{"id":9949,"date":"2024-03-04T01:45:30","date_gmt":"2024-03-03T23:45:30","guid":{"rendered":"https:\/\/uni-mag.gr\/?p=9949"},"modified":"2024-03-09T17:08:48","modified_gmt":"2024-03-09T15:08:48","slug":"the-moons-sky","status":"publish","type":"post","link":"https:\/\/www.uni-mag.gr\/en\/the-moons-sky\/","title":{"rendered":"THE MOON’S SKY"},"content":{"rendered":"\n
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IS IT THAT BLUE?<\/p>\n\n

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Photo of Adrian from northern Germany on Earth.<\/em><\/p>\n\n

Is the sky so blue on the Moon? Are we sure this photo is from Earth?<\/p>\n\n

WHY;<\/h2>\n\n
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The light from the Sun is white.<\/p>\n\n

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But there are times when this white light illuminates mom’s beautiful crystal vase in the living room. Then, a wonderful rainbow forms on the opposite wall. How is that?<\/p>\n\n

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Imagine that Mom’s beautiful crystal vase is the prism shown in the photo above.<\/p>\n\n

A transparent prism, like the next one, resolves white light into its spectrum.<\/p>\n\n

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In Optics, when white light passes through a prism, it is analyzed in its spectrum (from the Greek version of Wikipedia)<\/a> The spectrum of white light ranges from purple to red light. It also extends further to the left of violet towards X-rays and \u03b3-rays, and further to the right of red towards radio.<\/p>\n\n

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Humans can perceive with their eyes only a very small part of the white light spectrum. X-rays, for example, we cannot see with our eyes, but we can only see our bones when we go to the doctor and he takes X-rays. On the other side of the spectrum, the radio part of the spectrum we perceive with our radios and can thus listen to music!<\/p>\n\n

Since we have no natural detectors in our bodies to ‘see’ in X-rays and radio, we have built special machines that do this job. In Astrophysics, we have X-ray satellites (eg XMM-Newton) and radio telescopes (eg VLA) to ‘see’ what astronomical objects look like at these and other wavelengths.<\/p>\n\n

Of all these wavelengths contained in white light, how come we also see blue sky? Why don’t we see a green sky?<\/p>\n\n

The following video from NASA explains why very nicely. The video is in English. YouTube makes it possible to have Greek subtitles. But you need to see them on your computer.<\/p>\n\n

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