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
NASA has spotted an enormous black blotch growing on the surface of the Sun. It looks eerie, but this dark region is nothing to fear, though it does signal potential disruption to satellite communications.
The dark region is called a coronal hole, an area on the surface of the Sun that is cooler and less dense than the surrounding areas. The magnetic fields in these holes are open to space, which allows high density plasma to flow out into space. The lack of plasma in these holes is what makes them appear dark. Coronal holes are the origin of high-speed solar winds, which can cause problems for satellite communications.
The images were captured by the Solar Dynamics Observatory (SDO) on July 11th. Tom Yulsman at Discover’s ImaGeo blog created a gif from several of NASA’s images.
High-speed solar winds are made up of solar particles which are travelling up to three times faster than the solar wind normally does. Though satellites are protected from the solar wind, extremes like this can still cause problems.
Coronal holes may look like a doomsday warning; an enormous black hole on the surface of our otherwise placid looking Sun is strange looking. But these holes are a part of the natural life of the Sun. And anyway, they only appear in extreme ultraviolet and x-ray wavelengths.
The holes tend to appear at the poles, due to the structure of the Sun’s magnetosphere. But when they appear in more equatorial regions of the Sun, they can cause intermittent problems, as the high-speed solar wind they generate is pointed at the Earth as the Sun rotates.
In June 2012, a coronal hole appeared that looked Big Bird from Sesame Street.
The “Big Bird” coronal hole appeared on the Sun in June 2012. It was the precursor to a powerful storm that was considered a near miss for Earth. Image: NASA/AIA
The Big Bird hole was the precursor to an extremely powerful solar storm, the most powerful one in 150 years. Daniel Baker, of the University of Colorado’s Laboratory of Atmospheric and Space Physics, said of that storm, “If it had hit, we would still be picking up the pieces.” We were fortunate that it missed us, as these enormous storms have the potential to damage power grids on the surface of the Earth.
It seems unlikely that any solar wind that reaches Earth as a result of this current coronal hole will cause any disruption to us here on Earth. But it’s not out of the question. In 1989 a solar storm struck Earth and knocked out power in the province of Quebec in Canada.
It may be that the only result of this coronal hole, and any geomagnetic storms it creates, are more vivid auroras.
Those are something everyone can appreciate and marvel at. And you don’t need an x-ray satellite to see them.
This is an illustration to explain the dynamics of the ultra-relativistic third Van Allen radiation belt. Credit: Andy Kale
The dynamic relationship between Earth and the Sun two sides. The warmth from the Sun makes life on Earth possible, but the rest of the Sun’s intense energy pummels the Earth, and could destroy all life, given the chance. But thanks to our magnetosphere, we are safe.
The magnetosphere is our protective shield. It’s created by the rotation of the molten outer core of the Earth, composed largely of iron and nickel. It absorbs and deflects plasma from the solar wind. The interactions between the magnetosphere and the solar wind are what create the beautiful auroras at Earth’s poles.
Visualization of the solar wind encountering Earth’s magnetic “defenses” known as the magnetosphere. Clouds of southward-pointing plasma are able to peel back layers of the Sun-facing bubble and stack them into layers on the planet’s nightside (center, right). The layers can be squeezed tightly enough to reconnect and deliver solar electrons (yellow sparkles) directly into the upper atmosphere to create the aurora. Credit: JPL
In the inner regions of Earth’s magnetosphere are the Van Allen belts, named after their discoverer James Van Allen. They consist of charged particles, mostly from the Sun, and are held in place by the magnetosphere. Usually, there are two such belts.
The Van Allen radiation belts surrounding Earth. Image: NASA
But the output from the Sun is not stable. There are periods of intense energy output from the Sun, and when that happens, a third, transient belt can be created. Up until now, the nature of this third belt has been a puzzle. New research from the University of Alberta has shown how this phenomena can happen.
Researchers have shown how a so-called “space tsunami” can create this third belt. Intense ultra-low frequency plasma waves can transport the outer part of the radiation belt into interplanetary space, and create the third, transient belt.
