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.
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.
For the first time ever, astronomers have witnessed a coronal mass ejection (CME) on a star other than our very own Sun. The star, named HR 9024 (and also known as OU Andromeda,) is about 455 light years away, in the constellation Andromeda. It’s an active, variable star with a strong magnetic field, which astronomers say may cause CMEs.
Strictly speaking, there aren’t strict boundaries between Earth and space. Our atmosphere doesn’t just end at a certain altitude; it peters out gradually. A new study from Russia’s Space Research Institute (SRI) shows that our atmosphere extends out to 630,000 km into space.
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 mystery surrounding the closure of the Sunspot Solar Observatory has been (mostly) cleared up. After being closed and vacated on Sept. 6th due to an unspecified security threat, the facility is now open, and will resume normal scientific activities next week.
In a statement, Shari Lifson, spokesperson for the Association of Universities for Research in Astronomy (AURA), the body that operates the Sunspot Observatory, said that the facility was closed as a “precautionary measure.”
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.
When it comes to exploring our Solar System, there are few missions more ambitious than those that seek to study the Sun. While NASA and other space agencies have been observing the Sun for decades, the majority of these missions were conducted in orbit around Earth. To date, the closest any probes have gotten to the Sun were the Helios 1 and 2 probes, which studied the Sun during the 1970s from inside Mercury’s orbit at perihelion.
NASA intends to change all that with the Parker Solar Probe, the space probe that recently launched from Cape Canaveral, which will revolutionize our understanding of the Sun by entering it’s atmosphere (aka. the corona). Over the next seven years, the probe will use Venus’ gravity to conduct a series of slingshots that will gradually bring it closer the Sun than any mission in the history of spaceflight!
The spacecraft lifted off at 3:31 a.m. EDT on Sunday August 12th, from Space Launch Complex-37 at Cape Canaveral Air Force Station atop a United Launch Alliance Delta IV Heavy rocket. At 5:33 a.m., the mission operations manager reported that the spacecraft was healthy and operating normally. Over the course of the next week, it will begin deploying its instruments in preparation for its science mission.
Once inside the Sun’s corona, the Parker Solar Probe will employ an advanced suite of instruments to revolutionize our understanding of the Sun’s atmosphere and the origin and evolution of solar wind. These and other findings will allow researchers and astronomers to improve their ability to forecast space weather events (such as solar flares), which can cause harm to astronauts and orbiting missions, disrupt radio communications and damage power grids.
As Thomas Zurbuchen, the associate administrator of NASA’s Science Mission Directorate, said in a recent NASA press release:
“This mission truly marks humanity’s first visit to a star that will have implications not just here on Earth, but how we better understand our universe. We’ve accomplished something that decades ago, lived solely in the realm of science fiction.”
The Parker Probes mission certainly comes with its share of challenges. In addition to the incredible heat it will have to endure, there is also the challenge of simply getting there. This is due to Earth’s orbital velocity, which travels around the Sun at a speed of 30 km/s (18.64 mps) – or about 108,000 km/h (67,000 mph). Cancelling out this velocity and traveling towards the Sun would take 55 times as much energy as it would for a craft to travel to Mars.
To address this challenge, the Parker Probe has been launched by a very powerful rocket – the ULA Delta IV, which is capable of generating 9,700 kN of thrust. In addition, it will be relying on a series of gravity assists (aka. gravitational slingshots) with Venus. These will consist of the probe conducting flybys of the Sun, then circling around Venus to get a boost in speed from the force of the planet’s gravity, and then slingshoting around the Sun again.
Over the course of its seven-year mission, the probe will conduct seven gravity-assists with Venus and will make 24 passes of the Sun, gradually tightening its orbit in the process. Eventually, it will reach a distance of roughly 6 million km (3.8 million mi) from the Sun and fly through it’s atmosphere (aka. corona), effectively getting more than seven times closer than any spacecraft in history. In addition, the probe will be traveling at speeds of roughly 692,000 km/h (430,000 mph), which will set the record for the fastest-moving spacecraft in history.
