Sky viewers might get to enjoy some spectacular Northern Lights, or aurorae, tomorrow. After a long slumber, the Sun is waking up. Early Sunday morning, the Sun's surface erupted and blasted tons of plasma (ionized atoms) into interplanetary space. That plasma is headed our way, and when it arrives, it could create a spectacular light show.
"This eruption is directed right at us, and is expected to get here early in the day on August 4th," said astronomer Leon Golub of the Harvard-Smithsonian Center for Astrophysics (CfA). "It's the first major Earth-directed eruption in quite some time."
The eruption, called a coronal mass ejection, was caught on camera by NASA's Solar Dynamics Observatory (SDO) - a spacecraft that launched in February. SDO provides better-than-HD quality views of the Sun at a variety of wavelengths.
We'll have multiple opportunities for a display of the Northern Lights over the next two days. The latest word from the solar scientists is that the Sun erupted not just once, but four times. All four coronal mass ejections are headed toward Earth.
Space weather forecasts are even more challenging than regular weather forecasts. Dr. Leon Golub says a coronal mass ejection is like a hurricane: it’s large and fuzzy, and doesn’t always move at the same speed. Currently, the estimated arrival times are:
Wednesday, Aug. 4 – 3:00 a.m. EDT (07:00 am UTC)
Wednesday, Aug. 4 – 1:00 p.m. EDT (05:00 pm UTC aurorae not visible in daylight)
Wednesday, Aug. 4 – 8:00 p.m. EDT (12:00 am UTC on Aug 5)
Thursday, Aug. 5 – 2:00 a.m. EDT (06:00 am UTC)
Any one of these events may or may not generate an aurora. It depends on details like magnetic field orientation. If the magnetic field in the oncoming solar plasma is directed opposite Earth's magnetic field, the result could be spectacular aurorae. If the fields line up, the coronal mass ejection could slide past our planet with nary a ripple.
Viewing tips: No fancy equipment is needed to see the Northern Lights. You should seek a viewing location with dark skies, as far from city lights as possible. Then, look to the north. An aurora appears as a ghostly sheen of light, colored green or red, that slowly shimmers and undulates over time. An aurora can disappear within minutes or last for hours.
Ground-based magnetometers detected the moment a coronal mass ejection (CME) -- fired from the sun on Sunday -- slammed into the Earth's magnetosphere on Tuesday, producing a gorgeous Aurora Borealis.
Facing North from Silkeborg, Denmark, Jesper Grønne photographed this beautiful scene using a Canon 5D II camera.
Known as the Auroral Borealis (the "Northern Lights," focused around high latitudes in the Northern Hemisphere) and the Aurora Australis ("Southern Lights," around high latitudes in the Southern Hemisphere), these spectacular light displays are caused when energetic particles from the sun (mainly protons) stream into our magnetosphere.
Our nearest star has woken up for real and for sure. After several years of stubbornsilence, the Sun has unleashed several fairly big explosions of material. Called Coronal Mass Ejections, or CMEs, these gigantic events blast out hundreds of billions of tons of matter into space. They create vast interplanetary shock waves, and when they reach the Earth can cause all sorts of havoc. They are different from solar flares, but have similar origins in the Sun’s magnetic field.
NASA’s recently-launched Solar Dynamics Observatory caught the action mid-eruption. This image shows million-degree-hot gas blasting off the surface, entangled in the Sun’s strong magnetic field. The most recent CMEs probably won’t do much more than give us pretty aurorae — they’ve already been spotted — which is good (worse effects are the loss of satellites and potential blackouts on Earth). In fact, if you live in the far north or south you may be able to see the light show.
You can read more about this at Orbiting Frog, SpaceWeather (with pictures!), Universe Today, and pretty much every other space blog on the planet. I’m probably too far south and in far too light-polluted skies to see, but give it a try if you can. Aurorae can be quite spectacular.
But if you miss it, don’t fret: I’m sure we’ll get lots of other opportunities. The Sun is gearing up for the peak of its cycle in the next three years or so, and there will be plenty of chances to watch as our sky reacts.
On August 1st, almost the entire Earth-facing side of the sun erupted in a tumult of activity. There was a C3-class solar flare (white area on upper left), a solar tsunami (wave-like structure, upper right), multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection and more.
This multi-wavelength (211, 193 & 171 Angstrom) extreme ultraviolet snapshot from the Solar Dynamics Observatory (SDO) shows the sun's northern hemisphere in mid-eruption. Different colors in the image represent different gas temperatures ranging from ~1 to 2 million degrees K.
Earth's magnetic field is still reverberating from the solar flare impact on August 3, 2010, which sparked aurorae as far south as Wisconsin and Iowa in the United States. Analysts believe a second solar flare is following behind the first flare and could re-energize the fading geomagnetic storm and spark a new round of Northern Lights.
Credit: NASA/GSFC/SDO/AIA
Another great image from the Solar Dynamics Observatory (SDO) of the news-making solar event on August 1, 2010 resulting in two Coronal Mass Ejections (CMEs) launched in Earth's direction.
Geomagnetic activity resulting from the coronal mass ejection (CME) on August 1st has subsided to low levels and the aurora show of August 3rd and 4th has come to an end. At the height of the display, Northern Lights descended as far south as Wisconsin and Iowa in the United States.
