Science & Technology
The evidence is seen in tiny iron minerals that are aligned inside ancient dacite rocks from the Barberton mountains in South Africa.
Analysis of the 3.45-billion-year-old minerals indicates the strength the field was much weaker than today.
Earth's magnetic field protects all life on the planet.
It forms a shield that deflects harmful particles from the Sun around our world, and limits the ability of this "solar wind" to erode our atmosphere.

Interior of the Piedras Bolas aqueduct showing the abrupt reduction in conduit size near the exit.
"Water pressure systems were previously thought to have entered the New World with the arrival of the Spanish," the researchers said in a recent issue of the Journal of Archaeological Science. "Yet, archaeological data, seasonal climate conditions, geomorphic setting and simple hydraulic theory clearly show that the Maya of Palenque in Chiapas, Mexico, had empirical knowledge of closed channel water pressure predating the arrival of Europeans."
According to a statement issued on Tuesday by the Supreme Council of Antiquities, the sculpture was unearthed at Taposiris Magna, a site some 30 miles from the port city of Alexandria, by an Egyptian-Dominican team searching for the tomb of the doomed lovers.

The resulting image shown in Figure 1a (taken with a prototype using two-color video cameras) clearly demonstrates how the omni-focused output dramatically differs from that of a conventional camera, shown in Figure 1b. Note that in the omni-focused image, the fingers in the foreground are so sharply focused that even the fingerprints are easily recognized.
Two Indian scientists are wielding sophisticated mathematics to dissect and analyse the traditional meditation chanting sound "Om". The Om team has published six monographs in academic journals. These plumb certain acoustic subtleties of Om, which these researchers say is "the divine sound".
Om has many variations. In a study published in the International Journal of Computer Science and Network Security, the researchers explain: "It may be very fast, several cycles per second. Or it may be slower, several seconds for each cycling of [the] Om mantra. Or it might become extremely slow, with the mmmmmm sound continuing in the mind for much longer periods but still pulsing at that slow rate. It is somewhat like one of these vibrations:
'OMmmOMmmOMmm...The important technical fact is that no matter what form of Om one chants at whatever speed, there is always a basic Omness to it.
'OMmmmmOMmmmmOMmmmm...
'OMmmmmmmmOMmmmmmmmOMmm'."
If we measured the distance around the circle of the entire horizon - from north all the way around through east and south and west and back to north again - that would equal 360-degrees.
From the horizon to the point directly overhead (the zenith) would equal 90-degrees; from one horizon point through the zenith and continuing across to the opposite side of the sky would measure 180-degrees.
Tracking the doomed comet, named LINEAR, the Hubble telescope and the Very Large Telescope in Chile found tiny particles that made up the 2,000-mile-long dust tail and 16 large fragments, some as wide as 330 feet. But the telescopes didn't detect any intermediate-sized pieces. If they exist, then the fundamental building blocks that comprised LINEAR's nucleus may be somewhat smaller than current theories suggest.
The Hubble picture shows that that LINEAR's nucleus has been reduced to a shower of glowing "mini-comets" resembling the fiery fragments from an exploding aerial firework. This picture was taken with Hubble's Wide Field Planetary Camera 2 on August 5, 2000, when the comet was at a distance of 64 million miles (102 million kilometers) from Earth.
Object Name:
Comet LINEAR
"The red auroras were just visible to the naked eye and easily captured by my Nikon D300," says Shaw. "Excellent treat!"
NOAA forecasters estimate a 45% chance of continued geomagnetic activity over the next 24 hours. High-latitute sky watchers should remain alert for auroras.
Nature Genetics reports that scientists "resurrected" a woolly mammoth blood protein to come to their finding.
This protein, known as haemoglobin, is found in red blood cells, where it binds to and carries oxygen.
The team found that mammoths possessed a genetic adaptation allowing their haemoglobin to release oxygen into the body even at low temperatures.
The ability of haemoglobin to release oxygen to the body's tissues is generally inhibited by the cold.

A laser pulse (red) ionises air and triggers the condensation of water droplets to create a cloud, which is illuminated by a second, green laser
People have experimented with cloud seeding for decades in the hope of boosting rainfall, usually by sprinkling silver iodide crystals into clouds high in the atmosphere.
These crystals encourage large water droplets to form around them, and the droplets then fall as rain - in theory, at least. "The efficiency of this technique is controversial," says Jérôme Kasparian at the University of Geneva, Switzerland, one member of a research team that think lasers may be a better way to trigger rain on demand.
Kasparian and colleagues have just reported the first successful use of this technique to summon clouds from air both in the lab and in the skies over Berlin, Germany.











