Jennifer Lawrence plays Kate Dibiasky, a doctoral student in astronomy at a Michigan college.

Leonardo DiCaprio — whose longstanding advocacy on environmental issues reportedly was the reason of signing on to this project — plays Kate’s professor, Dr. Randall Mindy. “What would Carl Sagan do?” Dr. Mindy asks himself when Kate alerts him to her discovery of the killer comet rocketing toward Earth, predicting a direct hit in just over 6 months.

They take their findings to Dr. Clayton Oglethorpe (Rob Morgan), head of the Planetary Defense Coordination Office. Dr. Oglethorpe, who goes by Teddy, accompanies them to a White House meeting organized by Pentagon brass General Themes (Paul Guilfoyle). But President Janie Orlean (Meryl Streep) is too preoccupied by some embarrassing disclosures about her shady Supreme Court nominee to see them.

When they finally get some Oval Office face time, both the vain, arrogant president and her son and chief of staff, Jason (Jonah Hill), brush them off. “What is this going to cost me?” asks the president, looking warily toward the midterms before she decides to “sit tight and assess,” instructing Jason to get some Ivy Leaguers on it.

Randall and Kate then take their concerns about the Dibiasky Comet, as it’s now known, to morning television. Hosts Brie Evantee and Jack Bremmer (Cate Blanchett and Tyler Perry) are in full-blown sketch-comedy mode, determined to keep their show, “The Daily Rip,” perky and light no matter how gloomy the topic.

Their TV appearance is mostly overshadowed by that of pop star Riley Bina (Ariana Grande), on the show to talk about her breakup with fellow music celebrity DJ Chello (Scott Mescudi). But Randall does make enough of an impression on social media, while Kate becomes a viral crazy-lady meme.

NASA’s head of damage control (Hettienne Park) downplays their findings; the FBI steps in to silence them; Kate’s online journalist ex-boyfriend Philip (Himesh Patel) paints her as a crazy woman; and President Orlean adopts their plan to blow the rock off its course, although with a few tweaks to better serve her political purposes.

She asks Colonel Ben Drask (Ron Perlman) to pilot the mission, dismissing Randall’s suggestion that the same result could be achieved using drones.

The film gets so busy with surplus characters. The most prominent of the secondary players is Mark Rylance as Sir Peter Isherwell, head of global tech conglomerate Bash, whose prominence is illustrated in just about every device seen on camera. The character is Steve Jobs, Elon Musk and Mr. Rogers rolled into one, though his Zen demeanor doesn’t hide his hunger for profit, especially when he identifies the Dibiasky Comet as a potential asset.

At least Rylance’s annoying character serves a narrative purpose, unlike Timothée Chalamet’s Yule, a skater who sees Kate as some kind of prophet, ignored by the growing chorus of impact deniers. Even more superfluous is an unbilled star playing the lead in a US$300 million movie rushed into production, titled “Total Devastation.” Riley Bina and DJ Chello’s apocalyptic anthem, “Just Look Up,” carries on through an aftermath scene elsewhere in the universe and the post-credits sequence. (SD-Agencies)