Welcome to Wikipedia

,

the free encyclopedia that anyone can edit.

From today's featured article

Satellite image of the caldera, the gray-yellow area at lower centre left

The Cerro Blanco is a caldera in the Andes, located in Argentina's Catamarca Province. Part of the Andes' Central Volcanic Zone, it is a volcano collapse structure located at an altitude of 4,670 metres (15,320 ft) in a depression. It has been active for the last eight million years and its eruptions have created several ignimbrites. An eruption 73,000 years ago formed the Campo de la Piedra Pómez ignimbrite layer, while another eruption in 2,300 ± 160 BCE became the largest volcanic eruption of the Central Andes, and reached the highest level in the Volcanic Explosivity Index, ejecting an estimated 170 cubic kilometres (41 cu mi) of tephra. This eruption led to the formation of the most recent caldera, as well as thick ignimbrite layers. However, the Cerro Blanco has been dormant since then, although some deformation and geothermal activity have been recorded. The volcano is also known for giant ripple marks that have formed on its ignimbrite fields. (Full article...)

Recently featured:

Did you know ...

Forest Park Carousel

... that after the Forest Park Carousel (pictured) was acquired for $30,000 in 1972, one of its later operators likened the deal to "buying a Rembrandt for $25"?
... that Elisabeth Waterhouse founded the National Chamber Music Course summer school in 1974 and has managed it since?
... that Soviet cruiser Vasily Chapayev was ordered to sail on 24 December 1976, but its crew refused to comply, causing the removal of its senior officers?
... that Dawid Celt was Agnieszka Radwańska's hitting partner before he became her domestic partner?
... that the actor who played Screech on Saved by the Bell portrayed Harvey Weinstein in a music video for the song "Kill All the Things"?
... that comedian Frankie Boyle's debut novel Meantime is about a Glaswegian drug addict investigating his friend's death?
... that Jiří Kylián had all the dancers in his ballet Bella Figura appear topless to equalise men and women?
... that Canadian artist Tom Forrestall spent six months painting his own car?

In the news

Chris Hipkins

Chris Hipkins (pictured) is chosen to succeed Jacinda Ardern as Prime Minister of New Zealand and Leader of the New Zealand Labour Party.
A helicopter crashes near Kyiv, killing fourteen people, including the Ukrainian Interior Minister Denys Monastyrsky.
In the Antiguan general election, the Labour Party retains its majority in the House of Representatives.
A plane crash in Pokhara, Nepal, kills all 72 people on board.
In the elections to the parliament of Benin, the Progressive Union for Renewal–Republican Bloc alliance retains a majority, but the opposition Democrats win back parliamentary representation.

On this day

January 21

Members of the First Dáil

763 – The Abbasid Caliphate crushed the Alid revolt when a rebel leader was mortally wounded in battle near Basra in present-day Iraq.
1789 – The Power of Sympathy by William Hill Brown, widely considered to be the first American novel, was published.
1919 – The First Dáil (members pictured) convened at the Mansion House in Dublin and adopted a declaration of independence calling for the establishment of the Irish Republic.
1972 – Tripura, formerly part of the independent Twipra Kingdom, became a state of India.
2017 – Millions of people participated in the worldwide Women's March, to advocate for legislation and policies on human rights and other issues.

Theodor Fliedner (b. 1800)
Edith Tolkien (b. 1889)
Vincent Lingiari (d. 1988)

More anniversaries:

Today's featured picture

Rega is a private, non-profit air rescue service that provides emergency medical assistance in Switzerland and Liechtenstein. It was established in 1952 by Dr Rudolf Bucher, who believed the Swiss rescue organization needed a specialized air sub-section. This image is a sequence photograph, stitched from 207 separate frames, of Rega's rescue helicopter Da Vinci in operation in Stoos, Switzerland.

Photograph credit: Roy Egloff

Recently featured:

Other areas of Wikipedia

Community portal – The central hub for editors, with resources, links, tasks, and announcements.
Village pump – Forum for discussions about Wikipedia itself, including policies and technical issues.
Site news – Sources of news about Wikipedia and the broader Wikimedia movement.
Teahouse – Ask basic questions about using or editing Wikipedia.
Help desk – Ask questions about using or editing Wikipedia.
Reference desk – Ask research questions about encyclopedic topics.
Content portals – A unique way to navigate the encyclopedia.

Wikipedia's sister projects

Wikipedia is written by volunteer editors and hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other volunteer projects: