A “shooting star” is the visible streak of light produced when a meteoroid—a small piece of space rock or dust—enters Earth’s atmosphere. Many people imagine these events lasting for several seconds, slowly arcing across the sky. In reality, the vast majority of meteors are incredibly brief, a fleeting flash that can easily be missed. This rapid appearance and disappearance is driven by the extreme physics of an object traveling at interplanetary speeds meeting the resistance of our atmosphere.
The Typical Duration of a Meteor
Most visible meteors are exceptionally short-lived events, typically lasting for less than one second. It is rare for a common meteor to remain visible for two or three seconds. This extreme brevity is a direct consequence of the meteoroid’s immense entry speed, which can range from about 25,000 to over 160,000 miles per hour (11 to 72 kilometers per second).
The particles that cause these streaks travel a relatively short distance through the atmosphere before they are completely consumed. The luminous path usually begins around 75 miles above the surface and ends between 30 and 60 miles up. The object moves so fast that it traverses this window of visibility in a fraction of a second.
What Causes the Light to End
The intense light streak is not the meteoroid burning, but rather a process of superheating the surrounding air and the material of the meteoroid itself. The enormous speed of the object compresses the air in front of it, which instantly raises the temperature to thousands of degrees. This compression-induced heat is the main reason for the glow, not simple friction.
This extreme heat causes the outer layers of the meteoroid to vaporize, which creates a luminous trail of gas and dust. The light stops quickly because the meteoroid is rapidly eroded and consumed by this process as it slows down. Once the particle is completely vaporized or has decelerated significantly, the superheating of the air ceases, and the light streak disappears.
How Speed and Size Change the Streak
The duration and brightness of a meteor streak are heavily influenced by the size and speed of the incoming space debris. Larger meteoroids contain more mass to ablate, meaning the process takes slightly longer, which results in a marginally longer streak of light. However, the effect of velocity is often more dramatic than size.
Faster objects compress the air more violently, generating more heat and a much brighter flash. This intense heat often causes them to ablate and disintegrate more quickly. However, an object entering at a very shallow angle will traverse a greater amount of the upper atmosphere, potentially extending the total time the streak is visible to several seconds.
Fireballs and Bolides: The Longest Events
The rare, exceptionally bright meteors known as fireballs and bolides represent the longest-lasting events. A fireball is any meteor that appears brighter than the planet Venus. These events are caused by larger objects, often the size of a marble or grapefruit, which possess enough mass to survive longer in the atmosphere.
A bolide is a specific kind of fireball that explodes in a bright flash or produces a loud sonic boom. Due to their greater size and mass, fireballs and bolides can sometimes be observed for several seconds. The longest-lasting events occasionally reach up to 10 seconds, particularly if they enter the atmosphere at a shallow trajectory. These rare occurrences are the exception to the rule of the fleeting “shooting star.”