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Definition of planet
The definition of "planet" has for some time been the subject of intense debate. Although the word dates back thousands of years, no officially decreed scientific definition of "planet" existed before the early 21st century. Until the beginning of the 1990s, there was little need for one, as astronomers had only a single sample of planets in solar system to study, and one small enough for its many irregularities to be dealt with individually.
However, after 1992 and the discovery of the myriad tiny worlds beyond the orbit of Neptune, the size of the sample rose from nine to at least several dozen. Following the discovery of the first extrasolar planet beyond our solar system in 1992, the number of samples has now reached hundreds. These revelations not only increased the number of potential planets, but, in their variety and peculiarity (some nearly large enough to be stars, others smaller than our Moon) challenged long perceived notions of what a planet could be.
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Space & Time News
February 11, 2026
Feb. 2, 2026 NASA’s Perseverance rover has just made history by driving across Mars using routes planned by artificial intelligence instead of human operators. A vision-capable AI analyzed the same images and terrain data normally used by rover planners, ...
Feb. 2, 2026 Hidden lava tunnels on the Moon and Mars could one day shelter human explorers, offering natural protection from radiation and space debris. A European research team has unveiled a bold new mission concept that uses three different robots working ...
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Jan. 18, 2026 When scientists sent bacteria-infecting viruses to the International Space Station, the microbes did not behave the same way they do on Earth. In microgravity, infections still occurred, but both viruses and bacteria evolved differently over time. ...
Jan. 8, 2026 A team of physicists has discovered a surprisingly simple way to build nuclear clocks using tiny amounts of rare thorium. By electroplating thorium onto steel, they achieved the same results as years of work with delicate crystals — but far more ...
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Jan. 6, 2026 A distant pulsar’s radio signal flickers as it passes through space, much like stars twinkle in Earth’s atmosphere. By monitoring this effect for 10 months, researchers watched the pattern slowly evolve as gas, Earth, and the pulsar all moved. ...
Jan. 6, 2026 Mars looks familiar from afar, but surviving there means creating a protective oasis in a hostile world. Instead of shipping construction materials from Earth, researchers are exploring how to use Martian soil as the raw ingredient. Two tough ...
Jan. 2, 2026 A physicist has proposed a bold experiment that could allow gravitational waves to be manipulated using laser light. By transferring minute amounts of energy between light and gravity, the ...
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Feb. 11, 2026 For millions of years, a frozen wanderer drifted between the stars before slipping into our solar system as 3I/ATLAS—only the third known interstellar comet ever spotted. When scientists turned ...
Feb. 11, 2026 A distant star system with four super-sized gas giants has revealed a surprise. Thanks to JWST’s powerful vision, astronomers detected sulfur in their atmospheres — a chemical clue that they ...
Feb. 9, 2026 Time may feel smooth and continuous, but at the quantum level it behaves very differently. Physicists have now found a way to measure how long ultrafast quantum events actually last, without relying ...
Feb. 9, 2026 Baker’s yeast isn’t just useful in the kitchen — it may also be built for space. Researchers found that yeast cells can survive intense shock waves and toxic chemicals similar to those on Mars. ...
Feb. 8, 2026 A colossal ancient impact may have reshaped the Moon far more deeply than scientists once realized. By analyzing rare lunar rocks brought back by ...
Feb. 7, 2026 Voyager 2’s flyby of Uranus in 1986 recorded radiation levels so extreme they baffled scientists for nearly 40 years. New research suggests the spacecraft caught Uranus during a rare solar wind ...
Feb. 7, 2026 Astronomers propose that an ultra-dense clump of exotic dark matter could be masquerading as the powerful object thought to anchor our galaxy, explaining both the blistering speeds of stars near the ...
Feb. 6, 2026 Scientists have found that ancient Martian lakes could have survived for decades despite freezing air temperatures. Using a newly adapted climate model, researchers showed that thin, seasonal ice ...
Feb. 3, 2026 Astronomers have produced the most detailed map yet of dark matter, revealing the invisible framework that shaped the Universe long before stars and galaxies formed. Using powerful new observations ...
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