Brian Greene Quotes

I am not sufficiently conceited to think that my sun is the only one with a family of planets and, therefore, that our little earth is unique. Once we admit that the other stars probably also have planets, at any rate a goodly proportion of them, it is more than likely that a large fraction of these will be the right size to keep on their surface water and, possibly, an atmosphere of some sort; and, furthermore, at the proper distance from their parent sun, to maintain a suitable temperature.

Life is extremely resilient once it takes hold, but it requires rich chemistry, large energy sources, and stability, right from the beginning. The comparative planetology of our solar system makes it seem like those initial conditions are hard to come by.

The usual metric for whether a planet is habitable or not is to ascertain whether liquid water could exist on its surface. Most worlds will either be too cold, too hot or of a type (like Jupiter) that may have no solid surface and be swaddled in noxious gases.

In days gone by, scientists would speak solemnly about our solar system's 'habitable zone' - a theoretical region extending from Venus to Mars, but perhaps not encompassing either, where a planet would be the right temperature to have liquid water on its surface.

Generally speaking, exoplanets can be any size, and they are found in a wide range of orbits. Some have massive gas atmospheres; others are smaller with an icy or rocky composition.

Super-Earths are how we call a family of planets... up to two times larger and about ten times more massive than the Earth.

Here's a question we all ask ourselves at least once when we're young: Where does that starlight come from? It's been there before I was born, and before my grandmother, and her grandmother were born. So just how far is that star from Earth?

This plucky NASA telescope is able to find planets en masse. If you compare planet hunting to prospecting for gold, then Kepler is equivalent to trading in your trusty pan for a diesel-powered sluice box.

Mars is the only place in the solar system where it's possible for life to become multi-planetarian.

The cosmos is three times as old as Earth. During most of creation's 14 billion year history, our solar system wasn't around. Nonetheless, the early universe still had the right stuff for life, and contained worlds that were just as suitable for spawning biology and intelligence as our own.

Planets that don't currently sport plate tectonics, such as Venus and Mars, are scarcely habitable. Tectonics might be a requirement of any world that aspires to a rich diversity of life.

We do care about planets like the Earth because by now we understood that life as a chemical system really needs a smaller planet with water and with rocks and with a lot of complex chemistry to originate, to emerge, to survive.

We're going to understand that there is life on other bodies in the solar system.

Stars, of course, are too hot to support life, so wherever life might exist in the universe, it has to be on planets or moons that are warmed, but not incinerated, by the stars they travel around.

The bottom line is, like, one in five stars has at least one planet where life might spring up. That's a fantastically large percentage. That means in our galaxy, there's on the order of tens of billions of Earth-like worlds.

By monitoring auroral activity on exoplanets, we may be able to infer the presence of water on or within an exoplanet.

We go to learn about our solar system, to search for life, and to understand what happened to Mars so we avoid it ourselves.

I think Pluto has to be considered among the places in the solar system that are possible homes for life.

One of the first thoughts I had, when doing early exoplanet research, was that Earth and its many companions seemed very different from the planetary systems we were detecting.

Because Alpha Centauri is so close, it is our first stop outside our solar system. There's almost certain to be small, rocky planets around Alpha Centauri A and B.

Among the plausible niches for extraterrestrial life in our solar system, the clouds of Venus are among the most accessible and the least well explained.

Ultimately, what we're looking for in the long run is to find other Earth-like planets.

The story seems to be that almost every star has a planetary system... and, also, the definition of 'habitable zone' has expanded. In our system, it used to be that only Mars and Earth were potentially habitable. Now we've got an ocean on Europa... Titan.

As our sensitivity improves, we are finally seeing planets with longer orbital periods, planetary systems that look more like our solar system.

Every observation that we make, every mission that we send to various places in the solar system is just taking us one step further to finding that truly habitable environment, a water-rich environment.