The appearance of a mysterious white object in the sky over northern Japan on Wednesday set social media ablaze, with speculation ranging from UFOs to coronavirus and North Korean propaganda.
Television footage taken in the northeastern city of Sendai showed a balloon-like object above a cross, on which propellers seemed to be turning. Officials in the Sendai Weather Bureau said it had appeared near dawn and hung in the sky for hours, largely unmoving, until obscured by clouds.
By afternoon it was the third-most trending topic on Japanese Twitter, with theories including UFOs and North Korean balloons used to drop leaflets. One user said it could be spreading novel coronavirus, adding, "This gives me a very bad feeling, as if Godzilla might suddenly appear."
"PopcornParty010" created a tongue-in-cheek mockup of a London Times front page with the banner headline "Sendai Annihilated: A Nightmare come True."
Police could not be immediately reached for comment and a Sendai government official said inquiries were still proceeding, with both the size of the object and its origin, as well as its function, undetermined. No move had been made to retrieve it as of late afternoon.
"We have absolutely no idea what it is," said a weather bureau spokesman, declining to give his name. "It may be some kind of weather monitoring equipment, but it definitely isn't ours."
Pictures of the week: June 14 - 20
Pictures of the week: June 14 - 20
A woman wearing a facemask walks past a large rainbow in Covent Garden, London, after the UK's chief medical officers agreed to downgrade the coronavirus alert level from four to three after a "steady" and continuing decrease in cases in all four nations.
The Red Arrows and the Patrouille de France flypast over Nelson's Column in London to mark the visit of President of the Republic of France Emmanuel Macron. (Photo by Dave Rushen / SOPA Images/Sipa USA)
Bianca Walkden during the training session at the National Taekwondo Centre, Manchester. (Photo by David Davies/PA Images via Getty Images)
Larry, the No 10 Downing Street cat and Chief Mouser to the Cabinet Office out and about in Downing Street. (Photo by Brett Cove / SOPA Images/Sipa USA)
French President Emmanuel Macron meets Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall during a ceremony at Carlton Gardens. The French president is visiting London on June 18, 2020 to commemorate the 80th anniversary of Charles de Gaulle's BBC broadcast to occupied France following the Nazi invasion in 1940 "Appel" .
Police restrain a demonstrator who ran after Emmanuel Macron’s car convoy as a protest against French interference in Cameroon domestic affairs. The French president was attending an official event with British Prime Minister Boris Johnson during his visit to the UK to mark the 80th anniversary of French Resistance leader Charles de Gaulle’s wartime broadcast. Picture date: Thursday June 18, 2020.
A bear plays in a pool as four European brown bears and five grey wolves which are living together in British woodland for the first time in Bear Wood, a new enclosure at Bristol Zoo's Wild Place project. (Photo by Ben Birchall/PA Images via Getty Images)
Steven Butterly from Azurablu Scotland Ltd during an electrostatic disinfection clean which follows a deep clean at Ross Sales and Lettings in Glasgow. (Photo by Andrew Milligan/PA Images via Getty Images)
BIRMINGHAM, ENGLAND - JUNE 17: Black Lives Matter writing is seen on the back of Ollie Norwood and Billy Sharp of Sheffield United shirts during the Premier League match between Aston Villa and Sheffield United at Villa Park on June 17, 2020 in Birmingham, England. (Photo by Shaun Botterill/Getty Images)
LONDON, ENGLAND - JUNE 17: Workers uncover the statue of Winston Churchill in Parliament Square on June 17, 2020 in London, United Kingdom. The statue was covered up to protect it from vandalism over the weekend, after it was targeted by Black Lives Matter protesters. It is being uncovered ahead of French President Emmanuel Macronâs visit the UK to commemorate the 80th anniversary of Charles de Gaulleâs speech urging the French population to resist German occupation during World War II. (Photo by Ilyas Tayfun Salci/Anadolu Agency via Getty Images)
A protestor holds a placard depicting Dominic Cummings, Special Political Advisor for the Prime Minister Boris Johnson, as pro-EU supporters demonstrate outside Houses of Parliament against no-deal Brexit and call for an extension of the transition period on 17 June, 2020 in London, England. The EU and the UK are negotiating the post-Brexit relationship as Britain's transition period ends in December. (Photo by WIktor Szymanowicz/NurPhoto via Getty Images)
MANCHESTER, ENGLAND - JUNE 17: The Arsenal and Manchester City players minutes silence before the Premier League match between Manchester City and Arsenal FC at Etihad Stadium on June 17, 2020 in Manchester, England. (Photo by David Price/Arsenal FC via Getty Images)
A man walks past a mural of Malcom X and Martin Luther King paying tribute to George Floyd, a Black man who died in police custody in the U.S. Artists have been painting murals and sharing messages in London. (Photo by Thabo Jaiyesimi / SOPA Images/Sipa USA)