During the first week of its journey, the spacecraft will deploy its high-gain antenna and magnetometer boom, which houses the three instruments it will use to study the Sun’s magnetic field. It will also perform the first of a two-part deployment of its five electric field antennas (aka. the FIELDS instrument suite), which will measure the properties of solar wind and help make a three-dimensional picture of the Sun’s electric fields.
Other instruments aboard the spacecraft include the Wide-Field Imager for Parker Solar Probe (WISPR), the spacecraft’s only imaging instrument. This instrument will take pictures of the large-scale structure of the corona and solar wind before the spacecraft flies through it, capturing such phenomena as coronal mass ejections (CMEs), jets, and other ejecta from the Sun.
There’s also the Solar Wind Electrons Alphas and Protons (SWEAP) investigation instrument, which consists of two other instruments – the Solar Probe Cup (SPC) and the Solar Probe Analyzers (SPAN). These will count the most abundant particles in the solar wind – electrons, protons and helium ions – and measure their velocity, density, temperature, and other properties to improve our understanding of solar wind and coronal plasma.
Then there’s the Integrated Science Investigation of the Sun (ISOIS), which relies on the EPI-Lo and EPI-Hi instruments – Energetic Particle Instruments (EPI). Using these two instruments, ISOIS will measure electrons, protons and ions across a wide range of energies to gain a better understanding of where these particles come from, how they became accelerated, and how they move throughout the Solar System.
In addition to being the first spacecraft to explore the Sun’s corona, the Parker Solar Probe is the first spacecraft named after a living scientist – Eugene Parker, the physicist who first theorized the existence of the solar wind in 1958. As Nicola Fox, the probe’s project scientist at the JHUAPL, indicated:
“Exploring the Sun’s corona with a spacecraft has been one of the hardest challenges for space exploration. We’re finally going to be able to answer questions about the corona and solar wind raised by Gene Parker in 1958 – using a spacecraft that bears his name – and I can’t wait to find out what discoveries we make. The science will be remarkable.”
Dr. Parker was on hand to witness the early morning launch of the spacecraft. In addition to its advanced suite of scientific instruments, the probe also carries a plaque dedicating the mission to Parker. This plaque, which was attached in May, includes a quote from the renowned physicist – “Let’s see what lies ahead” – and a memory card containing more than 1.1 million names submitted by the public to travel with the spacecraft to the Sun.
Instrument testing will begin in early September and last approximately four weeks, after which the Parker Solar Probe can begin science operations. On September 28th, it will conduct its first flyby of Venus and perform its first gravity assist with the planet by early October. This will cause the spacecraft to assume a 180-day orbit of the Sun, which will bring it to a distance of about 24 million km (15 million mi).
In the end, the Parker Solar Probe will attempt to answer several long-standing mysteries about the Sun. For instance, why is the Sun’s corona 300 times hotter than the Sun’s surface, what drives the supersonic solar wind that permeates the entire Solar System, and what accelerates solar energetic particles – which can reach speeds of up to half the speed of light – away from the Sun?
For sixty years, scientists have pondered these questions, but were unable to answer them since no spacecraft was capable of penetrating the Sun’s corona. Thanks to advances in thermal engineering, the Parker Solar Probe is the first spacecraft that will be able to “touch” the face of the Sun and reveal its secrets. By December, the craft will transmit its first science observations back to Earth.
As Andy Driesman, the project manager of the Parker Probe mission at the Johns Hopkins University Applied Physics Laboratory (JHUAPL), expressed:
“Today’s launch was the culmination of six decades of scientific study and millions of hours of effort. Now, Parker Solar Probe is operating normally and on its way to begin a seven-year mission of extreme science.”
Understanding the dynamics of the Sun is intrinsic to understanding the history of the Solar System and the emergence of life itself. But until now, no mission has been able to get close enough to the Sun to address its greatest mysteries. By the time the Parker Solar Probe’s mission is complete, scientists expect to have learned a great deal about the phenomena that can give rise to life, and disrupt it!
In 2007, the European Southern Observatory (ESO) completed work on the Very Large Telescope (VLT) at the Paranal Observatory in northern Chile. This ground-based telescope is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors (measuring 8.2 meters in diameter) and four movable 1.8-meter diameter Auxiliary Telescopes.
