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Several dozen baby galaxies have turned up near the Milky Way and the findings may shed light on what triggers galaxies to form.
Most galaxies blinked into life more than 10 billion years ago, starting as small blobs of gas and stars that gradually merged into larger structures like the Milky Way. But after that initial baby boom, the galactic birth rate dropped significantly. So astronomers must look back through 10 billion light-years of mostly older galaxies to glimpse the small, faint infants from which those galaxies grew.
But now, a space telescope has found about three dozen of these galactic "building blocks" just 2 billion to 4 billion light years away. These relatively nearby finds appear eerily similar to the universe’s first galaxies. They have the same mass (equivalent to about 10 billion Suns), the same elemental composition (roughly that of the Sun), and the same age of stars (approximately 1 billion years old).
The discoveries were made with NASA’s Galaxy Evolution Explorer (GALEX), a space telescope that surveys ultraviolet wavelengths. GALEX detected the galaxies by the ultraviolet glow of their newborn stars, which are being formed at rates about a hundred times higher than in mature galaxies.
(Please search and read about GALEX in this blog)
Earth has already been hit by asteroids many times throughout history. A recent example, called the Tunguska event, occurred in 1908, when a meteor or comet exploded over the wilderness of Siberia, damaging farmland and leveling trees for miles around. Because most of the earth is covered by oceans, there may also be many small impacts that go unnoticed.
Although the odds of any one particular asteroid ever impacting Earth are quite low, it is still likely that one day our planet will be hit by another asteroid. At the current rate of impacts, we would expect about one large asteroid to impact Earth every 100 million years or so.
When a new asteroid is discovered, astronomers analyze it to determine whether its orbit around the sun could bring it close to the Earth. They take successive images of the asteroid over the course of days after its discovery in order to predict its probable orbital path for the near future. The predicted orbit is then compared to the orbit and position of Earth to check for any times when they might pass close to each other.
Although scientists can calculate a most-likely orbit from these early observations, each single observation of the asteroid’s position contains some uncertainty. Most asteroids are small objects, a few meters to a few tens of meters across, and even the resolving power of a large telescope cannot determine their positions exactly. The uncertainties in an asteroid’s position lead to uncertainties in how well we can determine its speed and direction of travel. As a result, a large number of possible orbits for an asteroid can be predicted within these windows of uncertainty.
Careful computer simulations are used to calculate the future orbital path of the asteroid, with randomly chosen initial positions and velocities that fall within the margin of error of the telescopic observations to date. A large number of these simulations are generated for each asteroid. The probability that any particular one will actually hit Earth is given by the fraction of the extrapolated paths that leads to an impact. For example, if one million different possible orbits are calculated, and one of those leads to an impact, then we say that the odds of the asteroid hitting our world are one million to one.
There’s a 1-in-300 chance that a recently discovered asteroid, named 2004 MN4, could hit Earth in 2029. 2004 MN4 was discovered in June 2004 and rediscovered this month.At about 1,320 feet in length, it would have about 1,600 megatons of energy. It takes less than a year to go all the way around the sun, and on each orbit it passes by Earth’s orbit twice. It is also nearly on the same plane as Earth’s orbit.
But the perceived risk probably will be eliminated once astronomers get more detail about its orbit.
(Please see coming entry "How sciencetists calculate the chance of an asteroid hitting Earth". It will be posted in 2 days time)
A Japanese spacecraft called Hayabusa is is now heading to an asteroid. Launch on 9 May 2003, its primary goal is to acquire and verify technology which is necessary to retrieve samples from a small body in the solar system and to bring back them to the earth. Hayabusa spacecraft is equipped with solar powered electrical propulsion system, and autonomous navigation and guidance system. The spacecraft will rendezvous with asteroid Itokawa on October 2005, touch down and take some amount of sample.
The spacecraft will remain with the asteroid for about three months before heading back to Earth. The sample return capsule will detach from the spacecraft and plunge through Earth’s atmosphereon June 2007. After re-entry, the container will parachute to Earth where it can be brought to a lab for study.
Hayabusa in Japanese means falcon. Asteroid Itokawa is named in honor of Dr. Hideo Itokawa, a founder of Japan’s space program.
When George Ellery Hale started building Mount Wilson Observatory in 20 December 1904, he used mules to carry tonnes of material to the mountaintop because motor vehicles struggled to climb the steep road to the construction site. The observatory would become home to the largest telescopes in the world for the next four decades.
Unfortunately, Hale’s craving for perfection and the responsibility of managing big projects became self-destructive. The overwhelming stress resulted in periods of psychosis that ultimately forced him to spend months in a sanatorium in Maine.
The telescope was eventually completed in 1917, and on the night of 1 November, Hale had the honour of being the first person to stare into the eyepiece.
The man who best exploited the power of the Mount Wilson telescopes was Edwin Hubble, whose first great discovery was to show in 1923 that the faint smudges that populated the heavens were in fact remote galaxies, each one consisting of billions of stars. By measuring the distances to these galaxies, Hubble could estimate the scale of the Universe. Mount Wilson became famous and Hubble became a celebrity.
