Astronomy Picture of the Day 11-12-03

Explanation: Does Mars have canals? A hot debate topic of the late 1800s, several prominent astronomers including Percival Lowell not only claimed to see an extensive system of long straight canals on Mars, but used them to indicate that intelligent life exists there. The relatively close opposition of 1894 was used to make drawings like the one digitally re-scaled on the above left. The above map was originally prepared by Eugene Antoniadi and redrawn by Lowell Hess for the book Exploring Mars, by Roy A. Gallant. In more modern times, the latest Mars opposition has allowed the Hubble Space Telescope to capture a picture of similar orientation. Comparison of the two images shows that large features were impressively recorded, but that an extensive system of long and straight canals just does not exist. Satellites orbiting Mars have now shown conclusively that the red planet does indeed have surface features similar to canals, but that these are usually smaller, curved, and less extensive than that previously claimed. Real canyon systems like Noctis Labyrinthus are most likely cracks caused by surface stress.

Classic case of people seeing what they WANTED to see.

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.

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