December 27 – Johannes Kepler

Today is Johannes Kepler’s birthday.

Kepler was born in Weil der Stadt, a small town near Stuttgart, on December 27th 1571, and was introduced to astronomy from an early age, whether he liked it or not, by being taken outside to witness the Great Comet of 1577, C/1577 V1, at age 6. The comet was also seen, incidentally, by Tycho Brahe, with whom Kepler would later spend some time studying at the site of Brahe’s new observatory near Prague.

Johannes Kepler

Johannes Kepler

Kepler’s works included many revolutionary (and I mean that in several ways) publications on the behaviour of planets. His Astronomia Nova, published in 1609, contained arguments in favour of a heliocentric ‘universe’, and Harmonia Mundi (“The Harmony of the World”, 1619) was the setting for his third law of planetary motion.

As well as being an influential astronomer, Kepler was also a major influence in the field of optics (possibly because his own eyesight wasn’t the best). He was the first person to explain how a telescope works; worked out how our eyes perceive depth; investigated how a pin hole camera might be used to produce pictures, and discovered total internal reflection.

Also today, globular cluster Messier 92 was discovered in 1777 by Johann Elert Bode.

M92 (Photo courtesy of the Isaac Newton Group of Telescopes, La Palma)

M92 (Photo credit: the Isaac Newton Group of Telescopes, La Palma)

M92 is located in the constellation of Hercules. It is one of the oldest and brightest globular clusters, and is about 27,000 light years from Earth.

1968 – Splashdown, south of Hawaii, of Apollo 8, following a 6 day flight that included the first Earthrise seen by humans, and the first Christmas broadcast from a craft orbiting the Moon.


November 15 – Asteroid 21 Lutetia

Asteroid 21 Lutetia was discovered on November 15th 1852 by Hermann Goldschmidt.  It’s about 100 km (60 miles) in diameter, is irregularly shaped,  fairly dense and heavily cratered.

Lutetia, for the second time in a week, is unusual for a low-numbered asteroid, in that you’re going to get an actual photograph of it, courtesy of the Rosetta probe, which paid it a visit in July 2010 on its way to study  comet 67P/Churyumov–Gerasimenko.

Lutetia from the Rosetta probe. (Photo: ESA)

Lutetia from the Rosetta probe. (Photo: ESA)

Today’s rock was named after Lutetia, the pre-Roman and Roman city that stood on what is now the site of Paris. Some of it still remains in the Latin Quarter, including the impressive Arènes de Lutèce, which I came across by accident a few years ago at the back of the Rue Monge.  I forget where I was going (probably looking for a coffee)  but it was quite a surprise to suddenly find myself in a Roman amphitheatre.

Arènes de Lutèce, Paris. (Image credit: me!)

Arènes de Lutèce, Paris. (Image credit: me!)

1630  ⇒  Death of Johannes Kepler in Regensberg, Bavaria, aged 58.

1738  ⇒  Birth of Frederick William Herschel in Hanover, Germany.

by Lemuel Francis Abbott,painting,1785

Herschel, by L F Abbott, 1785

The portrait above is by Lemuel Francis Abbott (1760-1802), mostly known for his famous portrait of Nelson.

1927  ⇒  Comet 29P/Schwassmann-Wachmann discovered by A Schwassmann and A A Wachmann at the Hamburg Observatory, Germany.