caption: An artist's concept of the vast envelope of atomic hydrogen that envelopes the nearby helium-dominated exoplanet Gliese 436b. The radiation pressure from the planet's host star causes the gradual escape over time of significant amounts of hydrogen from Gliese 436b's atmosphere into space, which subsequently forms a large comet-like tail that follows the planet in its orbit around its star. Image Credit: NASA, ESA, and G. Bacon (STScI)
exif: {"Image ImageDescription": "This artist's concept shows the enormous comet-like cloud of hydrogen bleeding off of the warm, Neptune-sized planet Gliese 436b just 30 light-years from Earth. Also depicted is the parent star, which is a faint red dwarf named Gliese 436. The hydrogen is evaporating from the planet due to extreme radiation from the star. A phenomenon this large has never before been seen around any exoplanet.", "Image Software": "Adobe Photoshop CS5 Macintosh"}