There's more to the universe than meets the eye. Astronomers have long suspected the existence of invisible material that pervades the universe, comprising particles entirely different from those that make up visible matter. This "dark" matter is thought to represent about 22 percent of all mass in the universe, but direct evidence of its existence has been debatable. This year, researchers at Johns Hopkins University found the strongest evidence to date that dark matter exists.
Astronomers think this galaxy cluster underwent a massive collision about one to two billion years ago, creating this ghostly ring of dark matter. (This image is composed from two superimposed Hubble telescope images: one of the ring and one of the cluster itself.) which is superimposed here on a Hubble image of the cluster. The researchers spotted the ring, which measures 2.6 million light-years across, unexpectedly while mapping the distribution of dark matter within the galaxy cluster. Simulations of galaxy cluster collisions show that when two of them crash together, the dark matter falls to the center of the combined cluster and then ripples back out.
In October 2007, children (including these two Mongolian boys) in 30 of the world's poorest countries connected to the Internet for the first time thanks to the One Laptop Per Child project. The cheap, rugged, bright green XO laptop created by the group is one of the worthiest causes in modern computing, designed to give economically deprived schoolchildren in developing countries the opportunity to join the Internet era.
Since the kids in these countries don't exactly work in sheltered, sterile cubicles, the XO is astoundingly rugged: Drop it, spill water on it, or cover it in dust and it still works. Most impressively, the laptop also has WiFi "mesh networking"--all you need to do is plant a satellite in a village and everyone's connected. The XO is the dream child of Nicholas Negroponte, cofounder of MIT's Media Lab, who currently has partnerships with the United Nations and several countries to help reach his goal of distributing 10 million to 50 million laptops by the end of 2008.
In February 2007, the world's largest magnet (weighing 1,920 tons, as much as five jumbo jets) was lowered 300 feet underground and placed within the Compact Muon Solenoid particle detector (pictured). The centerpiece of an effort to shed light on the very beginnings of the universe, this detector is part of the Large Hadron Collider (LHC), which runs in a 17-mile circle through France and Switzerland.
The enormous machine may re-create conditions that have not existed since the universe was less than one-trillionth of a second old; it will hunt for the long-sought Higgs boson, the hypothetical particle that explains why matter has mass. On November 1, the two main magnet systems were connected to seal the cryogenic system that will cool the superconductor's magnets to just 1.9 degrees above absolute zero. Built over 13 years, the collider is undergoing final construction and testing and is expected to begin operation in May 2008.
Molecular biologists at Harvard have produced stunning, full-color maps of the complex tangle of neurons in the brains of the lab's "brainbow" mice. Using ingenious genetic tricks and fancy proteins, the team, led by Jeff Lichtman, developed a technique that essentially paints individual neurons one of about 90 distinct hues. This allows scientists to trace the colorful path of each neuron and see how it connects with other neurons to form a circuit.
The research will boost efforts of figuring out how the circuits develop, how they function, and how wiring problems cause diseases like epilepsy. This slide shows the hippocampus (rotated clockwise 90 degrees), a region involved in memory formation, emotion, and spatial navigation.
Image credit: Jean Livet and Tamily Weissman, Harvard University
The multicolored neurons sit in the cerebral cortex, which is involved in higher thought processes and sensory perception. To create a unique color in each neuron, Lichtman did some clever genetic tinkering: He inserted the genes for different-colored fluorescent proteins into the mouse's genome so that each neuron would randomly express a combination of the genes. It ends up being a game of chance: Each neuron is essentially pulling the lever on a "molecular slot machine," says team member Jean Livet, receiving a random combination of the genes that endow it with one of 90 possible colors
Since the July 2004 arrival of NASA's Cassini spacecraft (launched from Earth in October 1997), Saturn and its satellites have been scrutinized as never before. In this natural-color mosaic image captured by Cassini, Saturn nests in its icy rings; the rings appear so much dimmer than the planet because of the steep angle from which the picture is taken.
In 2009 Saturn will reach its equinox and the shadows of the rings will momentarily disappear. By the time Cassini mission officially ends later this year, it will have complete 74 orbits around the mainly gaseous planet.
Roughly 600 volunteers stripped naked to pose on a shrinking Alpine glacier, hoping to draw attention to the impact of global warming. The Aletsch Glacier, near the Swiss town of Bettmeralp, receded almost 400 feet between 2005 and 2006. Scientists predict that nearly 1,800 Swiss glaciers will disappear by 2080. American artist Spencer Tunick, who was commissioned by the environmental group Greenpeace to create this living sculpture, is renowned for his provocative work with naked masses in unexpected public settings. This event was part of Greenpeace's campaign to increase awareness of climate change.
The Japanese Hinode spacecraft, dubbed a "Hubble for the sun" by astronomers, took this image of a developing sunspot colliding with an existing spot. The collision unleashes a powerful burst of X-ray radiation--a solar flare. Though 93 million miles from the sun, Hinode's solar telescope can see features on the sun as small as 90 miles wide and has the unique ability to detect the sun's magnetic field.
Solar flares are essentially magnetic: When lines of magnetic force are contorted, tension and energy build until the giant buildup of magnetic flux explodes, releasing all the energy in a solar flare. Hinode's ability to see these magnetic fields may help astronomers predict solar flares, which can disrupt GPS and all its associated technologies, such as cell phones and electric power grids.
Raging wildfires throughout Southern California left a patchwork of destruction across some 500,000 forested acres, from Simi Valley to San Bernardino to San Diego. A few of the 16 or so fires, which stretched from Malibu to the Mexican border, appeared to have been caused by arson. Still, the blazes raised questions about the role drought and other aspects of climate change may have played in these devastating events--and about what will happen as the world continues to warm. The fires, spread by the Santa Ana winds, occurred during the driest year in Southern California history, causing the largest mass evacuation ever in the state.