Recently, the VLT was upgraded with a new instrument known as the Multi Unit Spectroscopic Explorer (MUSE), a panoramic integral-field spectrograph that works at visible wavelengths. Thanks to the new adaptive optics mode that this allows for (known as laser tomography) the VLT was able to recently acquire some images of Neptune, star clusters and other astronomical objects with impeccable clarity.
In astronomy, adaptive optics refers to a technique where instruments are able to compensate for the blurring effect caused by Earth’s atmosphere, which is a serious issue when it comes to ground-based telescopes. Basically, as light passes through our atmosphere, it becomes distorted and causes distant objects to become blurred (which is why stars appear to twinkle when seen with the naked eye).
One solution to this problem is to deploy telescopes into space, where atmospheric disturbance is not an issue. Another is to rely on advanced technology that can artificially correct for the distortions, thus resulting in much clearer images. One such technology is the MUSE instrument, which works with an adaptive optics unit called a GALACSI – a subsystem of the Adaptive Optics Facility (AOF).
The instrument allows for two adaptive optics modes – the Wide Field Mode and the Narrow Field Mode. Whereas the former corrects for the effects of atmospheric turbulence up to one km above the telescope over a comparatively wide field of view, the Narrow Field mode uses laser tomography to correct for almost all of the atmospheric turbulence above the telescope to create much sharper images, but over a smaller region of the sky.
This consists of four lasers that are fixed to the fourth Unit Telescope (UT4) beaming intense orange light into the sky, simulating sodium atoms high in the atmosphere and creating artificial “Laser Guide Stars”. Light from these artificial stars is then used to determine the turbulence in the atmosphere and calculate corrections, which are then sent to the deformable secondary mirror of the UT4 to correct for the distorted light.
Using this Narrow Field Mode, the VLT was able to capture remarkably sharp test images of the planet Neptune, distant star clusters (such as the globular star cluster NGC 6388), and other objects. In so doing, the VLT demonstrated that its UT4 mirror is able to reach the theoretical limit of image sharpness and is no longer limited by the effects of atmospheric distortion.
This essentially means that it is now possible for the VLT to capture images from the ground that are sharper than those taken by the Hubble Space Telescope. The results from UT4 will also help engineers to make similar adaptations to the ESO’s Extremely Large Telescope (ELT), which will also rely on laser tomography to conduct its surveys and accomplish its scientific goals.
These goals include the study of supermassive black holes (SMBHs) at the centers of distant galaxies, jets from young stars, globular clusters, supernovae, the planets and moons of the Solar System, and extra-solar planets. In short, the use of adaptive optics – as tested and confirmed by the VLT’s MUSE – will allow astronomers to use ground-based telescopes to study the properties of astronomical objects in much greater detail than ever before.
In addition, other adaptive optics systems will benefit from work with the Adaptive Optics Facility (AOF) in the coming years. These include the ESO’s GRAAL, a ground layer adaptive optics module that is already being used by the Hawk-I infrared wide-field imager. In a few years, the powerful Enhanced Resolution Imager and Spectrograph (ERIS) instrument will also be added to the VLT.
Between these upgrades and the deployment of next-generation space telescopes in the coming years (like the James Webb Space Telescope, which will be deploying in 2021), astronomers expect to bringing a great deal more of the Universe “into focus”. And what they see is sure to help resolve some long-standing mysteries, and will probably create a whole lot more!
And be sure to enjoy these videos of the images obtained by the VLT of Neptune and NGC 6388, courtesy of the ESO:
To the naked eye, the Sun puts out energy in a continual, steady state, unchanged through human history. (Don’t look at the sun with your naked eye!) But telescopes tuned to different parts of the electromagnetic spectrum reveal the Sun’s true nature: A shifting, dynamic ball of plasma with a turbulent life. And that dynamic, magnetic turbulence creates space weather.
