March 9 2011 Astronomy Newsletter
After my trip to Norway, I thought it was time to write about the northern lights. Strictly speaking, the aurora isn't astronomical, but rather an atmospheric phenomenon. However it's caused by the particles from the Sun, so I think I'll count it.
Aurorae - polar light shows
There's a glow on the northern horizon. The Sun set hours ago and there are no city lights there. What's up? You could be seeing nature's great polar light show – an aurora. With solar activity on the rise, you might not have to go to the far north (or south) to see one.
Also look out for my companion piece about myths and legends of the aurora. It will be coming out on Friday. Here is a picture of an aurora that I saw – but not taken by me. http://tinyurl.com/6ag7o3a
There are a number of astronomical birthdays this week.
(1) John Herschel (March 7, 1792 – May 11, 1871)
Although he was the son of William Herschel and nephew of Caroline Herschel, astronomy didn't have an exclusive claim on John Herschel. He was also known as a mathematician, chemist and pioneer of photography. Herschel's father and aunt had catalogued the nebulae of the northern hemisphere and he himself completed the work by surveying the southern skies. Sir John Herschel was one of the most prominent scientists of his day and is buried in Westminster Abbey near Sir Isaac Newton.
(2) Henry Draper (March 7, 1837 – November 20, 1882)
On John Herschel's 45th birthday, a pioneer of astrophotography was born in America - Henry Draper. His father John William Draper is often considered the first astrophotographer, but Henry surpassed him. He was one of the first to photograph stellar spectra and began to collect spectra for a star catalog in which stars would be classified by spectra. When he died, his widow gave a grant to Harvard University to complete this work. Annie Cannon did most of the classification and you may still see stars listed by their HD numbers.
If you'd like to know more about Annie Cannon, see http://www.bellaonline.com/articles/art28074.asp and for more about early astrophotography, have a look at http://www.bellaonline.com/articles/art19545.asp.
(3) Urbain LeVerrier (11 March 1811 – 23 September 1877)
He predicted mathematically the existence of the planet Neptune based on observations of Uranus and his knowledge of celestial mechanics. LeVerrier sent his prediction to Johann Galle at the Berlin observatory, who found the new planet.
You can find out more about Uranus and Neptune at http://www.bellaonline.com/articles/art39799.asp.
(4) Percival Lowell (March 13, 1855–November 12, 1916)
Lowell had a varied career, but his interest in astronomy led to his founding the Lowell Observatory in Arizona. He had some rather crackpot ideas, including his insistence that there were canals on Mars built by a great, but dying, civilization. In fact, if there were canals on Mars we couldn't see them even with today's telescopes. However his observatory has produced some good astronomy and famously, it was where Clyde Tombaugh discovered Pluto.
On March 13, 1781 William Herschel discovered the planet Uranus, the first planet to be discovered since antiquity. It's twice as far from the Sun as Saturn is, so Herschel's discovery effectively doubled the diameter of the known Solar System.
Herschel's notes mentioned the possibility that Uranus had rings. At the time Saturn was thought to be unique in having rings. However on March 10, 1977 James L. Elliot, Edward W. Dunham and Douglas J. Mink found evidence of rings, though they weren't directly imaged until 1986 (by Voyager 2).
That's all for this now. Wishing you clear skies.
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