A team of researchers believes these mysterious masses might be the buried remains of a lost planet ... picture of how cosmic collisions shape planets. As we continue to probe Earth’s interior ...

There are a lot of satellites, and a lot of trash, around our planet — and the quantities ... Considering how quickly things in Earth orbit tend to zip around, a fragment of a spacecraft ...

And second, Mars doesn’t have a global magnetic field that concentrates auroras near its poles like Earth does ... auroras can appear all over the planet, but they’re relatively dim.

Only in this case the planet, seen anew, is Earth. A picture caption with an earlier version of this review misstated how far away the astronaut William Anders was when he took a photograph of ...