The lead author for this study is physics professor Ian Mann from the University of Alberta, and former Canada Research Chair in Space Physics. “Remarkably, we observed huge plasma waves,” said Mann. “Rather like a space tsunami, they slosh the radiation belts around and very rapidly wash away the outer part of the belt, explaining the structure of the enigmatic third radiation belt.”
This new research also sheds light on how these “tsunamis” help reduce the threat of radiation to satellites during other space storms. “Space radiation poses a threat to the operation of the satellite infrastructure upon which our twenty-first century technological society relies,” adds Mann. “Understanding how such radiation is energized and lost is one of the biggest challenges for space research.”
It’s not just satellites that are at risk of radiation though. When solar wind is most active, it can create extremely energetic space storms. They in turn create intense radiation in the Van Allen belts, which drive electrical currents that could damage our power grids here on Earth. These types of storms have the potential to cause trillions of dollars worth of damage.
A better understanding of this space radiation, and an ability to forecast it, are turning out to be very important to our satellite operations, and to our exploration of space.
The Van Allen belts were discovered in 1958, and classified into an inner and an outer belt.
The Van Allen Belts around Earth. The inner red belt is mostly protons, and the outer blue belt is mostly electrons. Image Credit: NASA
In 2013, probes reported a third belt which had never before been seen. It lasted a few weeks, then vanished, and its cause was not known. Thanks to Mann and his team, we now know what was behind that third belt.
“We have discovered a very elegant explanation for the dynamics of the third belt,” says Mann. “Our results show a remarkable simplicity in belt response once the dominant processes are accurately specified.”
An understanding of the radiation in and around Earth and the Van Allen belts is of growing importance to us, as we expand our presence in space. Our technological society relies increasingly on satellite communications, and on GPS satellites. Radiation in the form of high-energy electrons can wreak havoc on satellites. In fact, this type of radiation is sometimes referred to as a satellite killer. Satellites require robust design to be protected from them.
Organizations like the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and the International Living with a Star (ILWS) Program are attempts to address the threat that radiation poses to our system of satellites.
A composite image of the May 9, 2016 transit of Mercury across the face of the Sun, as seen by the Solar Dynamics Observatory. Credit: NASA's Goddard Space Flight Center/SDO/Genna Duberstein
On May 9, 2016, Mercury passed directly between the Sun and Earth. No one had a better view of the event than the space-based Solar Dynamics Observatory, as it had a completely unobstructed view of the entire seven-and-a-half-hour event! This composite image, above, of Mercury’s journey across the Sun was created with visible-light images from the Helioseismic and Magnetic Imager on SDO, and below is a wonderful video of the transit, as it includes views in several different wavelenths (and also some great soaring music sure to stir your soul).
Mercury transits of the Sun happen about 13 times each century, however the next one will occur in only about three and a half years, on November 11, 2019. But then it’s a long dry spell, as the following one won’t occur until November 13, 2032.
Mars from orbit. Valles Marineris and Volcanic region
Given it’s similarities to Earth, Mars is often referred to as “Earth’s Twin”. Like Earth, Mars is a terrestrial planet, which means it is composed largely of silicate rock and minerals that are differentiated into a core, mantle and crust. It is also located within the Sun’s “Goldilocks Zone” (aka. habitable zone), has polar ice caps, and once had flowing water on its surface. But beyond these, Mars and Earth are very different worlds.
In addition to their stark contrasts in temperature, surface conditions, and exposure to harmful radiation, Mars also takes a significantly longer time to complete a single orbit of the Sun. In fact, a year on Mars is almost twice as long as a year here on Earth – lasting 686.971 days, which works out to about 1.88 Earth years. And in the course of that orbit, the planet undergoes some rather interesting changes.
A new paper says that a Super-Earth may have formed in our Solar System and been swallowed by the Sun. Image Credit: ESA/Hubble, M. Kornmesser
Our Solar System sure seems like an orderly place. The orbits of the planets are predictable enough that we can send spacecraft on multi-year journeys to them and they will reliably reach their destinations. But we’ve only been looking at the Solar System for the blink of an eye, cosmically speaking.
