Edmond Halley of Halley's Comet fame celebrated

Google is saying comet as you are with today's home page, featuring a celebration of Edmond Halley, of Halley's Comet fame.

Halley was an English astronomer, geophysicist, mathematician, meteorologist and physicist, born on this day in 1656. He worked out the orbit of the comet that was named after him, which appears roughly every 75 years.

Halley's Comet is the only comet clearly visible to the naked eye that may potentially be seen twice in a lifetime (Hale Bopp, the great comet of 1997, isn't expected back for another 2,500 years). It was spotted by stargazers in ancient times but they didn't realise they were seeing the same comet returning.

It was Halley who worked out that the comet was indeed periodical, although he didn't live to see the comet on its next pass. Halley's Comet was named in his honour in 1759, just after it passed close to Earth once more, exactly as he had predicted.

A comet and a Google doodle? High praise indeed. The comet was last in our celestial neighbourhood in 1986 and will make its next comeback tour in 2061.

Halley also developed an early working magnetic compass, and captained the first purely scientific voyage by an English naval vessel. In his spare time he built a diving bell, which he took on jaunts to the bottom of the Thames.

Halley also paid for Sir Isaac Newton to publish a work on the laws of planetary motion, helping astronomers work out how planets orbit the Sun. He became Astronomer Royal in 1720, a position he held until his death in 1742.

Yesterday Google paid tribute to Marie Curie, the pioneering scientist who coined the term radioactivity, and the first person to win the Nobel prize in two different fields.