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Are We Alone?

NASA Ames/JPL-Caltech

In this episode of Our Island Universe, we are on the hunt for planets in the "Goldilocks Zone".

Transcript:

For thousands of years, our ancestors looked up at that dark starry night sky and asked are we alone? During that time, that has been a philosophical question, a theological question, and now in the 21st century, it is a scientific question. And one I believe we will find an answer to within the next 10-20 years.

At the turn of the 20th century, we knew of only 9 planets — the ones that made up our Solar System. Yes, at that time, Pluto was considered planet but today we know it is classified as a dwarf planet. In fact, looking for planets around nearby stars was thought to be a technological impossibility. Stars, via nuclear fusion in their cores, produce light. Planets largely reflect starlight. The contrast between stars producing light and planets reflecting light is so high, it was thought we could never “see” planets around stars.

Scientists are clever interrogators of the Universe and so they devised techniques that allowed them to pursue the quest to find planets orbiting nearby stars. The first confirmed detection of a planet around another star was in 1995 when a Jupiter-sized planet was orbiting very close to a Sun-like star called 51 Pegasi. The rate discovery slowly trickled for the next decade or so. But it has been NASA’s Kepler Space Telescope, launched in 2009, that has truly revolutionized our understanding of planets around other stars! Today, largely thanks to the Kepler Space Telescope, we know of nearly 2,000 planets around just the nearest stars to us!

Nearly 50 of these planets are located in the so-called “Habitable Zone”, that range of distance from a star that a planet should it have water would be in its liquid form rather than frozen as ice. In fact, of these ~50 planets in that Goldilocks Zone, Kepler has already discovered 8 planets that are small and rocky just like Earth! In the last few years, using the Hubble Space Telescope, astronomers have detected atmospheres around a few planets! How will we know we’ve found life on another planet? We’re looking for an exoplanet atmosphere that has oxygen— just like our planet that is produced via photosynthesis. The greatest discovery in science — that of life on another planet — is just waiting to happen and I suspect we’re going to get our answer very soon.