According to a news release from NASA, the space agency’s Solar Dynamics Observatory has spotted a massive coronal hole on the Sun. The picture, which was obtained on June 18, 2013, reveals a large coronal hole extended over nearly the entire upper left quadrant of the Sun. In the above image, the coronal hole can be seen in dark blue.
According to the Australian Government’s Bureau of Meteorology, coronal holes may spread across the Sun from pole to pole. They were first spotted most clearly in pictures obtained by astronauts on board the Skylab space station in 1973 and 1974. A coronal hole is a large region in the solar corona which is less dense and cooler than its surroundings. They are most common during the declining phase of the solar cycle. They form when the Sun’s magnetic field is open to interplanetary space.
According to NASA, this particular coronal hole is approximately 400,000 miles across, which is larger than 50 Earths placed side by side. Coronal holes spit out extremely fast solar wind, likely moving at around 400-500 miles per second, which is approximately two times the speed of the normal solar wind. Normal solar wind is regularly flowing from the Sun in all directions into the solar system.
Since first being spotted in the 1970s, astronomers have discovered that the size and number of coronal holes differs in connection with the Sun’s solar cycle, which hits a maximum of activity about every 11 years. As the Sun moves towards that maximum, the coronal holes shift closer to the Sun’s poles.
According to NASA, the blue color in the image above represents light in the 171 Angstrom wavelength, which reveals the coolest material shown in the image. The red color represents light in the 211 Angstrom wavelength and brown represents light in the 193 Angstrom wavelength.
Where does this photo rank on your list of the most awe-inspiring Sun photos of all time? What’s your favorite space photo of all time? Sound off in the comments section.