15th November 1738 – William Herschel born

William Herschel, German born British astronomer best known for his discovery of Uranus on 13th March 1781. He is also credited with the discovery of infrared radiation.

The William Herschel Telescope located on La Palma, Canary Islands is (guess what) named in his honour.

Why build such a large telescope on top of an island volcano you ask? The answer is seeing. Hey I just read about seeing in Phil Plaits book Bad Astronomy. Island volcanos are ideal for optical astronomical telescopes because the high altitude places the telescope above most of the water vapour in the atmosphere, and the ocean location combined with the roughly conical shape of the island means that turbulance caused by wind flow over the site is minimized. This combination makes for some of the world’s best seeing. No surprise then that La Palma in the Canary Islands and Mauna Kea in the Hawaiian islands host some of the worlds best optical telescopes.

The images these large telescopes produce is further improved by the use of adaptive optics. Here the mirror in the telescope is mechanically deformed in such a way that the deformation dynamically compensates for atmospheric distortion.

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One Response to 15th November 1738 – William Herschel born

  1. […] Sir William Herschel was not the first person to observe Uranus – John Flamsteed beat him to it. But Flamsteed did not recognise Uranus for what it was. The credit for the discovery therefore goes to Herschel. […]

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