In the course of conducting solar astronomy, scientists have noticed that periodically, the Sun’s tangled magnetic field lines will snap and then realign. This process is known as magnetic reconnection, where the magnetic topology of a body is rearrangedand magnetic energy is converted into kinetic energy, thermal energy, and particle acceleration.
However, while observing the Sun, a team of Indian astronomers recently witnessed something unprecedented – a magnetic reconnection that was triggered by a nearby eruption. This observation has confirmed a decade-old theory about magnetic reconnections and external drivers, and could also lead to a revolution in our understanding of space weather and controlled fusion and plasma experiments.
This visualization depicts what a coronal mass ejection might look like like as it interacts with the interplanetary medium and magnetic forces. Credit: NASA / Steele Hill
Exactly how dangerous are solar storms? Scientists think the Carrington Event was one of the most powerful ones to ever hit Earth. They also think that storms that powerful only happen every couple centuries or so. But a new study says we can expect more storms equally as strong, and more often.
The view of the corona during totality? This computational model was derived from NASA SDO data during the last solar rotation. Credit: Predictive Science Inc.
We’ve got a mystery on our hands. The surface of the sun has a temperature of about 6,000 Kelvin – hot enough to make it glow bright, hot white. But the surface of the sun is not its last later, just like the surface of the Earth is not its outermost layer. The sun has a thin but extended atmosphere called the corona. And that corona has a temperature of a few million Kelvin.
How does the corona have such a higher temperature than the surface?
The Parker Solar Probe's WISPR (Wide-field Imager for Solar Probe) instrument captured this image of a coronal streamer on Nov. 8th, 2018. Coronal streamers are structures of solar material within the Sun's atmosphere, the corona, that usually overlie regions of increased solar activity. The fine structure of the streamer is very clear, with at least two rays visible. The bright object near the center of the image is Mercury, and the dark spots are a result of background correction.
Credits: NASA/Naval Research Laboratory/Parker Solar Probe
It’s been 124 days since the Parker Solar Probe was launched, and several weeks since it made the closest approach any spacecraft has ever made to a star. Now, scientists are getting their hands on the data from the close approach. Four researchers at the recent meeting of the American Geophysical Union in Washington, D.C. shared what they hope they can learn from the probe. They hope that data from the Parker Solar Probe will help them answer decades-old question about the Sun, its corona, and the solar wind.
Scientists who study the Sun have been anticipating this for a long time, and the waiting has been worth it.
“Heliophysicists have been waiting more than 60 years for a mission like this to be possible. The solar mysteries we want to solve are waiting in the corona.” – Nicola Fox, director of the Heliophysics Division at NASA Headquarters.
According to current cosmological theories, the Milky Way started to form approximately 13.5 billion years ago, just a few hundred million years after the Big Bang. This began with globular clusters, which were made up of some of the oldest stars in the Universe, coming together to form a larger galaxy. Over time, the Milky Way cannibalized several smaller galaxies within its cosmic neighborhood, growing into the spiral galaxy we know today.
Many new stars formed as mergers added more clouds of dust and gas and caused them to undergo gravitational collapse. In fact, it is believed that our Sun was part of a cluster that formed 4.6 billion years ago and that its siblings have since been distributed across the galaxy. Luckily, an international team of astronomers recently used a novel method to locate one of the Sun’s long-lost “solar siblings“, which just happens to be an identical twin!
NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA
How in the world could you possibly look inside a star? You could break out the scalpels and other tools of the surgical trade, but good luck getting within a few million kilometers of the surface before your skin melts off. The stars of our universe hide their secrets very well, but astronomers can outmatch their cleverness and have found ways to peer into their hearts using, of all things, sound waves. Continue reading “Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves”
An artist's illustration of the Parker Solar Probe approaching the Sun. Image: NASA
NASA’s Parker Solar Probe is now the closest object to the Sun that we’ve ever sent into space. On Oct. 29, 2018, at about 1:04 p.m. EDT, NASA’s probe broke the old record for the close-to-Sun distance of 42.73 million km (26.55 million miles). That record was held by the German-American Helios 2 spacecraft in 1976. And the probe will keep getting closer to the Sun.
