6 November

2003: On 6 November 2003, it was announced that the massive solar X-ray flare which occurred on 4 November 2003 was, at best estimate, an X28.

X-class flares are big; they are major events that can trigger radio blackouts around the whole world and long-lasting radiation storms in the upper atmosphere.

This is a new ‘Number One’ X-ray flare for the record books, the most powerful in recorded observational history.

1638: On 6 November 1638, Scottish mathematician, astronomer and inventor of the reflecting telescope, James Gregory was born in Aberdeen.

Gregory was the first to investigate converging number series, which have an infinite number of terms but a finite sum. He made important contributions to the development of the calculus, although some of his best work remained virtually unknown until long after his death.

In 1660 he published his Optica Promota, in which he described the first practical reflecting (Gregorian) telescope. Light reflected from a concave elliptical secondary mirror is brought to a focus just behind a hole in the primary mirror. It was superceded by the Newtonian and Cassegrain telescopes. Gregory also introduced estimation of stellar distances by photometric methods.

1572: A supernova is observed in the constellation known as Cassiopeia.