<p>Stars are not actually gaseous, they are plasmas, i.e., highly ionized. Hence, the entire star is highly conductive and does not easily develop the voltage difference via friction needed for lightning like that in our atmosphere. On the other hand, stellar atmospheres have strong magnetic fields which reconnect, and that causes strong voltage spikes that generate high energy electrons. On the Earth we would call streams of high energy electrons lightning, but on the sun we call them flares.</p>

CC BY-SA 4.0
2020-10-23T16:36:32.947Z
2020-10-25T12:58:02.837Z
2020-10-25T12:58:02.837Z
eshaya
<p>An essential feature of the lightning is the <a href="https://en.wikipedia.org/wiki/Electrical_breakdown" rel="nofollow noreferrer">electrical breakdown</a> - an insulator (air) becomes a conductor for a while, relatively high current flows in the conducting channel for a short while, then stops. The conducting channel is an insulator again.</p>
<p>This requires</p>
<ol>
<li>insulating (dielectric) medium and</li>
<li>a means of creating an intense electric fields.</li>
</ol>
<p>Given enough temperature and/or pressure, everything becomes a conductor. So you need a cool enough star (way cooler than our Sun is). The sun is electrically conductive from its Corona all the way to the center.</p>
<p>Point 2 is easier as the Sun (and with somewhat lesser certainity all other stars that rotate and have convective zone) run some kind of <a href="https://en.wikipedia.org/wiki/Magnetohydrodynamics" rel="nofollow noreferrer">hydromagnetic dynamo</a> . These processes do create spectacular events (magnetic reconnections), but they are not lightnings in the true sense of the word as they happen in an already conducting medium.</p>
<p>The cooler brown dwarfs, as well as gas giant planets, do have layers of atmosphere that are sufficiently dielectric. Well, no hydromagnetic dynamo in these conditions (it may as well run deep below in the hotter and denser layers, but no ligthnings because of the reasons stated above). Some of upper layers are cool enough to host water and other clouds, giving them the right conditions for separating spatially a great deal of electric charges, just like our <a href="https://www.britannica.com/science/thunderstorm/Thunderstorm-electrification" rel="nofollow noreferrer">thunderstorms</a> do.</p>
<p>Both Jupiter and Saturn are known to host <a href="https://www.space.com/jupiter-thunderstorms-ammonia-mushballs.html" rel="nofollow noreferrer">powerful thunderstorms</a>, detectable both in radio waves and in visible light. I see no reason why the same processes can't happen in a brown dwarf, but I am not aware of any scientific research on the matter.</p>

CC BY-SA 4.0
2020-10-26T15:18:42.820Z
Another possible location that comes to mind are the envelopes of red giants. Probably too thin (near vacuum), and I'm not sure if they are cold enough to avoid full ionization, but they are surely hot enough to preclude water droplets. Yet, I imagine high melting point oxides and carbides could possibly form dust grains and get charged.
ksousa
CC BY-SA 4.0
2020-10-26T19:40:30.373Z
Red giants pose another set of problems. First, the envelope pressure is quite low. A recent question about the lightnings on Mars concluded that the density is not enough. Low pressure enables glow discharge instead of sparks. And the only solid matter near a red giant I can imagine is the soot around the carbon stars. Itself a conductor (and I am not sure if for thunderstorm-type electrification the solid phase should also be a dielectric). High melting point carbides/oxides require even heavier elements that don't surface until the final show.
fraxinus
CC BY-SA 4.0
2020-10-25T10:22:17.443Z
2020-10-26T14:35:16.317Z
2020-10-26T14:35:16.317Z
fraxinus
<p>In the Wikipedia article about <a href="https://en.wikipedia.org/wiki/Lightning" rel="nofollow noreferrer">lightining</a>, the following explanation is given about the electrification process in clouds:</p>
<blockquote>
<p>The details of the charging process are still being studied by
scientists, but there is general agreement on some of the basic
concepts of thunderstorm electrification. The main charging area in a
thunderstorm occurs in the central part of the storm where air is
moving upward rapidly (updraft) and temperatures range from −15 to −25
°C (5 to −13 °F); see Figure 1. In that area, the combination of
temperature and rapid upward air movement produces a mixture of
super-cooled cloud droplets (small water droplets below freezing),
small ice crystals, and graupel (soft hail). The updraft carries the
super-cooled cloud droplets and very small ice crystals upward. At the
same time, the graupel, which is considerably larger and denser, tends
to fall or be suspended in the rising air.</p>
<p>The differences in the movement of the precipitation cause collisions
to occur. When the rising ice crystals collide with graupel, the ice
crystals become positively charged and the graupel becomes negatively
charged; see Figure 2. The updraft carries the positively charged ice
crystals upward toward the top of the storm cloud. The larger and
denser graupel is either suspended in the middle of the thunderstorm
cloud or falls toward the lower part of the storm.</p>
</blockquote>
<p>This mechanism seems to rule out the possibility of lightning in absence of a condensed phase (liquid droplets/solid crystals). That makes me wonder, is lightning truly impossible in stars hot enough to be fully gaseous, like our Sun? Or could a alternative mechanism generate lightning in such environment.</p>
<p>Even in absence of any alternative mechanisms, I think lightning still could form at least in small, cold stars, or in old brown dwarfs. What would be the size/age threshold?</p>

