The Solar Dynamics Observatory captured an array of images of a solar flare on Aug. 24. This one spectacularly shows the locus of the flare, on the left side of the sun.
Solar flares are energy releases. They happen when electrons, which carry a negative electrical charge, encounter the sun’s plasma. When that occurs, an explosion occurs and the particles are rapidly heated. Accelerated to very high velocities, they then move through the sun’s atmospheric layers and disperse into the solar system. When they reach the vicinity of Earth, they can pose a radiation hahttps://wordpress.com/post/zard to spacecraft and the astronauts inside them.
Solar flares are sometimes accompanied by an independent phenomenon known as a coronal mass ejection, in which atoms and ions are expelled from the star and sent on a high-speed journey through space. Coronal mass ejections can damage satellites, including those that transmit worldwide communications and provide geographic positioning system information, and disrupt the transmission of electricity on the planet. They can also impair the functioning of electronic devices on board high-altitude aircraft.
This week’s solar flare was not among the most powerful known to occur on the sun. Scientists measure the intensity of a flare according the amount of flux they produce in x-rays near Earth. There are five classes, ranked from weakest to most powerful: A,B, C, M, and X. Each of the classes involve flares that are about ten times more powerful than the next-lower class on the scale.
Within each class of solar flare there are numbered divisions that allow a more precise distinction between solar flares to be drawn.
Sunday’s event was an M5 flare, which means that it was not as powerful as the X5.4-class flare that occurred on March 6, 2012, the X5-class “Bastille Day Storm” on July 14, 2000, or the X17-class (or maybe even an X28-class) event that wowed scientists in October 2003.
The October 28, 2003 flare was powerful enough to induce the European Space Agency to put its Solar and Heliospheric Observatory in a “safe mode,” so that sensitive instruments on board would not be damaged. The event caused numerous aircraft flight delays and forced astronauts aboard the International Space Station to take cover in an area shielded from the solar radiation. The operation of several satellites in Earth’s orbit was disrupted and even space probes as far away as Mars and Saturn were affected.
The Bastille Day storm caused some radio broadcast disruptions and some damage to satellites.
You can learn more about well-known solar flare incidents here.
A draft United Nations report has bad news on climate: greenhouse gas emissions are rising faster than the efforts to contain and reduce them are succeeding in lowering them.
Today’s New York Times article said that the draft report concludes that “severe, pervasive, and irreversible impacts” are unavoidable unless the trend is reversed within a decade or two at most.
Among those impacts that are already occurring are increases in sea levels, extreme weather phenomena including heat waves and heavy rains, lowered grain production, and losses of polar ice.
According to a Nov. 2013 report by the World Meteorological Association, worldwide GHG emissions hit a record in 2012, with 35.6 metric tons discharged. In fact, the decade 2000-2010 was the warmest in the historical record. Climate data has been obtained and archived around the world since about 1850.
During 1970-2000, GHG pollution rose by only about 1.2 percent per year.
The IPCC report was released to governments around the world earlier this month for comment. It is due to be released to the general public on Nov. 2 in Copenhagen, Denmark.
Researchers have chosen five possible landing sites for a spacecraft that will attempt in November to become the first ever to land on a comet.
The European Space Agency will consider several factors in making the final choice of a landing site on comet 67P/Churyumov-Gerasimenko for the Philae lander, including whether it has obstacles to landing and whether the amount of solar energy appropriate for the lander’s power array is available.
“The candidate sites that we want to follow up for further analysis are thought to be technically feasible on the basis of a preliminary analysis of flight dynamics and other key issues – for example they all provide at least six hours of daylight per comet rotation and offer some flat terrain,” Steven Ulamec, the lander manager at the German Aerospace Center in Cologne, Germany,, said. “Of course, every site has the potential for unique scientific discoveries.”
One of the most basic factors that will influence the choice of a landing site is whether it is one to which the lander can be accurately guided. That challenge is magnified somewhat by the unusual shape of comet C-G, which has been likened to a rubber duck.
