Space

Lost probes, distances that stop meaning anything on a human scale, celestial objects with no equivalent: astronomy in the details.

139 anecdotes, most recent first.
Highlights

The hottest planet in the Solar System is not the closest

Venus is a planet whose atmosphere is composed of 96.5% carbon dioxide. This thick layer causes a record greenhouse effect that generates surface temperatures of approximately 462 °C. It thus surpasses Mercury which nevertheless benefits from a solar irradiance four times higher according to the inverse-square law.

2026-05-21

A moon hides another on Uranus

Oberon is a satellite of Uranus that can occult its neighbors during the planet's equinoxes. This phenomenon occurs every forty-two years, when the equatorial plane of Uranus aligns with that of the Earth. Such an eclipse took place on May 4, 2007, during which the occultation of Umbriel by Oberon lasted six minutes.

2026-07-31

The first French woman to perform a spacewalk in an American spacesuit

Sophie Adenot is the first French person and the second European woman to perform an extravehicular activity in space. She carries out this operation on August 18, 2026, with NASA astronaut Anil Menon to replace a communication antenna. She thus distinguishes herself from Samantha Cristoforetti, who had used a Russian Orlan spacesuit in July 2022.

2025-12-07

An extraterrestrial civilization can live inside a black hole

A type III civilization could theoretically reside inside a supermassive black hole by following a stable periodic orbit. This hypothesis formulated by V. I. Dokuchaev would allow such a society to completely escape any external detection. Such cosmic habitat structures defy our current understanding of physics and interstellar travel.

2026-10-16

The unexpected origin of helium white dwarfs

A helium white dwarf is a miniature star resulting from a formation process too long for the current age of the Universe. Small main-sequence stars indeed take more than thirteen billion years to consume their hydrogen to produce this type of star. These white dwarfs actually result from a mass transfer within a binary system, a hypothesis confirmed in 2021 thanks to observations from the Lick Observatory.

2026-10-16

Moving a star with a giant device

Viorel Badescu and Richard B. Cathcart studied the use of a 450 million kilometer device by a type II civilization. This system allows for the orientation of solar radiation to give the star kinetic motion. The star can thus be deflected from its trajectory by approximately 35 to 40 parsecs in order to navigate the Galaxy.

2026-10-15

White dwarfs last for billions of years longer

The white dwarf is a dense star that undergoes crystallization at its center as it cools. This phenomenon releases heat and gravitational energy which slow down the cooling of the star. Observations based on Gaia data have thus revealed that these celestial objects could be up to two billion years older than expected.

2026-10-15

Patrick Blackett's exact prediction on white dwarfs

Patrick Blackett predicted in 1947 that white dwarfs possessed a surface magnetic field reaching one million gauss. This hypothesis relied on physical laws stating that a rotating body generates a magnetic field proportional to its angular momentum. The first magnetic white dwarf, named GJ 742, was finally observed in 1979 with an even higher surface field.

2026-10-14

An unexplained temperature gap exists for white dwarfs

The DB gap is an enigmatic temperature range observed in certain stars at the end of their life. Between 30 000 K and 45 000 K, no white dwarf presents an atmosphere dominated by helium. This phenomenon remains unexplained, although it is attributed to evolutionary processes such as convective mixing and gravitational settling.

2026-10-12

The green iguana sees ultraviolet light with its eyes

The green iguana is an arboreal reptile equipped with specific ocular cells called double cones. This specificity provides it with excellent color perception and helps it distinguish the ultraviolet range. This visual ability allows it to expose itself effectively to sunlight in order to absorb the UVA and UVB rays essential for synthesizing its vitamin D.

2026-10-11

Ganymede formed ten times faster than Callisto

Ganymede is the largest natural satellite of Jupiter and formed by accretion in about 10 000 years. This speed is explained by its proximity to Jupiter, in a sub-nebula denser than that of Callisto. This rapid formation allowed it to retain the heat necessary to separate rock and ice, unlike Callisto.

2026-10-11

Ganymede's hidden ocean exceeds Earth's

Ganymede possesses a vast salty underground ocean whose quantity of water exceeds that of all of Earth's oceans combined. This immense liquid expanse is nestled at extreme depths reaching approximately 800 km down to the rocky floor. The NASA Galileo probe in the 1990s and then the Hubble Space Telescope in March 2015 successively confirmed the presence of this water by studying its influence on the magnetic field and the auroras.

2026-10-11

Ganymede is larger than Titan

Ganymede is a moon of Jupiter whose size was specified by the Voyager 1 and Voyager 2 probes during their passage in 1979. They thus revealed that this moon exceeds the dimensions of Titan. Titan is a moon of Saturn that scientists previously believed to be bigger than Ganymede.

2026-10-11

The solar barques of Khufu were found in pieces

The funerary complex of Khufu houses two solar barques of the pharaoh. These were discovered in pieces at the bottom of a pit located near the pyramid. One of them has since been entirely reassembled and is kept in a dedicated museum.

