Top 10 Weirdest things in space


NUMBER 10
Brown Dwarfs


Brown dwarfs are the misfits of the universe, something like bit actors in a Hollywood movie -- not just extras, but not genuine stars, either. They are too big to be called planets, yet too small to generate the thermonuclear fusion required to become real stars.

They exist in a world all their own. Sometimes, it's a cold, dark world -- many wander through space alone. Others make a home in the shadow of a great star, gravitationally tethered in what scientists call a binary system.

Either way, they are weird things. And, as researchers are only beginning to learn, there may be as many brown dwarfs as there are stars. But only a few have been discovered since the first was found in 1995.

"Determining how many brown dwarfs exist will tell us about where these objects come from and what is their contribution to the overall chemical and dynamical budget of the Milky Way," says Eduardo Martin of the University of Hawaii.



NUMBER 9
Neutron Stars


Graphic explains how a neutron star generates a strong stellar wind.
Click to enlarge


Neutron stars are the walking corpses of the cosmos. But these weird objects, dense beyond belief, can pack a lively wallop.

A big star ends its life in a giant explosion called a supernova. If the star is massive enough -- roughly four to eight times more massive than our Sun -- and the conditions right, the core implodes, forming a very dense state of matter. So dense that electrons are squeezed into the protons, forming neutrons.

The result, a neutron star, can stuff the mass of 1.4 Suns into an area 7 to 12 miles (11 to 20 kilometers) across.

A neutron star often sucks the life out of a companion, using its immense gravity to steal gas and dust from the nearby normal star. When this matter smacks into the surface of the neutron star, the radiation and rotational force of the star blast some of the material back into space, creating a stellar wind that races through space at 4.5 million miles (7.2 million kilometers) per hour.

And neutron stars are prone to occasional flare-ups, similar to solar flares on our Sun. But in a single flare lasting just a few hours, a neutron star can generate 100 times more energy than our Sun does in an entire year.



NUMBER 8
High-Energy Cosmic Rays

Earth's atmosphere is regularly bombarded by very small numbers of incredibly energetic cosmic ray particles, a type discovered less than a decade ago. No one can explain where they come from or why.


Dust swirls into the center of a galaxy, presumably to a black hole. The process may create high-energy cosmic rays. IMAGE: NASA

Less energetic cosmic ray particles have long been known to bathe our planet. Hundreds slam into every square yard (or square meter) of Earth's atmosphere every second. Many are thought to originate within our galaxy, spawned by large exploding stars called supernovae.

Earth's atmosphere destroys the particles, protecting us. (Astronauts on space walks, on the other hand, are exposed to the potentially deadly particles and must limit time spend outside their craft.)

A decade ago, a new type of cosmic ray particle was discovered, one far more energetic (and much more rare) than the more common type previously known.

"How these microscopic particles achieve macroscopic energies is one of the most pressing questions of high-energy astrophysics," says Niel Brandt, assistant professor of astronomy and astrophysics at Penn State. "These particles cannot travel far through the universe because interactions with the cosmic microwave background quickly sap their energy, so they must be created relatively nearby."

But no one can find the source.

Brandt and others speculate that the particles might come from some unknown super powerful cosmic explosion, from a huge black hole, or could possibly represent exotic remnants of the early universe.



NUMBER 7
Electrostatic Levitation

Cheese is just one of the many weird things that come from the Moon.

Astronauts aboard the Apollo missions in the 1960s and 1970s reported a weird glow on the horizon of the Moon, one that resembled something that might occur in Earth's atmosphere.

"This was unexpected since apart from a few rogue atoms evaporated out of the Moon's barren surface, our satellite doesn't have an atmosphere to speak of," says Matthew Genge of the London Natural History Museum.

Moon clouds? Lunar aurora? The Man on the Moon with a lava lamp?

"The glow actually came from the reflection of sunlight from dust particles that lift up from the Moon's surface," Genge says. "It's a process known as electrostatic levitation."

Sunlight gives an electrostatic charge to dust particles on the Moon, Genge explains, causing some to lift off the surface. While it might sound like something out of I Dream of Jeannie, it's real, and it's one of the weirdest things in space.

So weird, in fact, that some of this Moon dust actually ends up on Earth.


NUMBER 6
The Sun's Hot Atmosphere

Ultraviolet-light image of coronal loops, large arcs of gas and energetic particles that make up the Sun's corona, as seen by the TRACE satellite telescope.

Hold your hands near a campfire -- in its "atmosphere," we'll say -- and they get warm. The closer you get, the warmer it is. If you stick your hands in the fire (and we don't recommend it) you would find it even hotter.

Likewise, you might expect the Sun to be hottest in the middle, and then get cooler as you moved to the surface and then farther out. But, in fact, the temperature rises sharply in the Sun's atmosphere, called the corona. And the same is true of other stars.

Weird, because there is a law that says this can't be so.

"The second law of thermodynamics says that temperature can only drop when you move away from the heat source," says Markus Aschwanden, a solar researcher at the Lockheed Martin Solar and Astrophysics Laboratory. "So there is something magic and invisible that heats the solar and stellar coronae."

