What was going on when I was born?

The Justice Department sued the Shell Oil Company today for nearly $1.9 billion in damage to the environment the Government says was caused by the company's pesticide factory near Denver. This is the largest amount ever sought by any Federal agency for damage to natural resources, according to F. Henry Habicht 2d, Assistant Attorney General in charge of the land and natural resources division. The Government charged that more than 40 hazardous substances produced at the Shell facility, situated on the grounds of the Army's Rocky Mountain Arsenal, had spilled and that some had leaked into underground water supplies used by nearby communities. Colorado Files Suit Shortly after the Justice Department filed its suit in Federal District Court in Denver, the State of Colorado filed its own suit there, naming not only Shell but also the Army and the United States. In addition to the Shell suit, the Justice Department also disclosed that it had filed suit today against 50 corporations, including some of the nation's largest, in an attempt to get them to help pay for the cleanup of a hazardous waste site in Seymour, Ind. And the Environmental Protection Agency announced a suit had been filed on Thursday against the Occidental Chemical Corporation to recover nearly $45 million spent by the Government to clean up the hazardous waste site at Love Canal, in Niagara Falls, N.Y.

This is the year in which the home computer will join the sled and the bicycle under the Christmas tree. In numbers that outstrip even the most optimistic predictions, Commodores, Ataris and Colecos are being snapped up from the shelves. Americans have embraced the home computer as their favorite gadget for a Christmas present, replacing the food processors and video games of Christmases past. ''Last year, computers were new, unique and expensive,'' said Egil Juliussen, president of Future Computing Inc., a market forecasting concern that expects 2.5 million home computers to be sold this Christmas, twice as many as last year. ''This year, they're cheap, and they have become the gift.''

Text of declaration, Page 4. BRUSSELS, Dec. 9 - The Atlantic alliance today offered the Soviet Union and the Warsaw Pact the prospect of a long-term relationship, based on ''moderation,'' that the allies said could build a peaceful future for the world. In a statement officially described as an ''important political signal,'' the alliance members addressed the Soviet Union as a potential partner and asserted, ''For the benefit of mankind, we advocate an open, comprehensive political dialogue, as well as cooperation based on mutual advantage. ''We extend to the Soviet Union and the other Warsaw Pact countries the offer to work together with us to bring about a long-term constructive and realistic relationship based on equilibrium, moderation and reciprocity,'' the statement said.

News Analysis WASHINGTON, Dec. 9 - A central axiom of the Reagan Administration has been that the best way to press the Soviet Union into reasonable compromises on arms control is to build up American strategic nuclear forces vigorously and push ahead with missile deployments in Western Europe. Eventually this strategy may pay off. But for the moment, the evidence is to the contrary. Rather than adopting a more flexible and compromising posture in the face of the American military assertiveness, the Kremlin has broken off the negotiations on medium- range nuclear forces in Europe and left the strategic arms talks dangling in suspension.

''This,'' said George Warner, standing before a six-foot-high altar of golden cigar boxes containing what he considered ambrosia of the gods, ''is a religious experience.'' All those who beheld the trove of 200,000 Cuban cigars - the first of the legendary cigars legally available in this country since a 1961 trade embargo against Cuba - said they could not help but be moved. Recalling Fidel Castro's takeover of Cuba in 1959, Jon Reiss seemed close to tears. ''All those wonderful cigars,'' he said, shaking his head. Another man, explaining that he was neither the religious nor the emotional type, said he simply considered the 200,000-cigar treasure ''man's greatest discovery in decades.''

An investigation began today into the computer failures that delayed the space shuttle Columbia's landing. Officials said they would not clear the shuttles for further flights until the problems were understood and corrected. Two malfunctioning computers were removed from the Columbia here and shipped to the vehicle manufacturer for a ''failure analysis,'' the National Aeronautics and Space Administration announced. Meanwhile, engineers at the Johnson Space Center in Houston pored over flight data for clues to the breakdowns that briefly disrupted the shuttle's navigation systems and delayed its landing on Thursday.

