09 August 2013

Marvel at the most detailed photos of the Sun ever taken

Astronomers at the Big Bear Solar Observatory have captured the most detailed, visible-light images of the Sun. In the image above, you can see the terrifying detail of a sunspot, where intense magnetic activity prevents the convective flow of superheated plasma. In the image below, the Sun’s photosphere (the surface region that emits light) shows off its “ultrafine magnetic loops.”

These images were captured by the New Solar Telescope, which is equipped with a 1.6-meter clear-aperture Gregorian telescope and the Visible Imaging Spectrometer (VIS). With a huge aperture and modern imaging sensor, the NST is the largest and best solar telescope on the planet — and indeed, it was built specifically by the New Jersey Institute of Technology (NJIT) to study the activity of the Sun. Scientific observations began in 2009, but it seems it took more than four years for the conditions to be just right to capture these photos.

In the image at the top of this story, you see the most detailed photo ever of a sunspot. The dark patch in the middle is the umbra, with the “petals” forming the penumbra. The texture around the outside is what most of the surface of the Sun looks like. Like most solar phenomena, we don’t know exactly what causes a sunspot, but it appears to be some function of the Sun’s intense magnetic fields and differential rotation (where internal regions of the Sun rotate at different speeds).
Basically, something causes the magnetic field to collapse in on itself. This intense magnetic field is vertical (normal to the Sun’s surface), pointing straight down, blocking the Sun’s normal convection and in turn reducing the sunspot’s surface temperature. This is why sunspots appear darker — a sunspot might be just 2,700-4,200 degrees Celsius, while a normal patch of the Sun is around 5,500 C. The lighter, petal-like regions are where the magnetic field is more inclined, allowing for some convection to occur.
The second image, above, appears to just be a close-up of the Sun’s photosphere, captured by the Visible Image Spectrometer’s H-alpha filter (red light produced by energetic hydrogen atoms). The lines/loops of hydrogen plasma are created by magnetic fields that emanate from the Sun’s inner layers. Basically, it just gives us a better idea of just how crazy the surface of the Sun is. In the image below, captured by the TRACE space telescope as it orbited near the Sun, you can see what a sunspot looks like from another angle.

The New Solar Telescope, and space-based telescopes such as NASA’s STEREO, are of vital scientific importance because they give us more data about one of the most significant objects in the universe:  the Sun. By learning more about sunspots, solar flares, and other heliophysical phenomena, we stand a better chance of weathering whatever the Sun throws at us and prospering here on Earth. 


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