J. Zhao

When a massive star exhausts its thermonuclear fuel, its core collapses, and the outer layers are ejected into space at speeds of thousands of kilometers per second. This is how a supernova remnant is born — an expanding cloud of shock-compressed gas spanning light-years.

Cosmic rays are like a downpour pelting from all sides. But when the wind blows, the droplets change direction. In the same way, a solar storm, a cloud of magnetized gas from the Sun, bends the paths of these particles that normally rain down on Earth evenly. Cosmic rays are invisible messengers from distant galaxies.

For three years straight, every night, telescopes have stared at one point in the sky. There lies the galaxy Mrk 421, whose core shoots a jet of particles aimed almost exactly at Earth. Such objects are called blazars. A black hole at the galaxy's center spins matter into a disk, and some of it is ejected outward in two narrow beams.

Cosmic rays are charged particles that constantly bombard Earth from deep space. When one of these particles enters the atmosphere, it collides with air nuclei and spawns a whole cascade of secondary particles: electrons, muons, photons.

In proton collisions at the Large Hadron Collider, physicists have for the first time caught a particle with two charm quarks. It is called Ξcc+ (pronounced "ksi-ksi-plus") and resembles a bead with not one but two heavy nuclei.

In a lab where crystals are studied, a technician stares at a screen covered in bright spots and slowly rotates the sample, trying to get the spots to form a symmetric pattern. It's like tuning an old radio: you turn the knob until the static gives way to a clear signal. Now, a machine can turn that knob. Scientists have created a program that learns to align crystals without any knowledge of how those spots work.

Every second, invisible projectiles from the depths of space pierce through us. These are cosmic rays — atomic nuclei accelerated to speeds nearly indistinguishable from the speed of light. Their energy is hundreds of millions of times greater than what our most powerful accelerators can achieve. Where does this monstrous force come from?

LIGO, Virgo, and KAGRA detectors act like giant microphones, listening in on gravitational waves — vibrations of space itself. The new GWTC-5.0 catalog recorded 161 black hole mergers, bringing the total count to 390 events.

Imagine a giant inflatable balloon with galaxies painted on it. As it inflates, the pattern stretches and neighboring dots move apart. The rate of that stretching is the Hubble constant. Astronomers usually catch light from distant stars and see how much it has reddened due to the stretching of space.

In the constellation Aquila, about 40,000 light-years away, one of the most powerful natural accelerators in the Galaxy is at work. It's the microquasar GRS 1915+105—a pair consisting of an ordinary star and a black hole.

A huge bowl of water. Drop a stone into it — ripples spread across the surface. The fabric of spacetime works much the same way: when two massive stars merge, they create ripples — gravitational waves. These waves travel to Earth and are picked up by giant detectors like LIGO and Virgo.

Pulsar PSR J1740+1000 is a city-sized star spinning faster than a kitchen blender. After a supernova explosion, it left behind a dense core that accelerates particles to near-light speeds. These particles fly into space, and previously it was thought they scatter in all directions, like splashes from a stone thrown into water.

At the Large Hadron Collider, protons are smashed together, and among the debris, a heavyweight particle, the lambda baryon, sometimes appears. It lives for a tiny fraction of a second before decaying into other particles.