

Meteors are what we get when a meteoroid enters Earth's atmosphere. As the meteoroid descends, it compresses the air below it. Compressing a gas causes the temperature to rise, which makes the meteor turn into a fireball.

Meteorites are bits of a meteor that survive the entry into the atmosphere and land on Earth. If the meteorite is large enough, it can cause a massive amount of damage. The June 30, 1908, Tunguska event in Russia was such a collision. The shock wave from the impact was strong enough to level nearly 800 square miles (2,000 square kilometers) of forest. A man sitting on his front porch 40 miles (64 kilometers) from the impact was thrown several feet and said he felt as if his shirt had caught on fire as a blast of heat traveled across the land.

The meteor over the Midwest was pretty tame compared to Tunguska. It provided a spectacular light show for the few who were awake and looking outside when it happened. The meteor was traveling faster than the speed of sound, which means it created a sonic boom. According to National Weather Service meteorologist Jeff Last, the shock wave rattled some windows in the region. It wasn't exactly a catastrophic event.

That appears to be the extent of the meteor's impact on life in the Midwest — unless in 20 years a mysterious, costumed hero starts flying around the world and rescuing people.