Thursday, April 27, 2006

Are We Alone in the Universe?

Are We Alone in the Universe?
Richard A. Kerr

Alone, in all that space? Not likely. Just do the numbers: Several hundred billion stars in our galaxy, hundreds of billions of galaxies in the observable universe, and 150 planets spied already in the immediate neighborhood of the sun. That should make for plenty of warm, scummy little ponds where life could come together to begin billions of years of evolution toward technology-wielding creatures like ourselves. No, the really big question is when, if ever, we'll have the technological wherewithal to reach out and touch such intelligence. With a bit of luck, it could be in the next 25 years.

Workers in the search for extraterrestrial intelligence (SETI) would have needed more than a little luck in the first 45 years of the modern hunt for like-minded colleagues out there. Radio astronomer Frank Drake's landmark Project Ozma was certainly a triumph of hope over daunting odds. In 1960, Drake pointed a 26-meter radio telescope dish in Green Bank,West Virginia, at two stars for a few days each. Given the vacuum-tube technology of the time, he could scan across 0.4 megahertz of the microwave spectrum one channel at a time.

Almost 45 years later, the SETI Institute in Mountain View,California, completed its 10-year-long Project Phoenix. Often using the 350-meter antenna at Arecibo, Puerto Rico, Phoenix researchers searched 710 star systems at 28 million channels simultaneously across an 1800-megahertz range. All in all, the Phoenix search was 100 trillion times more effective than Ozma was.

Besides stunning advances in search power, the first 45 years of modern SETI have also seen a diversification of search strategies. The Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations (SERENDIP) has scanned billions of radio sources in the Milky Way by piggybacking receivers on antennas in use by observational astronomers, including Arecibo. And other groups are turning modest-sized optical telescopes to searching for nanosecond flashes from alien lasers.

Listening for E.T. The SETI Institute is deploying an array of antennas and tying them into a giant "virtual telescope."
Still, nothing has been heard. But then, Phoenix, for example, scanned just one or two nearby sunlike stars out of each 100 million stars out there. For such sparse sampling to work, advanced, broadcasting civilizations would have to be abundant, or searchers would have to get very lucky.

To find the needle in a galaxy-size haystack, SETI workers are counting on the consistently exponential growth of computing power to continue for another couple of decades. In northern California, the SETI Institute has already begun constructing an array composed of individual 6-meter antennas. Ever-cheaper computer power will eventually tie 350 such antennas into "virtual telescopes," allowing scientists to search many targets at once. If Moore's law--that the cost of computation halves every 18 months--holds for another 15 years or so, SETI workers plan to use this antenna array approach to check out not a few thousand but perhaps a few million or even tens of millions of stars for alien signals. If there were just 10,000 advanced civilizations in the galaxy, they could well strike pay dirt before Science turns 150.

The technology may well be available in coming decades, but SETI will also need money. That's no easy task in a field with as high a "giggle factor" as SETI has. The U.S. Congress forced NASA to wash its hands of SETI in 1993 after some congressmen mocked the whole idea of spending federal money to look for "little green men with misshapen heads," as one of them put it. Searching for another tippy-top branch of the evolutionary tree still isn't part of the NASA vision. For more than a decade, private funding alone has driven SETI. But the SETI Institute's planned $35 million array is only a prototype of the Square Kilometer Array that would put those tens of millions of stars within reach of SETI workers. For that, mainstream radio astronomers will have to be onboard--or we'll be feeling alone in the universe a long time indeed.

What Is the Universe Made Of?

What Is the Universe Made Of?
Charles Seife

Every once in a while, cosmologists are dragged, kicking and screaming, into a universe much more unsettling than they had any reason to expect. In the 1500s and 1600s, Copernicus, Kepler, and Newton showed that Earth is just one of many planets orbiting one of many stars, destroying the comfortable Medieval notion of a closed and tiny cosmos. In the 1920s, Edwin Hubble showed that our universe is constantly expanding and evolving, a finding that eventually shattered the idea that the universe is unchanging and eternal. And in the past few decades, cosmologists have discovered that the ordinary matter that makes up stars and galaxies and people is less than 5% of everything there is. Grappling with this new understanding of the cosmos, scientists face one overriding question: What is the universe made of?

This question arises from years of progressively stranger observations. In the 1960s, astronomers discovered that galaxies spun around too fast for the collective pull of the stars' gravity to keep them from flying apart. Something unseen appears to be keeping the stars from flinging themselves away from the center: unilluminated matter that exerts extra gravitational force. This is dark matter.

Over the years, scientists have spotted some of this dark matter in space; they have seen ghostly clouds of gas with x-ray telescopes, watched the twinkle of distant stars as invisible clumps of matter pass in front of them, and measured the distortion of space and time caused by invisible mass in galaxies. And thanks to observations of the abundances of elements in primordial gas clouds, physicists have concluded that only 10% of ordinary matter is visible to telescopes.
In the dark. Dark matter holds galaxies together; supernovae measurements point to a mysterious dark energy.

But even multiplying all the visible "ordinary" matter by 10 doesn't come close to accounting for how the universe is structured. When astronomers look up in the heavens with powerful telescopes, they see a lumpy cosmos. Galaxies don't dot the skies uniformly; they cluster together in thin tendrils and filaments that twine among vast voids. Just as there isn't enough visible matter to keep galaxies spinning at the right speed, there isn't enough ordinary matter to account for this lumpiness. Cosmologists now conclude that the gravitational forces exerted by another form of dark matter, made of an as-yet-undiscovered type of particle, must be sculpting these vast cosmic structures. They estimate that this exotic dark matter makes up about 25% of the stuff in the universe--five times as much as ordinary matter.

