- New solar telescope takes best visible light image of Sun
- Shows a sunspot in remarkable detail
- Will help study “space weather”, which can affect Earth
The most detailed image ever made of a sunspot at visible light wavelengths has been taken by the New Solar Telescope (NST) at the Big Bear Solar Observatory (BBSO) in California.
The NST can produce images showing detail down to about 80 kilometres on the Sun’s surface—quite remarkable when you remember that the Sun is about 150 million kilometres away!
BBSO is located in the middle of a mountain lake, to cut down on land-based air currents that would disturb and distort the solar observations made there.
The NST has recently been equipped with an “adaptive optics” system that corrects for atmospheric turbulence that would otherwise ruin the images, and which enables more detail to be seen on the Sun’s surface.
The NST is the pathfinder for an even larger ground-based telescope, the Advanced Technology Solar Telescope (ATST), to be built over the next decade.
Why does the sunspot appear black? Isn’t it hot like the rest of the Sun?
Yes, a sunspot is very hot, but it is slightly cooler than the surrounding solar surface. And because the Sun is so bright overall, astronomers have to use special filters to dramatically cut down the sunlight entering their instruments, and this filtering makes the sunspot appear black in comparison to the surrounding region.
The Sun is a huge cauldron of hot electrified gases, called plasma, about 1.4 million kilometres across. Sunspots are connected with the Sun’s magnetic field, and their numbers rise and fall over an 11-year cycle—the Sun is just starting to come out of the latest minimum part of its cycle.
Scientists think magnetic structure, like sunspots, hold an important key to understanding space weather. Space weather, which originates in the Sun, can have dire consequences on Earth’s climate and environment. A bad storm can disrupt power grids and communication, destroy satellites and even expose airline pilots, crew and passengers to radiation.
Adapted from information issued by NJIT / Big Bear Solar Observatory.
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