How big would a telescope need to be to see Earth’s dinosaurs from 66 million light-years away? Think big—and then think ...

Determining the size of an Earth-size exoplanet by the amount of starlight it blocks hundreds of light-years away once was the realm of science fiction. Measuring the mass of such a small planet based ...

A NASA mission has spotted an Earth-size exoplanet orbiting a small star about 100 light-years away. The planet, named TOI 700 e, is likely rocky and 95% the size of our world. The celestial body is ...

Imagine for a moment that Earth suddenly shrank to the size of the Moon, while the Moon expanded to the size of Earth. How would life on our planet change? Could humans survive this dramatic cosmic ...

Add Yahoo as a preferred source to see more of our stories on Google. White dwarf stars, like this one shown shrouded by a planetary nebula, are much smaller than stars like our Sun. NASA/R. Ciardullo ...

the Earth you walk on today might not be the same planet that was born 4.5 billion years ago. Many scientists believe that in its infancy, Earth collided with another world the size of Mars, and that ...

Is our Milky Way galaxy home to other planets the size of Earth? Are Earth-sized planets common or rare? NASA scientists seeking answers to those questions recently revealed their discovery. “We went ...