You’ve no doubt heard about the moon landing? Fifty years ago this Saturday, Apollo 11 landed on the lunar surface. Television, and particularly television news, has been filled with documentary commemorations and reminiscences. To quote Lincoln’s Gettysburg Address, it’s altogether fitting and proper that we should do this. But when does all this backward glancing become too much? Does “news” cease being news, or relevant, when it leans too much on nostalgia? More importantly, when does a focus on yesteryear drive away younger viewers? Or make them feel ignored?

In addition to moon nostalgia, this is the inaugural week for “CBS Evening News With Norah O’Donnell” (5:30 p.m., CBS). O’Donnell, who can also be seen (with Topher Grace) on “The Late Show With Stephen Colbert” (10:35 p.m., CBS), has spent the week interviewing Apollo 11-related personalities, from a woman mathematician who worked at Mission Control to former ambassador Caroline Kennedy, the daughter of the president who challenged the country go to the moon.

O’Donnell marks the most recent reboot for the news program. Never the most popular, it has gone from the avuncular veteran Bob Schieffer to the cool yet dependable Scott Pelley to the eye-candy era of Jeff Glor.

The decision to dump Pelley for the younger Glor was a dumb one from the get-go. CBS lost viewers who had grown used to Pelley without attracting the younger “eyeballs” that Glor was supposed to bring. The fact that CBS thought a “prettier” face was going to attract younger viewers is incredible.

Despite its older audience, the evening news sets the tone for the prime time to come. And the more than 6 million people who tune into each of the three networks’ broadcasts still dwarfs that of any cable news program.

It’s hard to deny that O’Donnell brings a morning show vibe to the news program. She’s hardly the first to migrate from coffee time to the dinner hour. The list includes Barbara Walters, Tom Brokaw, Katie Couric and Jane Pauley. It has been a bit harder for anchors who once shared the shenanigans of the morning show pancake circuit to evoke the gravitas of a Walter Cronkite. But is that what viewers want?

And a quick glance at the network prime-time schedule of reality distractions and game shows reveals an environment not all that different from “daytime” TV.

  • Netflix likes to tell us that it has reinvented television. But some old chestnuts endure. Where would we be without amnesia? There was a time when half the shows seemed to be about memory loss, its convenient cure and the ever-present dangers of quicksand. That geological terror may have gone the way of the carburetor, but amnesia sticks around.

Brenda Song (“Fudge” and “100 Deeds for Eddie McDowd”) stars in “Secret Obsession” (streaming today) as Jennifer, a wife suffering trauma after a brutal attack. She can’t remember her past or her name, but she quickly discovers that her doting husband (Mike Vogel) may be more or less than he seems.

Other highlights

  • A drag queen’s brain transforms Liv’s diet on “iZombie” (7 p.m., CW, TV-14).
  • A sculptor’s death rings a bell on “Elementary” (9 p.m., CBS, TV-14).
  • Conjecture looms large on “Law & Order: Special Victims Unit” (9 p.m., NBC, r, TV-14).
  • An old pal gets Cat in trouble on “Reef Break” (9 p.m., ABC, TV-14).
  • Hot-footing it on “Baskets” (9 p.m., FX, TV-MA).

Cult choice

TCM unspools a marathon of collaborations between star Burt Lancaster and director John Frankenheimer: “The Train” (7 p.m., TV-PG); “Birdman of Alcatraz” (9:30 p.m., TV-PG); “The Gypsy Moths” (12:15 a.m. Friday, TV-MA) and “7 Days in May” (2:15 a.m. Friday, TV-14).

Series notes

Tropical distractions on “Love Island” (7 p.m., CBS, TV-PG) ... “The Wall” (7 p.m., NBC, r, TV-PG) ... Health matters on “MasterChef” (7 p.m., Fox, TV-14) ... Rob Riggle cracks wise on “Holey Moley” (7 p.m., ABC, TV-PG).

Julie Chen Moonves hosts “Big Brother” (8 p.m., CBS, TV-PG) ... Jane Lynch hosts “Hollywood Game Night” (8 p.m., NBC, TV-PG) ... “Spin the Wheel” (8 p.m., Fox, TV-PG) ... “Family Food Fight” (8 p.m., ABC, TV-PG) .... Talon adjusts to a rival’s moves on “The Outpost” (8 p.m., CW, TV-PG).

Late night

Isha Sesay is booked on “The Daily Show With Trevor Noah” (10 p.m., Comedy Central) ... “Conan” (10 p.m., TBS, TV-14) welcomes a “surprise” guest ... Jimmy Fallon welcomes Kenan Thompson, Joe Manganiello and Robyn on “The Tonight Show” (10:35 p.m., NBC) ... Billy Eichner, Sean McVay and Spoon appear on “Jimmy Kimmel Live” (10:35 p.m., ABC) ... Lisa Kudrow, Will Forte, Jason Sudeikis and Sarah Tollemache appear on “The Late Late Show With James Corden” (11:35 p.m., CBS, r).

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