The Sun is the major, but not the only source of space weather in the solar system. (And of course planets around other stars experience space weather, but that is another topic).

Galactic cosmic radiation (GCR) has been known and studied for many decades. This form of particulate radiation is generated outside the solar system, most likely by supernova. It now appears that GCR may be the limiting factor in human exploration of space. A trip to Mars using current chemical propulsion would expose astronauts to a radiation dose way beyond current allowable standards.

Meteor burst communication is currently used in a number of applications where traditional ionospheric or satellite communications are not appropriate. On the debit side, a large influx of meteoric material can seriously degrade the operation of an OTH radar system.

Small meteoroids (the interplanetary body that produces the meteor phenomenon) pose a small hazard to satellites and spacecraft (particularly large long lived operations), although man-made orbital space debris is now a more significant threat. If particulate radiation precipitating into the Earth's atmosphere is likened to rain, the terrestrial meteoroid influx might be regarded as hail.

Much larger individual meteoroids or asteroids (> 100m) can pose a hazard to the ecosystem, and bodies larger than 1 km hold the import of global catastrophe.

There is evidence that extrasolar X-ray and gamma ray sources may produce a measurable increase in the lower ionosphere, an increase detectable in VLF signal propagation. There is also growing satellite sensor evidence that our magnetosphere contains nuclei and ions initially injected into the heliosphere as it ploughs through the periphery of a giant interstellar cloud.

Crab Nebula A supernova occurring anywhere within a thousand light years of the solar system could create very stormy weather indeed, and may make life on the Earth quite uncomfortable.

A recent speculation on the nature of the enigmatic gamma-ray bursts ascribes them to the merging of neutron stars in binary systems. If such a collision were to happen in our galaxy, the intense gamma-ray influx to the lower mesosphere and stratosphere may produce enough nitric oxide to totally destroy the ozone layer, and enough nitric acid to produce years of high level acid rain.

There is more to space weather than what is under, or from, the Sun!

ASAAustralian Space Academy