Two aviators will take off from Iceland to take pictures of the sun while flying at high altitude along solar eclipse\u2019s path<\/p>\n
After lunch on Wednesday, two Nasa aviators will climb into a research plane and take off from Keflavik airport on a western tip of Iceland. They will climb north towards Greenland and then bank to head south on a gently curving course 40 miles (64km) off the Icelandic coast.<\/p>\n
Their mission can be described as chasing an eclipse, but in reality the eclipse is chasing them. As the plane cruises at 50,000ft (15,000 metres), the shadow of the moon will race up from behind, crossing the ocean below at more than 2,000mph (3,200km\/h). The pilot will aim to reach the point of greatest eclipse, when the largest fraction of the sun is obscured by the moon, at the moment the shadow catches up with them.<\/p>\n
For anyone standing directly beneath \u2013 or treading water, given the geography \u2013 the world will go dark for 2 minutes 18 seconds. But by flying at 460mph along the path of the eclipse, the pilot can extend totality to nearly 3 minutes. Which gives them more time to observe the blotted-out sun.<\/p>\n
Cary Klemm, a sensor equipment operator at Nasa\u2019s Johnson Space Center in Houston, who has flown eclipse missions in the past, described the experience at high altitude: \u201cThe big difference is that in the cockpit of an aircraft at 50,000 feet, it\u2019s very bright in the sun. There are no clouds above you, and then all of a sudden, you\u2019re hit with this slam of shadow.\u201d<\/p>\n
\u201cYou feel the temperature drop off; you\u2019ll notice that you need more light from your instruments, and it\u2019s kind of a weird, eerie shadow that you\u2019re surrounded by. It wraps around the view in the cockpit,\u201d he added.<\/p>\n
Hidden in the nose cone of the WB-57 aircraft are four cameras. These will take dozens of pictures a second of the occluded sun in different wavelengths of light. The images should capture large, looping ribbons of plasma called prominences and magnetic explosions called nanoflares. Only with the glare of the sun\u2019s disc blocked out are such observations possible.<\/p>\n
\u201cI\u2019m super-excited,\u201d said Dr Amir Caspi, the principal investigator on the mission at Southwest Research Institute in Boulder, Colorado. \u201cSolar eclipses give us an opportunity to do science we couldn\u2019t do at any other time.\u201d<\/p>\n
Despite the name, nanoflares pack a punch, each releasing thousands of atomic bombs\u2019 worth of energy as they go off around the sun. The flares at least partly explain one of the sun\u2019s greatest mysteries: why the corona or outer atmosphere is so hot, at more than 1,000,000C, while the surface is a mere 6,000C.<\/p>\n
For these observations, aircraft are hard to beat. Ground-based cameras have clouds to contend with and atmospheric interference. Space-based cameras are above such concerns, but can send back only so much data. \u201cAs you can imagine, this is terabytes of information,\u201d Caspi said.<\/p>\n
The WB-57 is based on the English Electric Canberra bomber, the RAF\u2019s cold war tactical nuclear strike aircraft, and flies above the clouds in the stratosphere. But other planes have been used for eclipse missions. In 1923, the US navy sent a fleet of biplanes to observe an eclipse, without much success. Fifty years later, scientists persuaded the French to cut holes in the roof of a Concorde prototype; hurtling over the Sahara at Mach 2, they kept up with an eclipse shadow for 74 minutes.<\/p>\n
The more scientists learn about the sun, the better they should be able to grasp space weather, the barrage of energetic particles and radiation that are hazardous to astronauts, satellites and even power grids and communications on Earth. Caspi said: \u201cUnderstanding space weather is critical for us as a technological species, and it starts with understanding the processes at the sun.\u201d<\/p>\n
Eclipses are not all about science though. \u201cWhat percentage of humanity has ever witnessed a total solar eclipse? It\u2019s a fraction of a fraction of a per cent,\u201d Caspi said. \u201cIf you\u2019re part of that rare group, you\u2019re connected to the Earth and the sun and the solar system. It\u2019s mind-blowing. It makes you feel very special, but also very small because you are this little mote in the universe.\u201d<\/p>\n