Even though scientists have not actually seen the recently discovered "planets," it's safe to say they're pretty weird objects. On 70 Virginis, for example, a star that's 80 light-years from Earth, astronomers Geoffrey Marcy and Paul Butler located an object 6.5 times as massive as Jupiter, at an orbital distance of less than half of Earth's.
Problem is, this "planet" is in a strange place, or so says David Black, director of the Lunar and Planetary Society in Houston. In fact, since many of the recently discovered "planets" don't fit our understanding of how a solar system should look, Black says some of the new announcements may be remembered as false alarms: "This subject is littered with failed claims to have discovered other planetary systems."
What? Can astronomers, having studied exactly one orbital system (ours), have the chutzpah (defined) to predict how others should look? Oddly enough, they can.
Nearby, globs of dust are attracting more dust. One of these globs (let's call it Earth for short) will eventually be populated by the only species known to wonder about the origin of planets, and about why their planet is dominated by heavy elements like iron and nickel, while the outer, gas planets are comprised largely of lighter elements. 
Enter
the time capsule
To do this, you've got to roll the calendar back a bit, say, 5 billion years or so and imagine that our solar system is forming from a giant, rotating disk of gas and dust called a protoplanetary nebula. Toward the center, hydrogen and a bit of helium are collapsing under gravity and forming a star we'll later call "sun."
Saturn © NASA.
Farther away, gases are coalescing around hunks of matter which will eventually make up the giant gas planets Jupiter, Saturn, Uranus and Neptune. These gas giants are made largely of common chemicals that evaporate at low temperature: hydrogen sulfide, ammonia, and methane. If they were closer to the sun, they'd just boil away.
And here we run up against a problem: Why are many of these newly discovered "planets" -- remember, they're all giants, since we can only detect giants with today's technology -- so close to the star? Since they're large, the candidate planets must be composed of common elements, like the giants in our solar system. But why wouldn't these gases boil away if the planets are so close to their stars?
The hydrogen solution
Black thinks hydrogen may be what's inside those giant "planets," an extra-planetary factoid that would make them more like stars than planets. But if they are stars, why don't they radiate light? Because they're a kind of star that never quite got cooking, Black says: "From my point of view, it's likely they are brown dwarfs."
Think of brown dwarfs (defined) as dud suns. They contain hydrogen, but, unlike stars, their gravity is too weak to pull that hydrogen close enough so fusion can occur (remember, fusion creates all that energy in stars).
Like stars, brown dwarfs form quickly when a hydrogen cloud collapses under gravity. In contrast, planets form by slowly "accreting" around a glob of mass which acts like the grain of sand in a pearl.
Brown dwarfs may not be planets, and they may not be stars, either, but they're a hot ticket in astronomy these days. Take the brown dwarf found in 1995 in the southern constellation Lepus. It's dim -- about 1/250,000 as bright as our sun, glowing a deep red. And although these dwarfs are hard to see, they could represent one of the most common objects in the universe, according to recent observations, possibly comprising a big chunk of the long-sought dark matter (defined). Read more about these weirdos in When a star is not born....
It turns out that there is an explanation, one that rests on the most common element in the primordial disk. Right, we're talking about hydrogen, which came together to form our sun way back when.
A real planet? (Getting back to the story at long last...)
But if planetary discoveries don't fit the theory, Black says, we may have to concoct a new founding story for solar systems.
While Black suspects that many of the other "planet" discoveries may actually be brown dwarfs, he says Gatewood's super-cautious planetary announcement may be on the mark. The object in question, after all, is far enough from the star that its gases might not boil away. "This is the first one that has some vague semblance to what an orbital system ought to be," Black observes. "In general, we'd expect to find great planets in the cool regions. If we're right, this is what should be out there."
Time to change the subject...
Are you ready for global change, cosmic style?
It turns out that the weather on our planet could change drastically as we enter a nearby gas cloud.
