One should not be too distracted by definitions. Ideas transcend definitions.

Luckily, there are some rocks left over from our earliest days, asteroids formed during our solar system's birth. Occasionally, some of them drop in on Earth, and when they do, they're called meteorites.

There is a theorem that colloquially translates, You cannot comb the hair on a bowling ball. ... Clearly, none of these mathematicians had Afros, because to comb an Afro is to pick it straight away from the scalp. If bowling balls had Afros, then yes, they could be combed without violation of mathematical theorems.

In astrophysics, we care about how matter, motion and energy manifest in objects and phenomenon in the universe. Stars are born. They live out their lives. They die. Some of the ones that die explode. Our sun will not be one of those, but it will die. And it'll take Earth with us. So we make sure we have other destinations in mind when that happens. And I've got it on my calendar.

'Boldly going where hundreds have gone before' does not make headlines.

If our solar system is not unusual, then there are so many planets in the universe that, for example, they outnumber the sum of all sounds and words ever uttered by every human who has ever lived. To declare that Earth must be the only planet with life in the universe would be inexcusably bigheaded of us.

There's a saying in the scientific community, that every great truth goes through three phases. First, people deny it. Second, they say that it conflicts with the Bible. Third, they say that they've known it all along.