2026-10-11

Kepler-22b is possibly an ocean planet

Kepler-22b is an exoplanet whose situation is comparable to that of Kamino. The American space agency indicates that it has chances of being covered by an ocean, if however it is not a gas giant. The presence of liquid water on this celestial body has not yet been confirmed by observations.

2026-10-11

A star opens the Chicago World's Fair

On May 27, 1933, the astronomical observatory annex of the University of Illinois captured the rays of the star Alpha Bootis. This light signal was then transmitted remotely to officially inaugurate the 1933 Chicago World's Fair, also called A Century of Progress. This technological feat preceded a period of severe budget cuts for the structure due to the Great Depression.

2026-10-11

A moon of Jupiter was discovered with the naked eye in antiquity

Gan De is an astronomer who observed a moon of Jupiter, probably Ganymede, as early as 362 BC. This discovery was made with the naked eye thanks to exceptional observation conditions during the maximum elongation of the celestial bodies. This feat precedes Galileo's observations with his astronomical telescope by nearly two millennia.

2026-10-10

Cosmic rays were used to probe the Pyramid of Khafre

Between 1967 and 1968, the physicist Luis Walter Alvarez searched for secret rooms in the Pyramid of Khafre using a completely novel method. This mission called Giza Project 1968 consisted of measuring the energy of cosmic ray particles called muons to map the interior of the monument. The experiment was a failure, because the Nobel Prize winner was unaware at the time that the pyramid contained granite denser than the limestone.

2026-10-10

Ganymede is larger than Mercury

Ganymede is the largest natural satellite in the Solar System, displaying a diameter eight percent larger than that of the planet Mercury. This moon of Jupiter possesses a liquid iron-rich core and a vast ocean beneath its icy surface. This immense underground volume of water could contain more water than all of Earth's oceans combined.

2026-10-09

The expansion rate of the Universe remains an unresolved mystery

The Hubble tension is a persistent disagreement between different methods of calculating the expansion of the Universe. Direct measurements of the distance of galaxies and the observation of the cosmic microwave background provide irreconcilable results. Observations conducted by the James Webb Space Telescope have validated these discrepancies, suggesting that an unknown component or exotic particles are missing from the standard model of cosmology.

2026-10-09

Tatooine hosts too many events for a desert planet

Tatooine is a desert planet in the Star Wars universe that hosts a surprising number of crucial events in the saga. According to critic Ian Goodwillie, the probability is infinitesimal for such an isolated world to concentrate so many destinies and inhabitants. It is indeed there that Anakin Skywalker is born, that Maul dies, that Jabba the Hutt resides and that Luke Skywalker then Boba Fett stay for a long time.

2026-10-08

A moon that rises in the west

Phobos is the largest of the two moons of Mars and is distinguished by a very particular orbital speed. It orbits the planet in only 7 h 39 min, while a Martian day lasts 24 h 37 min. This speed, which is higher than that of the rotation of Mars, causes a curious phenomenon where Phobos rises in the west and sets in the east.

2026-10-07

An exoplanet at 3,200 °C has a titanium oxide stratosphere

The exoplanet WASP-33 possesses a stratosphere generated by titanium oxide which absorbs visible ultraviolet radiation. This oxide can only exist in gaseous form in an extremely hot atmosphere. With a temperature of 3,200 °C, WASP-33 represents approximately four and a half times the mass of Jupiter.

2026-10-06

Tau Ceti and its misleading classification

Tau Ceti is a star visible to the naked eye located 11.9 light-years from the Sun. Johann Bayer listed it at the beginning of the 17th century in his Uranometria according to a Greek designation supposed to follow the decreasing order of brightness. However, this nomenclature proved to be inaccurate since the star actually has an apparent magnitude of 3.50 in the visible range.

2026-10-05

Whaling had no quota limits before 1970

The sei whale is a cetacean whose international protection was insignificant until the second half of the twentieth century. Before 1970, the number of catches of this marine mammal depended only on the whalers' ability to locate the pods. The International Whaling Commission finally put an end to these excesses by imposing quotas by species, then a moratorium in 1986.

2026-10-04

The sei whale sings as loudly as a jackhammer

The sei whale is a cetacean capable of emitting whistles whose acoustic power reaches 152 to 160 decibels. This sound intensity is explained by the physical characteristics of these vocalizations measured at a reference distance of one meter. A man placed at this distance would perceive a volume equivalent to that produced by a jackhammer located two meters away from him.

2026-10-04

A bell triggered by starlight

Joel Stebbins revolutionized astronomy by measuring the brightness of stars using a selenium cell. The idea came to him when he saw a teacher use this component to ring a bell during the university physics department's open house. With his colleague F.C. Brown, he installed this technology on the observatory's 300 mm telescope to obtain a light curve of the Moon in the autumn of 1907.

2026-10-04