A
The US have certainly looked at using some of the more esoteric astronomical phenomena, such as pulsars for navigational purposes.Prospect said:How do you navigate in deep space? You take readings from 2 or more beacons and use basic trigonometry.
Tin Finger said:only problem with space is there arnt any other points of refrence such as stars shame eh.
'Ere I be!intaglio said:rynner where are you when we need you???)
BBC LinkFor the first time scientists have predicted the explosion of a star.
The star in question is designated Supernova 2003dh and was seen to brighten on 8 April.
The prediction was the consequence of detecting a pulse of energy in the form of gamma rays from the same direction ten days earlier.
Before this observation, and the prompt given to them by the gamma-ray burst, scientists could not predict the explosion of a supernova to an accuracy of better than a few million years.
Right place, right time
Scientists Arnon Dar and Alvaro de Rujula from the European Centre for Nuclear Research and the Technion Institute of Technology in Israel made the prediction about the explosion and watched it happen.
The pair developed a theory to account for the mysterious gamma-ray bursts that come from the depths of the Universe.
For over 30 years these bursts of high-energy radiation have mystified scientists, who cannot explain their enormous energies.
According to the Cern-Technion team, gamma-ray bursts are linked to supernovae, the cataclysmic explosions of massive stars at the end of their lives.
To test their theory, the researchers needed to wait for a gamma-ray burst that was relatively close, in cosmic terms at least.
On 29 March a particularly close and powerful gamma-ray burst, designated GRB 030329 was detected.
Looking at their calculations the CERN-Technion team immediately predicted that light from a supernova would first become clearly visible on Earth on 8 April.
And so it did. It has even been detected by advanced amateur astronomers.
This is the first time that scientists have predicted the exact day of observation of a supernova.
Astronomers will now be very interested in why the gamma-ray burst occurred first and the explosion of the star several days later.
Tin Finger said:What if these are an atempt to kill us off.
If enough of these hit the earth when life was first forming could it have been enough to stop early life starting,before an atmosphear formed?
They could have just miss calculated the time scale for an attack!
that's a half truth at best, the sun is releasing gamma all the time from its center. I think you are confusing ionization energies (the energies it takes for an electron to jump orbitals) with the nuclear fusion reaction that takes place in the center of the sun. The thermonucler reaction goes as such 4H + E => 2He + neutrino + gamma rayFortis said:The sun is predominantly a mixture of hydrogen and helium, so in terms of electron transitions you would be limited to their electronic energy levels. Sadly (or happily, depending on your point of view ) none of these transitions are in the correct energy range to allow the emission of a gamma-ray.
Search said:that's a half truth at best, the sun is releasing gamma all the time from its center. I think you are confusing ionization energies (the energies it takes for an electron to jump orbitals) with the nuclear fusion reaction that takes place in the center of the sun. The thermonucler reaction goes as such 4H + E => 2He + neutrino + gamma ray
Dont atoms release an amount of energy whilst there electrons change to a lower orbit around them?
If the suns atoms did this all at once.
But the link to gamma rays?
A blip in time?
Eburacum45 says:
1/ the explosion of material that is deposited on a white dwarf star by a close companion- (smaller versions of this are seen as ordinary novae)
I'm afraid I must disagree. This type of novae is regular and is of a characteristic energy. This is the type of novae that was used to calculate the rate of expansion of the universe, due to knowing what the absolute luminosity of the event was. There are no big or small versions of this type of novae.
and here is an ordinary novaA Type 1 supernova is composed of two stars, one the ancient core of an old star like our own sun (a white dwarf, made of carbon and oxygen), the other is either a young (main sequence star like the sun) or a middle-aged (red-giant) star. The stars must orbit each other closely enough that gravity can pull material from the envelope of the younger star onto the surface of the white dwarf. Once enough matter builds up, the temperature and density of the white dwarf reach a point where a thermonuclear runaway begins.
"Then the entire star blows up. It's similar to a huge hydrogen bomb," Hoffman said. "Amazingly, research suggests the younger star may survive the explosion, although only its dense core would remain. In the process most of the white dwarf is transformed into radioactive nickel, which decays to iron."
so you can see where I get confused.If the white dwarf and main sequence remnant of a close double are close enough, the white dwarf can raise tides in the main sequence star, and mass will flow the other way, from the main sequence star to the white dwarf. Theory and observation both show that the flowing matter first enters a disk around the white dwarf from which it falls onto the white dwarf's surface. Instabilities in the disk can make such a star "flicker" over periods of days and weeks, even producing sudden outbursts of light. The star that became the white dwarf had lost almost all of its hydrogen envelope during its own evolution. When enough fresh hydrogen from the main sequence star has fallen onto the white dwarf, it can, in the nuclear sense, ignite, fusing suddenly and explosively to helium. The surface of the white dwarf blasts into space, the star becoming temporarily vastly brighter. On Earth we see a "new" star or "nova" (meaning "new in Latin) erupt into the nighttime sky, not a new star at all but an old one undergoing eruption. Novae are common, 25 or so going off in the Galaxy every year, once a generation one close enough to reach first magnitude.
This thread is very well researched. I enjoyed reading it. x
I have a really humourous sarcastic aussie surfer option on mineSat Nav is brilliant especially when you have a famous person voice on it.