The first images from NASA's Parker Solar Probe. Credit: NASA/Naval Research Laboratory/Parker Solar Probe
On August 12th, 2018, NASA launched the first spacecraft that will ever “touch” the face of the Sun. This was none other than the Parker Solar Probe, a mission that will revolutionize our understanding of the Sun, solar wind, and “space weather” events like solar flares. Whereas previous missions have observed the Sun, the Parker Solar Probe will provide the closest observations in history by entering the Sun’s atmosphere (aka. the corona).
And now, just over a month into the its mission, the Parker Solar Probe has captured and returned its first-light data. This data, which consisted of images of the Milky Way and Jupiter, was collected by the probe’s four instrument suites. While the images were not aimed at the Sun, the probe’s primary focus of study, they successfully demonstrated that the Parker probe’s instruments are in good working order.
The Sun in hydrogen alpha from August 25th, 2018, showing enigmatic sunspot AR 2720. Image credit and copyright: Damien Weatherly.
A precursor to the start of Solar Cycle 25? The Sun in hydrogen alpha from August 25th, 2018, showing enigmatic sunspot AR 2720. Image credit and copyright: Damien Weatherly.
What’s up with the Sun? As we’ve said previous, what the Sun isn’t doing is the big news of 2018 in solar astronomy. Now, the Sun sent us another curveball this past weekend, with the strange tale of growing sunspot AR 2720.
ESA's Solar Orbiter will capture the very first images of the Sun’s polar regions, where magnetic tension builds up and releases in a lively dance. Credits: Spacecraft: ESA/ATG medialab; Sun: NASA/SDO/P. Testa (CfA)
Our understanding of distant stars has increased dramatically in recent decades. Thanks to improved instruments, scientists are able to see farther and clearer, thus learning more about star systems and the planets that orbit them (aka. extra-solar planets). Unfortunately, it will be some time before we develop the necessary technology to explore these stars up close.
But in the meantime, NASA and the ESA are developing missions that will allow us to explore our own Sun like never before. These missions, NASA’s Parker Solar Probe and the ESA’s (the European Space Agency) Solar Orbiter, will explore closer to the Sun than any previous mission. In so doing, it is hoped that they will resolve decades-old questions about the inner workings of the Sun.
These missions – which will launch in 2018 and 2020, respectively – will also have significant implications for life here on Earth. Not only is sunlight essential to life as we know it, solar flares can pose a major hazard for technology that humanity is becoming increasingly dependent on. This includes radio communications, satellites, power grids and human spaceflight.
And in the coming decades, Low-Earth Orbit (LEO) is expected to become increasingly crowded as commercial space stations and even space tourism become a reality. By improving our understanding of the processes that drive solar flares, we will therefore be able to better predict when they will occur and how they will impact Earth, spacecraft, and infrastructure in LEO.
As Chris St. Cyr, the Solar Orbiter project scientist at NASA’s Goddard Space Flight Center, explained in a recent NASA press release:
“Our goal is to understand how the Sun works and how it affects the space environment to the point of predictability. This is really a curiosity-driven science.”
Both missions will focus on the Sun’s dynamic outer atmosphere, otherwise known as the corona. At present, much of the behavior of this layer of the Sun is unpredictable and not well understood. For instance, there’s the so-called “coronal heating problem”, where the corona of the Sun is so much hotter than the solar surface. Then there is the question of what drives the constant outpouring of solar material (aka. solar wind) to such high speeds.
As Eric Christian, a research scientist on the Parker Solar Probe mission at NASA Goddard, explained:
“Parker Solar Probe and Solar Orbiter employ different sorts of technology, but — as missions — they’ll be complementary. They’ll be taking pictures of the Sun’s corona at the same time, and they’ll be seeing some of the same structures — what’s happening at the poles of the Sun and what those same structures look like at the equator.”
