planetary system

The family album of this stellar pair has been filling up for 45 years, but the pictures were blurry and the captions contradictory. Now astronomers have pulled out the old photographs, taken new sharp shots, and put everyone back in their proper places. Gamma Cephei is a bright star visible to the naked eye, and it has an invisible companion that orbits it every 70 years.

Astronomers catch distant planets by the trembling of their stars: an invisible companion tugs the star toward us and away, and its light subtly shifts in color. But that trembling tells only half the truth. If the planet's orbit is tilted to our line of sight, only part of its weight rocks the star, so telescopes reveal not the true mass but its shadow.

The night sky seems unchanging, but galaxies constantly exchange matter. The Milky Way, like a great river, absorbs smaller streams — dwarf galaxies. Along with their stars, planets may also come to us.

Two stars circle each other like dancers who come together and drift apart. Over time, one swells, and its outer layers spill onto its neighbor. The star that receives foreign matter looks no different from a single star, but its surface remembers everything.

In a single star system, two teams of planets orbit. Some follow neat paths, like figure skaters on an ice rink, avoiding collisions. Others crowd together, their trajectories cross, and sooner or later a cosmic accident occurs — a giant impact.

At the center of the Milky Way, shrouded in dust and glare, lurks a supermassive black hole — Sagittarius A*. Around it, like moths around a flame, swarm dozens of guide stars. Two of them, S2 and S38, with eccentric orbits and periods of just a few years, have become the protagonists in testing the fundamental laws of the cosmos.

The universe sounds with silence. The lion's share of matter — about 85%—remains invisible, manifesting only through gravity. Back when Vera Rubin Vera Rubin showed that galaxies spin as if wrapped in unseen mass.

Remember the sensational comet 1I/‘Oumuamua — the first object to come to us from another star? Its hyperbolic trajectory left no doubt: it was a wanderer from the interstellar void. But astronomers wondered: could some of these visitors not be strangers at all, but our own, escaped from the Solar System millions of years ago?

Every star is a living archive, and its spectrum a multilayered manuscript. Over billions of years, the history of the galaxy is written into it: the galactic chemical evolution of the Milky Way leaves a smooth trace in elemental abundances.

Previously, Uranus and Neptune were considered ice giants because of assumed thick layers of frozen water, methane, and ammonia. New calculations paint a different picture: deep inside them hides an ocean of hot magma, which under immense pressure has absorbed a colossal amount of hydrogen.

In the catalogs of exoplanets, there are many worlds with sizes between Earth and Neptune. They are divided into two groups: rocky super-Earths and gaseous mini-Neptunes. The Solar System has none of these, and scientists debate where they come from. The authors of the study looked into each planet's 'passport'—its orbit.

On the periphery of the Solar System lurk thousands of objects comparable in size to an exoplanet — a body of planetary mass not bound to our star. Their orbits are chaotic, and from time to time the trajectory of such a wanderer crosses Earth's path.

The cosmic accounting has hit a snag. The bookkeeper is balancing the books: in one column, all the planets astronomers have counted in the galaxy; in the other, the stockpile of building material in the dusty cocoons of newborn stars. The numbers don't line up. Even if you gathered every last grain of dust and molded it into planets, there wouldn't be enough material.

Two black holes smash head-on at full speed — while a third one circles nearby. In ordinary life, such a crash would produce a burst of gravitational waves (ripples in space, like the ripples from a stone thrown into a pond). But here, part of the ripple passes by the massive neighbor, and changes, like light in a funhouse mirror.

The first exoplanet was discovered around an unusual cosmic lighthouse — a neutron star known as a pulsar. These ultra-dense remnants of dead stars spin at tremendous speeds and emit precise radio pulses.

The Oort Cloud is a spherical swarm of trillions of icy bodies at the very edge of the Solar System, about a light-year from the Sun. These objects are almost motionless relative to one another until some gravitational disturbance breaks their calm.

