Researchers said earth's magnetic field works as a protector. If there would not have been magnetic field then earth would have been a barren planet. For a long time now, a debate is going on about when the shield was formed.

Researchers have affirmed that they have found evidence as per which the magnetic field was formed at least 4.2 billion years ago, which is quite before than previously thought. Earlier, it was said that the field originated around 3.5 million years ago.

But as per the research, earth has been protected by the magnetic field from quite early in its history. Study's lead researcher John Tarduno from University of Rochester said that four billion years ago, the solar winds would have been quite more intense.

"Its erosional capability was perhaps 10 times greater than it is today. Without a magnetic shield, you would have this tremendous possibility of eroding the atmosphere and removing water from the planet", said Tarduno.

The researchers came up with the findings by focusing on a mineral called magnetite, which was having ancient zircon crystals from Australia's Jack Hills. The mineral was important as magnetite preserved a record of magnetic field strength when it was trapped in the zircon.

After assessing magnetite in zircon crystals, dating from around 3.2 billion to 4.2 billion years ago, the researchers reached at a conclusion that earth possessed a magnetic field in that period.