Pillars of Erosion

Narrator (Megan Watzke, CXC): Erosion is a process. To put it simply, erosion is what happens when some sort of force - be it wind, water or radiation - wears down an object. Erosion is in many places and occurs on lots of different scales. Usually, erosion is a two-step process: first some force such as rain breaks an object up, and then this same force, or another one, often combined with gravity, carries material away.

We can see erosion around us in our day-to-day experiences. For example, erosion is responsible for the small pillars of dust left behind after a rainstorm.

On a larger scale, the effects of wind, rain and gravity combine to form the spectacular buttes and spires in the southwestern deserts of the United States and elsewhere around the world. Perhaps the most famous example of this is the Grand Canyon. This natural wonder was created by erosion over a period of six million years by the Colorado River.

Erosion also takes place on a cosmic scale in interstellar space, where intense radiation in the form of ultraviolet energy and X-rays from bright stars can sculpt shapes from dense clouds of gas and dust that are trillions of miles in size. It is this process that helped sculpt the so-called "Pillars of Creation," one of the most spectacular and renowned images ever taken by the Hubble Space Telescope.

While erosion does indeed subtract things, it is worth considering that this is not always bad. In fact, by removing material from an object or an environment, erosion may be responsible for the creation of new and perhaps even more spectacular structures around our planet and across the Universe.

Return to Podcasts

Narrator (April Hobart, CXC): HD 189733b: An exoplanet in orbit around a star about 63 light years from Earth. It has been nearly two decades since the first exoplanets – that is, planets around stars other than our Sun – were discovered. Now for the first time, X-ray observations have detected an exoplanet passing in front of its parent star. The observations, made by NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory, took advantage of the alignment of a planet and its parent star in HD 189733. This alignment enabled the observatories to observe a dip in X-ray intensity as the planet moved in front of, or transited, the star. This technique is the one used so successfully at optical wavelengths by NASA's Kepler telescope. In earlier studies using optical light, astronomers discovered that the main star in the HD 189733 system had what is known as a "hot Jupiter" around it. This means the planet is about the size of Jupiter, but in very close orbit around its star. The planet – that has been named HD 189733b -- is over 30 times closer to its star than Earth is to the Sun, and goes around the star once every 2.2 days. The new X-ray data suggest that this planet has a larger atmosphere than previously thought. This, in turn, may imply that radiation from the parent star is evaporating the atmosphere of HD 189733b more quickly than expected. The results on HD 189733 demonstrate how we need information from many different telescopes that detect different types of light to get a fuller picture of these mysterious worlds that we are now able to explore.