What was going on when I was born?

Konstantin U. Chernenko, the Soviet leader, was quoted today as saying that an agreement with the United States on banning weapons in outer space would ease the way for discussions on other disarmament issues. The comment, in the form of answers to questions put to him by Pravda, the Communist Party newspaper, was the first major statement attributed to him since he left for a vacation July 15. It was not clear when or how the interview with Mr. Chernenko had been conducted. . The absence of the Soviet leader from public view has aroused rumors about his health and political standing. In the last week, his name has reappeared prominently in the official press on a number of minor statements. In the Pravda article Mr. Chernenko was quoted as repeating the Soviet position that the United States was scuttling the possibility of space-weapons talks because of its insistence on raising questions about stalled nuclear-weapons negotiations.

In the first test of electricity-generating systems to be erected on future space stations, an experimental solar power array was unfolded today and extended up from the space shuttle Discovery like a glistening stairway to the stars. The Discovery crew also successfully released the third and last communications satellite from the cargo bay, did some troubleshooting on a balky drug-processing machine and had a telephone conversation with President Reagan. With Judith A. Resnik at the controls, an epoxy-fiberglass mast rose slowly out of the Discovery's cargo bay and brought with it the unfolding sections of the solar panel. These are thin sheets of the plastic material Kapton that had been folded accordionlike. Attached to most of the 84 panels are dummy solar cells, though the outermost panels hold three working cells for converting sunlight to energy.

Structural decay forced the demolition five years ago of the Knickerbocker Inn, in Leonia, N.J., a pre- Revolutionary stopover point for the overland stage through northeastern Bergen County.

INVESTMENTS BUYING AN OCCUPIED CO-OP UNIT WITH the steep rise in the price of New York City co-op apartments has come a growing awareness that occupied unsold apartments - whose tenants may stay on indefinitely at a controlled or stabilized rent - can be worthwhile long- term investments. Normally, they can be acquired for much less than what their market value would be as vacant units. In the past, the sponsor of the conversion held on to most of them until they became vacant and then sold them for top dollar. Occasionally, occupied apartments would be sold in lots to another real-estate professional, but the ordinary citizen was rarely involved.

The Reagan Administration is nearing a decision to offer asylum to thousands of Vietnamese prisoners held by Vietnam in ''re-education'' camps, senior Administration officials said today. The contemplated American action would be in response to earlier Vietnamese offers to release the prisoners, many of whom had close ties to the United States during the Vietnam War, if the United States would agree to resettle them. The prisoners are believed to number between 6,000 and 15,000. In the past the Administration reacted skeptically to the proposal by Hanoi. But at the urging of refugee groups, some members of Congress and some high-ranking American officials, Washington is said to have decided in principle to test Vietnam's sincerity and to be forthcoming in seeking the release of the prisoners.

''It is always a windfall to have works by Degas to look at,'' the French art historian and critic Andre Chastel wrote in 1969 at the time of a Degas exhibition at the Louvre. The quality, elusiveness and sustained intelligence of Degas's achievement is such that an article on almost any exhibition of his work could begin the same way. It is particularly fortuitous to be able to see Degas this year, in the context of major exhibitions on Jean-Antoine Watteau, one of his key ancestors; Edouard Manet, one of Degas's inspirations; James McNeill Whistler, a kindred spirit and friend of Degas for more than 40 years, and Picasso, the heir apparent to the Parisian artist's extraordinary technical inventiveness and virtuosity.

C ONTINUING the pattern of the last decade, public schools in Nassau and Suffolk Counties will open this week with decreased enrollments and increased expenditures, reflecting declining birth rates and inflationary costs. However, this year there will be a new state aid formula for school districts, and many districts on the Island are phasing in new graduation requirements as mandated by the New York State Board of Regents. In Nassau County, the number of students in public schools is expected to decrease from 192,407 last year to 189,912 for the coming school year, according to New York State Department of Education estimates. In Suffolk County, the school population is expected to decline from 254,310 students to 250,367 for the 1984-85 school year. Statewide figures reflect the trend of declining enrollment as well: 2,625,900 students will be attending public schools this year, down by about 35,000 from last year. School officials said enrollment is not expected to increase again until the early 1990's.

WASHINGTON Spies generally don't like spy movies. They say it is not because of gadget envy or envy of James Bond's females, and I believe them. It is, well, because they don't like being thought of or portrayed as ''spies'' - those skulking or bionic creatures engaged in feats of superhuman hunches or violent acrobatics that you tend to see on film. They see themselves as intelligence agents, with the accent on intelligence. Their idea of fun is watching grass grow into an odd insight or, better still, a trend. If any fictional spy is heroic to them, it is George Smiley of John le Carre fame, portrayed by Alec Guinness in the BBC's ''Tinker, Tailor, Soldier, Spy.'' Even that television portrayal was a bit racy by their standards. ''The book was much better,'' said Ray S. Cline, a former head of covert operations in the Central Intelligence Agency, because it was even more leisurely and complex. After talking with a dozen or so former and present American spies about spy movies, I get the feeling that even the name of the organization, C.I.A., is not good enough. They seem to prefer the name used for the organization in World War II, the Office of Strategic Services, or better yet, Mensa.

ST.PAUL PRESIDENT Reagan and Walter F. Mondale formally launch their campaigns tomorrow at opposite ends of the country, speaking to different constituencies and, perhaps most important, with their campaigns dominated by sharply contrasting moods. While Republicans are optimistic about their prospects, the Democratic camp is plainly struggling to appear upbeat in the face of discouraging public opinion polls and the gloom of many party leaders. ''Our coalition is together, our case is strong, the contrast couldn't be greater,'' Mr. Mondale said the other day. ''From here on out, we're ready to move forward and win this election.''

If anyone wants to believe again, the signs were all over Shea Stadium last night as the Mets swept a doubleheader from the San Diego Padres, 7-4 and 10-6. Dwight Gooden pitched another good game in winning the opener; the Mets came from behind with an electrifying two-out, five-run rally in the fourth inning of the second game; Hubie Brooks kept swatting the ball and climaxed that rally with a three- run double, and Darryl Strawberry, who played the entire month of August without hitting a home run, hit one in each game and drove in a total of six runs. But if Mets' fans are looking for special signs, just check out John Stearns. John Stearns?

WHEN Susan Kelley looks out her window she sees a beginning. ''There are so many young professionals sitting on the stoops, ties undone, just talking,'' said the 24-year-old Wall Street real-estate broker as she surveyed East 13th Street, where she has lived for two years. ''There's a feeling of togetherness, of movement. A feeling that things are different every day.'' When Barbara Shaum looks out her window she sees an end. ''I see them walking down the street in identical blue suits with their briefcases and I think, 'There goes the neighborhood,' '' said the leathercrafts maker who has lived in a loft behind her studio on East Seventh Street for 21 years. ''Why are all these people coming here, where they're so riotously out of place? I don't want my neighborhood to change.'' How you see the East Village seems to depend on where you stand.

Consumer buying has been in the doldrums for three months, convincing economists that the long-awaited shopping letdown had arrived. Indeed, things have been so slow that some stores have extended their summer sales into the fall selling season. But the gloom may be premature, according to retailers and analysts. August sales reported Thursday by the nation's largest retailers, while not all that strong, did show a modest gain over the year-earlier period. In addition, the analysts say, sales in September are likely to thrive from a swell of back-to-school apparel buying and a general seasonal surge as the weather cools.