photosphere

In a pot on the stove, water starts to churn from the bottom long before the whole thing boils. Bubbles of steam rise from the base even though the burner itself hasn't heated up yet.

The Sun breathes, and that breath has a magnetic rhythm. Every 27 days, the visible surface of the star makes a full rotation, and with it, its magnetic field, like an invisible ribbon wrapped around the star.

A light ray passing by a massive body slightly changes its direction, like a stream of water bending around a rock in a creek. In the solar system, there are many such "rocks": planets, their moons, asteroids. And each one, with its own gravity, bends the path of light coming from distant stars.

The Sun's edge looks like a fuzzy fringe: thin jets of hot gas, spicules, shoot upward from it. They live only a few minutes and are constantly changing. In 2024, a balloon-borne telescope managed to spot not only the jets themselves but also their faint glow in hydrogen lines that had never been captured there before.

The solar wind is a stream of charged particles constantly blown off the Sun's surface, filling the entire solar system. It's not like a steady breeze: it has eddies, gusts, and calm patches. Scientists call this turbulence.

Cosmic rays aren't rays in the usual sense: they're fast particles bombarding Earth from all directions. Mostly they're protons and atomic nuclei. Their energies vary widely, from modest to fantastically huge. When such a particle heads our way and the Moon or Sun gets in its path, it gets absorbed.

Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.

One hundred forty parsecs, a distance light traverses in four and a half centuries, separate us from the Taurus molecular cloud. Within its depths hide dark condensations: prestellar cores, where gas and dust slowly contract under their own weight.

In a vast hall, billiard balls are scattered about. At first they lie sparsely, each on its own. Then someone adds more, and suddenly the balls compress into dense clusters. This is a phase transition — the moment when matter abruptly changes its state. Physicists have long described such a picture with the hard-sphere model: particles are identical balls that cannot overlap.

The Moon is an airless sphere of dense rocky grit called regolith. When fast particles from space slam into it, muons are born in the soil — unstable relatives of electrons, but two hundred times heavier. Most fly downward and fade away in the depths. But those that pop upward into the vacuum can travel tens of kilometers before decaying.

Imagine an artist whose canvas is an entire planet, and whose palette is molecules drinking starlight. His brush is billions of years of evolution, and his painting is a spectral portrait visible even from another star system.

For years, the Sun teased astrophysicists. In its atmosphere, refractory elements, like spices in a basic recipe, were slightly less abundant than in nearly identical twin stars. Suspicion arose: could our star be modest, skipping the planetary "dessert" that others devour with gusto?

A planet glides across a star's disk, and for a moment becomes a flashlight. It blocks a tiny patch of surface, revealing details that otherwise escape our view. That's exactly how astronomers peered into the dark spots on V1298 Tauri, a young twin of our Sun. They were aided by the James Webb Space Telescope JWST and three giant planets in orbit.

A black hole is a place where gravity is so strong that even light cannot escape. But around it there is a glowing ring of gas, and in the center a dark void known as the shadow. The size of this shadow depends on how spacetime is curved.

Moments before totality, swift shadow bands glide across the ground, like ripples from pebbles tossed into water. For centuries, this phenomenon baffled scientists. It turns out the key is that light is a wave. The Sun isn't a pinpoint lamp but a vast disk. When the Moon nearly covers it, a thin glowing crescent remains.

The atmosphere of Titan, discovered by Christiaan Huygens, is opaque to ordinary telescopes. But spectral analysis finds 'windows' of transparency — narrow regions where the haze parts.

Light passing by a black hole swirls like water down a bathtub drain. The most intriguing part is the thin ring where rays can orbit forever, neither falling in nor escaping. This is the photon sphere — an invisible boundary that paints the hole's shadow on the sky.

Two white sheets lie in the sun — one rough, one smooth. Which one heats up less? The rough one scatters light more strongly, so it seems it would stay cooler. But if the coating is made of many transparent glass beads, the logic changes. Light wanders through it like in a thick fog, and at some point it stops noticing individual droplets.

Neutron stars are super-dense spheres of the remnants of exploded stars. Some of them we see as pulsars — cosmic lighthouses sending out radio bursts. What's inside them long remained a mystery. Physicists assumed that hidden fields could affect their structure, but it was believed that if the field is short-range, its effect is negligible.

The ionosphere at an altitude of 70 kilometers acts like a giant mirror for radio waves. Ground antennas constantly beam signals into it and listen for the reflection. When a solar flare occurs on the Sun, a stream of X-rays reaches Earth in 8 minutes and compresses the lower layer of the ionosphere.

Light needs space. A camera lens sits several centimeters from the sensor so the rays have room to focus. Now, that gap has been squeezed to the thickness of a sheet of paper, and light still behaves as if it had traveled its rightful centimeters. That's what 'spaceplates' do: flat elements that mimic free-space propagation.

