 Do you ever wonder how they find out what planets could sustain life? Between 2003 and 2004, the Hubble Space Telescope looked further into the Universe than we have ever seen before. The result was a stunning glimpse of a vast cosmos that is way beyond human comprehension. We consider that among millions of galaxies and billions of solar systems that there must be life. We simply can't be alone in the Universe, but how will we ever know this for sure? Is it crazy to think that we may never even confirm for sure that we are not alone even though through sheer randomness of space we know there simply must be life in some form or the other elsewhere? Wait, do you hear this? So that is the question of all the billions of planets we peer at in the ultra-deep field image. How many will have life? Observing Earth's global biology on a massive planetary scale has given scientists the tools to answer important questions like how can we use models of our own planet to detect signs of life on other worlds? In short, the first thing to do is figure out how we would find ourselves. Only a few decades ago, talking about life on other worlds was pretty taboo to say the least. If you brought up talk about aliens or life on Mars, a few eyebrows would be raised. It just was not considered an important human subject, but that's all changed these days. We accept that it is impossible for life not to already exist elsewhere other than the Earth. Based on our understanding of how life operates on Earth, we are starting to derive principles of the signals that life creates that we could then look for on these planets around other stars. But how do we choose where to begin in our search for Earth-like planets, or planets capable of sustaining life in a universe as vast as ours? This is where the scientific approach is vital as we comb space for signals of life. The key to this lies with understanding Earth's climate over a long period of time. By understanding Earth, it gives us hope to search for another planet like the Earth in habitable zones of other solar systems similar to our own. So it fizzles down to where to look exactly in our solar system. The habitable zone, or the Goldilocks zone, as it is sometimes referred to, is bound by planet Venus, which is far too hot with no surface ocean and the planet Mars, which may be too cold and too small and lacks any life-sustaining atmosphere these days. So you have to be in the right size and in the right place. Consider the Moon. It too is in the perfect position, along with the Earth, and it gets the correct amount of energy from the Sun, but it is far too small to hold onto an atmosphere. Now consider Jupiter. It is too massive, and this puts an overwhelming pressure on liquid water to exist, which is the key to life as we know it. So this is why the Kepler space mission was developed. Consistently over the years, Kepler has been discovering Earth-like planets within a habitable zone of other solar systems. Cluster after cluster, the Kepler has now found thousands of planets that are the right size and the correct distance from their star to sustain life that could be similar to that of our own. Everywhere we look, whether it's a desert or Antarctica, or the deep ocean or the deepest parts of Earth's crust that we've explored, as long as water exists, life exists, and this is the key that we have been taught by Mother Earth. The more we see other planets, the more the question comes into focus. Obviously we're the weird ones. Decades of observing Earth from space has informed our search for signs of habitability and life on exoplanets and even planets in our own solar system. We're taking a closer look at what we've learned about Earth, our only example of a planet with life, to our search for life in the universe. If there isn't anything else out there, if we really are alone in the cosmos, then wouldn't that be a complete waste of the vastness of space? Just a thought. What do you guys think our chances are in our search for life elsewhere? Maybe aliens have already found us and are keeping an eye on our progress. If you consider the breakthroughs within the past 20 years alone, then the next 20 years will be exciting to look forward to. Wouldn't you agree? Comments below and as always, thank you for watching.