# How long between the moment a meteor is first visible and the moment a meteorite hits the ground?

A meteor is usually only visible for a couple seconds at most, but I would guess that it usually stops being visible high above the ground.

Meteors often don't make it to the ground as they completely burn up before. But among those that do reach the ground, how long does it take for a meteoroid to go through the Earth's atmosphere and hit the ground? How many seconds between the moment it is first visible and the moment it hits the ground?

• This is a fascinating question! Worldwide there are several Fireball Networks that triangulate in real time, and I think in some cases recovery crews will use an extrapolation/simulation to gauge where to star looking, but that could be days later. Presumably time to landing could be extracted from some of those models if they are detailed enough. (cf. 1, 2) – uhoh Sep 15 at 13:37
• Ob. reference : lpi.usra.edu/meetings/metsoc2010/pdf/5357.pdf . Which suggests that any meteor you actually see fall is not a meteorite. (Of course, arriving at that box is conditional on many other factors.) – Eric Towers Sep 15 at 21:16
• I recall, back around 1960, seeing a meteor while riding in the car with my parents. We stopped to watch it, as did several other cars. It was certainly in the air several minutes. (No way of knowing whether it "burned out" before hitting the ground, though.) – Hot Licks Sep 15 at 22:41
• Yeah, so fireballs can potentially last minutes if the entry angle (i.e. the slope) is very shallow. Typically these events are called 'grazing fireballs' and they can be quite spectacular. – Patrick Sep 16 at 3:50

## 1 Answer

I'm a researcher at Curtin University working on the Desert Fireball Network. The DFN is the largest fireball observation network in the world, and our primary goal is to recover meteorites with orbital information attached.

The traditional rule of thumb for meteorite-dropping events is a final luminous height below 35 km and a final luminous velocity below 10 km s-1

So when I refer to the luminous part of the trajectory, I am referring to the portion in which ablation is occurring and optical light is emitted. As you said, this portion typically lasts a few seconds depending on the initial size, strength, speed, and slope of the meteoroid. After this, if the object still has mass left, the speed continuously decreases. We call this portion of the trajectory the "dark-flight" (as opposed to the "bright-flight" which is the luminous part) because we can longer observe the meteoroid.

During the dark flight, the rock goes from <10 km s-1 to tens to a few hundred m s-1 when it finally impacts the ground as a meteorite. This part of the trajectory can be greatly affected by wind as seen below from the dark flight modeling done for the recovered Dingle Dell meteorite:

So, in total, from first becoming a meteor to impacting the surface, you should expect about tens of seconds to minutes to pass. Of course, this is dependent on things I have mentioned like mass, speed, and slope notably.

• Does it depend on the angle at which the object enters the atmosphere? – Rob Jeffries Sep 15 at 16:40
• Is -1 supposed to be a superscript? Use <sup>-1</sup> to display it as intended. Or you could use the less mathematical notation km/s – Barmar Sep 15 at 16:57
• "because we can longer observe the meteoroid." I take it "we" refers to ordinary people, and not people with sophisticated detectors? Or an even NORAD not observe a dark meteoroid? – Acccumulation Sep 16 at 3:22
• you can potentially still 'see' the rock during the dark flight using weather radar. Here in Australia, we have less dense coverage because no one essentially lives wherever our observatories are, but it is fairly common in the US to use weather radar data to help constrain the fall location of the meteorite. So even with our expensive cameras, we can't see the meteoroid during the dark flight. For us, this makes it even more important to have a good dark flight model. – Patrick Sep 16 at 3:55
• Just out of interest, how often do you manage to physically recover something you've previously flagged in space? – Valorum Sep 16 at 17:06