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It will be a spectacular show for the millions of people across North America who will watch the total solar eclipse on April 8th. This is your chance to see the moon completely hiding the face of the sun.
But for scientists, it’s a rare opportunity to study the Earth, moon and sun “in a completely different way than we normally do,” said NASA Deputy Administrator Pam Melroy.
One of the agency’s main priorities is observing the Sun’s outer atmosphere, or corona, which is usually impossible to see because the star is too bright. During a total solar eclipse, when the moon blocks light from the sun’s surface, the corona appears as a faint light around a glowing halo.
“There are things going on that we don’t fully understand when it comes to coronavirus, but the eclipse is gathering data that could give us insight into the future of the stars,” Melroy said at a press conference last week. “It gives us a unique opportunity to do that.”
Scientists are interested in the corona because it plays a critical role in transferring heat and energy to the solar wind, a continuous stream of charged particles emitted from the sun’s outer atmosphere. The solar wind waxes and wanes, occasionally sending powerful solar flares into space. These can hit the earth with electromagnetic radiation, causing radio interference and potentially destroying power grids.
Amir Caspi, a solar astrophysicist at the Southwest Research Institute in Boulder, Colorado, attaches an instrument to the nose of a WB-57 aircraft that will study the sun’s atmosphere as the plane tracks eclipses. It turns out.
This is a great opportunity, he said, because special telescopes that can block starlight, known as coronagraphs, have their limits.
“A total solar eclipse is like nature’s perfect coronagraph,” he said. “The moon comes between us and the sun. It’s just the right size in the sky to block the sun’s disk, but no more.”
Caspi will focus on understanding the origins of the solar wind. He also hopes to glean clues about the long-standing mystery of why the corona is millions of degrees hotter than the sun’s surface.
He pioneered this method of imaging the sun’s corona during the last total solar eclipse that crossed the continental United States in 2017.
“I didn’t know what I was going to get,” he says. “It was quite a long and hard process, but then we got some great data. We could see it coming in on the live satellite feed.”
The WB-57 plane can fly at an altitude of 60,000 feet, well above clouds and high enough that Earth’s atmosphere doesn’t interfere much with observations.
Many researchers plan to collect data about the Sun’s atmosphere from other advantageous locations, including space, during the eclipse.
Several spacecraft, including NASA’s Parker Solar Probe, will keep their eyes on the Sun throughout the astronomical event. The spacecraft was launched in 2018, so it wasn’t able to study the 2017 solar eclipse.
In 2021, the Parker spacecraft became the first spacecraft to fly into the corona, and has since flown more than a dozen approaches to “touch” the Sun. Due to orbital timing, the spacecraft will not have a close encounter on April 8. But it will be close enough to the sun to measure and image the solar wind as the charged particles pass by, said Parker’s Nour Lauafi. Solar exploration project scientist and astrophysicist at the Johns Hopkins Applied Physics Laboratory.
In addition, the European Space Agency spacecraft known as Solar Orbiter will orbit almost directly above the Parker Solar Probe during the eclipse. The two observatories will team up to capture details of the Sun’s atmosphere and solar wind.
“It’s one of the rare times these two spacecraft come this close,” Laoafi said. “So between all the observations we make during the eclipse from Earth, there will be a lot of synergy between them. This is completely, completely unprecedented.”
The Sun is accelerating toward the peak of its roughly 11-year cycle, expected in 2025. That means the Parker Solar Probe will have a front-row seat if there’s an eruption from the sun.
Although there is no guarantee that such an explosion will occur during a solar eclipse, Lauafi said measurements of the solar wind from space remain important to understanding the effects of solar activity on Earth.
“These are the drivers of space weather, and the spacecraft is probably the best tool we have and the best spacecraft mission we have to help us understand that,” he said. said. “And how? Let’s hope the sun gives us its biggest show.”
Even for non-scientists, the darkness that temporarily covers the afternoon sky along the so-called totality path can be an extraordinary experience.
“I remember the first time I learned that this was so unusual that our moon just happened to be at the right size and distance to cause this effect on Earth. ” Melroy said. “This is truly a miracle of our universe.”
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