As a follow-up to this question, what would be the effect(s) of a high-speed of super-heated plasma entering and impacting on a planet?

The planet is about the size of 1.2x Earth(s), with a similar atmosphere.

The plasma is the direct effect of the Earth getting "obliterated" by a large, fast asteroid impact.

What would be the effect of plasma entering the atmosphere on this planet? How much damage would it cause?

Also, would there be any long/short term effect(s) on the Flora and Fauna of the planet?

  • $\begingroup$ A big ball of Plasma (as often portrayed in games and movies) doesn’t really work as a projectile. First determine the lengths you will go to in order to create that contained projectile. Probably worth noting that any object intentionally fired down to a planets surface will likely develop plasma anyway via friction. $\endgroup$ – Darius Arcturus Dec 20 '19 at 14:44
  • $\begingroup$ (wait, did you just describe your own post as a "beautiful question"? with two downvotes and a total score of 4? dude, no) $\endgroup$ – Starfish Prime Dec 20 '19 at 15:36
  • $\begingroup$ Plasma makes a fine weapon -- at across-a-room distances, maybe even out to a block or two. Beyond that, you can't keep it dense enough to transfer enough energy to do much harm. Or if you can, you can probably make direct-squeeze fusion weapons and don't need plasma rifles. $\endgroup$ – Zeiss Ikon Dec 20 '19 at 17:45
  • $\begingroup$ How much plasma are we talking about? If it's less than a gram, probably nothing of significance happens, if it's the same mass as the planet, everyone dies in a puff of smoke. If it's somewhere between, then it would be somewhere in between those extremes. $\endgroup$ – Mathaddict Dec 20 '19 at 17:46

The Earth's atmosphere is hit by high-speed plasma continuously, in the form of the solar wind. The incoming plasma will be deflected by the Earth's magnetic field, and generally enters close to the north or south magnetic poles, forming aurora. Here's a nice picture of some:

Aurora borealis

(source: wikimedia)

Solar wind particles generally have kinetic energies of about 1keV per nucleon, which is about 500km/s, or about 0.0015c.

Occasionally though, you get blobs of plasma ejected from the Sun in the form of Coronal Mass Ejections which can travel a little bit faster. The flare that caused the Carrington Event of 1859 travelled at nearly 2500kms, still a bit shy of 1% of lightspeed.

According to wikipedia,

Auroras were seen around the world, those in the northern hemisphere as far south as the Caribbean; those over the Rocky Mountains in the U.S. were so bright that the glow woke gold miners, who began preparing breakfast because they thought it was morning. People in the northeastern United States could read a newspaper by the aurora's light. The aurora was visible from the poles to low latitude areas such as south-central Mexico, Queensland, Cuba, Hawaii, southern Japan and China, and even at lower latitudes very close to the equator, such as in Colombia.

It might be possible to get CMEs which reach velocities of about 0.01c from the Sun. Our star is just too relaxed to generate a superflare, so bigger and brighter CMEs will only likely occur in other planetary systems with unfriendly suns whose local environments will be so hostile that planets around them might not even have atmospheres anymore, let alone any sort of complex surface life.

Sticking with more plausibly sized Solar CMEs... as the velocity of the incoming cloud of plasma increases, you'll get brighter and brighter aurora, visible closer and closer to the equator. Almost inevitably, XKCD has some useful information on the subject:

XKCD Aurora

Note the scope of the plasma impact here: CMEs can be tens of millions of kilometres across, and require something the size of a sun to generate, and require the Earth to be relatively close to the sun. The blast expands and weakens rapidly. You won't be getting some giant superenergetic plasmoid trucking in from extrasolar space... by the time it got to us, it would be just too diffuse to do anything interesting. As mentioned elsewhere ad nauseam, plasma weapons are a silly idea.

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this will cause disturbances in the Earth's magnetic field, It'll make it weak.

so lot of radiation from the space will reach us means mutations in ADN that means a lot of cancer, There'll be also an electricity issues, The electricity grid may go down for years.

We call this Coronal Mass Ejection

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