Starship Asterisk*

Chris Peterson wrote:

DavidLeodis wrote:I would be grateful if someone could please clarify if the quadrillion in the explanation is the 10¹⁵ or the 10²⁴ definition of a quadrillion.

Since this is an American site sponsored by an American agency edited by American astronomers, I think you can safely assume "quadrillion" means 10¹⁵. (Which is quite close to being correct, given a meteor 100 km away and the nebula 7500 ly away.)

MarkBour wrote:

Chris Peterson wrote:As the meteor descends through the atmosphere, it encounters winds moving in different directions. That wind tears a persistent train in different directions. Most likely we're just seeing a transition in the middle of the train between winds blowing one way and winds blowing nearly opposite (not an uncommon occurrence). That split the train. The particular wind gradient is fooling us into thinking we're seeing a spiral pattern.

Thanks for the clarification. Is the green color in this persistent train likely produced by about the same process as in a green aurora ... oxygen transitioning back from an excited state? Can you tell from this image anything about the actual length of the train (e.g. to be specific, from the beginning to the end of the green region), its distance from the camera, and the speed of the meteor?

DavidLeodis wrote:I would be grateful if someone could please clarify if the quadrillion in the explanation is the 10¹⁵ or the 10²⁴ definition of a quadrillion.

Chris Peterson wrote:As the meteor descends through the atmosphere, it encounters winds moving in different directions. That wind tears a persistent train in different directions. Most likely we're just seeing a transition in the middle of the train between winds blowing one way and winds blowing nearly opposite (not an uncommon occurrence). That split the train. The particular wind gradient is fooling us into thinking we're seeing a spiral pattern.

geckzilla wrote:I've been dubious about the "spiraling" meteor imagery, myself. When I question it, though, the photographer will swear their system was motionless and that the meteorite must be spiraling.

Chris Peterson wrote:

APOD Robot wrote: Spiral Meteor through the Heart Nebula

Explanation: What is this meteor doing? Dynamically, the unusually short and asymmetric train may indicate that the sand-sized grain at the center of the glow is momentarily spinning as it ablates, causing its path to be slightly spiral.

There is little or no evidence that meteors wiggle or spiral. In this image, the path is perfectly straight. It was a long exposure with a meteor in the middle. Almost certainly, what we're seeing is the instant of the trail, and the much longer period of ionized gas blowing around, in different directions at different altitudes (very commonly seen in meteor trains). (The 2005 image doesn't show a wiggling meteor, either, but rather a wiggling optical system.)

Craig M. wrote:A quadrillion times closer? I hate that nonsensical form of comparison! 1,000,000,000,000,000 x what? What is so hard about expressing it correctly and accurately: one quadrillionth as distant?

MarkBour wrote:(If I understand what Chris just posted, the green may have appeared after the meteor was done burning, but a left-over phenomenon in the same region as the yellow streak in the middle.) What accounts for the various colors? Did the meteor actually distribute material in a shape to make the spiral, like a spinning pinwheel firework?

APOD Robot wrote: Spiral Meteor through the Heart Nebula

Explanation: What is this meteor doing? Dynamically, the unusually short and asymmetric train may indicate that the sand-sized grain at the center of the glow is momentarily spinning as it ablates, causing its path to be slightly spiral.

heehaw wrote:

Mactavish wrote:How is it determined that the meteor is the size of a grain of sand? Just curious.

http://www.amsmeteors.org/meteor-showers/meteor-faq/#3

The Geminid meteor shower during the ECOMA sounding campaign: specular and head echo radar observations wrote:...However,one essential point deriving absolute meteor fluxes is to estimate the particle size range of the observed particles. This particle size range was determined by applying the method as described in Stober et al. (2011) using a single body meteor ablation model. In a first step the meteoroid mass is inferred at the specular point by solving the equations of single body meteor ablation using all the measured parameters (e.g. electron line density, altitude, entry angle, velocity). By solving the model equations we compute the meteoroid deceleration, the meteoroid surface temperature and the meteoroid particle mass at this stage of its flight path. The upper atmospheric properties of the meteors are inferred by performing a backward integration. The Geminid upper atmospheric meteoroid mass was in the range of 3×10⁻³–10⁻⁵ g at both radar sites. The 10−5 g represents the lower mass limit to be detected by the system for Geminid entry velocity.

Mactavish wrote:How is it determined that the meteor is the size of a grain of sand? Just curious.