After many decades of research into this weird thing, scientists are only beginning to understand what might be going on.



NUMBER 5
Asteroid Companions

Our conception of what a moon is has taken on a whole new meaning in recent years, as scientists have discovered space rocks orbiting other space rocks in our solar system.

In one unlikely setup, an asteroid 90 miles (145 kilometers) wide harbors a "moonlet" about one-tenth that size, just 500 miles away and orbiting once every four days. In another, two asteroids of roughly equal size orbit around a common midpoint.

Scientists are stumped. The math says these asteroids should not be able to hold a moon in orbit.

"These objects exist despite the weak gravity field of the primary asteroid," says William Merline of the Southwest Research Institute. "The gravity field of the often odd-shaped asteroids is also irregular and uneven, further making it difficult to keep a moon in orbit."

And how these small moons can avoid being destroyed by other space rocks is a mystery to researchers. Merline says exploration by a spacecraft might be needed to figure out how asteroids manage to pair up, and it could be a decade or two before these weird things in space are understood.



NUMBER 4
Hypernovae

Sometimes in science, one weird thing leads to another. After more than 30 years of trying to find the source of mysterious deep-space bursts of energy known as gamma-ray bursts, researchers now suspect a newly devised culprit called a hypernova.

Hypernovae are so strange, scienists can't even agree on what they are, or if they are really behind the commotion of the extremely high-energy gamma-ray bursts.

"Gamma rays are the highest energy form of radiation," says NASA's Jerry Fishman. "They are higher energy than X-rays -- they are very penetrating. They'll go through several inches of steel, for example."

Scientists have long suspected that gamma-ray bursts, called GRBs, are triggered by the spiraling merger of two very dense objects, perhaps neutron stars.

But a pair of studies released in November 2000 supports another, stranger possibility.

Many old stars die in a colossal explosion known as a supernova, spewing matter and energy rapidly outward. In some cases, researchers think remaining material collapses into a black hole, which might later generate a burst of gamma rays -- a hypernova.

Understanding hypernovae, and thus pinning down at least one source of gamma-ray bursts, would give researchers clues about the formation of our galaxy and the universe.



NUMBER 3
Our Milky Way's Black Hole


At the center of the Milky Way, a black hole 2.6 million times as massive as our Sun gobbles gas and stars. This "food" is thought to swirl into the center, like muck going down a bathtub drain.

But all this swirling should create lots of friction, which should generate enormous energy. The black hole should, therefore, be very, very bright -- in visible light, X-rays and other wavelengths.

"Instead it is very faint," says Tom Geballe of the Gemini Observatory.

Why? Is there not much stuff falling in? Or is the stuff falling directly in instead of swirling, thereby creating less friction? Or is some unknown effect preventing us from seeing the radiation?

"Nobody is sure," Geballe says, but he suspects we may learn the answer in the next 5 to 10 years.

"One might argue that all black holes always will be strange," he said. "So perhaps I should simply predict that the galactic center black hole will no longer be considered stranger than other black holes by 2010."



NUMBER 2
The Accelerating Universe

Since the 1920s, scientists have known that the universe is expanding. Most believe that this expansion has been going on since the Big Bang, estimated to be 12 billion to 15 billion years ago.

But one of the most pressing questions in cosmology (the study of the structure and history of the universe) is whether this expansion will continue forever, or whether gravity will take over, reverse the course, and pull all of the galaxies back together into a Big Crunch, which would signify the end of time as we know it.

Suddenly, in the past two years, something weird has made the question loom even larger: The expansion of the universe, according to two independent studies, seems actually to be accelerating.

"This is completely unexpected," says Morris Aizenman, senior science associate in the National Science Foundation's Mathematical and Physical Science Directorate. "What force is causing that acceleration? We have no answer."

Researchers speculate that the acceleration might be caused by some strange and unknown matter or energy whose force of gravity repels, rather than attracts, over long distances.



NUMBER 1
Nothing

Whilethere are many weird things in space, one of the weirdest things is what isn'tthere -- the nothingness of the great black void. But what may be most strangeabout this nothingness is the possibility that it is in fact not reallynothing, but rather a whole lot of something we just can't see.

"The nothingness ofthe vacuum has come under theoretical scrutiny the past century, and what appearsmost plausible, and most fantastic, is that space is filled with a seethingfroth of virtual particles," says James C. White II, executive director ofthe Astronomical Society of the Pacific. "And space itself? At thesmallest scales we can consider, it may comingle with time in a foam ofspace-time."

White describes this"foam of space-time" as ubiquitous events, all defined by theirpositions in space and time. If empty space could be photographed, we'd see asea of virtual particles that spring into existence and disappear.

This ultimate small worldis thought to be composed of "particles that come into existence out ofseemingly nothing, from the very energy of the vacuum itself, that exist fortimes so short that their being does not seem to violate the law that says youcan't make something out of nothing," White says.

Researchers are justbeginning to knock on the door of this weird, small world.