The young Solar System was a much different place. Things were much more chaotic before the planets settled into the orbital stability that they now enjoy. There were crashings and smashings aplenty in the early days, as in the case of Theia, the planet that crashed into Earth, creating the Moon.
Now, a new paper from Rebecca G. Martin and Mario Livio at the University of Nevada, Las Vegas, says that our Solar System may have once had an additional planet that perished when it plunged into the Sun. Strangely enough, the evidence for the formation and existence of this planet may be the lack of evidence itself. The planet, which may have been what’s called a Super-Earth, would have formed quite close to the Sun, and then been destroyed when it was drawn into the Sun by gravity.
In the early days of our Solar System, the Sun would have formed in the centre of a mass of gas and dust. Eventually, when it gained enough mass, it came to life in a burst of atomic fusion. Surrounding the Sun was a protoplanetary disk of gas and dust, out of which the planets formed.
What’s missing in our Solar System is any bodies, or even rocky debris in the zone between Mercury and the Sun. This may seem normal, but the Kepler mission tells us it’s not. In over half of the other solar systems it’s looked at, Kepler has found planets in the same zone where our Solar System has none.
A key part of this idea is that planets don’t always form in situ. That is, they don’t always form at the place where they eventually reach orbital stability. Depending on a number of factors, planets can migrate inward towards their star or outwards away from their star.
Martin and Livio, the authors of the study, think that our Solar System did form a Super-Earth, and rather than it migrating outward, it fell into the Sun. According to them, the Super-Earth most probably formed in the inner regions of our Solar System, on the inside of Mercury’s orbit. The fact that there are no objects there, and no debris of any kind, suggests that the Super-Earth formed close to the Sun, and that its formation cleared that area of any debris. Then, once formed, it fell into the Sun, removing all evidence of its existence.
The authors also note another possible cause for the Super-Earth to have fallen into the Sun. They propose that Jupiter may have migrated inward to about 1.5 AUs from the Sun. At that point, it got locked into resonance with Saturn. Then, both gas giants migrated outward to their current orbits. This process would have shepherded a Super-Earth into the Sun, destroying it.
Some of the thinking behind this whole theory involves the size of the inner terrestrial planets in our Solar System. They’re very small in comparison to other systems studied by the Kepler Mission. If a Super-Earth had formed in the inner part of our System, it would have dominated the accretion of available material, leaving Mercury, Venus, Earth and Mars starved for matter.
A key idea behind this study is what’s known as a dead zone. In terms of a solar system and a protoplanetary disk, a dead zone is a zone of low turbulence which favors the formation of planets. A system with a dead zone would have enough material to allow Super-Earths to form in-situ, and they would not have to migrate inward from further out in the system. However, since large planets like Super-Earths take a long time to fully form, this dead zone would have to be long-lived.
If a protoplanetary disk lacks a dead zone, it is likely too turbulent for the formation of a Super-Earth close to the star. A turbulent protoplanetary disk favors the formation of Super-Earths further out, which would then migrate inwards towards the star. Also, a turbulent disk allows for quicker migration of planets, while a pronounced dead zone inhibits migration.
As the authors say in the conclusion of their study, “The lack of Super–Earths in our solar system is somewhat puzzling given that more than half of observed exoplanetary systems contain one. However, the fact that there is nothing
inside of Mercury’s orbit may not be a coincidence.” They go on to conclude that in our Solar System, the likely scenario is the in situ formation of a Super-Earth which subsequently fell into the Sun.
There are a lot of variables that have to be fine-tuned for this scenario to happen. The young solar system would need a dead zone, the depth of the turbulence in the protoplanetary disk would have to be just right, and the disk would have to be the right temperature. The fact that these things have to be within a certain range may explain why we don’t have a Super-Earth in our system, while over half of the systems studied by Kepler do have one.