CC BY-SA 4.0
2020-10-24T04:17:51.433Z
See this reddit post: https://www.reddit.com/r/askscience/comments/14eqro/is_there_lightning_on_the_sun/
Nilay Ghosh
CC BY-SA 4.0
2020-10-24T15:20:30.887Z
There are brown dwarves known to host water clouds. Our Jupiter has them, too, and is famous for having tunderstorms with lightnings detectable in visible as well as in radio frequencies. So for brown dwarves, why not?
fraxinus
CC BY-SA 4.0
2020-10-25T15:12:27.613Z
(*"[At first, dwarfs was the common plural in English. After J. R. R. Tolkien used dwarves in his works, that form became the standard for the plural of the mythological beings. For a non-mythological dwarf (people with dwarfism), dwarfs has remained the preferred plural form.](https://en.wiktionary.org/wiki/dwarf#Usage_notes)"*)
Peter Mortensen
CC BY-SA 4.0
2020-10-26T14:45:18.733Z
Brown dwarves aren't stars. Presumably the final paragraph is meant to refer both to small/cold stars like red dwarves, and also to brown dwarves?
Astrid_Redfern
CC BY-SA 4.0
2020-10-26T15:10:25.333Z
Thank You for the clarification, @PeterMortensen . I'm not a native english speaker, so sometimes I slip on details like that. I'll fix it.
ksousa
<star><the-sun><brown-dwarf><stellar-atmospheres>
Can lightning occur in stars like the Sun?
ksousa
# Can lightning occur in stars like the Sun?

(Asked by: username_0 on 2020-10-23)

In the Wikipedia article about [lightining](https://en.wikipedia.org/wiki/Lightning), the following explanation is given about the electrification process in clouds:

> The details of the charging process are still being studied by
> scientists, but there is general agreement on some of the basic
> concepts of thunderstorm electrification. The main charging area in a
> thunderstorm occurs in the central part of the storm where air is
> moving upward rapidly (updraft) and temperatures range from −15 to −25
> °C (5 to −13 °F); see Figure 1. In that area, the combination of
> temperature and rapid upward air movement produces a mixture of
> super-cooled cloud droplets (small water droplets below freezing),
> small ice crystals, and graupel (soft hail). The updraft carries the
> super-cooled cloud droplets and very small ice crystals upward. At the
> same time, the graupel, which is considerably larger and denser, tends
> to fall or be suspended in the rising air.
>
> The differences in the movement of the precipitation cause collisions
> to occur. When the rising ice crystals collide with graupel, the ice
> crystals become positively charged and the graupel becomes negatively
> charged; see Figure 2. The updraft carries the positively charged ice
> crystals upward toward the top of the storm cloud. The larger and
> denser graupel is either suspended in the middle of the thunderstorm
> cloud or falls toward the lower part of the storm.

This mechanism seems to rule out the possibility of lightning in absence of a condensed phase (liquid droplets/solid crystals). That makes me wonder, is lightning truly impossible in stars hot enough to be fully gaseous, like our Sun? Or could a alternative mechanism generate lightning in such environment.

