Science News Headlines . Horizon full moon illusion more intense near the Solstice . Unusual temperature variations in universe may indicate new physics at time of the big bang . Super atoms are super small pieces of matter . A nap is good for you . A century after the Tunguska event Solstice Moon Illusion On 18 June of this year there was a solctice moon. This is a full moon that looks huge. Yes, as the full moon rises in the east, it does look much larger than when it is high up in the sky. This is a well-known illusion. But a solstice moon looks even bigger! The photo was taken of the moon rise in in Manchester, Maryland, USA on June 18th. This is just two days before the beginning of summer in the northern hemisphere (for us as well). What is the significance of that? The Sun is at its northernmost point in the hemisphere, reaching the Tropic of Cancer. Soon it will start its apparent journey back over the Equator, and thence to the Tropic of Capricorn. So, right now the Sun and full Moon are like children on a see-saw; when one is high, the other is low. This week's high solstice sun gives us a low, horizon-hugging Moon and a strong Moon Illusion. Where is the illusion? While the moon appears big, it is actually not so. Of course, sky watchers realised very early that the moon is the same size always. So they said the illusion was because the Earth's atmosphere must be magnifying the Moon near the horizon. But if you photograph the moon when it is near the horizon, it comes out the same size as it is anywhere else ! So the moon is the same size on a film and it appears that only human beings see giant moons. This has many explanations. One of them is that the moon looks bigger near the horizon when compared to trees and houses seen along with it. Some believe that this is because of the shape of the sky, which distorts distances vertically up from distances along the horizon. In any case, the brain miscalculates the Moon's true distance and hence size. Whatever be the explanation, solstice full moons are a beautiful sight! Temperature variations in the Universe It is well-known that the Universe began about 13.7 billion years ago with a phase of rapid expansion. This is called the Big Bang theory. In tune with its predictions, scientists have measured the temperature of different parts of the Universe and found it to be remarkably uniform so far. This was measured from the cosmic microwave radiation that fills the Universe. Small temperature variations of the microwave background have been measured and these give important information on the evolution of the Universe. Recently, it has been found that there is a small asymmetry in the temperature variations. There appears to be more temperature variation on the left half of the sky than the right. Areas with small temperature excess cause matter to cluster together in that region. This ultimately causes the formation of galaxies and galaxy clusters. According to the simplest model the magnitude of those tiny hot and cold spots ought to be about the same over different parts of the sky. An analysis of the cosmic radiation recorded by NASA's Wilkinson Microwave Anisotropy Probe, or WMAP, shows that the temperature variations over half the sky appear to be about 10 percent greater than the variations in the other half. While this asymmetry looks quite significant, it is not yet confirmed. The European Space Agency's Planck mission will be launched at the end of this year. It will look at variations in the cosmic microwave background on finer scales than WMAP and should determine whether or not the asymmetry is real. Super atoms Gold comes in many colors. Since ancient times, glass artists and alchemists alike have known how to grind the metal into fine particles that would take on hues such as red or mauve. At scales even smaller, clusters of just a few dozen atoms display even more outlandish behavior. They become, as some researchers say, superatoms. Recently researchers have reported successes in creating new superatoms and deciphering their structures. In certain conditions, even familiar molecules such as buckyballs---the soccer-ball-shaped cages made of 60 carbon atoms---unexpectedly turn into superatoms. Scientists are already studying how superatoms bind to each other and to organic molecules. Tracking superatoms can help researchers learn how biological molecules move inside cells and tissues, or determine the structure of those molecules precisely using electron microscopes. And by assembling superatoms of elements such as gold, carbon or aluminum, researchers may soon be able to create entirely new materials. Such materials could store hydrogen fuel in solid form at room temperature, make more powerful rocket fuels or lead to computer chips with molecule-sized features. Designer materials made of superatoms could have combinations of physical properties that don't exist in nature. The physical properties of a material, such as hardness and color, are the same for a 1-pound lump of the stuff as they are for a 100-ton chunk. But when you get to specks made