instrument

kepler telescope

A space telescope that observed hundreds of thousands of stars to detect planets by their transits.
46 related articles

Description

The Kepler telescope was a space observatory launched by NASA in 2009 to discover exoplanets, particularly Earth-sized planets in the habitable zone of their stars. It monitored over 150,000 stars in a fixed field of view, looking for periodic dips in brightness caused by a planet transiting in front of its host star. Kepler's mission fundamentally changed our understanding of planetary systems, revealing that planets are common and that many are unlike anything in our solar system.

History

The Kepler mission was proposed in the 1980s by William Borucki and launched on March 7, 2009. It operated until 2018, having discovered over 2,600 confirmed exoplanets.

How it works

Kepler used the transit method: a sensitive photometer measured the brightness of thousands of stars every few minutes. A planet passing in front of its star blocks a tiny fraction of light, producing a periodic dimming. By analyzing the depth, duration, and timing of these dips, astronomers can infer the planet's size, orbital period, and sometimes even its atmosphere.

In practice

Kepler's data has been used to statistically estimate the frequency of Earth-like planets in the galaxy, guiding future missions like TESS and the James Webb Space Telescope in targeting promising systems.

Fun fact

Kepler's field of view covered only about 0.25% of the sky, yet it found thousands of planets, implying that there are likely billions of planets in our galaxy alone.