Even in absence of any alternative mechanisms, I think lightning still could form at least in small, cold stars, or in old brown dwarfs. What would be the size/age threshold?

**Tags:** star, the-sun, brown-dwarf, stellar-atmospheres
> **Comments:**
> **username_1**: See this reddit post: https://www.reddit.com/r/askscience/comments/14eqro/is_there_lightning_on_the_sun/  
> **username_2**: There are brown dwarves known to host water clouds. Our Jupiter has them, too, and is famous for having tunderstorms with lightnings detectable in visible as well as in radio frequencies. So for brown dwarves, why not?  
> **username_3**: (*"[At first, dwarfs was the common plural in English. After J. R. R. Tolkien used dwarves in his works, that form became the standard for the plural of the mythological beings. For a non-mythological dwarf (people with dwarfism), dwarfs has remained the preferred plural form.](https://en.wiktionary.org/wiki/dwarf#Usage_notes)"*)  
> **username_4**: Brown dwarves aren't stars. Presumably the final paragraph is meant to refer both to small/cold stars like red dwarves, and also to brown dwarves?  
> **username_0**: Thank You for the clarification, @PeterMortensen . I'm not a native english speaker, so sometimes I slip on details like that. I'll fix it.  

---

## 2 answers

### Answer by username_2 on 2020-10-25. Score: 9 | Accepted answer

An essential feature of the lightning is the [electrical breakdown](https://en.wikipedia.org/wiki/Electrical_breakdown) - an insulator (air) becomes a conductor for a while, relatively high current flows in the conducting channel for a short while, then stops. The conducting channel is an insulator again.

This requires

1. insulating (dielectric) medium and
2. a means of creating an intense electric fields.

Given enough temperature and/or pressure, everything becomes a conductor. So you need a cool enough star (way cooler than our Sun is). The sun is electrically conductive from its Corona all the way to the center.

Point 2 is easier as the Sun (and with somewhat lesser certainity all other stars that rotate and have convective zone) run some kind of [hydromagnetic dynamo](https://en.wikipedia.org/wiki/Magnetohydrodynamics) . These processes do create spectacular events (magnetic reconnections), but they are not lightnings in the true sense of the word as they happen in an already conducting medium.

The cooler brown dwarfs, as well as gas giant planets, do have layers of atmosphere that are sufficiently dielectric. Well, no hydromagnetic dynamo in these conditions (it may as well run deep below in the hotter and denser layers, but no ligthnings because of the reasons stated above). Some of upper layers are cool enough to host water and other clouds, giving them the right conditions for separating spatially a great deal of electric charges, just like our [thunderstorms](https://www.britannica.com/science/thunderstorm/Thunderstorm-electrification) do.

Both Jupiter and Saturn are known to host [powerful thunderstorms](https://www.space.com/jupiter-thunderstorms-ammonia-mushballs.html), detectable both in radio waves and in visible light. I see no reason why the same processes can't happen in a brown dwarf, but I am not aware of any scientific research on the matter.

> **Comments:**
> **username_0**: Another possible location that comes to mind are the envelopes of red giants. Probably too thin (near vacuum), and I'm not sure if they are cold enough to avoid full ionization, but they are surely hot enough to preclude water droplets. Yet, I imagine high melting point oxides and carbides could possibly form dust grains and get charged.  
> **username_2**: Red giants pose another set of problems. First, the envelope pressure is quite low. A recent question about the lightnings on Mars concluded that the density is not enough. Low pressure enables glow discharge instead of sparks. And the only solid matter near a red giant I can imagine is the soot around the carbon stars. Itself a conductor (and I am not sure if for thunderstorm-type electrification the solid phase should also be a dielectric). High melting point carbides/oxides require even heavier elements that don't surface until the final show.  

---

### Answer by username_5 on 2020-10-23. Score: 39

Stars are not actually gaseous, they are plasmas, i.e., highly ionized. Hence, the entire star is highly conductive and does not easily develop the voltage difference via friction needed for lightning like that in our atmosphere. On the other hand, stellar atmospheres have strong magnetic fields which reconnect, and that causes strong voltage spikes that generate high energy electrons. On the Earth we would call streams of high energy electrons lightning, but on the sun we call them flares.


---

