Boaz Katz

In the southern sky, the star Acrux shines brightly — the lowest point of the Southern Cross constellation. It is not a single star but a whole family. New observations revealed that it contains not five, but seven stars bound by gravity, like children holding hands in a circle dance.

The biggest puzzle in physics is how to reconcile spacetime curvature with quantum mechanics. At the Planck length, billions of billions times smaller than an atom, the rules break down. This frontier was discovered by Max Planck.

A match flares from both ends. First the head ignites, and a moment later the flame engulfs the wooden stick. Something similar may happen in some Type Ia supernovae — except the match is a white dwarf (a star the size of Earth), and the flame is a thermonuclear explosion.

Two thousand years ago, a brilliant beacon shone in the constellation Eridanus, recorded in the registers of ancient astronomers. Hipparchus in 129 BCE noted it as a first-magnitude star, Ptolemy confirmed its brightness in the Almagest, and the Persian scholar Al-Sufi still saw it among the brightest in 964.