For aurora imagery from this event, visit the Aurora Photo Gallery on Spaceweather.com.
At 1825 UT on August 7th, Earth-orbiting satellites detected a long-duration M1-class solar flare. The source of the blast was sunspot 1093. Several amateur astronomers caughtthe active regionin mid-flare. First-look data confirm that the blast produced a CME, but the cloud is not heading directly toward Earth. A glancing blow to our magnetic field on August 9th or 10th might produce auroras, but this does not appear to herald a major space weather event at Earth.
FAREWELL SOLAR MINIMUM: Solar activity is picking up and that gives some astronomers reason to wake up in the morning. "Ah the dawn of a new day... and what a day it was!" says Wouter Verhesen of the Netherlands, who took this picture of the morning sun on August 6th:
"There were massive prominences sticking out of the sun everywhere, sunspots galore, and even a small flare in AR1093," says Verhesen. "I can't remember the last time I had so much to do with my small solarscope. Farewell solar minimum, you will not be missed!"
On August 7th (1825 UT), magnetic fields around sunspot 1093 became unstable and erupted, producing a strong M1-class solar flare. Several amateur astronomers caught the active region in mid-flare, while NASA's Solar Dynamics Observatory recorded an extreme ultraviolet movie of the entire event:
The eruption hurled a coronal mass ejection (CME) into space, just missing a direct sun-Earth line. Forecasters expect the cloud to deliver no more than a glancing blow to our planet's magnetic field when it billows by on August 9th or 10th--not be a major space weather event.
Future eruptions could turn out differently. Active region 1093 is rotating toward Earth. By the end of this weekend, we'll be in the line of fire if its magnetic fields become unstable again.
EXTRA! SOLAR RADIO BURSTS: The flare produced intense radio bursts detectable by ordinary shortwave receivers on Earth. In New Mexico, amateur radio astronomer Thomas Ashcraft picked up strong emissions around 21 MHz. "Listen to some of the sounds than came out of the loudspeakers," he says. "This was a complex flare and very exciting. Yet it is still small stuff compared to what is coming in the future as Solar Cycle 24 intensifies."
The solar eruption of August 7th might affect Earth after all. Newly-arriving data from the Solar and Heliospheric Observatory (SOHO) show a CME heading our way with a significant Earth-directed component. ("Difference movie" of the expanding cloud)
The impact of this lopsided CME probably won't trigger a major geomagnetic storm---but the SOHO data show it could be bigger than expected. High latitude sky watchers should be alert for auroras when the cloud arrives probably on August 10th.
An M-class flare erupted in active sunspot region 1093, peaking at 1824 UTC on August 7, 2010. The eruption hurled a coronal mass ejection (CME) into space. NASA's Solar Dynamics Observatory observed the flare. The CME is not fully directed toward Earth, but some of the plasma cloud may glance the magnetosphere between August 9 and August 10, causing a geomagnetic disturbance and possible aurora.
Scientists classify solar flares according to their x-ray brightness in the wavelength range 1 to 8 Angstroms. There are 3 categories: X-class flares are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms. M-class flares are medium-sized; they can cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow M-class flares. Compared to X- and M-class, C-class flares are small with few noticeable consequences on Earth.
Skywatchers around the world's Northern Hemisphere, who were treated to spectacular auroras last week, could get lucky again Monday night or Tuesday night, the result of another major solar flare over the weekend.
Though it was not pointed straight at Earth, Saturday's eruption of charged particles from the sun's surface was even stronger than the Aug. 1 solar flare, which was assigned to C-class status based on the brightness of its X-ray emissions. The flare could boost the northern lights displays this week for skywatchers at northern latitudes.
The latest flare has been given M-class status, the second most-intense category (after X-class). M-class flares are capable of causing radio interference around the Earth's poles.
Five sunspots appeared on the Sun on August 11, 2010. Image from SolarCycle24.com
Here's something we've not seen in a long while: five sunspots on the Sun at once. Is the Sun finally waking up from its unusually long and deep solar minimum slumber? While activity on the Sun usually ebbs and flows on a fairly predictable 11-year cycle, this current cycle has been anything but conventional. In 2010 so far, the Sun has had spots for only 35 days, which is 16% of the time. With the last solar maximum occurring in 2001, it was thought the Sun would be steadily ramping up to the next maxiumum, which is set for 2013. But instead the Sun has been quiet and relatively spot free for quite some time. Recent solar flares on August 1 and 7, and now these sunspots may be signaling that the Sun is "throwing off the covers" and starting to wake up.
The marvelous image (see above) from the Solar Dynamics Observatory shows that at about 8:55 UTC on August 1, a measurable solar flare triggered an event known as a coronal mass ejection (CME). This is where the “atmosphere” of the Sun sends out a burst of energized plasma. In this case, nearly the entire Earth-facing side of the Sun was involved.
The High Energy Astrophysics Picture of the Week Page (see HEAPOW: Waking Up) used that great "covers" analogy:
...
And another CME on August 7 has not yet triggered a major geomagnetic storm, but high latitude sky watchers should take a look tonight, just in case.
