A Type Ia supernova, SN1994D, is shown exploding in lower left corner of the image at the top of the page of the galaxy NGC 4526 taken by the Hubble Space Telescope. (High-Z Supernova Search Team, HST, NASA)Excerpt from dailygalaxy.com Cer...
Tag: beacons (page 1 of 2)
Excerpt from thewestsidestory.net
The Universe is expanding and any student of astronomy will vouch to this fact. However according to a team of astronomers the acceleration of the universe may not be as quick as it was assumed earlier.
A team of astronomers have discovered that certain types of supernova are more varied than earlier thought of and in the process have led to the biggest mystery of the universe-how fast is the universe expanding after the big bang?
Peter A. Milne of the University of Arizona said, “We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances — and thus when the universe was younger, there are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn’t appear to be the case.”
Milne said, “The idea behind this reasoning, is that type Ia supernovae happen to be the same brightness — they all end up pretty similar when they explode. Once people knew why, they started using them as mileposts for the far side of the universe.The faraway supernovae should be like the ones nearby because they look like them, but because they’re fainter than expected, it led people to conclude they’re farther away than expected, and this in turn has led to the conclusion that the universe is expanding faster than it did in the past.”
Milne said, “We’re proposing that our data suggest there might be less dark energy than textbook knowledge, but we can’t put a number on it, until our paper, the two populations of supernovae were treated as the same population. To get that final answer, you need to do all that work again, separately for the red and for the blue population.
Type la supernovae are considered as a benchmark for far away sources of light they do have a fraction of variability which has limited our knowledge of the size of the universe.
The distance of objects with the aid of our binocular vision and the best space-based telescopes and most sophisticated techniques works out in the range of ten or twenty thousand light years.
However as compared to the vastness of space, this is just pea nuts.
For Distances greater than that it is imperative to compare the absolute and observed brightness of well understood objects and to use the difference to determine the object’s distance.
In astronomy it is difficult to find an object of known brightness since there are examples of both bright and dim stars and galaxies. However there is one event which can be used to work out its absolute brightness. Supernovas are the final stages of a dying star and it explodes with such violence, the flash can be seen across the vast universe.
Type la Supernovae occurs in a binary star system when a white dwarf scoops off mass from its fellow star. This reproducible mechanism gives a well determined brightness and therefore scientists term such Type la supernovae as ‘standard candles’.
Astronomers found that the Type la supernovae is so uniform that it has been designated as cosmic beacons and used to assess the depths of the universe. It is now revealed that they fall into different populations and are not very uniform as previously thought. .
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| Frank Drake, the founder of Search for Extraterrestrial Intelligence (SETI), at his home in Aptos, Calif. (Ramin Rahimian for The Washington Post) |
Excerpt from washingtonpost.com
It was near Green Bank, W.Va., in 1960 that a young radio astronomer named Frank Drake conducted the first extensive search for alien civilizations in deep space. He aimed the 85-foot dish of a radio telescope at two nearby, sun-like stars, tuning to a frequency he thought an alien civilization might use for interstellar communication.
But the stars had nothing to say.
So began SETI, the Search for Extraterrestrial Intelligence, a form of astronomical inquiry that has captured the imaginations of people around the planet but has so far failed to detect a single “hello.” Pick your explanation: They’re not there; they’re too far away; they’re insular and aloof; they’re zoned out on computer games; they’re watching us in mild bemusement and wondering when we’ll grow up.
Now some SETI researchers are pushing a more aggressive agenda: Instead of just listening, we would transmit messages, targeting newly discovered planets orbiting distant stars. Through “active SETI,” we’d boldly announce our presence and try to get the conversation started.
Naturally, this is controversial, because of . . . well, the Klingons. The bad aliens.
NASA discovers first Earth-size planet in habitable zone of another star
"NASA's Kepler Space Telescope has discovered the first validated Earth-size planet orbiting in the habitable zone of a distant star, an area where liquid water might exist on its surface. The planet, Kepler-186f, is ten percent larger in size than Earth and orbits its parent star, Kepler-186, every 130 days. The star, located about 500 light-years from Earth, is classified as an M1 dwarf and is half the size and mass of our sun." (NASA Ames Research Center)
This objection is moot, however, according to the proponents of active SETI. They argue that even if there are unfriendlies out there, they already know about us. That’s because “I Love Lucy” and other TV and radio broadcasts are radiating from Earth at the speed of light. Aliens with advanced instruments could also detect our navigational radar beacons and would see that we’ve illuminated our cities.
“We have already sent signals into space that will alert the aliens to our presence with the transmissions and street lighting of the last 70 years,” Seth Shostak, an astronomer at the SETI Institute in California and a supporter of the more aggressive approach, has written. “These emissions cannot be recalled.”
That’s true only to a point, say the critics of active SETI. They argue that unintentional planetary leakage, such as “I Love Lucy,” is omnidirectional and faint, and much harder to detect than an intentional, narrowly focused signal transmitted at a known planet.
The first signals were received at the mission's control center at Johns Hopkins University's Applied Physics Laboratory in Maryland via a giant radio antenna in Australia just before 9:30 p.m. ET, nearly four and a half hours after it was sent by the piano-sized probe. It takes that long for signals to travel between there and here at the speed of light.
Later readings confirmed that New Horizons was fully awake.
New Horizons has been spending about two-thirds of the time since its launch in 2006 in hibernation, to save on electronic wear and tear as well as operational costs. Every few months, the spacecraft's systems have been roused to wakefulness for a checkup, or for photo ops such as its Jupiter flyby in 2007.
The probe also has been sending weekly blips known as "green beacons" — to let the mission team know it's not dead, but only sleeping.
From now on, New Horizons will remain awake continuously through its Bastille Day flyby of Pluto and its moons next July 14. After a few weeks of preparation, the probe's instruments will start making long-range observations on Jan. 15.
The spacecraft is currently about 162 million miles away from Pluto, but as that distance shrinks, the observations will get better and better. By next May, New Horizons' images of Pluto should be sharper than the best pictures taken by the Hubble Space Telescope. And in July, the probe may catch sight of the clouds and ice volcanoes that scientists suspect may exist on the dwarf planet.
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Friday, November 4, 2011
Memories are the pathway to present moments. They are those things which you wish to keep in the storehouse of your mind to be drawn up to empower the present moment. All things are coexistent and holograp...
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