A massive meteor shower destroys the orbiting Space Shuttle Atlantis and bombards a swath of land from America's East Coast from South Carolina through Finland. NASA discovers that a rogue asteroid the size of Texas passed through the asteroid belt and pushed forward a large amount of space debris. The asteroid will collide with Earth in 18 days, causing an extinction event that will even wipe out bacteria. NASA scientists, led by Dan Truman, plan to trigger a nuclear detonation 800 feet (240 m) inside the asteroid to split it in two, driving the pieces apart so both will fly past the Earth. NASA contacts Harry Stamper, considered the best deep-sea oil driller in the world, for assistance. Harry travels to NASA with his daughter Grace, to keep her away from her new boyfriend and one of Harry's drillers, A. J. Frost. Harry explains he will need his team, including A. J., to carry out the mission. They agree to help, but only after their list of unusual rewards and demands are met.
On May 10, 1998, teenage amateur astronomer Leo Biederman discovers an unusual object near the stars Mizar and Alcor at a star party in Richmond, Virginia with his school's astronomy club. His teacher alerts astronomer Dr. Marcus Wolf, who realizes that the object is a comet on a collision course with Earth. Wolf dies in a car accident before he can alert the world.
In the year 1899, Dr. Alexander Hartdegen (Guy Pearce) is a moderately young inventor teaching at Columbia University in New York City. Unlike his conservative friend David Philby (Mark Addy), Alexander would rather do pure research than work in the world of business. After a mugger kills his fiancée, Emma, he devotes himself to building a time machine that will allow him to travel back in time and save her. When he completes the machine four years later, he travels back to 1899 and prevents her murder, only to see her killed by a horse and buggy.
In the 23rd century, Earth has become a space-faring federation. While colonizing new planets, humans have encountered an insectoid species known as Arachnids or "Bugs", with their home being the distant world Klendathu. The bugs appear to be little more than killing machines, though there are suggestions that they were provoked by the intrusion of humans into their habitats.
In 2065, Earth is infested by alien life forms known as Phantoms. By physical contact Phantoms consume the Gaia spirit of living beings, killing them instantly, though a minor contact may only result in an infection. The surviving humans live in "barrier cities", areas protected by an energy shield that prevents Phantoms from entering, and are engaged in an ongoing struggle to free the planet. After being infected by a Phantom during one of her experiments, Aki Ross (Ming-Na) and her mentor, Doctor Sid (Donald Sutherland), uncover a means of defeating the Phantoms by gathering eight spirit signatures that, when joined, can negate the Phantoms. Aki is searching for the sixth spirit in the ruins of New York City when she is cornered by Phantoms but is rescued by Gray Edwards (Alec Baldwin) and his squad "Deep Eyes", consisting of Ryan Whittaker (Ving Rhames), Neil Fleming (Steve Buscemi) and Jane Proudfoot (Peri Gilpin). It is revealed that Gray was once romantically involved with Aki.
The film begins with an introductory sequence involving the main characters and images from space and introducing many of the film's visual leitmotifs. These are motifs of virtually still images revealing the key elements of the film: Justine the bride in deep melancholy with birds falling behind her; of a lawn with trees and sundial with two different shadows; Pieter Breughel's Hunters in the Snow (often used as interpretation of an idealised nostalgia) burning; the non existent 19th hole (limbo) and the Black Horse collapsing catastrophically in slow motion (Id, ego and super-ego battle); Justine as a bride being swept along by a river; and her being held back by her wedding dress; and finally Justine and her nephew building their magic cave before the Earth crashes into Melancholia becoming one.
The Earth is passing through the tail of a comet, an event which has not occurred in 65 million years, the last time coinciding with the extinction event that wiped out the dinosaurs. On the night of the comet's passage (which takes place eleven days before Christmas), large crowds gather outside to watch and celebrate.
One day Moomintroll wakes to notice that grey dust is covering everything in the Moominvalley. He runs to ask the philosophical Muskrat if he knows what is happening, who advises him that things tend to look like this before an awful fate coming from the sky hits the Earth. With the help of his father, Moominpappa, Moomintroll and his close friends Sniff and Snufkin build a raft and head out on a challenging journey to the observatory in the Lonely Mountains hoping to find out more from the wise professors there. The friends have to overcome several adversities in order to make it there. When they arrive, they find the professors deep in calculations. They reveal that a comet will reach the Earth in four days, four hours, four minutes and 44 seconds.
A news report is broadcast informing the world that a mission to stop an incoming asteroid from destroying life on earth has failed and that it will make impact in three weeks time. Dodge Petersen (Steve Carell) and his wife Linda (Nancy Carell) listen to the broadcast from the side of the road. After Dodge has an uninterested response, Linda looks at him in abject disgust and flees the vehicle without saying a word.
After the asteroid Orpheus is hit by a comet, a five-mile chunk of Orpheus is sent on a collision course towards Earth, which will cause an extinction-level event. While the United States government engages in political maneuvering, smaller asteroid fragments precede the main body, wreaking havoc on the planet. The United States has a secret orbiting nuclear missile platform satellite named Hercules, which was designed by Dr. Paul Bradley (Sean Connery). It was intended to defend Earth against a massive space rock, but instead was demoted to become an orbiting super weapon now aimed at Russia. However, its fourteen nuclear missiles are not enough to stop the meteor.
In 2022, a comet strikes Earth causing an 11-year drought. By 2033, most of the little remaining water is held in reserve by Kesslee (Malcolm McDowell) and his Water & Power (W&P) corporation, which uses the water to control the population. Rebecca Buck – "Tank Girl" (Lori Petty) – is a member of a commune in the Australian outback that operates the last water well not controlled by the corporation. In an attack on the commune, W&P troops kill Tank Girl's boyfriend, Richard (Brian Wimmer), and capture Tank Girl and her young friend Sam (Stacy Linn Ramsower). Rather than killing her, Kesslee tortures and enslaves the defiant Tank Girl. Jet Girl (Naomi Watts), a talented but introverted jet mechanic who has given up trying to escape W&P, urges Tank Girl to make less trouble for their captors, though Tank Girl refuses. Among other forms of torture, W&P personnel push her down into a long pipe and fill it with water.
Pilot David Randall is paid to fly top-secret photographs from South African astronomer Dr. Emery Bronson to Dr. Cole Hendron in the United States. Hendron, with the assistance of his daughter Joyce, confirms their worst fears: Bronson has discovered a rogue star named Bellus that is on a collision course with Earth.
The film takes place in Perth, and begins ten minutes after a meteor has collided with earth in the North Atlantic, leaving approximately twelve hours until the subsequent global firestorm reaches Western Australia. James and his lover, Zoe, are having sex for the last time at her beach house, where she reveals that she's pregnant with James' child. Not wanting to feel his inevitable death, James disregards Zoe's news and leaves for "the party to end all parties". After having his car stolen, he comes across two men who have kidnapped a young girl and are planning to rape her. James kills them, and rescues the girl. The girl, named Rose, explains that she was separated from her father in Malaga en route to her aunt's house in Roleystone. Not wanting to waste petrol, James instead plans to leave her with his sister and her children. But upon arriving, he finds his sister and her husband dead in the shower, and three crosses marking what appears to be his nieces' graves, in what is an apparent murder suicide.
Late one night, near Billings, Montana, a gas tanker is driving by when meteoroid suddenly hits in front of the truck. The driver attempts to swerve out of the way, but loses control and overturns and the tanker explodes, causing a massive fire.