Illustration of the Parker Solar Probe spacecraft approaching the Sun. Credits: Johns Hopkins University Applied Physics Laboratory
For its mission, the Parker Solar Probe will get closer to the Sun than any spacecraft in history – as close as 6 million km (3.8 million mi) from the surface. This will replace the previous record of 43.432 million km (~27 million mi), which was established by the Helios B probe in 1976. From this position, the Parker Solar Probe will use its four suites of scientific instruments to image the solar wind and study the Sun’s magnetic fields, plasma and energetic particles.
In so doing, the probe will help clarify the true anatomy of the Sun’s outer atmosphere, which will help us to understand why the corona is hotter than the Sun’s surface. Basically, while temperatures in the corona can reach as high as a few million degrees, the solar surface (aka. photosphere), experiences temperatures of around 5538 °C (10,000 °F).
Meanwhile, the Solar Orbiter will come to a distance of about 42 million km (26 million mi) from the Sun, and will assume a highly-tilted orbit that can provide the first-ever direct images of the Sun’s poles. This is another area of the Sun that scientists don’t yet understand very well, and the study of it could provide valuable clues as to what drives the Sun’s constant activity and eruptions.
Both missions will also study solar wind, which is the Sun’s most pervasive influence on the solar system. This steam of magnetized gas fills the inner Solar System, interacting with magnetic fields, atmospheres and even the surfaces of planets. Here on Earth, it is what is responsible for the Aurora Borealis and Australis, and can also play havoc with satellites and electrical systems at times.
Artist’s impression of a solar flare erupting from the Sun’s surface. Credit: NASA Goddard Space Flight Center
Previous missions have led scientists to believe that the corona contributes to the process that accelerates solar wind to such high speeds. As these charged particles leave the Sun and pass through the corona, their speed effectively triples. By the time the solar wind reaches the spacecraft responsible for measuring it – 148 million km (92 million mi) from the Sun – it has plenty of time to mix with other particles from space and lose some of its defining features.
By being parked so close to the Sun, the Parker Solar Probe will able to measure the solar wind just as it forms and leaves the corona, thus providing the most accurate measurements of solar wind ever recorded. From its perspective above the Sun’s poles, the Solar Orbiter will complement the Parker Solar Probe’s study of the solar wind by seeing how the structure and behavior of solar wind varies at different latitudes.
This unique orbit will also allow the Solar Orbiter to study the Sun’s magnetic fields, since some of the Sun’s most interesting magnetic activity is concentrated at the poles. This magnetic field is far-reaching largely because of solar wind, which reaches outwards to create a magnetic bubble known as the heliosphere. Within the heliosphere, solar wind has a profound effect on planetary atmospheres and its presence protects the inner planets from galactic radiation.
In spite of this, it is still not entirely clear how the Sun’s magnetic field is generated or structured deep inside the Sun. But given its position, the Solar Orbiter will be able to study phenomena that could lead to a better understanding of how the Sun’s magnetic field is generated. These include solar flares and coronal mass ejections, which are due to variability caused by the magnetic fields around the poles.
In this way, the Parker Solar Probe and Solar Orbiter are complimentary missions, studying the Sun from different vantage points to help refine our knowledge of the Sun and heliosphere. In the process, they will provide valuable data that could help scientists to tackle long-standing questions about our Sun. This could help expand our knowledge of other star systems and perhaps even answer questions about the origins of life.
As Adam Szabo, a mission scientist for Parker Solar Probe at NASA Goddard, explained:
“There are questions that have been bugging us for a long time. We are trying to decipher what happens near the Sun, and the obvious solution is to just go there. We cannot wait — not just me, but the whole community.”
In time, and with the development of the necessary advanced materials, we might even be able to send probes into the Sun. But until that time, these missions represent the most ambitious and daring efforts to study the Sun to date. As with many other bold initiatives to study our Solar System, their arrival cannot come soon enough!
