It is the closest star to Earth and, arguably, the most important one – the sun. Despite its relative proximity, though, there's still much we don't know about it.
"We still need to be able to predict it a lot better,” said Dr. Terry Kucera, a NASA Scientist.
Predicting the sun involves understanding its solar storms and flares, which can travel tens of millions of miles to affect satellites orbiting Earth and electrical grids on the ground.
"I mean, people make jokes about weather forecasting, and how accurate it is, but it’s actually pretty good these days, and we’re not that good yet with space weather,” Dr. Kucera said. “We really need to understand better things like why some of these solar storms, why some move faster than others, why some move in different ways than others."
That effort is about to get a boost from a mission called Solar Probe Plus. NASA will launch that spacecraft in 2018 to reach out and “touch” the sun. It will come within just 4 million miles of the sun's corona, or outer atmosphere. That will mark the first time a human spacecraft has ever visited a star.
"That's the closest we'll ever be to the sun,” Dr. Kucera said. “That's 25 times closer to the sun than we are here on Earth."
Several of the mission investigators for Solar Probe Plus are based at CU Boulder and a CU-built science instrument will also be onboard collecting data.
"Almost all stars emit this tremendous amount of matter into space and it's one of the frontiers we don't really fully understand," Solar Probe Plus Principal Co-Investigator Robert Ergun said.
Meanwhile, a separate mission – called STEREO – is celebrating a decade of studying the sun. STEREO consists of two identical spacecraft monitoring the sun from a unique perspective.
"It's really useful to have more than one point of view on the sun, for the same reason it's useful to have two eyes -- because it can give you a 3-D view of what you're looking at," Dr. Kucera said.
NASA scientists also hope to learn more about the sun's atmosphere next year during a major solar eclipse that will be visible in North America on Aug. 21, 2017. One of the best spots to see the total eclipse will be in Wyoming, as it carves it's way diagonally, from the Pacific Northwest to the southeast.