Solar Probe Plus, its primary solar panels retracted into the shadows of its protective solar shield, approaches the Sun. Credit: NASA/JHUAPL
A car-sized spacecraft will be launched sometime before 2018 on a mission to the center of the solar system – the sun itself. NASA’s Solar Probe Plus (+) will be sent into the atmosphere of the sun called the corona. “For the first time, we’ll be able to ‘touch, taste and smell’ the sun,” said Lika Guhathakurta, Solar Probe+ program scientist at NASA.
Unlike Earth’s life-friendly atmosphere of nitrogen, oxygen, water vapor and carbon dioxide, the sun’s corona is a thin, extremely hot gas of subatomic particles -Â electrons and protons – called a plasma. While the sun’s surface temperature is around 10,000 degrees, the atmosphere is nearly 200 times hotter. With its 3-D imaging of the solar wind and solar shock waves, scientists hope to nail down both the source of the corona’s heat and what accelerates particles in it to stream into space as the solar wind. Recall that it’s the sun’s fast-moving wind that precipitates those spectacular displays of northern lights we all hope to see sometime soon.
Getting to the sun won’t be a cakewalk. Solar Probe + will require seven flybys of the planet Venus over seven years to gravitationally shrink its orbit and bring it closer to the sun. During its final three orbits, it will pass just 3.7 million miles from the sun and experience temperatures of 2600 degrees. An 8-foot diameter carbon-foam-filled solar shield will face sunward during these times, literally “taking the heat” while shadowing the probe and keeping the instruments at room temperature.
Here on Earth, the sun spans 1/2 of a degree in the sky. Your little finger held at arm’s length covers one degree or two sun diameters. From the probe’s perspective, the sun will span an awesome 23 degrees – big enough to completely cover the entire Big Dipper as seen from Earth. Even Mercury, the innermost planet, only ventures as close as 29 million miles to the sun. Solar Probe + will get right in there, study particles, magnetic fields and take pictures directly within the sun’s atmosphere. A daring venture if there ever was.
You can read more about the mission HERE.
In this photo taken by the Solar Dynamics Observatory Saturday, the coronal hole is the large dark gash on the right side of the sun. Credit: NASA
Speaking of solar wind, speedy electrons and the like, there’s currently an opening in the sun’s atmosphere called a coronal hole where some of that hot plasma is streaming out toward Earth. Sky watchers at high latitudes should be on the lookout the next few nights for possible auroras when these emissaries of the sun’s atmosphere arrive.
In tomorrow’s blog, we’ll drop by a weekend star party and explore those strange creatures of the night: amateur astronomers.
