The most remarkable discovery in all of astronomy is that the stars are made of atoms of the same kind as those on the earth.
The strangest thing I've found is that when I got to space, I felt more comfortable in space that I've ever been on Earth before. I just felt this is my home.
Frequently on the lunar surface I said to myself, 'This is the Moon, that is the Earth. I'm really here, I'm really here!'
That planet has a considerable but moderate atmosphere. So that the inhabitants probably enjoy a situation in many respects similar to ours.
Mars once was wet and fertile. It's now bone dry. Something bad happened on Mars. I want to know what happened on Mars so that we may prevent it from happening here on Earth.
Standing on the Moon looking back at Earth - this lovely place you just came from - you see all the colours, and you know what they represent. Having left the water planet, with all that water brings to Earth in terms of colour and abudance life, the absence of water and atmosphere on the desolate surface of the Moon gives rise to a stark contrast.
The mind of man is a thousand times more beautiful than the earth on which he dwells.
We are the laws of chemistry and physics as they have played out here on Earth, and we are now learning that planets are as common as stars. Most stars, as it turns out now, will have planets.
Our planet has been around only for four and a half billion years. Let's imagine a planet that has life on it such as life is on Earth and it's seven billion years old. Let's say that planet evolved intelligence. Well, that intelligence would be way more advanced than what we call intelligence here on Earth. How long has intelligence been around on Earth as we've come to define it?
There is good science you can do in space. There is stuff there you cannot do on Earth and we can gain understanding from it.
Mars is much closer to the characteristics of Earth. It has a fall, winter, summer and spring. North Pole, South Pole, mountains and lots of ice. No one is going to live on Venus; no one is going to live on Jupiter.
Planet Bog - Pools of toxic chemicals bubble under a choking atmosphere of poisonous gases... but aside from that, it's not much like Earth.
When we come to a comparison of heaven and earth, then we may indeed not only forget all about the present life, but even despise and scorn it.
Super-Earths are how we call a family of planets... up to two times larger and about ten times more massive than the Earth.
So I saw many planets, and they looked just a little bit brighter than they do from Earth.
Pluto is as far across as Manhattan to Miami, but its atmosphere is bigger than the Earth's.
I can hit it farther on the moon. But actually, my swing is better here on Earth.
There was a long history of people believing there was life on Venus. It was about the same size as Earth. It had clouds. It was commonly believed it was tropical - wet, hot and steamy.
Titan is the one place in our solar system whose geographical and atmospheric diversity and complexity are rivaled only by the Earth's. It's very Earth-like, but it's also very different, which means we have a lot to learn as well as a prayer of understanding what we find.
The Earth is like one of those balls made of twelve pieces of skin.
