When Worlds Collide

Paid courier and pilot David Randall flies top-secret photographs from astronomer Dr. Emery Bronson to Dr. Cole Hendron. Hendron, with the assistance of his daughter Joyce, confirms their worst fears: Bronson has discovered that a rogue planet named Bellus is on a collision course with Earth. By a misunderstanding, Randall is included among those who have foreknowledge of the impending disaster.
Hendron warns the United Nations that the end of the world is little more than eight months away. He pleads for the construction of spaceships to transport a lucky few to Zyra, the sole planet in orbit around Bellus, in the faint hope that some of the human race can be saved from extinction. Other equally distinguished scientists scoff at his claims, and he is not believed by the UN delegates.
Hendron receives help from wealthy humanitarians, who arrange a lease on a former proving ground to construct an ark spaceship. To finance the construction, Hendron is forced to accept money from the self-centered, wheelchair-bound industrialist Sidney Stanton. Stanton demands the right to select the passengers, but Hendron insists that he is not qualified to make those choices; all he can buy is a seat aboard the ark.
Joyce, attracted to Randall, prods her father into to keeping him around, much to the annoyance of her boyfriend, Dr. Tony Drake. As Bellus nears, former skeptics admit that Hendron was right and governments prepare for the inevitable. Other groups begin to build spaceships in other nations. Martial law is declared before Bellus' arrival, and residents in coastal regions are moved to inland cities.
When Zyra makes its close approach, it causes massive earthquakes, volcanic eruptions, and tidal waves that wreak havoc around the world. Several people are killed at the ark's construction camp, including Dr. Bronson. Drake and Randall travel by helicopter to provide survivor assistance. When Randall leaves the helicopter to rescue a stranded little boy, Drake nearly abandons him but quickly accepts that Joyce has chosen Randall over him.
As the day of doom approaches, the spaceship is loaded with food, medicine, microfiche copies of books, equipment, and animals. The lucky passengers are selected by lottery, though Hendron reserves seats for himself, Stanton, Joyce, Drake, pilot Dr. George Frey, the young boy who was rescued, and Randall, for his daughter's sake. When a young man turns in his winning ticket because his sweetheart was not selected, Hendron arranges for both to go. Randall refuses his seat and only pretends to participate in the lottery, believing he has no skills needed for settling on Zyra. For Joyce's sake, Drake fabricates a "heart condition" for Frey, making a co-pilot necessary.
The cynical Stanton, knowing human nature, fears what the desperate lottery losers might do, so as a precaution, he has stockpiled weapons; Stanton's suspicions prove to be well-founded. His much-abused assistant, Ferris, tries to add himself at gunpoint to the passenger manifest, only to be shot dead by Stanton. During their final night on Earth, the selected passengers and animals are quietly moved to the launch pad to protect them from more violence.
Shortly before blast off, many of the lottery losers riot, taking up Stanton's weapons to try to force their way aboard the ark. Hendron surprises everyone by staying behind at the last moment and forcibly keeps Stanton with him in order to conserve fuel for the flight to Zyra. With an effort born of ultimate desperation, Stanton stands up and tries to walk in a futile attempt to board the departing spaceship.
The crew are rendered unconscious by the g-force of acceleration and do not witness on the forward monitor the Earth's destruction by Bellus. When Randall comes to and sees Dr. Frey already awake and piloting the ship, he realizes he has been deceived.
As the space ark enters Zyra's atmosphere, the fuel finally runs out; Randall takes control of the spaceship, gliding to to a rough but safe landing. Earth's survivors begin to disembark, finding Zyra to be habitable. David Randall and Joyce Hendron follow, walking hand-in-hand down the ramp to explore an unknown but hopeful future.

Question: who warns the United Nations that the end of the world?
Answer: Hendron; Hendron