Photo credit: NASA/JPL-Caltech
By Amina Khan
Eureka! Astronomers say they’ve discovered clear skies and water vapor on a Neptune-sized exoplanet named HAT-P-11b — which, at roughly four times the Earth’s radius, is the smallest planet yet known to host water in its atmosphere.
The discovery, described in the journal Nature, marks a milestone for scientists seeking to learn whether even smaller planets in far-off solar systems have atmospheres comparable to Earth’s.
Finding exoplanets is difficult enough, but examining the molecular contents of their atmospheres is even harder. Scientists wait for the planets to pass in front of their stars and then examine the starlight that filters through the translucent gassy shell around the planet’s silhouette. If there’s water in that slim atmospheric lining, it will absorb certain wavelengths of the filtered light, leaving a chemical fingerprint that astronomers can identify.
It’s a process known as transmission spectroscopy, and it’s not easy work. Thus far, scientists have only been able to really probe the contents of the air around big planets, such as those the size of Jupiter, which are easier to spot and have wider, more extended atmospheres.
Read the full article by clicking the name of the source located below.