NASA has conducted a recent survey of our home galaxy and through the sheer power of statistics, came up with this astonishing find:
The survey results show that our galaxy contains, on average, a minimum of one planet for every star. This means that it’s likely there are a minimum of 1,500 planets within just 50 light-years of Earth.They seem to be on to something--three more smaller-than-Earth-sized exoplanets were just discovered.
The study is based on observations taken over six years by the PLANET (Probing Lensing Anomalies NETwork) collaboration, using a technique called microlensing to survey the galaxy for planets. In this technique, one star acts like a magnifying lens to brighten the light from a background star. If planets are orbiting the foreground star, the background star's light will further brighten, revealing the presence of a planet that is otherwise too faint to be seen.
The study also concludes that there are far more Earth-sized planets than bloated Jupiter-sized worlds. A rough estimate from this survey would point to the existence of more than 10 billion terrestrial planets across our galaxy.
All of this comes on the heels of last month's discovery of Kepler22-b, hypothosized to be the first habitable planet outside our own solar system.
Kepler22-b; artist's rendering
And the 100 billion+ discovery STILL does't count the billion+ rogue planets thought to be out there as well.
It's such an exciting moment for science and the whole human race. I'm really, profoundly moved just to be hearing news like this. Take a moment and think about this pale blue dot we live on and it's true place in the universe, and sheer promise of what lies out there waiting for us to discover.
The Milky Way study will appear in tomorrow's issue of Nature.
All images: NASA