Once upon a time he was walking in space.

Now he’s hosting TV for fun.

Science Channel’s got him for

A total eclipse of the sun.

With apologies to Bonnie Tyler, that does well describe former NASA astronaut and Long Island native Mike Massimino, who in two missions to the Hubble Space Telescope spent a remarkable 30 hours and 4 minutes out in the starry void during four spacewalks. The first person to tweet from space, he’s also been a recurring guest as himself on CBS’ “The Big Bang Theory.” So who better to bring outer-space media savvy to two Science channel projects: the special “Great American Eclipse,” Monday at 9 p.m., and the documentary series “The Planets,” premiering Tuesday at 10 p.m. Science Channel will offer complete eclipse coverage Monday from 11 a.m. to 4 p.m.

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“We’re all space voyagers, and we get this reminder when an eclipse happens that we’re part of a larger cosmic dance,” the Oceanside-born Massimino, who turned 55 on Saturday, says of the total solar eclipse, which occurs when the orbiting moon perfectly blocks the sun and casts a shadow on our planet. This will be the first total solar eclipse to cross the lower 48 states from ocean to ocean since 1918, though a total solar eclipse went across a smaller portion of the country in 1979.

That gives ground-based American scientists “a once-in-a-lifetime opportunity to study the sun from places where people actually live,” Massimino says. “When eclipses occur, oftentimes they’re over the ocean or over part of one of the continents where people aren’t normally living.”

Massimino grew up in Franklin Square, the youngest of three siblings. Their father, Mario, was a fire inspector for the FDNY, and their mother, Vincenza, now 90, was “more or less a stay-at-home mom, a homemaker,” he says. Massimino’s grandparents had all emigrated from Sicily, and his parents lived in the Bronx before moving to Franklin Square, where he graduated from H. Frank Carey Junior-Senior High School in 1980.

His father died in 1998, two years after the Columbia University- and M.I.T.-educated Massimino was chosen for astronaut training. “He knew that I was selected,” he says. “But he didn’t get a chance to be there when I was launched into space” on two shuttle missions — STS-109, on the Columbia, in 2002, and STS-125, the fifth and final Hubble servicing mission, on the Atlantis in 2009.

And, yes, “Getting a chance to put on a space suit and exit the spaceship and work out in the vacuum of space is a wonderful experience,” Massimino confirms. And more prosaically, in case you’ve ever wondered, astronauts don’t eat during a seven- or eight-hour spacewalk.

“You have a drink bag, 32 ounces of liquid, attached to the space suit,” Massimino says. “It’s right in front of you and you have a bite valve sticking up that you can get your mouth onto to get some hydration. As for food, they tried using food sticks and food bars and stuff like that in the space suit. But that didn’t work out so well — it just made a big mess. So you need to eat a good breakfast before you go out spacewalking — you’re hungry when you get done!”