International Astronomical Union

What's a planet anyway? The International Astronomical Union, the group charged with coming up with definitions and names for astronomical objects, has never had a formal definition for "planet." It's never really needed one. Many textbooks and encyclopedias don't even formally define the word. Why should they? It's always been so simple. For centuries, planets were considered to be big, round objects that orbited a sun and reflected light but did not give off light of their own.

How I Killed Pluto And Why It Had It Coming Mike Brown Spiegel & Grau: 267 pp., $25 Moon A Brief History Bernd Brunner Yale University Press: 290 pp., $25 Pluto. Poor little guy. He never wanted much. The others could be bigger, they could be better-looking or brag about themselves ("I'm burning hot!" or "I have rings!" or "I support life!"). He didn't care. All he wanted was to be part of the planet club. And for about 75 years, that tiny frozen world billions of miles from the sun was a card-carrying member.

Far beyond the moon and stars, Twenty light-years south of Mars, Spins the gentle Bunny Planet, And the Bunny Queen is Janet. -- Voyage to the Bunny Planet by Rosemary Wells Kids love the Bunny Planet books by Rosemary Wells. Maybe you failed a test, or ate a bad hot dog, or got in trouble for making rude noises on the school bus. No problem! Janet the Bunny Queen will make you feel better. If only the Bunny Planet were real -- it almost was. A few years ago, astronomer Mike Brown of Caltech discovered a small planet.

Last month, a team of researchers hunting extrasolar planets — those that reside around stars other than our sun — discovered a solar system with at least five and possibly seven planets. This is a remarkable discovery, bringing the number of known exoplanets to nearly 500. One of the planets sits smack in the middle of the star's "Goldilocks zone" — the area around the star where the porridge — er, water — might be just right for life.

Scientists at the Jet Propulsion Laboratory have downgraded the threat of an asteroid now speeding toward Earth and say there is no chance it will hit Earth in 2030, but a 1 in 1,000 chance it could hit Earth on Sept. 16, 2071. Last week, scientists with NASA's Office of Near Earth Objects and the International Astronomical Union announced there was a 1 in 500 chance that an object could hit Earth in 2030.

An asteroid widely reported to be on a near-collision course with Earth actually will miss the planet by 600,000 miles, astronomers at the Jet Propulsion Laboratory said Thursday. The JPL scientists used new data to calculate the path of the mile-wide planetoid.

There goes the solar system. The elite society of nine lordly bodies of rock, ice and gas would grow to at least 12 and as many as 53 members under a new definition of "planet" proposed Tuesday by the International Astronomical Union. The core of the definition? Planets are round. And they orbit a star. The proposal was hammered out after two years of intense astronomical debate among leading experts of the Astronomical Union, the international authority for naming celestial objects.

There is a small but significant chance that an asteroid will strike Earth in 2030 with a force up to 100 times the Hiroshima bomb, an international team of astronomers concluded Friday. The International Astronomical Union and space scientists at NASA's Jet Propulsion Laboratory said there is a 1-in-500 chance that a newly discovered asteroid-like object called 2000 SG344 will hit Earth on Sept. 21, 2030. The object could be anything from a discarded rocket booster to a sizable asteroid.

According to Greek mythology, the goddess Eris was so miffed at being left off the guest list of a banquet of the gods that she stirred up the Trojan War. Could there be a better name than that of the goddess of discord for the dwarf planet that spawned a pitched battle among astronomers and threw the public's ideas about the solar system into a cocked hat? Apparently not.

Poor besotted Pluto--the planet, not Mickey's dog. In case you haven't paid close attention to the distant reaches of our corner of space, after 72 years of distinction as the outermost planet in our solar system, that lumbering hunk of ice and rock that hasn't completed one single solar orbit since the American Revolution may not be a planet anymore. Not that such a decision down here would alter the minus-400-degree temperature out there.

