M 51

Some days I think of the vast amount of new knowledge that humanity has acquired in the last 60 years (even in the humanities) and I say, "In the future, if humanity survives, people will look back and ask, 'What the heck were they doing up till the Second World War?'" Other times I think that view is entirely too stingy in granting credit to pioneers of earlier eras who had brilliant insights or just did a lot of hard, systematic work, efforts in both cases that we still benefit from today.

This picture of Messier Object 51 is a good example of old and new work coming together. The bigger, more spectacular galaxy is known by its number in Charles Messier's catalog of "deep sky objects" which was compiled between the American and French Revolutions. Messier had no way of knowing that M 51 was 31,000,000 million light-years away. He was just interested in bright objects that might be confused with comets, and the catalog was meant to help other skywatchers separate permanent from temporary features of the sky. His catalog is still of use today.

The picture of course is the result of one of the proudest accomplishments of modern technology, the Hubble project. And I guess the fact that we can -- even with backyard telescopes -- see better than Charles Messier (and his assistant Pierre Mechain) but still use his numbers, illustrates that some of the most impressive and constructive examples of human collaboration stretches across the centuries.