Concept graph →

Related articles · 46

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Stellar2026-08-141 minarXiv:2608.13895express
Planets from foreign galaxies hiding in the Milky Way
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.
A Symmetric Shadow in the Chaos of Tabby's Star
Tabby's Star, a beacon in the cosmic sea, has baffled astronomers since 2015. Its light flickered not in the rhythm of planets, but as if scattered by a storm — deep dips, sharp spikes. But amid this chaos, a smooth, nearly perfect dip was found. The eye of the storm.
How Polarizing Sunglasses Unveiled the Invisible Waves of Venus
Night on La Palma. The 4.2-meter William Herschel Telescope is aimed at Venus. At the focus is the experimental polarimeter ExPo, designed to catch the ghostly light of exoplanets.
Cosmology2026-07-133 minarXiv:2607.12144
Hearing the Silence: The Hunt for Scalar Dark Matter
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.
Exoplanets2026-07-112 minarXiv:2607.10175express
How to Weigh a Planet by Its Shadow
When a distant planet passes in front of its star, it briefly blocks part of the light. Astronomers call this a transit and judge the planet's size by the depth of the dip. But light has a property: a massive body acts like a lens. Even a giant planet can slightly bend the star's rays, and the dip becomes a bit shallower than you might expect.
Optics2026-07-082 minarXiv:2607.06931express
How to Spot a Pale Planet in a Star's Blinding Light
A spotlight blazes straight into your eyes, and a few steps away a tiny firefly flickers. That's roughly what it's like hunting for an Earth-like planet around a neighboring star: the planet is a hundred million to ten billion times fainter than its star, and in the sky they almost merge into a single point.
Stellar2026-07-082 minarXiv:2607.07781
Cosmic Brake: How to Catch Aliens by the Spin of Stars
For decades, SETI has hunted for Dyson spheres — hypothetical shells that capture a star's light stars and re-radiate it in the infrared. But the cosmos remains silent. Perhaps an alien intelligence operates more elegantly: instead of collecting light, it tames the rotation of a sun, like a giant flywheel.
Invisible Planet in Warped Light
The light of a distant star is no perfect beacon. Passing through the gravitational field of another star, it bends, splits, and magnifies, creating a fleeting Einstein ring in the sky. This is how gravitational microlensing manifests, predicted by Fritz Zwicky back in the 1930s.
Exoplanets2026-06-221 minarXiv:2606.23789express
James Webb Fishes Out an Invisible Planet from a Dusty Disk
Using James Webb, astronomers 'fished out' a third giant planet from the murky dust disk of the star β Pictoris. Two others were already known, but this one was hiding in the bright light, like a fish in muddy water.
Stellar Orthography: How ExoVeil Reads Missed Planets
A star's light curve is not chaotic noise, but a text written by pulsations, spots, and the steady glow of a thermonuclear furnace. Any planet slipping across the disk leaves a typo in this text: a tiny dip in brightness lasting hours.
Exoplanets2026-05-212 minarXiv:2605.22931express
Catching a Sunset on a Distant Planet
When a planet slips behind the edge of its star, the star backlights the planet's atmosphere, just as a setting sun illuminates clouds on the horizon. This brief moment, lasting only minutes, carries the imprint of the gases through which the starlight has passed.
High Energy2026-05-161 minarXiv:2605.17048express
Magnetars: How Magnetic Fields Fool Light
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High Energy2026-05-082 minarXiv:2605.07641express
A Cosmic Visitor with the Energy of a Cannonball
Deep in the Mediterranean Sea, where water presses down with the force of hundreds of atmospheres, a network of light-sensitive spheres waited for a rare guest. And it came — a neutrino that carried through the bulk of the Earth an energy comparable to the impact of a flying brick.
Instrumentation2026-05-061 minarXiv:2605.05408express
Cosmic Silence: 70,000 Stars Without a Signal
Searching for extraterrestrial signals is like trying to hear a whisper at a roaring stadium. The Green Bank Telescope listened to 70,000 stars, but 100 million bursts turned out to be earthly noise — from phones, satellites, microwave ovens.
Cosmology2026-04-301 minarXiv:2604.27867express
Galaxies at the Edge of the Universe Are Brighter Than We Thought
Edwin Hubble and Georges Lemaître discovered the expansion of the Universe nearly a century ago. One way to test it is the surface brightness test: in an expanding cosmos, the light of a distant galaxy should fade like a pattern on a stretching film.
Exoplanets2026-04-281 minarXiv:2604.25990express
Planet X Loses Its Footing
At the edge of the solar system, far beyond Neptune, hundreds of icy chunks circle the Sun. Some of them move as if an invisible hand had aligned their orbits like compass needles. Ten years ago, this led astronomers to suspect that a massive planet, about ten times heavier than Earth, is hiding there.
HEP Phenomenology2026-04-282 minarXiv:2604.26004express
A Window for Invisible Particles: Axions Are Back
In 1987, astronomers saw a supernova flare up in a neighboring galaxy — the Large Magellanic Cloud. It was a rare gift: the explosion was close enough to catch not just light but also neutrinos, those nearly undetectable particles that pass straight through Earth.
Galaxies2026-04-242 minarXiv:2604.22702express
More Than a Hundred Distant Stars in a Single Galaxy
Light from the distant Dragon Galaxy has been traveling toward us for more than seven billion years. On its way, it passes by a huge galaxy cluster whose gravity bends the path of light like a lens. As a result, the galaxy appears brighter and larger than it really is, just as a magnifying glass enlarges fine print.
