The fastest object ever built by humans will fly within a whisker of the sun today.

The Parker Solar Probe will race past at 435,000mph as it studies the sun's surface and atmosphere.

That's so fast it would cover the distance between London and New York in just 29 seconds.

It has picked up such an extraordinary speed because it is being pulled in by immense gravitational forces.

Now in its closest orbit yet, Parker will pass just 3.8 million miles above the sun's surface.

It will be within the corona, the super-heated outer atmosphere that's visible from Earth as bright whisps during a total solar eclipse.

The front of the spacecraft is expected to reach 1,400C, and mission scientists won't know whether it has survived until it signals back to Earth that all is well on 27 December.

Yanping Guo, the mission design and navigation manager, told Sky News that it will be an anxious wait.

"We will be looking forward to that," she said. "It's like a baby to me.

"But I'm pretty confident we will hear good news and get more data from the spacecraft."

The Parker probe was launched in August 2018 and it has been spiralling ever closer to the sun. This is its 22nd orbit - and it is as close as it will get.

Scientists are hoping for a huge batch of data to help understand our sun. A team at Imperial College London analysed data from a previous orbit and found sharp kinks in the sun's magnetic field that were generating the million-mile-an-hour solar wind.

Professor Tim Horbury, who led the research, said the stream of particles drives the aurora on Earth - but they are also a threat.

"The radiation can damage astronauts, it can knock out satellites and even have effects on the ground, for example, on the power grid," he said.

"By understanding how the solar wind is made and how it carries the magnetic field out into interplanetary space, we hope in the long run to be able to make better predictions about what's going to arrive at the Earth."

Scientists hope the new orbit will help them understand the sun's super-heated outer atmosphere. It reaches more than 1 million degrees Celsius - yet the surface of the sun is only 6,000C or so.

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A mission to fly close to the sun was conceived by scientists in 1958, but it was only at the start of this century that engineers were able to build a spacecraft that stood a chance of surviving such a hostile atmosphere.

Their design was for a huge heat shield that faces the sun, shading the delicate instruments.

"I'm incredibly lucky to be at this moment in my career when finally this mission is flying so we can do the science we've wanted to do for decades," said Prof Horbury.

"The science is great, but the engineering achievement is extraordinary. It's an extraordinary environment in which to travel."

(c) Sky News 2024: NASA's Parker Probe: Fastest object ever built to make closest approach to sun today