Exoplanets astro-ph.EP

Over the tropical Pacific, air pressure breathes with periods from two to fourteen years. The barometer on Tahiti rises while it falls in Darwin, Australia, and the entire planet's climate shudders: El Niño arrives. Meteorologists call this the Southern Oscillation and have tracked it for 138 years, but until now they couldn't answer a simple question: where do such periods come from?

In 2019, northern and southwestern Iran received 50% more rainfall than usual, and rivers overflowed their banks. A year earlier, in 2018, rainfall was 53% below normal, and fields cracked under drought. Such swings are not random; they are responses to three distant oceanic pulses that set the rhythm for Iran's rains.

The Atacama Desert in northern Chile is the driest non-polar place on Earth. The sky is almost always clear, and the air is so devoid of moisture that even distant galaxies are visible without interference.

The three planets in the Kepler-51 system have long intrigued astronomers: they are Saturn-sized but less dense than water. These 'super-puff' worlds, with masses no more than ten Earths, are like cosmic dandelions — massive yet almost weightless. Their orbits are arranged like musicians in an orchestra, each playing its part, beating the rhythm with transits.

In August 2024, the MIRI coronagraph on the James Webb Space Telescope stared at Alpha Centauri A, the nearest Sun-like star to our Sun. At 1.5 arcseconds from the star, a point source, S1, blinked into view. Flux: 3.5 mJy, contrast: 5.5×10⁻⁵. Four to six sigma. A lighthouse flashing in the fog.

A spinning top tilted over a table, with a dusty pancake swirling around it. That is what a young stellar system looks like when the star's spin axis and the plane of its protoplanetary disk do not align. Until recently, astronomers did not know how common such a configuration is in nature.

Water is the gold standard for life. We search for its traces on Mars, in icy moons, and in the atmospheres of distant planets. But what if life doesn't need water? On a warm rocky exoplanet with a thin atmosphere, water would evaporate within hours.

Three bodies attracting each other by universal gravitation: a problem that has stumped mathematics for three centuries. After Poincaré, it became clear that no general solution exists and trajectories are chaotic. But within this chaos there are islands of order: periodic orbits where motion repeats.

Every few hours, narrow beams of radio waves leave the Mojave Desert, near Madrid, and near Canberra, heading into the sky. This is NASA's Deep Space Network: three antenna complexes that keep in touch with spacecraft across the solar system.

Deep inside a molecular cloud, where temperatures drop to 10–20 kelvin and gas densities reach a million particles per cubic centimeter, a frozen shadow prevails. There, far from starlight, water, carbon dioxide, and other molecules freeze onto dust grains.

Four hours and fifty-eight minutes. With a rhythm like a metronome, something passes in front of the white dwarf ZTF J1944+4557, dimming its light by a third, sometimes almost by half.

In 2022, the Subaru telescope photographed a point of light 100 astronomical units from the star AB Aurigae. The point was named planet AB Aur b, but debates did not subside: what exactly is glowing, the planet itself or dust around it?

The dayside of WASP-121b is scorching at 2358 kelvins, hotter than the surface of many stars. Here, in perpetual light, the atmosphere does not just boil: it melts rock and turns it into gas. But not all gas stays gaseous. Some condenses into clouds, and those clouds hide titanium the way a trap hides its prey.

A wind blowing against the planet's rotation stokes a carbon forge. That is what the atmosphere of PSR J2322-2650b looks like: a Jupiter-like companion to a millisecond pulsar.

For 36 days, tropical cyclone Freddy raged over the Indian Ocean, the longest-lived cyclone on record. Meteorologists tracked it from satellites, aircraft, and ground stations. But one detail eluded all instruments: the precise air density deep within the vortex. And that density determines where the cyclone will turn tomorrow.

The Moon harbors a secret that has puzzled planetary scientists for decades: its isotopic composition is almost indistinguishable from Earth's. According to the canonical giant impact model, the Moon should have inherited most of its material from the impactor Theia, a Mars-sized planet that slammed into the young Earth.

A young sub-Neptune is a pressure cooker where hydrogen and rock simmer in the same pot. Six Earth masses, three percent hydrogen by mass, and interior temperatures above 4000 K. At that heat, silicate melt and hydrogen don't just coexist: they mix completely, forming a single supercritical fluid. There is no boundary between core and envelope.

In 2023, the James Webb Space Telescope turned its gaze toward a distant star in the constellation Virgo. Orbiting it is HAT-P-26 b, a warm Neptune, a world with a mass of 18.6 Earths and a radius of 6.33 Earths. The planet transited across the star's disk, and at that moment its atmosphere became briefly visible.

The super-hot super-Earth TOI-561 b completes an orbit around its star in just 10.7 hours. It is a scorched rocky sphere, so close to its star that its dayside should heat up to 2950 K, a temperature at which many minerals melt.