The Solar and Heliospheric Observatory (SOHO) took these photos of Mercury during its last transit of the Sun on Nov. 8, 2006. Credit: NASA/ESA
Be sure to mark your calendar for May 9. On that day, the Solar System’s most elusive planet will pass directly in front of the Sun. The special event, called a transit, happens infrequently. The last Mercury transit occurred more than 10 years ago, so many of us can’t wait for this next. Remember how cool it was to see Venus transit the Sun in 2008 and again in 2012? The views will be similar with one big difference: Mercury’s a lot smaller and farther away than Venus, so you’ll need a telescope. Not a big scope, but something that magnifies at least 30x. Mercury will span just 10 arc seconds, making it only a sixth as big as Venus.
Two basic types of safe solar filters for telescopes: an aluminized polymer such as Baader film and a dedicated glass solar filter for a particular make and model. Credit: Bob King
Map showing Mercury’s path across the Sun at three key points on May 9: transit start or ingress (left); midpoint and transit end or egress (right). Credit: Tom Ruen with additions by author
If I might make a suggestion, consider buying a sheet of Baader AstroSolar aluminized polyester film and cutting it to size to make your own filter. Although the film’s crinkly texture might make you think it’s flimsy or of poor optical quality, don’t be deceived by appearances.
The material yields both excellent contrast and a pleasing neutral-colored solar image. You can purchase any of several different-sized films to suit your needs either from Astro-Physicsor on Amazon.com. Prices range from $40-90.
Nov. 8, 2006 Transit of Mercury by Dave Kodama
With filter material in hand, just follow these instructions to make your own, snug-fitting telescopic solar filter. Even I can do it, and I kid you not that I’m a total klutz when it comes to building things. If for whatever reason you can’t get a filter, go to Plan B. Put a low power eyepiece in your scope and project an image of the Sun onto a sheet of white paper a foot or two behind the eyepiece.
World map showing where the May 9-10 Mercury transit will be visible. Universal times of the four key contacts (see below for details), mid-transit time and position angle on the Sun’s limb where the planet will first appear and disappear are given at upper left. Credit: Xavier M. Jubier
Since May 9th is a Monday, I’ve a hunch a few of you will be taking the day off. If you can’t, pack a telescope and set it up during lunch hour to share the view with your colleagues. Mercury will spend a leisurely 7 1/2 hours slowly crawling across the Sun’s face, traveling from east to west. The entire transit will be visible across the eastern half of the U.S., most of South America, eastern and central Canada, western Africa and much of western Europe. For the western U.S., Alaska and Hawaii the Sun will rise with the transit already in progress.
Time Zone
Eastern (EDT)
Central (CDT)
Mountain (MDT)
Pacific (PDT)
Transit start
7:12 a.m.
6:12 a.m.
5:12 a.m.
Not visible
Mid-transit
10:57 a.m.
9:57 a.m.
8:57 a.m.
7:57 a.m.
Transit end
2:42 p.m.
1:42 p.m.
12:42 p.m.
11:42 a.m.
Nov. 2006 animation by Hinode. Credit: NASA
At first glance, the planet might look like a small sunspot, but if you look closely, you’ll see it’s a small, perfectly circular black dot compared to the out-of-round sunspots which also possess the classic two-part umbra-penumbra structure. Oh yes, it also moves. Slowly to be sure, but much faster than a typical sunspot which takes nearly two weeks to cross the Sun’s face. With a little luck, a few sunspots will be in view during transit time; compared to midnight Mercury their “black” umbral cores will look deep brown.
I want to alert you to four key times to have your eye glued to the telescope; all occur during the 3 minutes and 12 seconds when Mercury enters and exits the Sun. They’re listed below in Universal Time or UT. To convert UT to EDT, subtract 4 hours; CDT 5 hours; MDT 6 hours, PDT 7 hours, AKDT 8 hours and HST 10 hours.
The black drop effect seen to good advantage during the June 2004 transit of Venus. Credit: Jan Herold
First contact (11:12 UT): Watch for the first hint of Mercury’s globe biting into the Sun just south of the due east point on along the edge of disk’s edge. It’s always a thrill to see an astronomical event forecast years ago happen at precisely the predicted time.
Second contact (11:15 UT): Three minutes and 12 seconds later, the planet’s trailing edge touches the inner limb of the Sun at second contact. Does the planet separate cleanly from the solar limb or briefly remain “connected” by a narrow, black “line”, giving the silhouette a drop-shaped appearance?
