Did you know that Percival Lowell was quite famous for another astronomical endeavor? He spent a LOT of time searching for "Planet X", which had been mathematically predicted to exist. But no one had any idea that Planet X was small, and Lowell died in 1916 without locating the elusive planet.
Clyde Tombaugh (1906-1997) discovered the planet in 1930 and it was given the name Pluto. Its symbol is a linked PL 
which coincidentally is the initials of Percival Lowell.
The biggest solar X-ray flare ever is classified as X28
EUROPEAN SPACE AGENCY NEWS RELEASE
Posted: November 7, 2003
It has been announced that the massive solar X-ray flare which occurred on November 4 was, at best estimate, an X28. There is still a small chance this will be revised by a small amount, but it is now official: We have a new number 1 X-ray flare for the record books, the most powerful in recorded observational history.
On Tuesday, this flare saturated the X-ray detectors on several monitoring satellites. The associated coronal mass ejection (CME) came out of the Sun's surface at about 2300 kilometres per second (8.2 million km/h). Only part of the CME is directed towards Earth, so we expect the Earth will receive only a glancing blow, since the source region is pointing away from us on the right on the limb of the Sun as seen from Earth.
 Credit: NASA/ESA/SOHO |
Scientists classify solar flares according to their brightness in the x-ray wavelengths. There are three categories:
- 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.
- M-class flares are medium-sized; they generally cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.
- Compared to X- and M-class events, C-class flares are small with few noticeable consequences here on Earth.
