PASADENA, California – It's 7:30 on a Monday morning, and a crowd has started to gather at the gates of NASA's Jet Propulsion Laboratory. In a few minutes, the doors will open, and we'll get a coveted glimpse into one of the hearts of the United States space program. The crowd is filled with educators and engineers, artists, programmers, parents, students from three countries and 22 U.S. states. We're linked by two common factors: We all use social media, and we're all really, really into space.

The NASA Socials are the brainchild of JPL News and Social Media Manager Veronica McGregor, who started the program in January of 2009 (in those days, they were called "tweetups"; NASA switched to "socials" in 2012). For a year, McGregor had seen NASA's burgeoning social media community connect space fans around the world. Now, she wanted to see if that engagement could translate to real life.

Four years and over 70 events later, nearly 5,000 space enthusiasts have attended 73 NASA meetups at 10 locations. Some give attendees a front-row seat to milestone events like launches and landings; others – like the one we're at now – are intensive introductions to current and upcoming missions. Cumulatively, their impact has been significant: Not only have they given NASA fans an up-close and personal glimpse of their space program, but they've created a legion of enthusiastic and informed ambassadors for science and space exploration, armed with new tools and connections.

"The NASA Social alumni community are family to me," says Shannon Moore. She's been attending NASA tweetups and socials since the STS-129 launch in November of 2009. These days, she's one of the group of volunteers who run and maintain the community wiki NASAtweet.com – the unofficial online hub for NASA socials and other space-related meetup events.

For some NASA Social alumni, attending the events has been a wake-up call – a catalyst to pursue education and careers in science and engineering. Others have gone on to organize SpaceUp, an independent "unconference" series, as well as reunions and informal astronomy and science-themed meetups across the globe.

For other attendees, NASA Socials aren't just a chance to meet like-minded peers, but an opportunity to touch something that's profoundly influenced their lives. Saramoira Shields, who blogs as Mathematigal, was inspired to return to school to study mathematics after watching the Curiosity landing: "I figured if the people at JPL could shoot a robot the size of a van at a moving target 350,000,000 miles away and manage to get it to land safely, I could at least finish my undergrad degree."

This time, McGregor and JPL are hoping to translate some of that passion around space exploration to a subject much closer to home. NASA is preparing to launch a slew of Earth-science missions in what they've named the "Year of Earth," and trying to make the urgent work of understanding our home planet as appealing as the exploration of space. This NASA Social event – officially titled "Earth Now," is one of the first steps to bridging that gap.

Earth Now NASA Social attendees. Photo: NASA-JPL/CalTech

Earth missions are a tricky topic for NASA, and a source of chronic frustration for McGregor. Over a billion viewers may have tuned in when Curiosity touched down on Mars, but even die-hard NASA buffs tend to tune out when it comes to their home planet – even though Earth missions make up about a third of NASA's work.

In fact, as McGregor reminded us in her opening remarks, space exploration has been critical to our understanding of our own planet. Images of the Earth from space radically changed the way we saw it, giving us our first glimpses of our world as a single, connected system, unbroken by national borders. It's no coincidence that McGregor opens her introduction to the Earth missions by showing us the 1968 photograph "Earthrise." The image, which shows the Earth cresting the horizon of the moon, is credited with launching Earth Day and, along with subsequent images of Earth from space, propelling the modern environmental movement.

As she speaks, we type on laptops, tablets and smartphones, tweeting furiously, taking and sharing notes and distilling complex science to 140-character bites as viewers follow along with NASA's livestream. By the end of the day, we'll have heard more than a dozen scientists and engineers, representing half as many Earth missions – and #NASASocial will be trending worldwide.

One of NASA's goals is not only to analyze and draw connections between a mind-boggling mass of raw data, but to render it in terms accessible to both the scientific community, policymakers – and citizens like us. One way they're doing that is through apps like Eyes on the Earth, which translates complex quantitative maps to fascinating visuals, letting users see Earth's gravity field shift as her oceans grow warmer. Due to the high heat capacity of water, the first and strongest impact of global warming has been felt in the oceans, where thermal expansion is responsible for almost as much sea-level rise as melting ice.

Seeing the data rendered in three dimensions drives home how critical NASA's contributions to climate science are to understanding and responding to climate change, and understanding and mitigating not only future escalation, but the impact of what by now is essentially inevitable. While Earth science may not hold the immediate romance of exploring – remotely or otherwise – where no human has gone before, it's a faceted, fascinating field, and one ever more critical to our survival as a species.

"NASA data is free. Anyone can download it," says Ernesto Rodriguez, a Project Scientist on RapidScat, a device which will monitor ocean winds from a mount on the International Space Station. It's a sentiment I remember from my first visit to JPL, and one we'll hear echoed again and again over the weekend: the idea that the work NASA does, and science in general, belongs to all of us. We're here as guests, but also as visiting stockholders surveying our investment – both as individuals who vote and pay taxes in the United States and as human beings with the desire and capacity to better understand the planet on which we live.

Curiosity Flight Director Bobak Ferdowsi shows us around JPL's Mars Yard. Photo: Rachel Edidin

After a tour through JPL's Mars Yard with Curiosity Flight Director Bobak Ferdowsi – aka NASA Mohawk Guy – as our tour guide, we finally make our way to Mission Control. This is the nerve center of NASA's exploration of the universe, and the core of the Deep Space Network. In the middle of Mission Control, embedded into the floor, is a plaque – half tongue-in-cheek – marking "the center of the universe," and it's not entirely wrong, at least from where humans stand.

Every point of data from every NASA spacecraft beyond low earth orbit, according to Space Flight Operations Facility Jim McClure, comes through this pipeline: rovers, orbiters, deep-space probes. The room can seat a hundred, but at the same time, it feels amazingly, precipitously small – our little blue dot's mainline to the infinite expanse of the universe, and a vital window back onto itself, and exactly the sort of perspective that the NASA Socials aim to promote.

Everyone I had talked to about the NASA Social community emphasized how tight-knit and proactive it was, but it's another thing to see it firsthand. There's a unity of purpose and generosity of resources; when I mentioned in the Facebook group that I would be writing this article, I was immediately inundated by offers for information and links, photos and facts. Soon, we were sharing data, educational resources and talking to SpaceUp about starting new local chapters.

The conversations that began at the Earth Now social are still rippling through my social media streams – less constant now, but still intact. One participant, who works in healthcare social-media analytics, has been crunching our numbers, creating beautiful and complex visualizations of the social and topical topography of our visit using thousands of tweets; another is using the data and missions we've learned about as a lens for understanding the destruction wrought by Super Typhoon Haiyan.

All of us – some for the first time, others with newfound focus – are now paying a new and different sort of attention to the sky above us, and the ground below.