After whirling through space for a year, astronaut Scott Kelly came home this week a temporarily changed man: a tad taller, with poorer eyesight and a slightly smaller heart. He also returned invigorated by the breathtaking views he photographed throughout his odyssey for the gravity-bound denizens of Earth.

Kelly called the third planet from the sun “beautiful” during a news conference Friday, which NASA carried live online. And the International Space Station offered “a great vantage point” for sharing what he saw.

Exactly 340 days after blasting a hole in the night sky over the frigid desert of Kazakhstan, Kelly fell back to Earth on Tuesday with a million-plus followers on Twitter, Instagram and Facebook.

Recapturing the attention of a public that once wearied of moon landings and space shuttles, the rocket man for the Reddit generation showed he could inspire and excite — often in 140 characters or fewer.

From 250 miles up, Kelly witnessed Category 5 Hurricane Patricia churn on to the coast of Mexico, plumes of volcanic ash streak the skies over the Aleutian Islands and the glittering clouds of the aurora borealis paint the night neon. He also tweeted about pollution “riding up against” the walls of the Himalayas and suffocating the space over China. It was “heartbreaking,” he said.

In his first interview since returning to earth, Astronaut Scott Kelly reflects on his record-breaking year-long venture aboard the International Space Station. (Reuters)

When Kelly successfully grew zinnias aboard the space station, the news flashed around the planet. And when he donned a gorilla suit and chased Russian cosmonaut Mikhail Kornienko through the space station, the video went viral.

“Needed a little humor to lighten up a #YearInSpace,” Kelly tweeted. “Go big, or go home. I think I’ll do both. #SpaceApe.”

Even the photo of Kelly’s first dinner back on Earth garnered more than 14,000 “likes” on Twitter. (The 16-second video of his first swim back home in Texas, when he plunged into his pool at 4 a.m., registered 12,600 thumbs up.)

Although it may be difficult to quantify the effect of Kelly’s popularity on the future of the space program, it’s worth noting that when NASA advertised job openings for eight to 14 astronauts last December, the agency received a record 18,300 applications.

The 52-year-old Kelly, a native of New Jersey, now holds the American record for longest stay in space. He flew 144 million miles on his nearly year-long voyage, took part in three space walks and performed more than 400 scientific studies, from the macro (dark matter) to the micro (stem cells), with forays into vegetable growing.

His mission’s chief goal, however, was an experiment in analyzing the physical and psychological effects of long-term spaceflight in anticipation of an eventual manned mission to Mars. Kelly’s identical twin brother, Mark, a retired astronaut, served as a kind of control for NASA.

Scientists and doctors will look at facets as diverse as aging, which Scott is likely to have done faster than Mark, and the effects of radiation on the body without the protection of Earth’s ozone layer.

Astronaut Scott Kelly spent 340 days aboard the International Space Station, longer than any American astronaut. Here's a look at the year he spent in space, through his eyes above Earth. (Victoria Walker/The Washington Post)

Both men took blood, fecal, saliva and urine tests during the year, and monitored their heart rate and blood pressure. An ultrasound machine installed on the space station was used to capture images of Kelly’s heart and eyes. Some of the samples he took himself remain in a storage freezer there; a SpaceX Dragon capsule will deliver them to NASA sometime this year.

The agency reiterated Friday that it may be years before the results of all these tests are fully analyzed and made public. In the meantime, neither Kelly nor the agency’s doctors can cite any significant physiological changes that might have occurred. Because of the lack of gravity, Kelly said, his sense of touch is more sensitive right now, and his skin “feels like it’s burning” when he sits in a chair.

His sensations were immediately heightened as the hatch of the Soyuz craft opened in Kazakhstan.

“The air was refreshing. It was cool and different from the air I experienced for the last 340 days,” Kelly said, who was told that what he thought was the smell of a flowering plant was actually the odor of the charred Soyuz after its fiery reentry.

“It had a kind of sweet smell,” he said.

It may have been the small, unexpected curiosities that most endeared Kelly to the public, which learned that it’s hard to throw something straight in space because everything tends to “loft,” and that astronauts are always seen with their arms folded when interviewed in zero gravity because “otherwise they just float in space in front of you.”

The three things Kelly particularly missed, other than his family and friends: grass under his feet, breezes and the crunch of broccoli. Jill Biden, wife of the vice president, greeted Kelly in Houston with apple pie and beer.

“Nothing’s more American than that,” she told CNN. “That’s what he said he wanted.”

Kelly’s return to terra firma has been remarkably pedestrian. He said he has undergone a lot of physical exams and blood work, and when shooting hoops at his home a couple of days after returning, he hit nothing — including the net. But that wasn’t at all unusual, he admitted.

When asked by reporters Friday whether he would miss anything about living in space, he said, “Absolutely, many things.” Mostly he will miss “doing something difficult and being fulfilled by it when it’s a success.”

“It’s like why I wanted to be a [Navy] pilot and land on aircraft carriers — because I knew it was hard, there were risks, and it was important and, therefore, for me, rewarding,” Kelly said.

Perhaps that’s why he also said he would “never be done with space.”

About the future of planet Earth, which Kelly said looked so fragile from afar, he was sanguine: “I do believe we have an impact [on the environment] and the ability to change it.”

As the man who has come down from the heavens now muses, “If we can dream it, we can make it so.”