Now playing Next USA How seals helped scientists explain huge holes in the Antarctic ice Two of the large "polynyas" opened up in the Weddell Sea in 2016 and 2017. 12/06/2019
Now playing Next USA 72 injured after protesters, police clash in Hong Kong over extradition bill Legislators, at least temporarily, postponed debate on the controversial proposal amid the mass protests. 12/06/2019
Now playing Next USA Two Wisconsin men die after competing in IronMan 70.3 triathlon Todd Mahoney, 38, a Madison firefighter, and Michael McCulloch, 61, were both found unresponsive in the water while swimming in the athletic competition, according to the Madison Fire Department. 12/06/2019
Now playing Next USA 'Chernobyl' miniseries creator asks tourists to show 'respect' when ta "If you visit, please remember that a terrible tragedy occurred there." 12/06/2019
Now playing Next USA 'Real justice' would've put OJ Simpson in prison: Ron Goldman's father "Every day, I miss my son," Fred Goldman tells Lester Holt, 25 years after the killings of Ron Goldman and Nicole Brown Simpson. 12/06/2019
Now playing Next USA 9/11 bill clears House hurdle as Schumer rips 'delay after delay' Echoing comedian Jon Stewart, the Senate minority leader said the way Congress has treated first responders was "shameful," and urged a vote as soon as possible. 12/06/2019
Now playing Next USA New trove of father's letters released to mark Anne Frank's 90th birthday New trove of father's letters released to mark Anne Frank's 90th birthday 12/06/2019
Now playing Next USA FBI investigating three deaths at same Dominican Republic resort More reports of apparently mysterious deaths in the Dominican Republic have surfaced since three people died at Bahia Principe resorts in May. 12/06/2019
Now playing Next USA Trump asserts executive privilege over census citizenship question info as Dems prepare contempt vote AG William Barr and Commerce Secretary Wilbur Ross defied House Oversight Committee subpoenas issued in April to produce documents on the census citizenship question. 12/06/2019
Now playing Next USA House hearing asks questions Mueller left unanswered about Trump, Russia ties House Intel Committee chair Schiff said Wednesday's hearing is meant to address unanswered questions from the Mueller report about Russian influence. 12/06/2019
Now playing Next USA Mysterious blob discovered under moon's crater Scientists say the blob may be remnants of the metallic asteroid that smashed into the lunar surface billions of years ago. 12/06/2019
Now playing Next USA Bernie Sanders has upped his game, but does it matter? First Read is your briefing from "Meet the Press" and the NBC Political Unit on the day's most important political stories and why they matter. 12/06/2019
Now playing Next USA Reps of 22 foreign governments have spent money at Trump properties The number of foreign governments hints at a significant foreign cash flow to the U.S. president that critics say violates the Constitution. 12/06/2019
Now playing Next USA Tiny plastic particles have been found in the deep ocean — and animals are eating them At depths of 200 to 600 meters, the concentration of plastic particles was found to be roughly four times what it was near the surface. 12/06/2019
Now playing Next USA NATO member Turkey to get Russian missiles within weeks despite U.S. anger "There is no future for Turkey having both Russian weapons and American F-35s," the chairman of the House Committee on Foreign Affairs said. 12/06/2019
Now playing Next USA Trump waves paper with Mexico immigration plans written on it US President Donald Trump on Monday waved a paper containing details of his immigration deal with Mexico after refusing to comment on plans to reporters, saying they were "secret". 12/06/2019
Now playing Next USA Man held in shooting of David Ortiz charged as accomplice to attempted murder Authorities did not say the person in custody was the man who allegedly shot the famed former Red Sox star. 12/06/2019
Now playing Next USA Protesters jam Hong Kong streets to rally against China extradition bill Demonstrations again erupted over the measure that would clear the way for Hong Kong to send people to mainland China to face charges. 12/06/2019
Now playing Next USA Bernie Sanders turns the tables on Trump over 'democratic socialism' The 2020 contender says the president and his "fellow oligarchs" actually "love corporate socialism." 12/06/2019
Now playing Next USA Biden, Yang feud over former VP's absence from candidate forum "To me, I have to admit to you, this particular person said he would've been there," Biden said Tuesday of Yang. "Well, I have different values than him." 11/06/2019
Now playing Next USA House approves enforcing subpoenas in court against Trump officials The vote is part of the Democrats' larger oversight strategy, which they are ramping up this week. 11/06/2019
Now playing Next USA Large mass discovered under moon's crater, believed to be metal from asteroid Large mass discovered beneath moon's crater, believed to be metal from asteroid 11/06/2019
Now playing Next USA As Biden and Trump battle in the trenches, Buttigieg attacks from higher ground Analysis: The military veteran mayor suggested U.S. foreign policy and national security would be stuck in the past with either the current president or the former VP at the helm. 11/06/2019
Now playing Next USA Never used Zelle? Scammers can still use it to drain your bank account The digital payment service embedded in banking apps has made it easier for thieves to access funds in personal checking and savings accounts, experts say. 11/06/2019
Now playing Next no comment Exhibition's tribute to human rights activists killed in Colombia The artist Doris Salcedo directed an exhibition of public art in Bogotá in tribute to dozens of human rights leaders killed in Colombia after the signing of the peace agreement. 11/06/2019
Now playing Next USA Everything you need to know about the first Democratic debate The first debate will take place on June 26 and June 27 in Miami. 11/06/2019