But Mount Wilson’s dominance began to diminish after the Second World War, when rival telescopes were constructed and the lights of an expanding Los Angeles began to pollute the skies above the San Gabriel Mountains. Today’s astronomers prefer to head to places such as Chile and Hawaii, where observatories are sited on even more remote and higher mountaintops.
However, the spirit of Edwin Hubble, George Ellery Hale and Mount Wilson lives on. For example, the Hubble Space Telescope, in name and ambition, proves that astronomers continue to push the limits of astronomy.
A telescope launched into orbit by a space shuttle might seem far removed from one hauled to a mountaintop by mules, but both are the result of an insatiable curiosity and a never-ending obsession about the Universe.
Engineers are making the final preparations for the launch of NASA’s Deep Impact spacecraft, due to lift off from Cape Canaveral on January 12, 2005. The spacecraft will make a six-month journey to reach the nucleus of Comet Tempel 1, and then mothership will eject the 360kg projectile, called an "impactor", directly into the path of Tempel 1. The projectile will crash into it on 4 July 2005 at 37,000 km/h (23,000 mph). Before crashing the camera aboard the projectile will take pictures of Tempel 1. Under optimal conditions, the camera could send back images of the comet’s surface with a resolution of up to 20cm per pixel..The 1-metre square copper probe will completely vapourize, and should carve out a hole the size of the Roman Coliseum. From a distance of 500km, Deep Impact will analyse Temple 1’s chemistry and structure by taking pictures and readings as comet debris is hurled out. The impact will also be recorded by Hubble, Spitzer, Chandra, and dozens of Earth-based observatories
Spirit rover on Mars has discovered a mineral called goethite in the bedrock at Gusev which forms only in the presence of water.
Spirit had previously identified the mineral haematite in the bedrock at Columbia Hills, where it is exploring. This mineral usually forms in wet conditions, but it can occasionally form without the presence of water
The discovery of goethite, however, makes the evidence for a watery past at Gusev more compelling.
Spirit has now driven past a feature called the West Spur and has started to ascend Husband Hill, a section of Columbia Hills.
On the other side of Mars, Opportunity has spotted clouds and frost on the flat plain of Meridiani Planum, a sign of the changing seasons on the planet. They are caused by water vapour moving from the planet’s North Pole toward the South Pole during the current northern-summer and southern-winter period. A thin frost was observed by Opportunity on the calibration target for its panoramic camera
Russian scientists are selecting volunteers to be locked in a capsule for 500 days to test plans for a trip to Mars. A team of six men will be physically cut off from the outside world to test equipment intended to make them self-sufficient for long periods. Their capsule will consist of a bedroom, a kitchen and a laboratory. The capsule’s own equipment should make all of the oxygen they need, repeatedly recycle three tonnes of water and grow some food to add to five tonnes of supplies packed inside. Scientists only have two of their six volunteers so far and will not begin the mock-up mission until some time in 2006.
Rosetta, Europe’s spacecraft to land on Comet 67P/Churyumov-Gerasimenko is now travelling towards Jupiter’s orbit where it will meet with its target. Once near the giant planet, Rosetta will attempt to land on Comet 67P.
The stakes for Rosetta are high: the scientific breakthroughs have to be big enough to convince a skeptical public that the expense was worth it, and the execution of the mission has to be seamless enough to convince ESA’s competitors and collaborators that Europe is in the space game to stay.
Apart from Rosetta, other ESA crafts are scheduled to make a number of stops throughout the solar system over the next few years. The Cassini/Huygens, a joint NASA-ESA craft is to land on Titan, Saturn’s largest moon, next year.
Then there’s Venus Express, which will investigate the planet’s super-hot surface and thick, heavy atmosphere, which is 96% carbon dioxide.
Europe is also moving ahead with the Columbus science laboratory, its biggest single contribution to the International Space Station, and further down the road are projects for the advanced study of gravitational waves and cosmic microwave background radiation.
But the greatest of all ESA missions is Aurora. Now in an initial three-year preparatory stage, Aurora is laying the groundwork for the next steps in the human exploration of space. With a European human landing on Mars in 30 years as Aurora’s ultimate goal, EADS Space Transportation, a Bremen-headquartered firm that makes space vehicles and components, is in the initial stages of exploring a Mars Sample Return mission, which would land a craft on Mars and return a small capsule with Martian surface samples to Earth.
Astronomers have noticed the first direct evidence that solar storms can wreak havoc with comets, destroying their ion tails
The ion tails of comets constantly stream away from the Sun, pushed back by solar wind blowing at about 894,774 mph (400 kilometers per second). But the charged particles of CMEs, among the worst of solar storms, can slam into a comet’s ion tail at about 2.2 million mph (1,000 kilometers per second), causing kinks, scalloped patterns or disrupting the tail altogether.
But by watching comet tail behavior, researchers could learn more about changes in CME structure and speed as they move through space. At the heart of Jones’ study is the comet 153P/Ikeya-Zhang, which passed through the inner solar system during spring 2002. Ikeya-Zhang’s ion tail was studied NASA/European Space Agency SOHO spacecraft and by amateur astronomers.
CME events recorded by SOHO instruments on March 2, March 9-10 and April 17 appear to have slammed into Ikeya-Zhang’s ion tail each about a day or so after leaving the Sun. None of the CMEs distorted the comet’s tail for more than an hour.
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
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