“Depending on where you try to make the lander land, the errors associated with everything can actually vary,” Dr. Daniel Scheeres, a professor of aeronautical engineering at the University of Colorado at Boulder and an expert in the navigation of space vehicles, said. “There will be regions on the surface where they can be more accurate than others.”
Another problem for mission planners is whether a potential site impedes Philae’s ability to anchor itself to the surface and remain upright. Rocky sites pose hazards to the spacecraft, but there’s no guarantee that a smooth site would be one to which the lander could be easily guided.
“There’s no reason why the easiest spot is also going to be the smoothest spot,” Scheeres said. “That’s where the challenge is going to be. They’ll have to make some sort of compromise.”
Yet another consideration will be the degree of solar illumination that predictably hits the landing site. Philae depends on batteries rechargeable by sunlight for its power.
“The real issue is what happens if the sun is blocked,” Scheeres explained. “Then you lose the power. And the comet is rotating. Even if you put it in the right spot, in a half a day it’s going to be in the dark.”
Because the movement of the comet will prevent Philae’s batteries from being constantly re-charged, it will be important for the landing site to be fully illuminated when that area of the comet faces the sun.
“If it lands somewhere where it’s shadowed, once the batteries are dead it won’t get any more power,” Scheeres said.
ESA faces a mid-September deadline to choose Philae’s destination on the comet. It will continue to gather information about the five potential landing sites for several more weeks.
“The process of selecting a landing site is extremely complex and dynamic; as we get closer to the comet, we will see more and more details, which will influence the final decision on where and when we can land,” Fred Jansen, the Noordwijk, The Netherlands-based Rosetta mission manager, said.
Three of the possibilities are located on the comet’s smaller lobe, while two are on the larger lobe.
Each of the sites must accommodate the one square meter-sized Philae lander, which will examine the chemical and physical structure of the comet and obtain close-up images of the comet’s nucleus.
Actual landing of Philae will occur when Rosetta and comet C-G are about 450 million kilometers from the sun.
Researchers want to make the attempt before the comet gets too close to the sun. Too much solar energy would make landing, and operation of the lander once on the surface of the comet, more difficult.
Rosetta is currently in orbit around the comet. It will continue efforts to study the comet through 2015, following it through an orbit around the sun.
The spacecraft Rosetta has met up, after a decade-long journey, with a comet orbiting the Sun between Mars and Jupiter, becoming the first vessel to do so.
Comet 67P/Churyumov-Gerasimenko will have its Earthly companion for about the next year as it moves around our star.
“After ten years, five months and four days traveling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometers, we are delighted to announce finally ‘we are here’,” Jean-Jacques Dordain, the director-general of the European Space Agency, said in a statement.
In May Rosetta began the process of slowing and positioning itself for the rendezvous. The spacecraft, which is now about 100 kilometers from the comet, will now prepare for an effort to land a probe on the comet’s surface.
That probe, called Philae, is to be launched in mid-November.
Rosetta is likely to help scientists learn about the comet’s nucleus and coma.
Launched on March 2, 2004, Rosetta has flown by Earth three times, by Mars once, and by two asteroids on its way to Comet 67P/Churyumov-Gerasimenko.
As the one hundredth anniversary of the passenger pigeon’s extinction approaches, the National Museum of Natural History is giving Americans the chance to see the last individual of the species.
The stuffed remains of Martha, who died at the Cincinnati Zoo on Sept. 1, 1914, will be posed on a branch for the display.
Passenger pigeons once numbered in the billions. At one time it was the most abundant bird on Earth and accounted for at least one quarter of all individual birds in North America.
Ectopistes migratorius was a fast flyer. One scientist estimated in 2002 that the bird could travel at a velocity exceeding 60 miles per hour. Passenger pigeons could also travel long distances, migrating in huge flocks that routinely numbered in the millions or more.
The display at the Smithsonian Institution museum in Washington, DC will also include specimens of the heath hen and the great auk, other notable examples of bird species driven to extinction by humanity.
This website provides information about the exhibition, entitled Once There Were Billions: Vanished Birds of North America.