But even this mysterious entity pales by comparison to another mystery: dark energy. In the late 1990s, scientists examining distant supernovae discovered that the universe is expanding faster and faster, instead of slowing down as the laws of physics would imply. Is there some sort of antigravity force blowing the universe up?

All signs point to yes. Independent measurements of a variety of phenomena--cosmic background radiation, element abundances, galaxy clustering, gravitational lensing, gas cloud properties--all converge on a consistent, but bizarre, picture of the cosmos. Ordinary matter and exotic, unknown particles together make up only about 30% of the stuff in the universe; the rest is this mysterious anti-gravity force known as dark energy.

This means that figuring out what the universe is made of will require answers to three increasingly difficult sets of questions. What is ordinary dark matter made of, and where does it reside? Astrophysical observations, such as those that measure the bending of light by massive objects in space, are already yielding the answer. What is exotic dark matter? Scientists have some ideas, and with luck, a dark-matter trap buried deep underground or a high-energy atom smasher will discover a new type of particle within the next decade. And finally, what is dark energy? This question, which wouldn't even have been asked a decade ago, seems to transcend known physics more than any other phenomenon yet observed. Ever-better measurements of supernovae and cosmic background radiation as well as planned observations of gravitational lensing will yield information about dark energy's "equation of state"--essentially a measure of how squishy the substance is. But at the moment, the nature of dark energy is arguably the murkiest question in physics--and the one that, when answered, may shed the most light.

Tuesday, April 25, 2006

Tycho Brahe Planetarium

Tycho Brahe Planetarium

In the planetarium you get introduced to interesting stories about space travel, astronomy and the actual starry sky. Movies, star performances and laser shows are shown at the dome screen. The movies are of the type OMNIMAX - a complex projector. The razor sharp picture is projected at the hemispherically shaped planetarium dome, and a specially designed sound system, constructed by SONICS, surrounds the audience. The result of this is an amazing experience of being in the center of the events as well as being a part of the movie. Tycho Brahe Planetarium also offers many other exciting experiences.
Tycho Brahe Planetarium
Gl. Kongevej 10
1610 København V
Tlf: 33 121224

Monday, April 24, 2006

Moon Mythology

According to Harivansha Purana moon was the son of Sage Atri and was nurtured by the ten DISHAS (directions). Moon married the daughters of Daksha Prajapati. They were 27 in number. The names of these daughters are the 27 Nakshatras of the Zodiac. Moon visits each of them for one day in rotation. But he showed Rohini, one of the 27th wives undue favors. He also ran away with the Wife of Brihaspati the Deva Guru. Daksh the father in law cursed Moon to suffer from consumption, a gradual decay. Mercury was born a result of interaction of Moon with the wife of Brihaspati.
According to western concept Moon is considered as Virgin Mary of the Roman Catholics and nourishing mother of the heavens. She is the queen of the night also called Luna (Diana). Diana is the twin sister of Apollo. She governs chastity as well as fertility.

Monday, April 17, 2006

The Science of Space Recycling

Where does water used on the International Space Station come from? What happens to the water when it's used? How are the station's water and air supplies connected? And what does any of that mean for your classroom?

Image: Expedition 12 Commander Bill McArthur shows a coffee container at the beginning of the video. Credit: NASA

NASA's newest educational resource answers all of those questions, and more. In a six-minute informal video, International Space Station Expedition 12 Commander Bill McArthur explains how other spacecraft bring water to the ISS and how it is used once it gets there. He also tells how water can be recycled or converted into air, using equipment on board the space shuttle and the station. The video is part of a series of educational demonstration activities, in which station crewmembers have discussed life and work in space.

During the educational demonstration activity, station astronauts and cosmonauts talk informally in space about basic principles of science, math, physics, engineering and geography. The crew uses hardware already on board the ISS. The videotaped demonstrations address K-12 audiences, support national standards and enhance existing NASA education products and programs.

Accompanying the recycling video is a free, downloadable supplement. This additional material contains discussion questions and further insights that outline a number of related science, technology, engineering and mathematics, or STEM, concepts. The supplement equips educators with interesting information that is unique to NASA and is provided by its scientists and engineers. The supplement is aligned with national science learning standards and complements STEM lessons for grades 9-12. Educators of other grade levels may find them useful as well.

Image: Fuel cells that provide electrical power for the space shuttle also produce water that is used by space station crews. Credit: NASA

McArthur began his six-month mission on the International Space Station in October 2005, along with Russian flight engineer Valery Tokarev. The crew returned to Earth after handing the station over to the Expedition 13 crew in April 2006. McArthur performed his first educational demonstration activity early in his stay on the ISS. He recorded a lecture about the orbiting laboratory's large solar panels in which he showed how the station's power systems work. He also has demonstrated the importance of safety while working in the Destiny laboratory, shown how supplies are delivered to the station by the Russian Progress vehicle, and compared U.S. and Russian spacesuits. Look for these videos and their accompanying educator insights in the near future at the NASA Web site.

Sunday, April 16, 2006

Word From Admin

Topics below are about planets in our solar system. You can find there some basic information about planets.
From now on I will post interesting (I hope it will be) stories about space and science.

~ Aleksa ~

Tags: , , , ,

eXTReMe Tracker