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From today's featured article

Illustration of redshift and blueshift

In physics, a redshift is an increase in the wavelength, or equivalently, a decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift. The terms derive from the colours red and blue, which form the extremes of the visible-light spectrum. Three forms of redshift occur in astronomy and cosmology: Doppler redshifts due to the relative motions of radiation sources, gravitational redshift as radiation escapes from gravitational potentials, and cosmological redshifts caused by the universe expanding. Automated astronomical redshift surveys are an important tool for learning about the large scale structure of the universe. Examples of strong redshifting are a gamma ray perceived as an X-ray, or initially visible light perceived as radio waves. The initial heat from the Big Bang has redshifted far down to become the cosmic microwave background. (Full article...)

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Did you know ...

Gibraltar Mountain

... that Gibraltar Mountain (pictured) is one of a few documented U.S. sites where Okanogan fameflower is native?
... that Mohamed Saïl refused prisoner support from International Red Aid in protest against the treatment of Soviet prisoners in the Solovki prison camp?
... that the 1939 NIT and the 1939 NCAA tournament determined two different national champions in men's college basketball?
... that Jeannette Ng accepted the 2019 John W. Campbell Award for Best New Writer with a speech in which she called the award's namesake, John W. Campbell, a "fucking fascist"?
... that Euclid's Elements has been estimated to be second only to the Bible in its number of published editions?
... that Linda Anne Hutchison performed as a leading soprano of the D'Oyly Carte Opera Company, including during its first visit to continental Europe since the 1880s?
... that the modern cinnamon fern has existed since the Cretaceous?
... that John Greenewald Jr. founded a U.S. government transparency website when he was a teenager?

In the news

Sanae Takaichi

Sanae Takaichi (pictured) is elected as the first female prime minister of Japan by the National Diet.
Eric Lu wins the International Chopin Piano Competition.
Pieces of the French Crown Jewels are stolen during a robbery from the Galerie d'Apollon of the Louvre in Paris.
Michael Randrianirina becomes President of Madagascar after Andry Rajoelina flees the country following mass protests and a military coup.

On this day

October 23: Mole Day

Jeannette Piccard

1641 – Irish Catholic gentry in Ulster tried to seize control of Dublin Castle, the seat of English rule in Ireland, to force concessions to Catholics.
1934 – Jeannette Piccard (pictured) piloted a hot-air balloon flight that reached 57,579 feet (17,550 m), becoming the first woman to fly in the stratosphere.
1957 – A screening of Mother India, one of the most influential Indian films in history, was held for President Rajendra Prasad and Prime Minister Jawaharlal Nehru two days before its release.
1995 – The runway show for Alexander McQueen's collection The Hunger was staged at London's Natural History Museum.
2018 – An escalator accident in Rome left 24 people injured, mostly fans of the CSKA Moscow football team who were in town for a UEFA Champions League match against Roma.

John Heisman (b. 1869)
Douglas Jardine (b. 1900)
Toshio Hosokawa (b. 1955)
Soong Mei-ling (d. 2003)

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Today's featured picture

Pachygrapsus marmoratus, also known as the marbled crab, is a species in the family Grapsidae, the marsh crabs. The species is found in southern Europe and northern Africa, in the waters of the Black Sea, the Mediterranean Sea, and parts of the Atlantic Ocean. It is a dark violet-brown crab, with yellow marbling, and with a body up to 36 millimetres (1.4 inches) long. A semiaquatic omnivore, it feeds on algae and various animals including mussels and limpets. This P. marmoratus crab was photographed near the shore of Butrint Lagoon in Butrint National Park, southern Albania, near the coast of the Ionian Sea. The picture has been focus-stacked from 12 separate images.

Photograph credit: Charles J. Sharp

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