IRIS, a solar observatory new set for launch June 27, may reveal some of the Sun's best-kept secrets. The Interface Region Imaging Spectrograph (IRIS) observatory will examine one of the least-understood regions of our local star, the interface.
The interface is a region of the Sun that lies between the surface, which has a temperature of around 10,000 degrees Fahrenheit, and the corona, or atmosphere of the Sun, where temperatures can reach 3.6 million degrees. During solar storms, temperatures in the corona have been known to climb to 18 million degrees Fahrenheit.
Within the Sun itself, temperatures are hottest at the core, and get significantly cooler closer to the surface. Away from the surface, however, the temperatures rise dramatically. Although astronomers have some theories as to why this occurs, including fountains of plasma called spicules, the process is still largely a mystery.
The IRIS craft will orbit at a height of around 400 miles above the surface of the Earth, traveling around our planet from pole to pole, so that the Sun remains in view eight months a year. IRIS will observe the interface of the Sun in ultraviolet light, most of which is blocked by the atmosphere of the Earth, requiring the telescope to be launched into space.
Cameras aboard IRIS, designed and built by Lockheed Martin, will be able to resolve details on our local star as small as 150 miles across. But, instead of taking pretty (an informative) photographs, the light is sent to a spectrograph, which breaks it into component wavelengths, like a prism. A new spectrograph, covering about one percent of the visible area of the Sun, will be recorded every one or two seconds, with an ultraviolet picture being taken about every five seconds.
"By studying that light, we can understand how hot the gas is on the sun that we're looking at, what kind of densities it has, and how fast it moves (away from us or towards us). The combination of those three things allows us to really understand what makes the plasma cool and heat and how the magnetic field of the sun drives these solar storms," Bart De Pontieu, project leader, said.
Research into the workings of the Sun can also help predictions of solar storms, which could cause disruptions of electronics on Earth.
The launch was originally scheduled for 10:27 pm on the night of June 26, but was delayed for 24 hours due to power outages in the southeast. That announcement was made by NASA via Twitter early in the afternoon of June 25.