View the sun using the cross image fader

By Grant Jacobs 22/04/2010

Kristian Larsen’s clever cross image fader lets you see regions of different temperatures on the sun on the WWW by moving a slider.


Sciblogs latest video shows some of the first images from astronomers’ latest ’toy’, the Hinode satellite. (Geeks can check out Nasa’s ’lite’ take on it’s technical specifications.)

The satellite has several telescopes. The opening frames of the video showing the sun in red, green, blue then yellow are from the Extreme ultraviolet Imaging Telescope, or EIT for short.

(Source: wikipedia.)

Light can be thought of as repeated waves, like ripples on a pond. The wavelength of light is the length from the top of one wave to the top of the next wave.

Each colour in the video represents light from a different wavelength in the extreme ultraviolet.

Ultraviolet light have shorter wavelengths than visible light, what you and I see with our eyes. The shortest light we can see is perceived as a deep purple.

)”](Source: wikipedia [cropped from original])

The EIT records light at four different wavelengths: 304, 171, 195 and 284 Ã…ngströms (or Ã…). An Ã…ngström is one ten-millionth of a millimetre, or 10-10 of a metre. (The scale in the graphic above is in metres. One Ã…ngströms is a 10-10 of a metre. 100 Ã…ngströms is 10-8 metres, which you can see in the left extreme of the UV region.)

(Screen capture of Larsen’s cross-image fader of sun images. Source: Nasa.)
(Screen capture of Larsen’s cross-image fader of sun images. Source: Nasa.)

These different measurements are used to determine which regions surrounding the sun are at several different temperatures: 60,000 – 80,000, 1, 1.5 and 2 million degrees Kelvin, respectively for each wavelength of 304, 171, 195 and 284 Ã…ngströms. They’ve coloured the regions detected red, blue, green then yellow, respectively. (A degree Kelvin is temperature measured with zero set at absolute zero, or -273.15ËšC. The scale is named after Lord Kelvin.)

Kristian Larsen, an applied physics engineer from Denmark, developed a web application to show the latest images from the Hinode satellite using a slider (show to right) that fades the images from one wavelength into the next, so that you can easily compare them.

Try it out.

As you move the slider, the text below will tell you what you are seeing.


I’m not an astronomer; I’m just offering a few steps towards breaking down the jargon.

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