Yasir Arafat appealed to the United Nations today for additional guarantees of security on the sea lanes out of Tripoli after Israeli gunboats backed by helicopters attacked a Palestinian post here early this morning. (New Israeli gunboat attacks were reported Saturday morning on P.L.O. positions in Tripoli, according to Reuters.) Mr. Arafat, the chairman of the Palestine Liberation Organization, also asked France and Greece to reinforce their warship escort for the Greek transport vessels that are expected to take him and about 4,000 of his men away from Tripoli, possibly as soon as next week. Ahmed Abdul Rahman, one of Mr. Arafat's senior aides, said the Israeli attack against what he described as a lightly manned coastal position had put ''an obstacle in the face of our withdrawal, so we are asking for new measures to protect our withdrawal.''

New York City will build new jail cells and dormitories for 2,200 prisoners on Rikers Island and in the brig at the Brooklyn Navy Yard at a cost of $154 million, Mayor Koch announced yesterday. The money, he said at a news conference at City Hall, will be added to the $123 million already earmarked for jail construction. City officials said the expanded plan should prevent a repetition of last month's release of prisoners because of overcrowding in city jails. ''I am faced with the choice of releasing prisoners onto city streets or taking scarce capital dollars from other programs to build more jails,'' the Mayor said. ''The only real and the only responsible choice is to build more jails.'' He said he did not know which of those other programs would be affected.

The TalkofDublin DUBLIN - This is a city that is beginning to fear its young. Out on the street, where decorative Christmas lights arch over a pedestrian mall, undercover policemen move with the shoppers looking for the heroin pushers who haunt the video arcades and fast-food places where the teen-agers hang out. In department stores like Clery's across the River Liffey on O'Connell Street the security guards say the young shoplifters and pickpockets are more brazen than ever. Also in evidence are the glue-sniffers, stumbling along the back alleyways, collapsing into giggly piles with puffed-up plastic bags mashed against their face, inviting hallucination. Some are as young as 10 or 12.

Danuta Walesa arrived here this morning to accept the 1983 Nobel Peace Prize for her husband, Lech, who had decided not to come himself out of fear that if he left Poland he would not be permitted to return. Mrs. Walesa, a slight, demure woman, answered questions from foreign reporters with a poise and a confidence that seemed to belie her description of herself as ''a kitchen manager.'' As reporters and photographers pushed and shouted, she parried political inquiries, said her husband was in ''blooming'' health, called the Nobel award a great event that encouraged ''those everywhere who are concerned with human life'' and apologized if some of her responses seemed ''superficial.'' Mrs. Walesa is to accept the Nobel award at a ceremony Saturday at which she will read brief remarks composed by her husband. The prize lecture, which he also wrote, will be delivered Sunday by Bogdan Cywinski, a writer and member of Mr. Walesa's outlawed free trade union, Solidarity.

Despite American objections, the General Assembly adopted resolutions today accusing El Salvador, Chile and Guatemala of human rights violations. The annual human rights debate, which lasted 10 days, centered on these three nations, as it has in previous years. The resolutions all expressed concern for violations of human rights in each country and called on their Governments to ''take effective measures'' to insure ''fundamental freedoms.'' The vote on the resolution on El Salvador was 78 to 13 with 41 abstentions; on the Guatemala resolution, 80 to 14 with 36 abstentions, and on Chile, 86 to 15 with 36 abstentions.

President Reagan told Congressional leaders today that the United States military force on Grenada had been reduced below 2,700, but he said ''it is still not possible to predict'' when all American forces would be withdrawn from the Caribbean island. White House spokesmen have pledged that all United States combat forces will be withdrawn from Grenada by Dec. 23. Mr. Reagan did not repeat that pledge in his letter to Congressional leaders, but spokesmen said nothing in the letter should be interpreted as a change in that plan.