A guitar string only sounds at certain notes, when pressed at the frets. So it is with the gas-dust disk around a young star: it's shot through with standing waves, but only chosen oscillations survive. Where the wave crests, cosmic dust and hydrogen collect, and later exoplanets are born.

At night, a distant streetlamp seems motionless, but if you walk closer and look carefully, you might notice it swaying slightly in the wind. That's roughly how astronomers hunt for planets around other stars: they measure how a star shifts ever so slightly under the gravitational tug of its invisible companions.

Around distant icy bodies the size of a city, circling beyond Neptune, rings of dust and ice have been found. Small moons often whirl nearby. Mathematical analysis shows that a moon's gravity rocks the ring like a swing, making it tilt.

Other galaxies are just ancient snapshots, but we watch the Milky Way live. Comparing data over 30 years, scientists found that the Galaxy’s center is, like, speeding up: the supermassive black hole got heavier, swallowing the mass of a large asteroid each year; the stellar bar (a huge beam of billions of suns, like the…

The Kepler telescope spent years watching thousands of stars, spotting planets by the tiny dips in starlight when a planet passes in front of its star. Such a passage, or transit, lets us measure the planet's size but not the shape of its path.

An icy rock is flying through the Solar System on an open trajectory — coming in from interstellar space, swinging around the Sun, and heading back into the dark.

A sugar cube sits on a saucer next to a cup of hot tea. Drop it in, and it dissolves within minutes. But if you lower it slowly, the sugar melts gradually, releasing its sweetness into the drink. Something similar is happening in two newly discovered stellar pairs, except the sugar is a brown dwarf and the tea is a star.

A thundercloud stores electricity like a battery before a flash. It can discharge in two ways: by lightning or by producing particles with a tiny charge: these are called millicharged particles. Such particles are nearly invisible to detectors, but their trace can be caught by how often lightning strikes. The authors compared thunderstorms on different planets in the Solar System.

In the star cluster NGC 2158, which is over a billion years old, astronomers have counted how often stars live in pairs. The Hubble telescope stared at the cluster for a long time to catch even the faintest stars: those lighter than one-third of the Sun.

Blue giant stars are usually born in tight stellar nurseries — open clusters within the thin disk of our Galaxy. But sometimes such stars are found high above the disk, as if thrown out of their home. How did they get there?

350 light-years away, four planets orbit the star V1298 Tau. They are 5–10 times larger than Earth but lighter than they appear. For nine years, astronomers tracked their motion to understand what they are made of and how they lived in the past. The planets are lined up in a chain: their orbital periods are nearly in 3:2, 2:1, and 3:1 ratios.

Space works like a billiard table. Massive outer planets, like heavy balls, transfer their energy to light inner worlds. Such a gravitational kick can fling a small planet out of the stellar system. It turns into a free-floating wanderer — a rogue exoplanet without a star. Detecting these invisible bodies is hard: they neither emit nor reflect light.

In a star cluster, like on a crowded dance floor, massive stars rarely stay single. More often they whirl in pairs or triples, and the distance between them can be less than from Earth to the Sun. But how do they manage to get so close to each other? Simulations showed: it's all about the disk of gas and dust that envelops the pair. This disk, like a drain funnel, swirls the stars and slowly pulls them inward.

Two stars, drawing together in a cosmic dance, experience an extra wobble — a consequence of spacetime curvature (an effect predicted by Einstein). A planet orbiting them also wobbles. Sometimes the rhythms align: the gravitational tugs from the stars fall in step with the planet’s orbit, like hands pushing a swing.

The Universe is filled with invisible mass, dark matter, which reveals itself only through gravity. One hypothesis suggests that dark matter consists of primordial black holes — objects formed in the extreme conditions just after the Big Bang.

In the dark cloud NGC 6334I-North, 5500 light-years from Earth, the ALMA radio interferometer spotted something unexpected: around a young massive star, a disk of gas and dust is swirling, and inside it are seven dense clumps. Each one could become a star. This is what the birth of a stellar family looks like, and an unusually large one at that.

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.