Global eye

An astrophysicist has made a daring proposal to send ...

Astronomers love a challenge. They place their observatories on the highest mountains, in the driest deserts, on the coldest ice shelves, beneath the deepest oceans, in orbit around Earth and the Sun,

Yes. On cosmic timescales, comets hit Earth frequently, but because they’re largely made of ice rather than solid rock, they tend not to leave obvious craters. A small comet is more likely than an asteroid to break up as it plunges into Earth’s atmosphere and heats up, often resulting in an explosion called an airburst that can devastate large areas of the landscape but doesn’t leave a crater. Perhaps the most famous such event happened over the Russian region of Tunguska in 1908, when an exploding comet flattened some 770 square miles of Siberian forest. A comet would have to be pretty big in order to hit the ground intact.

How our knowledge of these worlds beyond the Solar System has exploded in the last three decades

Did you know? The nearest black hole is ...

How the scanning electron microscope takes detailed images of things too tiny for our naked eye to see