Like Earth, Mars once had a strong magnetic field that shielded its thick atmosphere from the solar wind. But now only the magnetic imprint remains. What's long baffled scientists, though, is why this ...

Earth's core contains nine to 45 times more hydrogen than the planet's oceans do, according to a new study that could settle a debate about when and how hydrogen was delivered to Earth.

Earth’s inner core has long puzzled scientists because seismic waves move through it unevenly. Compressional waves from earthquakes travel about 3 to 4 percent faster along the planet’s rotation axis ...