Far beyond the moon and stars, Twenty light-years south of Mars, Spins the gentle Bunny Planet, And the Bunny Queen is Janet. -- Voyage to the Bunny Planet by Rosemary Wells Kids love the Bunny Planet books by Rosemary Wells. Maybe you failed a test, or ate a bad hot dog, or got in trouble for making rude noises on the school bus. No problem! Janet the Bunny Queen will make you feel better. If only the Bunny Planet were real -- it almost was. A few years ago, astronomer Mike Brown of Caltech discovered a small planet.

According to Greek mythology, the goddess Eris was so miffed at being left off the guest list of a banquet of the gods that she stirred up the Trojan War. Could there be a better name than that of the goddess of discord for the dwarf planet that spawned a pitched battle among astronomers and threw the public's ideas about the solar system into a cocked hat? Apparently not.

Question: What is a planet? Answer: Something round that orbits a star, according to the new definition proposed last week by the International Astronomical Union. In the case of our solar system, that star is the sun. Q: Didn't we already know that? A: Actually, no. Although many people thought they knew what a planet was, there had been no clear definition that all astronomers could agree on. Q: So why do we need one now? A: Recent discoveries of bodies in the Kuiper Belt, a huge region of icy objects beyond the orbit of Neptune, raised the question of whether they should be considered planets.

There goes the solar system. The elite society of nine lordly bodies of rock, ice and gas would grow to at least 12 and as many as 53 members under a new definition of "planet" proposed Tuesday by the International Astronomical Union. The core of the definition? Planets are round. And they orbit a star. The proposal was hammered out after two years of intense astronomical debate among leading experts of the Astronomical Union, the international authority for naming celestial objects.

Poor besotted Pluto--the planet, not Mickey's dog. In case you haven't paid close attention to the distant reaches of our corner of space, after 72 years of distinction as the outermost planet in our solar system, that lumbering hunk of ice and rock that hasn't completed one single solar orbit since the American Revolution may not be a planet anymore. Not that such a decision down here would alter the minus-400-degree temperature out there.

What's a planet anyway? The International Astronomical Union, the group charged with coming up with definitions and names for astronomical objects, has never had a formal definition for "planet." It's never really needed one. Many textbooks and encyclopedias don't even formally define the word. Why should they? It's always been so simple. For centuries, planets were considered to be big, round objects that orbited a sun and reflected light but did not give off light of their own.

A cat. A Vulcan. And an asteroid. Mix them together and you have a controversy of cosmic proportions brewing around James Gibson, a planetary scientist from Tujunga who has become the target of scientific ire for naming an asteroid after his late cat, Mr. Spock. "We knew that there would probably be some flak for it, but we didn't expect it to go this far," said Gibson, 66, who chose the name in 1985 with the help of his wife. He could have done far worse, he argued.

A cat. A Vulcan. And an asteroid. Mix them together and you have a controversy of cosmic proportions that has been brewing for nearly a decade around James Gibson, a planetary scientist from Tujunga. Gibson is the target of scientific ire because he named an asteroid after his late cat, Mr. Spock. "We knew that there would probably be some flak for it, but we didn't expect it to go this far," said Gibson, 66, who chose the name in 1985 with the help of his wife.

Scientists at the Jet Propulsion Laboratory have downgraded the threat of an asteroid now speeding toward Earth and say there is no chance it will hit Earth in 2030, but a 1 in 1,000 chance it could hit Earth on Sept. 16, 2071. Last week, scientists with NASA's Office of Near Earth Objects and the International Astronomical Union announced there was a 1 in 500 chance that an object could hit Earth in 2030.

There is a small but significant chance that an asteroid will strike Earth in 2030 with a force up to 100 times the Hiroshima bomb, an international team of astronomers concluded Friday. The International Astronomical Union and space scientists at NASA's Jet Propulsion Laboratory said there is a 1-in-500 chance that a newly discovered asteroid-like object called 2000 SG344 will hit Earth on Sept. 21, 2030. The object could be anything from a discarded rocket booster to a sizable asteroid.