Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

A person viewing the Northern lights over the lava landscape, Reykjanes Peninsula, Iceland. (Photo by Arctic-Images/Getty Images)

Photo taken on January 3, 2018 shows the snow-light show at the Sun Island International Snow Sculpture Art Expo in Harbin, capital of northeast China's Heilongjiang Province. Snow Wonderland, a 3D snow-light show applying modern sound, light and digital technologies has been displayed at Sun Island International Snow Sculpture Art Expo recent days. (Photo by Wang Jianwei/Xinhua via Getty Images)

Boys play with a drainage culvert used for flood control in Las Pinas, Metro Manila February 28, 2016. (Photo by Erik De Castro/Reuters)

Hindu devotees (not pictured) touch a child with their feet as part of a ritual to bless him during a religious procession held to mark the Gajan festival in Kolkata, India, April 13, 2018. (Photo by Rupak De Chowdhuri/Reuters)

A plane battling the Ferguson Fire passes the setting sun in unincorporated Mariposa County Calif., near Yosemite National Park on Sunday, July 15, 2018. (Photo by Noah Berger/AP Photo)

Farmer Ash Whitney stands in the middle of a dried-up dam in a drought-effected paddock on his property located west of the town of Gunnedah in New South Wales, Australia, June 3, 2018. “I have been here all my life, and this drought is feeling like it will be around a while”, said Whitney. (Photo by David Gray/Reuters)

A handout photo made available by the Roscosmos State Corporation for Space Activities shows the Soyuz-2.1b launch vehicle with the OneWeb communication satellites launching from the Baikonur Cosmodrome, Kazakhstan, 07 February 2020. Thirty-four satellites from OneWeb were successfully put into orbit on a single Soyuz rocket from Baikonur. (Photo by Roscosmos/EPA/EFE)