This “black drop effect”is caused primarily by diffraction, the bending and interfering of light waves when they pass through the narrow gap between Mercury and the Sun’s edge. You can replicate the effect by bringing your thumb and index finger closer and closer together against a bright backdrop. Immediately before they touch, a black arc will fill the gap between them.
The “black drop effect” can be reproduced by slowly bringing your thumb and index finger together. It’s caused by diffraction combined with blurring from the atmosphere. Credit: Bob King
Third contact (18:39 UT): A minute or less before Mercury’s leading edge touches the opposite limb of the Sun at third contact, watch for the black drop effect to return.
Fourth contact (18:42 UT): The moment the last silhouetted speck of Mercury exits the Sun. Don’t forget to mark your calendar for November 11, 2019, date of the next transit, which also favors observers in the Americas and Europe. After that one, the next won’t happen till 2032.
Other interesting visuals to keep an eye out for is a bright ring or aureole that sometimes appears around the planet caused when our brain exaggerates the contrast of an object against a backdrop of a different brightness. Another spurious optical-brain effect keen-eyed observers can watch for is a central bright spot inside Mercury’s black disk. Use high power to get the best views of these obscure but fascinating phenomena seen by many observers during Mercury transits.
NASA’s Hinode X-ray telescope captured this view of Mercury silhouetted against the Sun’s corona during the Nov. 2006 transit. Similar views are possible in H-alpha light should the planet pass in front of a prominence. Credit: NASA
While I’ve been talking all “white light” observation, the proliferation of relatively inexpensive and portable hydrogen-alpha telescopes in recent years makes them another viewing option with intriguing possibilities. These instruments show solar phenomena beyond the Sun’s limb, including the flaming prominences normally seen only during a total eclipse. That makes it possible to glimpse Mercury minutes in advance of the transit (or minutes after transit end) silhouetted against a prominence or nudging into the rim furry ring of spicules surrounding the outer limb. Wow!
One final note. Be careful never to look directly at the Sun even for a moment during the transit. Keep your eyes safe! When aiming a telescope, the safest and easiest way to center the Sun in the field of view is to shift the scope up and down and back and forth until the shadow the tube casts on the ground is shortest. Try it.
I hope the weather gods smile on you on May 9, but it they don’t or if you live where the transit won’t be visible, Italian astrophysicist Gianluca Masi will stream it live on his Virtual Telescope websitestarting at 11:00 UT (6 a.m CDT).
Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
One of the biggest new mysteries in our Solar System is the purported presence of a large and distant “Planet Nine,” traveling around the Sun in a twenty-thousand-year orbit far beyond Pluto. Although this far-flung world’s existence has yet to actually be confirmed (or even directly detected) some scientists are suggesting it might have originally been an exoplanet around a neighboring star, pilfered by our Sun during its impudent adolescence.
Composite images from the Chandra X-Ray Observatory and the Hubble Space Telescope show the hyper-energetic x-ray auroras at Jupiter. The image on the left is of the auroras when the coronal mass ejection reached Jupiter, the image on the right is when the auroras subsided. The auroras were triggered by a coronal mass ejection from the Sun that reached the planet in 2011. Image: X-ray: NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI
The Earthly Northern Lights are beautiful and astounding, but when it comes to planetary light shows, what happened at Jupiter in 2011 might take the cake. In 2011, a coronal mass ejection (CME) struck Jupiter, producing x-ray auroras 8 times brighter than normal, and hundreds of times more energetic than Earth’s auroras. A paper in the March 22nd, 2016 issue of the Journal of Geophysical Research gave the details.
The Sun emits a ceaseless stream of energetic particles called the solar wind. Sometimes, the Sun ramps up its output, and what is called a coronal mass ejection occurs. A coronal mass ejection is a massive burst of matter and electromagnetic radiation. Though they’re slow compared to other phenomena arising from the Sun, such as solar flares, CMEs are extremely powerful.