of a few million atoms or less, properties usually begin to change. A material such as silicon, which is usually brittle, can become as ductile as gold. Another example is particles called quantum dots, which fluoresce in a rainbow of different colors depending on their size. But with even fewer atoms a few hundred or less the changes become more dramatic. If you keep going smaller, then you enter a region where properties are erratic. Often, one atom counts. For example, tin clusters behave like conductors or semiconductors, depending on their size. So also magnesium. The interest in making crystals out of superatoms goes beyond pure curiosity. By adjusting the types, shapes and sizes of a material's ingredients, scientists and engineers could tune physical properties to their likes. You would have a way of making materials with tailored properties. For example, a material that can be transparent typically won't conduct electricity, and vice versa. But a suitable all-metal salt, say, might be able to do both. And with a stretch of imagination, all-aluminum salts could make airplanes with see-through fuselages possible! A nap is good for you Researchers from the Sleep Research Center at Loughborough University in England tested 20 healthy young adults for daytime sleepiness. All of the volunteers got about 7.4 hours of sleep per night, and none of them complained of feeling sleepy. But when researchers put them in a quiet room and asked them to close their eyes, all fell asleep within five to 10 minutes in the afternoon, indicating sleepiness. It took longer for the people to fall asleep when tested at other times, indicating that while they were drowsy in the afternoon, the people weren't generally fatigued or tired. Previous studies by other groups have shown that extending nighttime sleep by 90 minutes for two weeks could help combat afternoon sleepiness, but the Loughborough team wanted to know whether naps or caffeine might also help. The researchers compared sleeping extra for 90 minutes each day to taking a 20-minute nap at 2:30 p.m. or taking 150 milligrams of caffeine (equivalent to about two cups of coffee) at 2:00 p.m. Each participant tried each of the three methods of combating afternoon slumps for one week. Although all of the volunteers normally drank caffeinated beverages, during the experiment they received decaffeinated drinks and took caffeine pills when tested for the effect of the afternoon caffeine kick. When the volunteers did nothing, they fell asleep within nine minutes on average when tested at 3:30 in the afternoon. Sleeping late kept people awake only a minute longer on average than did doing nothing. Caffeine worked better, keeping people awake for about 12 minutes longer on average. But nothing beat a nap. After a 20-minute nap, people nearly doubled the amount of time it took to fall asleep when tested later in the afternoon, indicating that they were no longer sleepy. None of the measures reduced people's ability to fall asleep at night. So napping should not be seen as some kind of laziness, or something associated with old people. It may help you be more alert in the afternoon. Tunguska, a century later Early on the morning of June 30, 1908, a massive explosion shook central Siberia. Witnesses told of a fireball that streaked in from the southeast and then detonated in the sky above the desolate, forested region. At the nearest trading post, about 70 kilometers away from the blast, people were reportedly knocked from their feet. Seismic instruments in the area registered ground motions equivalent to those of a magnitude-5 earthquake. The event is often called the Tunguska blast, after a major river running through the area. Its effects were not restricted to Siberia. Sensitive barometers in England detected an atmospheric shock wave as it raced westward and then detected it again after it traveled around the world. High-altitude clouds that formed over the region after the event were so lofty that they caught light from beyond the horizon, illuminating the sky so much that people at locales in Europe and Asia could read newspapers outdoors at midnight. A number of factors including the site's remote location, World War I and the Russian Revolution prevented scientists from mounting an expedition to the blast zone for almost two decades. When researchers eventually reached the region, they found that a 2,150-square-kilometer patch of forest had been flattened, with most of the 80 million trees lying in a radial pattern. What the researchers didn't find, however, was an obvious crater. A century later, scientists are still debating the cause of the Tunguska blast. Most researchers, however, now pin the blame on the mid-air explosion of a small comet or asteroid, which typically can't stand up to the forces received while blazing through the atmosphere. The damage in Siberia suggests that the Tunguska detonation happened at an altitude of between 6 and 8 kilometers and released the energy of about 15 megatons of TNT, about a thousand times more than the bomb that destroyed Hiroshima.