By Kevin Liptak

CNN White House Producer

WASHINGTON (CNN) -- Gliding toward Joint Base Andrews in his military helicopter Friday, Barack Obama watched a dramatically altered Washington recede from view, the work of his presidency now over and the future of his accomplishments uncertain.

Waving at a crowd gathered to witness his political and ideological opposite sworn into office, Obama revealed no apprehension at handing the most powerful job in the world to Donald Trump. His head cocked, there were no outward signs of hard feelings as Donald Trump derided his tenure during his inaugural address.

But the differences with his successor were plain. The White House's final tweet under Obama was a photo of Obama hand-in-hand with Democratic Rep. John Lewis, the civil rights leader who Trump lambasted this week, walking down the Alabama bridge where Lewis was beaten by police in 1965.

And Obama previewed a return to public life when he was addressing members of his staff at Joint Base Andrews moments after Trump was sworn in.

"This is just a little pit stop," he said. "This is not a period, this is a comma in the continuing story."

Obama is more popular by far than his successor, but the accomplishments that defined his presidency are in doubt. Trump ran on a change agenda, vowed to end many of Obama's programs, and has a Republican Congress that's largely in step with his governing priorities.

The two men share a long and personal animosity. Trump stoked the racist birther conspiracy that suggested Obama wasn't a legitimate president. Obama jabbed Trump at the White House Correspondents' Dinner 2011, enraging the real estate mogul.

Unease about the future, however, was cast aside Friday, as Obama and Trump carried out the traditional rituals of transferring power.

The handoff began in the morning when Obama and his wife greeted the incoming first couple on the steps of the North Portico. The mood was jocular; Obama told Trump he would get used to the camera snaps that will soon accompany many of his movements. It's only the second time the two have met, after their post-election huddle in the Oval Office.

The moment was a symbol of Democracy's reins being handed off peacefully.

Not handed off quite as gracefully: a blue box from the American jeweler Tiffany and Co., a gift from Melania Trump to her predecessor, Michelle Obama that was awkwardly given to an aide before the formal photo was snapped.

Inside, the couples sat for tea and coffee in the White House Blue Room. The space is situated one floor below the private living quarters where the Obamas slept on Thursday night and where Trump will sleep Friday.

The Obamas, who traveled to Capitol Hill in the same armored limousine with the Trumps, dutifully watched the swearing-in and speech. They stood on the East Front steps of the Capitol with their replacements, he chatting amiably and she stoic. They stepped for a final time into the military helicopter, known for this flight as Executive One without a sitting president aboard.

The former president and his wife decamped for the West Coast, flying for a final time on the presidential aircraft to Palm Springs, California. They're expected to remain for a time in the desert oasis at the home of Michael Smith, who decorated their private living quarters and designed Obama's Oval Office. His aides said they didn't expect to see Obama at least until next month.

Obama has spent the last two months bidding farewell, sitting for lengthy media interviews, delivering a prime-time address in Chicago, and using the White House's social media channels to tout his presidential record.

His final acts in office hewed closely with the legacy he hopes to leave as president: On Thursday, Obama commuted the sentences of more than 300 non-violent drug offenders, continuing his clemency push. And he transferred four more detainees from the Guantanamo Bay naval prison, which he spent eight years trying unsuccessfully to close.

What's next?

In his post-presidency, Obama is expected to begin writing a book with the help of his White House speechwriter Cody Keenan. He's named a senior adviser and a chief of staff for his private office, and on Friday a website that allows users to inquire about speaking engagements went live.

The Obamas will remain in Washington, living in the same neighborhood as Trump's daughter Ivanka and her husband, Jared Kushner, named as Trump's senior adviser. Like other ex-presidents, he'll work from an office, in this case inside the headquarters of the World Wildlife Foundation.

But he's said he'll lay low, quietly processing the events of the past eight years and only speaking out against Trump's actions if they threaten "core values."

Before he faced Trump on Friday, Obama made his final visit to the Oval Office, the cauldron of power where he plotted a health care overhaul, diplomatic agreements with Iran and Cuba, and a global climate accord.

As he left for the final time, he slipped a single-page letter to Trump into the top drawer of the Resolute Desk -- crafted from timbers of a 19th century Arctic exploration ship -- that he hopes his successor will read carefully as he absorbs the magnitude of his new life.

As he departed the Oval Office, Obama was upbeat and smiling.

"Are you feeling nostalgic?" a reporter asked from the Rose Garden.

"Of course," said the President.

"Any last words for the American people?" asked another.

"Thank you."