In the scorching solar corona, where temperatures soar past a million degrees, float cold, dense clouds — solar prominences. They hang for weeks, neither falling nor dissolving, like icebergs in a boiling ocean. How they got there is a question that has puzzled astronomers for decades.

The solar wind, a stream of charged particles from the Sun, slams into the tenuous gas that fills the space between the stars. The collision produces a faint X-ray glow. For astronomers, this is like fog in front of headlights: it obscures distant objects.

The glow of an ultrathin sandwich made of two semiconductor layers, molybdenum selenide and tungsten selenide, resembles a tangled musical score: many narrow colored lines that merge into a general background. Figuring out which line comes from where is nearly impossible. The authors did not try to disentangle the lines one by one.

After the Big Bang, the Universe was filled with cold gas — mostly neutral hydrogen and helium. It enveloped the cosmos like a morning fog, impenetrable to light. The Dark Ages began. When the first galaxies ignited, their radiation, like a searchlight beam, started knocking electrons out of atoms.

A hot skillet on the stove glows in the dark, but if you cover it with a lid, the heat escapes more slowly and the surface doesn't look as bright. That's roughly the situation on planet HD 3167 b: it always shows the same face to its star, and the dayside is heated to temperatures that melt rock.

On the outskirts of our Galaxy, far beyond the familiar stellar disk, the Subaru Telescope has spotted something unexpected: a scattered cloud of stars spanning an area of one hundred square degrees across the sky.

A gamma-ray burst is a brief but extremely powerful flash of light, born from the merger of neutron stars or the collapse of a massive star. Inside such a flash, plasma flows race at enormous speeds and collide with each other.

Dark matter is an invisible substance that keeps galaxies from flying apart. If its particles occasionally decay near the Sun, they shoot out streams of fast particles, like invisible hammers striking light. Each impact turns a particle of sunlight into a gamma ray — a super-powerful flash that telescopes can spot.

At night in a dark room, the human body emits a barely perceptible glow. This light is so faint that only highly sensitive detectors can catch it. Some researchers thought this glow from the head could tell us about brain activity — no scanners or wires needed. But when put to the test, the story changed.

A water droplet on a leaf disappears faster under the sun than heat calculations would predict. A few years ago, a hypothesis emerged: light itself, without heating, could knock water molecules off the surface. This was dubbed the photomolecular effect. If it exists, clouds, climate, and even everyday clothes drying could work differently.

The Sun's corona looks like a shaggy dandelion: bright petal-like loops hold hot gas near the surface, while long, tenuous jets escape into space between them. These jets, the heliospheric current sheet, stretch across the entire solar system.

If you build a giant blanket around a star, you get a Dyson sphere. It absorbs all the radiation and glows in invisible heat rays. No such sphere has been seen yet, but astronomers know: to find it, look for this thermal glow.

Oxygenic photosynthesis requires splitting water. It's kind of like a water wheel: to make it spin, you need a strong current. Light acts as the current, and light particles are the streams. For red dwarfs, the most common stars, the light is "cool" and weak — the streams barely move the wheel.

At the bottom of lunar craters, where sunlight never reaches, an eternal cold reigns — about minus 240 degrees Celsius. In these icy pockets, known as permanently shadowed regions, plans are underway to install a mirror resonator made of monolithic silicon.

A solar flare is like an explosion in a star's atmosphere: in minutes, it releases energy comparable to billions of nuclear bombs. On May 4, 2022, the RT-7.5 radio telescope in Moscow was watching an M5.7-class flare. The instrument was catching millimeter radio waves: those shorter than a centimeter and invisible to the eye.

When light hits a transparent plate, some of it bounces off the surface. For astronomers, that means losing precious photons from distant stars. New 3D-printed microlenses made from IPX Clear resin transmit visible and near-infrared light, but at the air boundary they lose about 8%. The solution came from nature.

At night, the sky is never completely black. Even far from cities, the upper atmosphere glows faintly: sunlight makes hydrogen atoms emit a reddish glow that astronomers call geocoronal emission. For a telescope, it's like a fogged-up window: it adds extra light and hinders seeing distant galaxies.

In Chile's Atacama Desert, at an altitude of nearly five kilometers, stands a radio telescope that catches millimeter waves from the depths of space. These waves carry the heat of distant galaxies, but first they must pass through a window — a thin plate of silicon that separates the cold receiver from the warm outside world.

Light from the hottest young stars usually cannot leave its galaxy: hydrogen absorbs it, like a thick curtain blocking a sunbeam. But sometimes the curtain parts, and ultraviolet photons burst into intergalactic space.