Expert: Philip Stahl - 1/5/2007

Question
Hello! From what I understand, in this year the most intense display in recorded history occured. I read that several astronomical events occured at the same time, and that the Northern Lights were visible from most of the Earth. Other than shorted power lines, what are the terrestrial effects of such an event, either in general or specific to the 1859 incident?
Thank you!  

Answer
Hello,

In 1859, Carrington and Hodgson independently observed a brightening of an area on the Sun in the vicinity of a large sunspot group. Two days later, a powerful geo-magnetic storm erupted on Earth, which was accompanied by bright aurora borealis and widespread interruption in telegraphic communications.

This was perhaps the first recognition of solar flares as independent events on the Sun - as well as their electric and magnetic influence. Few hard records were kept at that time, beyond the obvious ones for the aurora, etc.

Unfortunately, one can only speculate on what other manifestations tied to the specific flare(s) occurred, since there was still much conjecture at the time - and the matter was really only settled years later in retrospect.

What we do know, is that powerful x-rays from historic flares (e.g. one in 1982) have actually knocked out various Earth-orbiting satellites. By 'knocked out' I mean fried their electronic systems to the point of dysfunction.

We also know that such large flares, say as occurred in August, 1972 can disrupt aircraft navigation systems. This includes sytems aboard large, commercial aircraft.

Shortwave signals are also diluted, or severely disrupted, if not knocked out entirely.

Lastly, before the Skylab space craft crashed back to Earth, it reported the effects of a large flare (in 1973) which evidently eroded up to 20% of the ozone layer at that time. It also, coincidentally, caused an expansion of atmosphere (recall that the atmosphere is a gas, and gases epxand on heating).