Commentary Magazine

Off to the Sun

In 1957, an astrophysicist at the University of Chicago named Eugene Parker submitted a paper to The Astrophysical Journal, the most prestigious journal in that field.  In it, he predicted the existence of the solar wind, a stream of charged particles, streaming out from the sun in all directions. The idea was considered so ridiculous that two reviewers rejected the article. But the editor of the Astrophysical Journal, Subrahmanyan Chandrasekhar, (one of the giants of 20th-century astrophysics, who would win the Nobel Prize in 1983) couldn’t find any flaws in the math, so he overrode the reviewers and published it. Within four years, the paper had been vindicated by the earliest space probes, and our understanding of the sun and its dynamics took a quantum leap forward

On Sunday, a Delta IV heavy-lift rocket took off from Cape Canaveral carrying the Parker Solar Probe (the first time a NASA mission has been named for a living person) to explore the sun and its outer atmosphere, the corona, close up. Very close up. The Parker space mission will get within 3.83 million miles of the sun’s photosphere (the “surface” that you see when you look at the sun, which you should do only with proper eye protection).

How close is that? Well, since sunlight is subject to an inverse square law, just like gravity, when you get twice as close to the sun, you are getting four times as much sunlight per unit of area. At 3.83 million miles the Parker space probe will be getting about 590 times as much sunlight per square inch as we get on earth. In other words, the sunburn you would get in one hour of a bright sunny day on the equator, you would get in about six seconds if you were 3.83 million miles from the sun. In one hour, you would be, well, long since toast.

The Parker mission will (we hope) be able to withstand such an enormous energy flux thanks to some very fancy engineering. According to Space.com, “To deal with heat, the solar-powered probe is equipped with a 7.5-foot-wide (2.3 meters), 4.5-inch-thick (11.4 centimeters) shield made of an advanced carbon-composite material, which will keep most of the spacecraft’s scientific instruments at a comfortable 85 degrees F (29 degrees C).”

The probe, at times, will accelerate to about 430,000 miles an hour over the course of its seven-year mission, by far the fastest man-made object in history. (A high-powered bullet has a muzzle velocity of about 4000 feet a second, or 2,700 miles an hour, not even one percent the speed that the Parker space mission will achieve).

If all goes well, within a decade, our knowledge of the sun will have taken another quantum leap forward.

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