The Sun —
Three years after NASA launched its Parker Solar Probe, the probe has become the first human spacecraft to “touch” the Sun. The probe first flew through the Sun’s outer atmosphere, or “corona” in April.
The Parker Solar Probe was named for Eugene Parker, the scientist who first suggested that the Sun sent out a stream of tiny, invisible particles. Mr. Parker called this stream of particles “solar wind”. At first, very few people took Mr. Parker’s idea seriously, but he turned out to be right.
(Source: Screenshot NASA, via YouTube.)
NASA launched the Parker Solar Probe in August of 2018 to learn more about what goes on in the Sun’s corona. The corona is the outer atmosphere of the Sun. If you imagine a simple drawing of the Sun as a yellow ball with lines coming out of it, the corona is the part where the lines are.
Solar storms and other activity, like solar flares, happen in the corona. Studying the corona is important because this activity can affect satellites, GPS, and other important systems back on Earth.
(Source: Luc Viatour, from Wikimedia Commons.)
The corona is far hotter than the surface of the Sun itself. Scientists are trying to understand why. In order to work so close to the Sun, the probe is protected by special, thick foam. This allows it to keep cool inside, even when the heat is as high as 2,500º Fahrenheit (about 1,400º Celsius).
The Parker probe has already revealed details about unusual “switchbacks” in the solar wind inside the corona. These switchbacks are magnetic zigzag patterns where the solar wind moves away from the Sun, then back towards the Sun, then away again.
(Source: Screenshot NASA, via YouTube.)
The probe has also proven that the outer boundary of the Sun’s corona isn’t smooth like a ball. Instead, it’s uneven, bumping out in places, and pushed in in others (see first picture).
In April, on its eighth trip around the Sun, the probe crossed this bumpy boundary and actually entered the Sun’s corona. It flew through the corona for about five hours, recording information on the solar winds and magnetic fields around it. Later, the probe flew in and out of the corona several more times.
(Source: NASA/Johns Hopkins APL/Naval Research Laboratory.)
The Parker probe was going incredibly quickly as it passed through the corona. On its first trip through the corona, the probe was traveling at about 223,200 mph (360,000 kph).
At its closest, the probe was about 6.5 million miles (10.5 million kilometers) above the surface of the Sun. Though this happened in April, it took months for the information to reach Earth and for scientists to confirm it.
Scientists are looking forward to learning more as the probe enters the corona in the future. Its next trip into the corona will be in January. In 2025, the probe will go even closer – about 3.83 million miles (6.16 million kilometers) from the Sun’s surface.
(Source: NASA/Johns Hopkins APL.)
Did You Know…?
The size of the Sun’s corona depends on the Sun’s activity, which usually increases about every 11 years. Parker will still be visiting the Sun in 2025, when the next period of high solar activity is expected.