The National Aeronautics and Space Administration scored an impressive first a few weeks ago by capturing an enormous solar coronal mass ejection with its new Interface Region Imaging Spectrograph.
A CME is a massive burst of solar wind and magnetic fields that rises above the solar corona and may be released into interplanetary space. NASA explains the phenomenon viewed by IRIS and presented in the video below as a curtain or sheet of solar material erupting outward from the Sun at speeds of 1.5 million miles per hour. Coronal mass ejections are often associated with similar forms of solar activity such as solar flares, but no causal relationship has yet been established.
“This is the first clear CME for IRIS so the team is very excited,” said Bart De Pontieu, the IRIS science lead at Lockheed Martin Solar & Astrophysics Laboratory in Palo Alto, California. Examining the spectra produced from imaging allows investigators to determine how much solar material is present at specific velocities, temperatures, and densities. The field of view seen in the video is about five Earths wide and about seven-and-a-half Earths tall.
When these ejections reach Earth, as they sometimes do, a shock wave causes a geomagnetic storm that may disrupt Earth’s magnetosphere. Solar energetic particles can intensify aurorae in large regions around Earth’s magnetic poles. Along with solar flares of other origins, CMEs can damage satellites, disrupt cell phone, GPS, and radio transmissions on Earth, and stop power lines from transmitting electricity, resulting in power outages. They can also emit intense, potentially lethal cosmic rays capable of reaching humans at high altitudes (airplanes or space stations).
A NASA Small Explorer, IRIS was launched last June so scientists can observe how solar material moves, gathers energy, and heats up as it travels through the chromosphere, a somewhat mysterious region in the Sun’s lower atmosphere. It’s the first observatory to image and record the chromosphere and space transition area with high resolution and wide temperature coverage (ranging from 5000 degrees K and 65,000 K, and up to 10 million K during solar flares). State-of-the-art 3-D numerical modeling on supercomputers compiles the data from IRIS. From the NASA websites:
“Tracking how material and energy move through this region is a crucial part of understanding the dynamics of the sun. Such information can help explain what causes the ejection of solar material—from the steady stream of the solar wind to larger, explosive eruptions such as coronal mass ejections—that travels toward Earth and causes space weather that can disrupt human technology.”
The IRIS mission’s primary goal is to understand how heat and energy move through the lower levels of the solar atmosphere. The instrument seeks to answer the following questions:
• Which types of nonthermal energy dominate in the chromosphere and beyond?
• How does the chromosphere regulate mass and energy supply to the corona and heliosphere?
• How do magnetic flux and matter rise through the lower atmosphere, and what role does flux emergence play in flares and mass ejections?
IRIS weighs 440 pounds and is approximately 7 feet (2.1m) long. With its solar panels extended, it’s a little over 12 feet (3.7m) across. It travels in a polar, sun-synchronous Earth orbit. Lockheed Martin Solar and Astrophysics Laboratory has overall responsibility for the mission, with major contributions from Lockheed Martin Civil Space, NASA Ames, Smithsonian Astrophysical Laboratory, Montana State University, Stanford University, and the University of Oslo.