A Quote by Galileo Galilei

But what exceeds all wonders, I have discovered four new planets and observed their proper and particular motions, different among themselves and from the motions of all the other stars; and these new planets move about another very large star [Jupiter] like Venus and Mercury, and perchance the other known planets, move about the Sun. As soon as this tract, which I shall send to all the philosophers and mathematicians as an announcement, is finished, I shall send a copy to the Most Serene Grand Duke, together with an excellent spyglass, so that he can verify all these truths.

Galileo Galilei

Quote Topics

About Among Announcement Another Copy Different Discovered Duke Excellent Finished Four Grand Jupiter Known Large Like Mathematicians Mercury Most Motions Move New Observed Other Particular Planets Proper Send Serene Shall Soon Star Stars Sun Themselves Together Truths Venus Verify Very Which Wonders

Quote Author

Galileo Galilei
Italian - Scientist
February 15, 1564 - January 8, 1642

The motions of the comets are exceedingly regular, and they observe the same laws as the motions of the planets, but they differ from the motions of vortices in every particular and are often contrary to them.

Isaac Newton

Venus and Mars are our next of kin: they are the two most Earth-like planets that we know about. They're the only two other very Earth-like planets in our solar system, meaning they orbit close to the sun; they have rocky surfaces and thin atmospheres.

David Grinspoon

We're just learning that a lot of planets are small planets, and we didn't know that before, fact is, in planetary science, objects such as Pluto and the other dwarf planets in the Kuiper Belt are considered planets and called planets in everyday discourse in scientific meetings.

Alan Stern

What is there in places empty of matter? and Whence is it that the sun and planets gravitate toward one another without dense matter between them? Whence is it that Nature doth nothing in vain? and Whence arises all that order and beauty which we see in the world? To what end are comets? and Whence is it that planets move all one and the same way in orbs concentrick, while comets move all manner of ways in orbs very excentrick? and What hinders the fixed stars from falling upon one another?

Isaac Newton

Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion.

Isaac Newton

The key to proving that there's a black hole is showing that there's a tremendous amount of mass in a very small volume. And you can do that with the motions of stars. The way the star moves around the center of the galaxy is very much like the way the planets orbit the sun.

Andrea M. Ghez

I'm a fan of the planets in any combination. When I was born, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, Pluto, the Sun, and the Moon were all in the sky.

Neil deGrasse Tyson

A major puzzle for which nobody has an answer is this: is there some size at which the planets change their nature from water-rich planets like Neptune, to rocky planets like the Earth? We have found two planets that are the size of the Earth in radius, but they are very close to their host star, so water on the surface would evaporate away.

Geoffrey Marcy

A 'serious' scientist in 1992 or 1993 had to admit the possibility that planets were really rare, that most stars might not have planets. We've gone from there to here - where most stars have planets.

Debra Fischer

It will be a long time, if ever, before we get to study Earth-like planets orbiting around other stars, so really, the study of Venus and Mars is the best opportunity that we have, and can imagine having anytime in the future, to understand the evolution of Earth-like planets.

David Grinspoon

Our sun enlightens the planets that belong to him; why may not every fixed star also have planets to which they give light?

Bernard le Bovier de Fontenelle

When I grew up as a kid, we didn't know there were any other planets outside of our own solar system. It was widely speculated that planet formation was an incredibly rare event and that it's possible that other planets just don't exist in our galaxy, and it's just this special situation where we happen to have planets around our sun.

John M. Grunsfeld

Oh, my dear Kepler, how I wish that we could have one hearty laugh together. Here, at Padua, is the principal professor of philosophy, whom I have repeatedly and urgently requested to look at the moon and planets through my glass, [telescope] which he pertinaciously refuses to do. Why are you not here? what shouts of laughter we should have at this glorious folly! and to hear the professor of philosophy at Pisa laboring before the grand duke with logical arguments, as if with magical incantations, to charm the new planets out of the sky.

Galileo Galilei

I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations.

Galileo Galilei

Maybe the search for life shouldn't restrict attention to planets like Earth. Science fiction writers have other ideas: balloon-like creatures floating in the dense atmospheres of planets such as Jupiter, swarms of intelligent insects, nano-scale robots and more.