A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. Image taken by NASA's Hubble Space Telescope. Released September 24, 2015. (Photo by Reuters/NASA/ESA/Hubble Heritage Team)

A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Long Exposure pictures showing Mount Sinabung spewing out hot lava on August 2, 2017 in Karo, Indonesia. Sinabung located in North Sumatra Province roared back to life in 2010 for the first time in 400 years. After another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Albert Damanik/Barcroft Images)

A policeman controls traffic at 42nd Street and 7th Avenue as New York City remains without electricity caused by a blackout that affected the entire city and most of the eastern part of the nation August 15, 2003 in New York, New York. More than 50 million people were affected by the outage, in Toronto, Detroit, Cleveland and New York City. (Photo by Jose Jimenez/Primera Hora/Getty Images)

A colourful morning sunrise on Christmas Eve at Victoria Tower on Castle Hill, West Yorkshire, England on December 24, 2017. The history of human activity on the Castle Hill goes back over 4000 years. The site was developed as an iron age hill fort, surrounded by defensive ditches and ramparts. In the Middle Ages there was a castle on the hill, of which the well remains. The present tower was built to commemorate Queen Victoria's Diamond Jubilee of 1897. (Photo by Charlotte Graham/ZUMA Wire/Rex Features/Shutterstock)

An employee of cake shop prepares chocolate Easter bunnies with masks in Lykovrisi, northern Athens, on Wednesday, April 8, 2020. Cake shops and bakeries in Greece have remained open during a strict circulation ban in Greece to contain the spread of the COVID-19, but authorities have intensified a crackdown on lockdown violations ahead of Easter, which is celebrated by Orthodox Christians on April 19. Greece's Orthodox Church says it will not permit any public gatherings for Easter services. (Photo by Thanassis Stavrakis/AP Photo)

A pedestrian wearing a form of PPE (personal protective equipment) of a perspex full-face covering, as a precautionary measure against COVID-19, walks across Oxford Street in central London on June 11, 2020, as non-essential shops prepare to re-open on June 15. Britain's current guidelines on social distancing remain at two metres (2M), but business leaders and some politicians are on Thursday calling for it to be reduced to one (1M), or one-and-a-half (1.5M) metres. (Photo by Justin Tallis/AFP Photo)

Brenda, a Honduran girl who is seeking asylum in the U.S., is carried from the Rio Grande in distress, where she had been bathing across the river from a Brownsville, Texas U.S. Customs and Border Protection tent facility as immigration hearings were being held by video teleconference, in Matamoros, Mexico September 12, 2019. Most of the people living in an encampment near the Gateway International Bridge have been sent back under the “Remain in Mexico” program, officially named Migrant Protection Protocols (MPP). (Photo by Veronica G. Cardenas/Reuters)