When the CME in 2011 reached Jupiter, NASA’s Chandra X-Ray Observatory was watching, the first time that Jupiter’s X-ray auroras were monitored at the same time that a CME arrived. Along with some very interesting images of the event, the team behind the study learned other things. The CME that struck Jupiter actually compressed that planet’s magnetosphere. It forced the boundary between the solar wind and Jupiter’s magnetic field in towards the planet by more than 1.6 million kilometers (1 million miles.)
The scientists behind this study used the data from this event to not only pinpoint the source of the x-rays, but also to identify areas for follow-up investigation. They’ll be using not only Chandra, but also the European Space Agency’s XMM Newton observatory to collect data on Jupiter’s magnetic field, magnetosphere, and aurora.
NASA’s Juno spacecraft will reach Jupiter this summer. One of its primary missions is to map Jupiter’s magnetic fields, and to study the magnetosphere and auroras. Juno’s results will be fascinating to anyone interested in Jupiter’s auroras.
Here at Universe Today we’ve written about Jupiter’s aurora’s here, coronal mass ejections here, and the Juno mission here.
Our Sun in all its intense, energetic glory. When life appeared on Earth, the Sun would have been much different than it is now; a more intense, energetic neighbor. Image: NASA/SDO.
The early Solar System was a much different place than it is now. Chaos reigned supreme before things settled down into their present state. New research shows that the young Sun was more chaotic and expressive than it is now, and that Earth’s magnetic field was key for the development of life on Earth.
Researchers at the Harvard Smithsonian Centre for Astrophysics have been studying a star called Kappa Ceti, about 30 light years away in the Cetus constellation. Kappa Ceti is in many ways similar to our own Sun, but it’s estimated to be between 400 million to 600 million years old, about the same age as our Sun when life appeared on Earth. Studying Kappa Ceti gives scientists a good idea of the type of star that early life on Earth had to contend with.
Kappa Ceti, at its young age, is much more magnetically active than our 4.6 billion year old Sun, according to this new research. It emits a relentless solar wind, which the research team at Harvard says is 50 times as powerful as the solar wind from our Sun. It’s surface is also much more active and chaotic. Rather than the sunspots that we can see on our Sun, Kappa Ceti displays numerous starspots, the larger brother of the sunspot. And the starspots on Kappa Ceti are much more numerous than the sunspots observed on the Sun.
We’re familiar with the solar flares that come from the Sun periodically, but in the early life of the Sun, the flares were much more energetic too. Researchers have found evidence on Kappa Ceti of what are called super-flares. These monsters are similar to the flares we see today, but can release 10 to 100 million times more energy than the flares we can observe on our Sun today.
So if early life on Earth had to contend with such a noisy neighbour for a Sun, how did it cope? What prevented all that solar output from stripping away Earth’s atmosphere, and killing anything alive? Then, as now, the Earth’s electromagnetic field protected it. But in the same way that the Sun was so different long ago, so was the Earth’s protective shield. It may have been weaker than it is now.
The researchers found that if the Earth’s magnetic field was indeed weaker, then the magnetosphere may have been only 34% to 48% as large as it is now. The conclusion of the study says “… the early magnetic interaction between the stellar wind and the young Earth planetary magnetic field may well have prevented the volatile losses from the Earth exosphere and created conditions to support life.”
Or, in plain language: “The early Earth didn’t have as much protection as it does now, but it had enough,” says Do Nascimento.
Small helium white dwarfs can be caused by a binary partner (NASA)
Scientists have understood for some time that the most abundant elements in the Universe are simple gases like hydrogen and helium. These make up the vast majority of its observable mass, dwarfing all the heavier elements combined (and by a wide margin). And between the two, helium is the second lightest and second most abundant element, being present in about 24% of observable Universe’s elemental mass.
Whereas we tend to think of Helium as the hilarious gas that does strange things to your voice and allows balloons to float, it is actually a crucial part of our existence. In addition to being a key component of stars, helium is also a major constituent in gas giants. This is due in part to its very high nuclear binding energy, plus the fact that is produced by both nuclear fusion and radioactive decay. And yet, scientists have only been aware of its existence since the late 19th century.