Space weather is mostly invisible to us, but the part we can see is one of nature’s most stunning displays, the auroras. The aurora’s are triggered when energetic material from the Sun slams into the Earth’s magnetic field. The result is the shimmering, shifting bands of color seen at northern and southern latitudes, also known as the northern and southern lights.
There are two things that can cause auroras, but both start with the Sun. The first involves solar flares. Highly-active regions on the Sun’s surface produce more solar flares, which are sudden, localized increase in the Sun’s brightness. Often, but not always, a solar flare is coupled with a coronal mass ejection (CME).
A coronal mass ejection is a discharge of matter and electromagnetic radiation into space. This magnetized plasma is mostly protons and electrons. The CME ejection often just disperses into space, but not always. If it’s aimed in the direction of the Earth, chances are we get increased auroral activity.
The second cause of auroras are coronal holes on the Sun’s surface. A coronal hole is a region on the surface of the Sun that is cooler and less dense than surrounding areas. Coronal holes are the source of fast-moving streams of material from the Sun.
Whether it’s from an active region on the Sun full of solar flares, or whether it’s from a coronal hole, the result is the same. When the discharge from the Sun strikes the charged particles in our own magnetosphere with enough force, both can be forced into our upper atmosphere. As they reach the atmosphere, they give up their energy. This causes constituents in our atmosphere to emit light. Anyone who has witnessed an aurora knows just how striking that light can be. The shifting and shimmering patterns of light are mesmerizing.
The auroras occur in a region called the auroral oval, which is biased towards the night side of the Earth. This oval is expanded by stronger solar emissions. So when we watch the surface of the Sun for increased activity, we can often predict brighter auroras which will be more visible in southern latitudes, due to the expansion of the auroral oval.
Something happening on the surface of the Sun in the last couple days could signal increased auroras on Earth, tonight and tomorrow (March 28th, 29th). A feature called a trans-equatorial coronal hole is facing Earth, which could mean that a strong solar wind is about to hit us. If it does, look north or south at night, depending on where your live, to see the auroras.
Of course, auroras are only one aspect of space weather. They’re like rainbows, because they’re very pretty, and they’re harmless. But space weather can be much more powerful, and can produce much greater effects than mere auroras. That’s why there’s a growing effort to be able to predict space weather by watching the Sun.
A powerful enough solar storm can produce a CME strong enough to damage things like power systems, navigation systems, communications systems, and satellites. The Carrington Event in 1859 was one such event. It produced one of the largest solar storms on record.
That storm occurred on September 1st and 2nd, 1859. It was preceded by an increase in sun spots, and the flare that accompanied the CME was observed by astronomers. The auroras caused by this storm were seen as far south as the Caribbean.
The same storm today, in our modern technological world, would wreak havoc. In 2012, we almost found out exactly how damaging a storm of that magnitude could be. A pair of CMEs as powerful as the Carrington Event came barreling towards Earth, but narrowly missed us.
We’ve learned a lot about the Sun and solar storms since 1859. We now know that the Sun’s activity is cyclical. Every 11 years, the Sun goes through its cycle, from solar maximum to solar minimum. The maximum and minimum correspond to periods of maximum sunspot activity and minimum sunspot activity. The 11 year cycle goes from minimum to minimum. When the Sun’s activity is at its minimum in the cycle, most CMEs come from coronal holes.
NASA’s Solar Dynamics Observatory (SDO), and the combined ESA/NASA Solar and Heliospheric Observatory (SOHO) are space observatories tasked with studying the Sun. The SDO focuses on the Sun and its magnetic field, and how changes influence life on Earth and our technological systems. SOHO studies the structure and behavior of the solar interior, and also how the solar wind is produced.
Several different websites allow anyone to check in on the behavior of the Sun, and to see what space weather might be coming our way. The NOAA’s Space Weather Prediction Center has an array of data and visualizations to help understand what’s going on with the Sun. Scroll down to the Aurora forecast to watch a visualization of expected auroral activity.
NASA’s Space Weather site contains all kinds of news about NASA missions and discoveries around space weather. SpaceWeatherLive.com is a volunteer run site that provides real-time info on space weather. You can even sign up to receive alerts for upcoming auroras and other solar activity.