Reshuffling something we have taken for granted since childhood as common sense may not be as simple as refreshing an electronic database.

That is why seeing Pluto off from the planets list, a matter of scientific definition, has come with an emotional touch.

Astronomers who had preferred the proposal to allow three new members into the exclusive club, instead of disqualifying Pluto, may feel frustrated.

"It kind of sounds like I just lost my job," 93-year-old Patricia Tombaugh, whose husband, American astronomer Clyde Tombaugh, discovered Pluto 76 years ago, was quoted as saying.

Pluto's demotion may also have an effect on children sentimentally attached to the Disney cartoon character who has wowed young audiences the world over as Mickey Mouse's faithful pet dog. Pluto the dog was named after the celestial body, granted planethood in 1930 and an astronomical sensation of the year.

A more practical trouble, however, is that all textbooks and lessons for the new semester need an immediate update to reflect the latest development.

But in spite of the slight initial dismay, and even lingering doubts about Pluto's status change, everybody seems to accept that the bright side matters a lot more.

It is not that children have one less planet to memorize.

It is an important step toward better understanding of the universe.

At the outset, Pluto's downgrade is an outcome of standard change.

The definition the International Astronomical Union adopted on Thursday represented a precious, historic agreement on what constitutes a planet.

Altogether, 10 celestial entities have been labelled as planets in the absence of a universal definition since well before the time of Nicolas Copernicus (1473-1543), who proved that the Earth revolves around the sun.

Ceres, the largest of the asteroids located between Mars and Jupiter, was initially considered a planet in the early 1800s. It will now become a "dwarf planet" along with Pluto.

The mere existence of a definition suffices for celebration. It is the fruit of our stargazers' collective endeavours to unveil the astronomical mysteries around us.

It is a stepping-stone for further probes into the solar system and beyond.

At the same time, it is an educating reminder that science is not a static subject, and that common sense is not truth per se.

Reducing Pluto to a "dwarf planet" in no way reduces its importance to science.

Clyde Tombaugh said before he died: "It's there. Whatever it is. It is there."

It always will be.

NASA said Pluto's re-classification would not affect its New Horizons spacecraft mission, a 9 1/2-year journey to Pluto that began this year.

Nor will it make us think any less of the discovery by Clyde Tombaugh, a small amount of whose ashes is said to be onboard the NASA spacecraft bound for Pluto.

He should be glad to know that his colleagues have taken another step forward.

(China Daily 08/26/2006 page4)