Brown dwarfs are objects that sit between planets and stars: they are more massive than planets but not heavy enough to sustain stable fusion in their cores.

Astronomers couldn't understand why the 'hot Neptune desert' — a region right next to stars — has almost no Neptune-sized planets. It was thought that there they are doomed: the star's proximity boils off the atmosphere, leaving a bare rocky core. But the exoplanet LTT-9779 b, 29 times heavier than Earth and with a 19-hour orbit, survived.

Using the most powerful space telescope, James Webb, astronomers peeked into the cosmic dressing room and saw how the rings of asteroid Chariklo are changing.

Many planets around other stars — exoplanets — have elongated orbits. With each close approach, the star’s gravity squeezes and stretches them, like kneading dough. Friction heats up the interior to the point where rock melts, creating underground oceans of magma.

Planet WASP-121b orbits so near its star that the fierce heat boils its atmosphere away, streaming like a comet's tails. With the James Webb Space Telescope, astronomers continuously watched this process for the first time.

The TESS telescope, usually hunting for planets around other stars, spotted 24 dimmings around RZ Psc. These were comets — chunks ranging from 1 to 7 km in size, transiting the star's disk. Like a distant searchlight momentarily blocked by a tiny pebble: the deeper the shadow, the larger the object.

The Moon can have its own tiny moon — like a nesting doll, but in space. The outer doll is a planet, the middle one is a moon, the inner one is a small moon-satellite, or submoon. Ньютон showed that all bodies attract each other, and gravity holds them together.

Only by passing in front of a star did Chiron reveal its secret. Three icy hoops encircle the 200-kilometer body — a hybrid of comet and asteroid. Previously, they were only hinted at by spectra of reflected light and brightness fluctuations.

Stretched for millions of kilometers, the tail of Comet 3I/ATLAS consists of rarefied gas and microscopic dust grains. In late October 2025, two Earth probes, Europa Clipper and Hera, will plunge into it. Neither was designed to encounter a comet: Clipper is headed for a moon of Jupiter, Hera for an asteroid.

The camera lens is no bigger than a quarter. You'd find it in a smartphone, but here it was mounted on the Hayabusa2 probe for asteroid landings.

Back in the 18th century, William Herschel was searching for life on Mars. Today, astronomers are targeting not planets but artifacts — for example, alien probes lurking in the Solar System. The problem is that spotting a tiny object next to the blinding Sun is nearly impossible.

In the vast darkness of interstellar space, the rogue planet WISE 0855 flickers with a barely perceptible heat glow, like a cooling ember. Its temperature is only a few dozen degrees above freezing — if life existed there, it would see a sunless sky, in an eternal icy haze.

The chemical composition of a sample is like a soundscape. A living forest sounds polyphonic: chirping, rustles, the hum of insects. A barren desert is just the whistle of the wind.

After the Moon's birth, Earth resembled a sizzling lump of dough: a continuous liquid magma and a dense shroud of gases. The Moon acted like a giant spoon, constantly kneading this lump with its gravity. Friction generated heat, delaying cooling.

The most common type of planet in our Galaxy — rocky worlds around other stars, or exoplanets, shrouded in the simplest gas hydrogen. Their innards remained a mystery until scientists recreated the conditions of the interior in the lab.

The planet's gravity rhythmically squeezes and kneads the moon like dough: from this constant 'kneading', the interior heats up, and oceans of water can persist under the icy crust for ages. In the Galaxy, there are plenty of rogue planets, thrown out by supernova explosions.

The Moon is not just a rocky sphere, but a giant bell. Passing through it, gravitational waves cause it to vibrate almost imperceptibly. This tremor was predicted by Einstein, and Weber was the first to try to hear it with Earth-based detectors.

Sub-Neptunes — worlds slightly smaller than Neptune — are common among exoplanets. They are detected using the transit method (by the dimming of a star), pioneered by William Borucki.

Life began with molecules akin to natural sunscreen — based on carbon, they soaked up the mild ultraviolet of the young Sun and turned it into heat. This way of dissipating energy wasn’t just heating: it made molecules self-organize, like chefs kneading structured dough out of a chaos of ingredients. But ultraviolet is a finicky tool.

A bus schedule drifts: if you don't check it, you'll miss your ride. Planets around other stars have the same problem – their crossings of the star's disk gradually shift. The ExoClock project pooled 30,000 observations from Earth and space to refine the schedule for 620 distant worlds. For 45% of the planets, transits were found to be off by hours.

The hunt for exomoons — the search for satellites around planets of other stars — resembles watching shadows in a theater where the spotlight keeps fading and flaring. The planet Kepler-167e, a gas giant near a scorching star, was discovered by William Borucki and his team.