Galileo's Pendulum

The Horsehead Nebula, in infrared light. [Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)]

Little round planet in a big universe
Sometimes it looks blessed,
Sometimes it looks cursed.
Depends on what you look at, obviously
But even more it depends on the way that you see.
– Bruce Cockburn *

The past week was not a healthy one: it was marked by violence, natural disasters, and the more subtle hatreds surrounding race, gender, and ethnicity that masquerade as “civilized” discourse. Sadly, the main reason many in the United States paid attention is because many of those events happened here, instead of at a safe remove in another country. I can only hope that the violence in Boston would lead to increased sympathy on the part of Americans toward those in other nations for whom such things are a common occurrence.

However, this week also marked the 23rd anniversary of the Hubble Space Telescope, an occasion marked by a new observation of a familiar object. Many of us no doubt have seen photos of the Horsehead Nebula, a large cloud of gas and dust in the constellation Orion; some of us may even have seen it through a telescope, as it’s a relatively easy thing to spot. In visible light, the cloud takes the form of a dark shape similar to—yes—a horse’s head, in front of a somewhat brighter background of red light from hydrogen atoms.

The dark shape is made of dust: molecules and aggregates of molecules, containing carbon and other atoms. Such dust clouds are frequently opaque to visible light, but in the infrared they can glow, thanks to the presence of young stars hiding within. That’s true for the Horsehead Nebula: the “horse” hides a creche of newborn stars, which the Hubble’s infrared Wide Field Camera revealed in the image above.

The Horsehead Nebula in both infrared (left) and visible light. [Credit: NASA, ESA, and the Hubble Heritage Team (AURA/STScI); ESO]

The infrared also shows details in the dust that aren’t obvious in visible light, even with high-resolution images. What is a shadow in one form of light is a beautiful glowing cloud in another. The darkness hides new birth, but we can see the renewal if we know how to see it.

* I know, I’ve used this quote before. So sue me. I’ll probably use it again.