You are here


March 3, 2018

A brilliant streak of light flashed above Long Island on the afternoon of October 18th, startling hundreds of observers. Another one was seen above northern New York a few weeks later. And in early January, yet another one punctuated the night skies of Manitoba and Ontario.

All three of these events were fireballs — chunks of space rock burning up as they slammed into Earth’s atmosphere.

At least one fireball streaks across the sky every day. But most of them happen over the oceans or uninhabited land, so no one sees them.

Space rocks pelt Earth all the time, forming the streaks of light known as meteors. Most of them are faint, so you need a dark sky to see them. They’re caused by small bits of rock — the size of BBs, for example.

Fireballs, on the other hand, are caused by much larger rocks — some of them as big as boulders. As one of these rocks plunges into the atmosphere at high speed, friction causes it to heat up and shine brightly. Friction also strips away much of its material.

As the rock plunges deeper into the atmosphere, it may explode. And if it’s the right size and composition, some of its remains may fall to the ground as meteorites.

NASA and others operate cameras that look for fireballs. Plotting a fireball’s path and appearance can reveal its size and where it came from. And that can tell spacecraft designers how much of a hazard space rocks can present — helping them protect their charges from a cosmic threat.

Script by Damond Benningfield

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.