Nasa yesterday launched a $1.5 billion spacecraft toward the Sun on a historic mission to protect the Earth by unveiling the mysteries of dangerous solar storms.

"Three, two, one, zero, and liftoff! Of the mighty Delta IV Heavy rocket with Nasa's Parker Solar Probe, a daring mission to shed light on the mysteries of our closest star, the Sun," said the narrator on NASA TV. The launch lit the night sky at Cape Canaveral, Florida at 3:31 am (0731 GMT).

Less than an hour later, mission managers confirmed that the spacecraft separated from the rocket as planned and was safely on its journey.

"At this point, spacecraft is up and happy," said a spokesman with United Launch Alliance, the company that operates the rocket.

The unmanned spacecraft's mission is to get closer than any human-made object ever to the center of our solar system, plunging into the Sun's atmosphere, known as the corona, during a seven-year mission.

The probe is guarded by an ultra-powerful heat shield that can endure unprecedented levels of heat, and radiation 500 times that experienced on Earth.

Nasa has billed the mission as the first spacecraft to "touch the Sun."

In reality, it should come within 3.83 million miles (6.16 million kilometers) of the Sun's surface, close enough to study the curious phenomenon of the solar wind and the Sun's atmosphere, known as the corona, which is 300 times hotter than Sun's surface.

The car-sized probe will give scientists a better understanding of solar wind and geomagnetic storms that risk wreaking chaos on Earth by knocking out the power grid. These poorly understood solar outbursts could potentially wipe out power to millions of people.

Knowing more about the solar wind and space storms will also help protect future deep space explorers as they journey toward the Moon or Mars.

The spacecraft is protected from melting during its close shave with the Sun by a heat shield just 4.5 inches thick.

Even in a region where temperatures can reach more than a million degrees Fahrenheit, the sunlight is expected to heat the shield to just around 1,371 degrees Celsius. Yet the inside of the spacecraft should stay at just 85 degrees Fahrenheit.

Scientists have wanted to build a spacecraft like this for more than 60 years, but only recently did the heat shield technology capable of protecting sensitive instruments become available.

When it nears the Sun, the probe will travel at some 430,000 miles per hours -- the fastest ever human-made object.