ASCOT, ENGLAND - JUNE 17: Frankie Dettori in The Queens silks prior to the Hampton Court Stakes during Day 2 of Royal Ascot at Ascot Racecourse on June 17, 2020 in Ascot, England. (Photo by Edward Whitaker/Pool via Getty Images)
Florist Trish Collins-Morgan works behind a plastic screen as she re-opens her shop, with various safety policies in place, in West Kirby north west England on June 17, 2020, as lockdown restrictions are eased during the novel coronavirus COVID-19 pandemic. - Various stores and outdoor attractions in England opened Monday for the first time in nearly three months, as the government continues to ease its coronavirus lockdown. (Photo by Paul ELLIS / AFP) (Photo by PAUL ELLIS/AFP via Getty Images)
Members of Kurdish Community Scotland during a demonstration in Edinburgh protesting against Turkish air raids in Iraq. (Photo by Jane Barlow/PA Images via Getty Images)
A pro-Kurdish protester who ran into the road toward the car of Britain's Prime Minister Boris Johnson as it was leaving the Houses of Parliament in London on June 17, 2020 is led away by police officers. - The protester ran into the road towards the Jaguar that normally carries the Prime Minister Boris Johnson and was stopped by police. As the Jaguar stopped it was subsequently struck from behind by the next vehicle in the convoy resulting in a large dent. (Photo by DANIEL LEAL-OLIVAS / AFP) (Photo by DANIEL LEAL-OLIVAS/AFP via Getty Images)
MILTON KEYNES, UNITED KINGDOM - 2020/06/15: A couple walk past the Victoria's Secret store.
Non essential shops were reopened today in both the 'Intu Shopping Centre' and the 'centre:mk' in Milton Keynes, for the first time since the coronavirus (Covid-19) pandemic lockdown. Social distancing measures were in place for all stores, including a one way system for shoppers and plenty of queuing around both shopping centres. (Photo by Keith Mayhew/SOPA Images/LightRocket via Getty Images)
LONDON, UNITED KINGDOM - 2020/06/15: A woman in a facemask walks over Waterloo Bridge.
Secretary of State for Transport Grant Shapps, announced that all passengers must wear face masks on public transport starting from 15 June and warned that wearing of a face mask would be a condition for travel and failure to comply will result either in not being allowed to travel or a fine. (Photo by Dave Rushen/SOPA Images/LightRocket via Getty Images)
Rubbish left by a bus stop at the end of lockdown on 15th June in Southampton Row, London, United Kingdom. (photo by Barry Lewis/InPictures via Getty Images)
An employee at Top Gift Mobile stall wears a face shield and mask as preventive measure while working. (Photo by Dawn Fletcher-Park / SOPA Images/Sipa USA)
A customer carrying bags of shopping leaves Primark in Birmingham as non-essential shops in England open their doors to customers for the first time since coronavirus lockdown restrictions were imposed in March. (Photo by Jacob King/PA Images via Getty Images)
(Permission granted) A school pupil wearing a face mask on a bus in Newcastle as face coverings become mandatory on public transport in England with the easing of further lockdown restrictions during the coronavirus pandemic. (Photo by Owen Humphreys/PA Images via Getty Images)
Loyalist Defence League members gather in George Square in Glasgow, Sunday June 14, 2020, during a protest between people calling for the removal of a statue Robert Peel and counter protesters. (Jane Barlow/PA via AP)
LONDON, ENGLAND - JUNE 14: A view of the closed Music Venue, Electric Ballroom, on June 14, 2020 in London, UK .As the British government further relaxes Covid-19 lockdown measures in England, this week sees preparations being made to open non-essential stores and Transport for London handing out face masks to commuters. International travelers arriving in the UK will face a 14-day quarantine period. (Photo by Jo Hale/Getty Images)
Passengers wearing face masks at Waterloo station in London as face coverings become mandatory on public transport in England with the easing of further lockdown restrictions during the coronavirus pandemic. (Photo by Victoria Jones/PA Images via Getty Images)
A man walks past a Be kind. Let's look out for one another poster in London. (Photo by Dinendra Haria / SOPA Images/Sipa USA)
Barriers seen packed outside a property in north London. (Photo by Dinendra Haria / SOPA Images/Sipa USA)
Police officers wearing face masks at Leeds railway station as face coverings become mandatory on public transport in England with the easing of further lockdown restrictions during the coronavirus pandemic. (Photo by Danny Lawson/PA Images via Getty Images)
LONDON, ENGLAND - JUNE 14: Social Distancing Signs on the Cobbles of Camden Market on June 14, 2020 in London, UK .As the British government further relaxes Covid-19 lockdown measures in England, this week sees preparations being made to open non-essential stores and Transport for London handing out face masks to commuters. International travelers arriving in the UK will face a 14-day quarantine period. (Photo by Jo Hale/Getty Images)