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)

Chinese soldiers leave after Chinese President Xi Jinping inspected troops of People's Liberation Army (PLA) Hong Kong Garrison at the Shek Kong Barracks in Hong Kong, Friday, June 30, 2017. Xi landed in Hong Kong Thursday to mark the 20th anniversary of Beijing taking control of the former British colony, accompanied by a formidable layer of security as authorities showed little patience for pro-democracy protests. (Photo by Kin Cheung/AP Photo)

Girls hold hands as they arrive their New Year parties in Newcastle, England on December 31, 2019. (Photo by Craig Connor/North News and Pictures)

Participants perform parade in the street during Grebeg Sudiro festival on January 19, 2020 in Solo City, Central Java, Indonesia. Grebeg Sudiro festival is held as a prelude to the Chinese New Year, which falls on January 25th this year, welcoming the Year of the Rat. People bring offerings known as gunungan, including Chinese sweetcakes piled up into the shape of mountains, which are paraded in the streets followed by Chinese and Javanese performers. (Photo by Ulet Ifansasti/Getty Images)

In this Sunday, February 23, 2020, photo, sumo wrestlers wearing masks arrive at Shin Osaka railway station in Osaka, western Japan. A viral outbreak that began in China has infected more than 79,000 people globally. The World Health Organization has named the illness COVID-19, referring to its origin late last year and the coronavirus that causes it. (Photo by Kyodo News via AP Photo)

People take photos of hotel room lights shaping the word “Zero”, referring to Covid-19 cases, in Taipei, Taiwan, 17 April 2020. According to news reports Taiwan records no new COVID-19 cases for third time this week. Medical experts are rushing to develop a vaccine for the COVID-19 disease caused by the SARS-CoV-2 coronavirus and advising people to practice social distancing and proper hygiene. (Photo by David Chang/EPA/EFE/Rex Features/Shutterstock)

A Palestinian man waves from his home as a clown and a man in a costume perform to entertain people amid concerns about the spread of the coronavirus disease (COVID-19), in Khan Younis in the southern Gaza Strip on April 19, 2020. (Photo by Ibraheem Abu Mustafa/Reuters)

A four-legged robot dog called SPOT patrols a park as it undergoes testing to be deployed as a safe distancing ambassador, following the coronavirus disease (COVID-19) outbreak, in Singapore on May 8, 2020. (Photo by Edgar Su/Reuters)