Reflected Light from First True Exoplanet Observed

The first exoplanet ever discovered was 51 Pegasi b in 1995.  It kicked marked the slow beginning of what would soon become the ‘exoplanet gold rush.’  It meant that for the first time, we had the technological capacity to discover new worlds, and science fiction soon became science fact.  51 Pegasi b was also a very strange planet.  A massive Jupiter sized world orbiting very close to its home star.  On one hand it was this characteristic that made it much easier to detect.  On the other, it showed us that we did not understand planetary system formation as well as we thought.  Since this original discovery, we have dedicated telescopes to the search for new planets of all sizes, and are beginning to discover planets similar to our own home.  As our technology improves it seems as if we are finding unusual new configurations on a weekly basis, everything from planets with rings that make Saturn look tiny to fast orbiters that are being vaporized by the heat of their home star. Now our technology has taken us a step further, and for the first time we have seen the light reflected off of 51 Pegasi b.

This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b. Image credit: ESO / M. Kornmesser / Nick Risinger,

In astronomy, light is everything. Photons bounce around the universe, and the study of their characteristics allows us to unlock the secrets of the universe. By directly detecting light from 51 Pegasi b, we can figure out the planet’s mass, orbital inclination, what it’s made of, what it’s atmosphere is made of, and how reflective it is.  This is a truly deep study of a non-solar planet.

Of course, the real difficulty in such a process in blocking out the light from the planet’s parent star.  This has been an issue for years during the detection of exoplanets in general.  But with the development of better telescopes and more precise instruments, the starlight can be blocked more easily, allowing us a much clearer view of the reflecting planet.

51 Pegasi b is only 50 light years from Earth, making it a much easier target for astronomers than some of the more distant exoplanets.  For this reason, it’s a good starting point for the direct study of exoplanets, and paves the way for future exploration.  I’ve said it before, but it bears repeating: We are in a renaissance of exoplanet science.  Years from now this period will be talked about as a milestone of humanity’s quest for the stars.


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