Instrumentation2026-04-221 minarXiv:2604.20182express
A Swarm of Tiny Sails Heads to Proxima b
A handful of coins accelerates to one-fifth the speed of light. That's what Coracle interstellar probes will be like — tiny spacecraft weighing just a few grams, each with an ultrathin sail film. A powerful laser beam pushes them forward: light presses on the sail like wind fills a yacht's sails, except instead of air, it's a stream of photons.
Stellar2026-04-221 minarXiv:2604.20280express
Ghostly Nebulae in an Amateur Telescope
A glowing cloud in a telescope looks like a wisp of fog about to dissipate. Planetary nebulae are gas shells cast off by dying stars. Young nebulae are bright and compact, but as they age, they expand, cool, and become increasingly transparent until they vanish into the interstellar medium.
Exoplanets2026-04-201 minarXiv:2604.18579express
Quiet Stars, Loud Discoveries
The TESS telescope photographed the sky for a full year, but its standard pipeline skipped over dim stars. The T16 project took the same images and cleaned them from scratch — resulting in 83,717,159 light curves, like EKGs for every star. Planets passing in front of their star briefly dim it, and these dips in the EKGs are what we look for.
General Relativity2026-04-141 minarXiv:2604.12787express
Planet Nine Heats Up with Dark Matter
At the edge of the solar system, far beyond Neptune's orbit, something is knocking icy chunks off their paths. Their orbits are stretched and tilted in the same way, as if an invisible hand arranged them in a pattern.
Stellar2026-03-242 minarXiv:2603.22938express
The Mystery of Gamma Cassiopeiae: Half a Century to Solve the X-ray Phantom
For half a century, astronomers puzzled over the nature of the powerful X-ray emission from Gamma Cassiopeiae — a bright beacon in its constellation whose X-ray glow didn't fit models of single stars. An invisible companion was suspected, but direct evidence was lacking.
Atomic Physics2026-03-241 minarXiv:2603.22981express
All Atoms Fall Alike: A Cosmic Verdict
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Exoplanets2026-03-242 minarXiv:2603.23644express
How Orbits Reveal a Planet's Past
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.
Exoplanets2026-03-191 minarXiv:2603.19402express
A Quiet Star: How They Searched for a Planet and Found Nothing
The Gaia space telescope measures star positions with an accuracy of a microarcsecond, like spotting a coin on the Moon from Earth. In 2022, it noticed that the bright star HD 12800 was wobbling slightly, as if tugged by an invisible companion. Astronomers hypothesized that a planet orbits the star. But a wobble can be deceiving.
Stellar2026-02-232 minarXiv:2602.20311express
Stellar Flares Ignite Each Other
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Exoplanets2026-02-051 minarXiv:2602.05168express
Surprise Planet Around a Young Star
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Exoplanets2026-01-271 minarXiv:2601.19870express
One Transit, One Year
For ten hours, the star HD 137010 dimmed a little, like a lamp with a speck of dust on it. The K2 telescope caught this in 2017, and in all the observing time, it happened only once. Astronomers realized: a planet had passed in front of the star. This way of finding worlds is called the transit method. When a planet crosses the star's disk, the star briefly fades.
Exoplanets2026-01-122 minarXiv:2601.07465express
Space Telescope Searches for a Second Earth
The night sky is dotted with stars, and many of them have planets. But how do you spot a tiny dark disk against the glare of a distant sun? The Kepler telescope spent nine years watching hundreds of thousands of stars, waiting for a planet to pass in front of its star and briefly dim it. That 'wink' is the only way to find worlds like ours.
Cosmology2026-01-092 minarXiv:2601.06023express
Gravitational waves will reveal how dark matter is arranged
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Stellar2026-01-051 minarXiv:2601.02012express
Betelgeuse Is Not Alone: A Stellar Companion Found
In 2019, Betelgeuse suddenly dimmed, sparking rumors of an imminent explosion. But clouds of cosmic dust turned out to be the culprit. Now, the Gemini North telescope has discerned a minuscule companion star in its dazzling glare, just as calculations had predicted.
Exoplanets2026-01-011 minarXiv:2601.00325express
Rogue Planet Gave Itself Away with Warped Light
The lone planet KMT-2024-BLG-0816, one of many free-floating planets, was discovered when its gravity acted like a magnifying glass for a few hours. Passing in front of a distant star, the invisible body warped space like a glass marble, and boosted the background light.
Stellar2026-01-011 minarXiv:2601.00470express
Giant Star Betelgeuse Gains a Companion
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Exoplanets2025-12-311 minarXiv:2601.00057express
A Cosmic Wanderer Steps on the Scales for the First Time
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Stellar2025-12-031 minarXiv:2512.03611express
Solar Magnetic Poles: First Shots from Beyond the Equator
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General Relativity2025-12-022 minarXiv:2512.03118express
Planet-Mass Black Holes: Invisible Partners of Stars or the Key to Dark Matter?
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Instrumentation2025-11-291 minarXiv:2512.00492express
Mission: Catch a Guest from Another Star System
The Comet Interceptor mission launches without a target. The spacecraft freezes at a point of space equilibrium, like a fighter jet on combat standby: engine warmed up, but takeoff only on alert.