This is how close NASA's Parker Solar Probe will fly by the sun

The Parker Solar Probe will soon be the closest any human-made object has ever gotten to the sun.

The probe, engineered to study the corona -- the outermost layer of the sun's atmosphere, launched in August 2018 and has been gradually orbiting closer to the sun's surface ever since, Nicki Rayl, NASA deputy director of heliophysics, told ABC News.

"It'll be inside the upper atmosphere of the sun, literally touching the star," Rayl said.

In November, the probe conducted its seventh and final flyby of Venus, where it used the planet's gravity to alter its speed and direction so it could enter its final orbit around the sun.

"These cosmic catapults, where we pinball off of the various planets, allow a spacecraft to change its orbit without wasting a lot of fuel," Patricia Reiff, a professor of physics and astronomy at Rice University in Houston, told ABC News. "If you want to get closer and closer to the sun, you have to slow yourself down, and that takes fuel. They don't have a lot of onboard fuel."

Tools aboard the probe will collect data on the energy flowing out from the star, Rayl said. Research like this is integral because so much of life on Earth is dependent on the sun, she added.

By getting close to the sun, Reiff said, scientists will be able to measure the inner part of the solar wind, "which is where the solar corona expands out and becomes the solar wind, and it will travel inside that boundary where it's now mostly corona and not solar wind."

"And by understanding that process, where the corona becomes supersonic and turns into the solar wind, then we can help predict space weather and understand the sun and its processes better," she continued.

Solar activity can have negative impacts on satellites orbiting in space, as well as navigation and control for astronauts navigating through space, Rayl said.

"Getting a better understanding of what's happening in our local neighborhood really helps us protect our investments in space and the future of astronaut space travel," she said.

This is how close the Parker Solar Probe will get to the sun

The Parker Solar Probe is expected to pass within an "unprecedented" 3.86 million miles of the solar surface on Dec. 24, according to NASA.

"It's about to be on its closest approach to the sun," Rayl said.

There, the probe will cut through plumes of plasma connected to the sun and will even be close enough to pass through a solar eruption -- "like a surfer diving under a crashing ocean wave," the space agency said.

The probe has moved closer to the sun throughout its mission. In October 2018, just months after its launch, it broke the record of being the closest a human-made object has ever gotten to the sun, at 26.55 million miles -- a record previously set in 1976 by the Helios 2 spacecraft, which got within 27 million miles of the sun.

How fast is the Parker Solar Probe traveling?

The Parker Solar Probe is traveling at 430,000 mph, making it the "fastest human-made object in history," Rayl said.

The importance of the Parker Solar Probe's heat shield

The probe has been heralded by NASA as an engineering marvel. Its heat shield has been designed to withstand temperatures of about 2,500 degrees Fahrenheit while facing the sun at its closest approach, according to NASA.

At the same time, the heat shield will insulate the important scientific measurement equipment located toward the back of the probe, keeping that area at room temperature, Rayl said. The probe won't burn up due to the protective heat shield.

"This heat shield not only needs to protect the spacecraft from the sun but also needs to insulate all those precious science instruments that are getting us that incredible data on solar wind and the energy flowing out from the sun toward Earth," Rayl said.

The heat shield also allowed researchers to learn more about Venus during the numerous flybys. In July 2020, its camera -- the Wide-Field Imager for Parker Solar Probe, or WISPR -- captured images of Venus' scorching-hot surface through the thick cloud cover.

The WISPR cameras were able to see through the clouds to the surface of Venus, which glows in the near-infrared because it's so hot, Noam Izenberg, a space scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, said in a statement last month.

Reiff said the recent flyby of Venus not only helped change the Parker Solar Probe's orbit so it could get close to the sun, but it also helped scientists learn more about Venus, including data that can help distinguish physical or chemical properties of the planet's surface.

After the latest flyby of Venus, this will be the final orbital configuration for Parker. Once the probe runs out of fuel, it will no longer be able to fight against pressure from the sun, which will cause it to flip around and be incinerated.