One of the most iconic images to be taken by NASA’s Hubble Space Telescope in the last 25 years is the image it took in 1995 of the so-called “pillars of creation”, part of the Eagle Nebula. To celebrate the Hubble’s 25th anniversary, NASA has recently re-imaged this star-forming region, the image below shows the comparison.
The differences between these two images are due to several factors. The more recent image was taken with a newer camera, WFC3, which is the 3rd generation optical camera on the Telescope (the 1995 image was taken with the 2nd generation optical camera, which was called WFPC2). The newer camera has both a better dynamic range, a larger field of view and a higher resolution than WFPC2.
Another reason for differences is more subtle – the pillars are slowly being destroyed by radiation outflows from the stars being formed in the pillars, and the newer image allows us to see subtle changes in the structure of the pillars. It is even possible to see the outflowing gas directly in some places (or rather the light emitted from the outflowing gas due to its excitation by the ultraviolet photons from the hot young stars).
NASA has also released a new near-infrared image of the pillars, and this image nicely shows how longer wavelength light is more able to penetrate the gas and dust than visible light. However, because the density of dust is so high in these giant molecular clouds, they do not appear totally transparent at these near infrared wavelengths; but rather as wispy ghosts rather than the thick pillars we see at visible wavelengths. Some background stars are visible in the near infrared, but many are still hidden, as are the actual star-forming regions which lie deep within the pillars.
The final image below shows the location of the pillars in the Eagle Nebula, which is otherwise known as Messier 16 (or M16). It is a nebula which is relatively easy to find with even a small telescope in the constellation Serpens.